中心静脉血氧饱和度监测技术资料

中心静脉血氧饱和度监测

技术资料

PCCI

飞利浦医疗保健

2011‐05‐25

目 录

1.参考文献

2.操作指南

附：CeVOX导管引导色标

CeVOX导管技术参数

CeVOX导管使用问答

Open Access

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Research

Multicentre study on peri- and postoperative central venous oxygen saturation in high-risk surgical patients

Collaborative Study Group on Perioperative ScvO2 Monitoring

Received: 5 Jul 2006Revisions requested: 27 Jul 2006Revisions received: 30 Aug 2006Accepted: 13 Nov 2006Published: 13 Nov 2006Critical Care 2006, 10:R158 (doi:10.1186/cc5094)

This article is online at: https://www.wendangku.net/doc/3f7074773.html,/content/10/6/R158

? 2006 Collaborative Study Group on Perioperative ScvO2 Monitoring; licensee BioMed Central Ltd.

This is an open access article distributed under the terms of the Creative Commons Attribution License (https://www.wendangku.net/doc/3f7074773.html,/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.For a complete list of authors and their affiliations, see Appendix. Corresponding author: Stephen M Jakob

Abstract

Introduction Low central venous oxygen saturation (ScvO 2) has been associated with increased risk of postoperative complications in high-risk surgery. Whether this association is centre-specific or more generalisable is not known. The aim of this study was to assess the association between peri- and postoperative ScvO 2 and outcome in high-risk surgical patients in a multicentre setting.

Methods Three large European university hospitals (two in Finland, one in Switzerland) participated. In 60 patients with intra-abdominal surgery lasting more than 90 minutes, the presence of at least two of Shoemaker's criteria, and ASA (American Society of Anesthesiologists) class greater than 2,ScvO 2 was determined preoperatively and at two hour intervals during the operation until 12 hours postoperatively. Hospital length of stay (LOS) mortality, and predefined postoperative complications were recorded.

Results The age of the patients was 72 ± 10 years (mean ±standard deviation), and simplified acute physiology score

(SAPS II) was 32 ± 12. Hospital LOS was 10.5 (8 to 14) days,and 28-day hospital mortality was 10.0%. Preoperative ScvO 2decreased from 77% ± 10% to 70% ± 11% (p < 0.001)immediately after surgery and remained unchanged 12 hours later. A total of 67 postoperative complications were recorded in 32 patients. After multivariate analysis, mean ScvO 2 value (odds ratio [OR] 1.23 [95% confidence interval (CI) 1.01 to 1.50], p = 0.037), hospital LOS (OR 0.75 [95% CI 0.59 to 0.94], p = 0.012), and SAPS II (OR 0.90 [95% CI 0.82 to 0.99],p = 0.029) were independently associated with postoperative complications. The optimal value of mean ScvO 2 to discriminate between patients who did or did not develop complications was 73% (sensitivity 72%, specificity 61%).

Conclusion Low ScvO 2 perioperatively is related to increased risk of postoperative complications in high-risk surgery. This warrants trials with goal-directed therapy using ScvO 2 as a target in high-risk surgery patients.

Introduction

Several randomised controlled clinical studies have shown improved morbidity and mortality in high-risk surgical patients with perioperative optimisation of haemodynamics using strict treatment protocols in the single-centre setting [1-3]. The haemodynamic endpoints in goal-directed studies have been based on values derived from the pulmonary artery catheter [1-4], oesophageal Doppler [5-10], or (very recently) lithium indi-cator dilution and pulse power analysis [11]. Central venous oxygen saturation (ScvO 2) and mixed venous oxygen satura-tion (SvO 2) have been proposed to be indicators of the oxygen supply/demand relationship. However, the relationship between SvO 2 and ScvO 2 remains controversial [12]. Venous

oxygen saturations differ among organ systems because dif-ferent organs extract different amounts of oxygen. It is there-fore conceivable that venous oxygen saturation depends on the site of measurement [13]. Redistribution of blood flow and alterations in regional oxygen demand (for example, in shock,severe head injury, general anaesthesia, as well as microcircu-latory disorders) may affect the difference between ScvO 2 and SvO 2. Although ScvO 2 principally reflects the relationship of oxygen supply and demand, mainly from the brain and the upper part of the body [13], it correlates reasonably well with concomitantly measured SvO 2 [12,13], which is more dependent on changes in oxygen extraction in the gastrointes-tinal tract.

HDC = high-dependency care; ICU = intensive care unit; LOS = length of stay; OR = odds ratio; ROC = receiver operator characteristic; SAPS II = simplified acute physiology score; ScvO 2 = central venous oxygen saturation; SvO 2 = mixed venous oxygen saturation.

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In patients with severe sepsis and septic shock, early ScvO 2-driven haemodynamic treatment was found to reduce mortality [14]. More recently, low postoperative ScvO 2 values were associated with an increased risk of complications in high-risk surgical patients [11]. Despite increasing evidence of benefi-cial effects on outcome, goal-directed therapies are not widely used in clinical practice. The reasons are a lack of demon-strated effect in large multicentre studies, the need for postop-erative intensive care resources, the necessity of instituting complex protocols, as well as the need for monitoring tech-niques that are not routinely used in these specific patient groups. Using the ScvO 2 as a potential target variable for haemodynamic optimisation is attractive because central venous catheterisation is routinely used in high-risk patients undergoing major surgery, ScvO 2 can be screened, pre-emp-tive treatment is possible, and no major changes are neces-sary for the infrastructure in the operation area.

The present investigation was a pilot study designed to assess the incidence of low perioperative ScvO 2 in high-risk surgical patients and the association of low ScvO 2 with outcome in a multicentre setting. The aim was to evaluate whether the asso-ciation of ScvO 2 and postoperative complications in a strictly protocolised, interventional single-centre study on goal-directed haemodynamic management in high-risk surgical patients [11] could be confirmed in a purely observational,multicentre setting. Specifically, this pilot study was designed to clarify (a) the recruitment rate of patients scheduled for major surgery in a multicentre setting, (b) the range of periop-erative ScvO 2 in such patients, (c) the number of postopera-tive complications, and (d) the potential association between ScvO 2 and complications. With these data, it should be possi-ble to define whether a trial with goal-directed therapy using ScvO 2 as a target is reasonable to conduct.

Materials and methods

Two university hospitals in Finland and one in Switzerland par-ticipated in the study. The study was approved by the appro-priate ethics committee for each institution, and written informed consent was obtained from each patient. Patients were screened for inclusion and exclusion criteria between September 20 and December 20, 2004.

Inclusion criteria

For a patient to be included in the study, both of the following criteria had to be fulfilled: (a) increased surgical risk based on intra-abdominal or retroperitoneal surgery with an expected duration of at least 90 minutes or on abdominal aortic surgery and (b) two or more of Shoemaker's criteria of high risk [2].These criteria include patient history (more than 70 years old with limited major physiological function, previous severe car-diopulmonary or vascular illness, and severe nutritional disor-ders), current clinical condition (severe multiple trauma,massive acute blood loss, shock, septicaemia or septic shock,respiratory failure, acute abdominal catastrophe, and acute

intestinal or renal failure), the surgical procedure (extensive surgery for cancer or prolonged surgery more than eight hours), ASA (American Society of Anesthesiologists) class of greater than two, and a perioperative need for a central venous catheter.

Exclusion criteria

Exclusion criteria for the study were a contraindication for a central venous catheter, unstable angina pectoris, primary hepatic or hepato-biliary surgery, the refusal of blood prod-ucts, and the inability to give informed consent or refusal to consent.

Study protocol

Anaesthesia, operation, and postoperative treatment were performed according to the local standards. All patients were postoperatively admitted either to an intensive care unit (ICU)or another high-dependency care (HD C) area (intermediate care unit or postanaesthesia care unit). Blood samples for the measurement of ScvO 2 and haemoglobin were taken after induction of anaesthesia and thereafter at two hour intervals up to 12 hours postoperatively. Blood gas analyses were per-formed by intermittent blood sampling and co-oximetry (ABL 725; Radiometer, Copenhagen, Denmark [centres 1 and 2];GEM Premier 3000; Instrumentation Laboratory, Barcelona,Spain [centre 3]).

Complications

Complications and deaths occurring within 28 days of enrol-ment were included in the data analysis. Complications were prospectively defined and were diagnosed by clinical staff.Length of stay in the study hospital was censored at 28 days,and the patient's location at 28 days was recorded.

Statistics

Data are presented as mean ± standard deviation when nor-mally distributed, as medians (interquartile range) when not normally distributed, or (for categorical variables) as a percent-age of the group from which they were derived. Normality was tested with the Kolmogorov-Smirnov test. Categorical data were tested with Fisher's exact test. Continuous data were tested with the t test when normally distributed and with the Mann-Whitney U test when not normally distributed. Trends in physiological parameters over time were compared with repeated-measures analysis of variance.

Univariate analysis was performed to test associations with complications and death. For data recorded hourly during the study period, the baseline values, the lowest values, and the mean over the 12-hour study period were tested. A multiple logistic regression model was used to identify independent risk factors for postoperative complications. A stepwise approach was used to enter new terms into the logistic regres-sion model, where p < 0.05 was set as the limit for inclusion of new terms. Results of logistic regression are reported as

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adjusted odds ratios (ORs) with 95% confidence intervals (CIs). Receiver operator characteristic (ROC) curves were constructed to identify optimal cutoff values for association with outcome. The optimum cutoff was defined as the value associated with the highest sum of sensitivity and specificity.Analysis was performed with SPSS version 12.01 (SPSS Inc.,Chicago, IL, USA) and Sigma Plot version 10.01 (Systat Soft-ware, Inc., Richmond, CA, USA) software, and significance was set at p < 0.05.

Results

Of 218 screened patients, 60 patients fulfilled requirements for both inclusion and exclusion criteria and gave written informed consent (21 females, 39 males). Their mean age was 72 ± 10 years, and simplified acute physiology score (SAPS II) was 32 ± 12. In two centres, all patients were elective sur-gical cases, whereas in the third centre, 12 out of 21 patients were emergencies. Demographics and outcome data as well as indications for laparatomy stratified for the three centres are indicated in Table 1. Mean SAPS II scores in the three centres were 30, 26, and 40, respectively, and the associated mortal-ity rates were 0%, 6%, and 24%, respectively.

As compared with preoperative values, ScvO 2 was lower immediately after surgery. Haemoglobin decreased (preopera-tive 110 ± 19 g/l versus 102 ± 17 g/l immediately after sur-gery, p = 0.003).

Overall length of stay in the ICU/HDC was 1.0 (0 to 1) days,and hospital LOS was 10.5 (8 to 14) days (observation period 28 days). Six patients died (28-day mortality 10%); three of them were emergency cases (28-day mortality in emergency cases 25%).

Sixty-seven postoperative complications were recorded in 32patients (20 cardiorespiratory, 23 surgical, 19 infectious, and 5 other; between 1.0 and 1.3 per patient per centre). Univari-ate analysis identified nine variables associated with postoper-ative complications (Table 2). Six of them were ScvO 2variables (Figure 1a,b). Additionally, haemoglobin (111 ± 18versus 105 ± 23 g/l, p = 0.018), SAPS II (27 ± 11 versus 45± 26, p = 0.003), and hospital LOS (10 [8 to 12] versus 14[10 to 17] days, p = 0.001) were associated with postopera-tive complications.

After multivariate analysis, mean ScvO 2 value (OR 1.23 [95%CI 1.01 to 1.50], p = 0.037), hospital LOS (OR 0.75 [95% CI 0.59 to 0.94], p = 0.012), and SAPS II (OR 0.90 [95% CI 0.82 to 0.99], p = 0.029) were independently associated with postoperative complications. ROC curves for these variables are displayed in Figure 2. The areas under the ScvO 2 and SAPS II, but not LOS, ROC curves were significantly different from 0.5 (p = 0.004 and 0.002, respectively). The optimal value of mean ScvO 2 for discriminating between patients who did or did not develop complications was 73% (sensitivity

Table 1

Demographics and outcome data stratified for the three centres

All centres (n = 60)

Centre 1 (n = 17)

Centre 2 (n = 22)

Centre 3 (n = 21)

Age in years 72 ± 1068 ± 1172 ± 974 ± 10Male/female 40/2013/418/416/5SAPS II a

32 ± 1226 ± 1030 ± 440 ± 14Emergency surgery (percentage)

200057Aortic/iliacal aneurysm/dissection (percentage)47825014Carcinoma upper abdomen (percentage)121255Carcinoma lower abdomen (percentage)2464138Infection (percentage)70419Other (percentage)

100024Duration of operation (minutes)218 ± 111323 ± 92178 ± 81177 ± 99Hospital LOS (days)

11 (8 to 14)

13 (11 to 15)

8 (4 to 10)

11 (9 to 14)

Patients at home on day 28 (percentage)

65239038Patients in hospital/nursing facility on day 28 (percentage)2265538Unknown patient location on day 28 (percentage)3650Mortality (percentage)

10

6

24

a One-way analysis of variance (p < 0.01). LOS, length of stay; SAPS II, simplified acute physiology score.

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72%, specificity 61%). The relation between ScvO 2 and hos-pital LOS in survivors and non-survivors is displayed in Figure 3.

Discussion

The main finding of this study was that in the multicentre set-ting, low ScvO 2 during the peri- and postoperative period was associated with an increased risk of postoperative complica-tions in high-risk patients undergoing major surgery. Our results support the feasibility of testing ScvO 2 as a target var-iable to improve outcome in high-risk surgery. The criteria to define patients at high risk were pragmatic and clinically ori-ented and resulted in a sufficient recruitment rate. Further-more, despite the relative heterogeneity of the patient population, ScvO 2 had a reasonable predictive value for post-operative complications.

Pearse et al . [11] found that low minimum ScvO 2 values during the first eight postoperative hours were associated with increased risk of postoperative complications. Their findings

Table 2

Variables associated with postoperative complications

Patients with complications (n = 32)

Patients without complications (n = 28)P value a

ScvO 2 (percentage)Preoperative 74 ± 1080 ± 90.031

Intraoperative

After 1 hour of surgery 74 ± 1080 ± 90.046After 2 hours of surgery 73 ± 1280 ± 110.022After 3 hours of surgery 71 ± 1181 ± 80.001Lowest 60 ± 764 ± 70.036Mean

70 ± 574 ± 60.005Haemoglobin at ICU admission (g/l)95 ± 17105 ± 130.018SAPS II

41 ± 1427 ± 110.003Hospital LOS (days)13 ± 7

10 ± 4

0.001

a Univariate analysis of variance. ICU, intensive care unit; LOS, length of stay; SAPS II, simplified acute physiology score; ScvO

2, central venous

oxygen saturation.

Figure 1

Intraoperative (a) and postoperative (b) ScvO 2 variables in patients who did and did not develop postoperative complications. P values correspond to univariate analysis of variance. ICU, intensive care unit; IMC, intermediate care unit; intraop, intraoperative; preop, preoperative; postop, postoper-ative; ScvO 2

, central venous oxygen saturation.

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Figure 2

Receiver operator characteristic (ROC) analysis for (a) mean ScvO 2, (b) SAPS II score, and (c) hospital length of stay (LOS). Outcome parameter for ROC analysis is occurrence of postoperative complications. Area under the curve (AUC) was 0.74 for mean ScvO 2 (p = 0.004), 0.78 for SAPS II score (p = 0.002), and 0.61 for LOS (p = 0.15). SAPS II, simplified acute physiology score; ScvO 2, central venous oxygen saturation.Figure 3

Central venous oxygen saturation (ScvO 2) (percentage) in survivors and non-survivors and in patients with high and low mean ScvO 2 values. The numbers above the error bars indicate the corresponding LOS data for the different sub-groups. *Wilcoxon signed rank test versus preoperative (p < 0.05). #Mann-Whitney test versus ScvO 2 >73% (p

= 0.001). ICU/IMC, intensive care unit/intermediate care unit; LOS, length of stay in hospital.

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come from a strictly protocolised, interventional single-centre study on goal-directed haemodynamic management in high-risk surgical patients. Our results further confirm the associa-tion between ScvO 2 and postoperative complications in a purely observational, multicentre setting. Furthermore, intraop-eratively, we were able to demonstrate a significant difference in ScvO 2 between patients who did and did not develop com-plications. Taken together, the present study and that of Pearse et al . suggest that the overall peri- and postoperative course of ScvO 2 should be taken into account if ScvO 2-tar-geted interventions are considered for testing in large-scale clinical trials.

Despite the relative similarity of the participating centres and the presence of comparable infrastructures for postoperative care, the hospital LOS varied widely between the centres. The reason for this is certainly multifactorial and likely to include,among other things, care processes within the individual cen-tres, discharge policies, and variations in local health care organisation. These variations were likely to dilute any associ-ation between ScvO 2 and length of stay in the relatively small sample size. Hence, we used clinically relevant predefined complications as the main outcome measure. The hospital mortality in the present study was comparable with the recent study of Pearse et al . [11] and clearly lower than what would be expected from several previous studies on high-risk sur-gery. Due to the small sample size and different proportions of emergency patients, relevant between-centre comparisons cannot be made.

The prognostic significance of ScvO 2 less than 65% has been demonstrated in myocardial infarction [15], trauma [16],severe sepsis [17], and cardiac failure [18]. However, the only interventional trial of ScvO 2 conducted so far used a target of 70% [14]. In the study of Pearse et al . [11], a level of 65%seemed to discriminate best between patients with and without complications. This may be related to the lower tissue oxygen delivery in surgical patients as compared with patients with sepsis. D espite complex physiology, the association between ScvO 2 and outcome after major surgery seems to be similar to the association between cardiac index and outcome or between oxygen delivery and outcome [19-22].

The best cutoff for ScvO 2 in predicting complications in our study was 73%. This corresponds well with the mean ScvO 2of 75% found by Pearse et al . [11] in patients who did not develop complications. The observed cutoff value of ScvO 2should be interpreted with some caution due to the sample size. Nevertheless, the somewhat higher best cutoff of ScvO 2for predicting complications in our study could be related to the fact that our study was observational, whereas Pearse et al . used protocolised treatment. When using protocols, the fluctuation in ScvO 2 is likely to be reduced. This may also explain why in our study the mean ScvO 2, rather than the min-imum ScvO 2, had predictive value.

In our study, the perioperative mean of ScvO 2 was 74% in patients who did not develop postoperative complications.This is comparable with previous measurements in healthy subjects [23] and in patients after surgery [11,22] but is higher than in patients with favourable outcome after severe sepsis, trauma, cardiac failure, or myocardial infarction [15-18]. Accordingly, targets for ScvO 2 in future prospective trials should probably be adapted to the specific study groups.We believe that our results encourage trials with goal-directed therapy using ScvO 2 as a target in high-risk surgery patients.Based on our data and in agreement with results from others [11], target values should be in the range of 70% to 75%, and values less than 65% should be strictly avoided. In patients with cardiac failure or trauma, lower targets (at approximately 65%) may be appropriate [15,16].

Obviously, in a multicentre approach, the inclusion of 60patients with an observed 28-day mortality of 10% is enough to be able to demonstrate a benefit in terms of complication rate but not in terms of length of stay and mortality. To demon-strate a relative reduction in 28-day mortality of 34% (as in the study of Rivers et al . [14], with a beta error of 80% and an alpha error of 5%, the sample size in a patient group similar to that in this study would be 85 for both groups. Although the risk factors for postoperative complications agree well with previous studies, the small sample size for the multivariate analysis should be considered in interpreting our results.Because oxygen demands are normally well controlled during general anaesthesia, efforts to increase ScvO 2 should target oxygen delivery (arterial oxygen saturation, haemoglobin, and cardiac output). In fact, in this trial, preoperative haemoglobin concentrations were significantly lower in patients with com-plications as compared with patients without. To avoid sudden drops in ScvO 2 as a consequence of the combination of hypo-volaemia and anaemia during surgical bleeding, it may be pru-dent to correct low (<10 g/dl) preoperative haemoglobin concentrations.

A drop in ScvO 2 was noted between the end of surgery and the first readings in the ICU. This finding is consistent with pre-vious findings on ScvO 2 [11] and SvO 2 [19,21] in surgical patients. Both decreased systemic oxygen delivery and increased oxygen consumption may have contributed. Pearse et al . [11] reported unchanged cardiac output in the postoper-ative period. If this was the same in our patients, oxygen deliv-ery still could have decreased due to the significantly lower postoperative haemoglobin concentrations. Postoperative oxygen consumption is determined by various factors, includ-ing pain, emergence from anaesthesia, body temperature, and shivering. To avoid low postoperative ScvO 2, all of these fac-tors may have to be controlled.

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Conclusion

In our study, low ScvO 2 was frequently observed in patients during and after major surgery and was related to postopera-tive complications. In prospective trials using ScvO 2 as a goal,the specific patient group has to be taken into account when target levels are https://www.wendangku.net/doc/3f7074773.html,peting interests

The authors declare that they have no competing interests. No author received individual funding in connection with this study.

Authors' contributions

HB performed programming of databases for all centres, data acquisition, data analysis, calculation of statistics and manu-script revision. VE, DI, SL, IP, CR, and AV provided data acqui-sition and manuscript revision. MH carried out data acquisition and interpretation and manuscript revision. SMJ participated in the study design and coordination, performed the measure-ments, and wrote a first draft of the manuscript. HL and SN recruited patients, performed data acquisition, data analysis and interpretation, and manuscript revision. KM and PM carried out patient recruitment, data acquisition, and manu-script revision. MN and ER performed data interpretation and manuscript revision. JT provided study conception and design,data interpretation, and manuscript revision. All authors were given the opportunity to read and approve the final manuscript.

Appendix

The Collaborative Study Group on Perioperative ScvO 2 Moni-toring is composed of authors from three centres:Bern:

Hendrik Bracht 1, Verena Eigenmann 2, Matthias Haenggi 1,Daniel Inderbitzin 3, Stephan M Jakob 1 (co-principal investiga-tor), Stefanie Loher 1, Christine Raeber 1, Jukka Takala 1 (coordi-nating investigator), Andreas Vogt 7Kuopio:

Kimmo M?kinen 5, Pekka Miettinen 5, Minna Niskanen 6, Ilkka Parviainen 6 (co-principal investigator)Tampere:

Heli Leppikangas 4, Silvia Nunes 4, Esko Ruokonen 4 (co-princi-pal investigator)

1Department of Intensive Care Medicine, University Hospital

Bern, CH-3010 Bern, Switzerland

2D epartment of Cardiovascular Surgery, University Hospital

Bern, CH-3010 Bern, Switzerland

3Department of Visceral and Transplantation Surgery, Univer-

sity Hospital Bern, CH-3010 Bern, Switzerland

4Department of Intensive Care, Tampere University Hospital,

P.O. Box 2000, 33521 Tampere, Finland

5Department of Surgery, Kuopio University Hospital, P.O. Box

1777, 70211 Kuopio, Finland

6Department of Anesthesia and Intensive Care Medicine, Kuo-

pio University Hospital, P.O. Box 1777, 70211 Kuopio,Finland

7Department of Anesthesiology, University Hospital Bern, CH-

3010 Bern, Switzerland

Acknowledgements

This study was supported by a grant from Edwards Lifesciences.

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Abstract

Measurements of central venous oxygen saturation (ScvO2) have been successfully used to guide haemodynamic therapy in critical care. The efficacy of this approach in the treatment of severe sepsis and septic shock has stimulated interest in the use of ScvO2to guide management in patients undergoing major surgery. The physiological basis of ScvO2measurement is complex. A number of outstanding issues will need to be resolved before incorporating ScvO2measurement into routine practice. First, it is not yet clear which value of ScvO2should be targeted. Second, there is some uncertainty as to which interventions are the most effective for achieving the desired value of ScvO2or how long this value should be maintained. The study by The Collaborative Study Group on Perioperative ScvO2Monitoring published in this edition of Cr i t i cal Care may help provide answers to some of these questions. Our understanding of ScvO2measurement remains limited, however, and the routine use of peri-operative ScvO2-guided goal-directed therapy cannot be recommended until a large randomised trial has confirmed the value of this approach.

The use of central venous saturation (ScvO2) to guide haemo-dynamic management is an important and evolving aspect of clinical practice. An observational study [1] published in this issue of Critical Care has advanced our understanding of this form of monitoring by exploring the association between derangements in ScvO2and complication rates after major abdominal surgery. This study provides a detailed description of peri-operative trends in ScvO2and confirms the findings of previous work which suggests that reductions in ScvO2are associated with increased post-operative complication rates [2]. Although the study is relatively small, the robust multi-centre approach and consistency with previous work support the applicability of the findings.

The comparative simplicity of ScvO2measurement makes this an attractive technique. With the blood gas analysis technology available in most institutions, intermittent ScvO2monitoring can be performed in any patient with a central venous catheter. However, it is not yet clear whether ScvO2 measurement through intermittent blood sampling is an adequate alternative to continuous monitoring with a fibre-optic catheter. Interest in ScvO2measurement is not new, and several reports have explored the physiology and clinical significance of this parameter over the past 50 years [3]. Of these, the work of Rivers and colleagues [4] has proved the most influential. These authors used a ScvO2value of 70% as a target for goal-directed haemodynamic therapy (GDT) in patients presenting to hospital with severe sepsis and septic shock. They demonstrated that it may be possible to achieve substantial mortality reductions without the need for complex or invasive cardiac output monitoring technology. The success of Rivers’ work and several trials of peri-operative GDT indicates that the use of ScvO2as a haemodynamic goal may be equally valuable in surgical patients [5-8].

H owever, several questions must be considered before embarking on an interventional trial of ScvO2-guided peri-operative GDT. First, what treatments should be used to achieve the target value for ScvO2? Second, which target value is most appropriate? Finally, how long should the target value be maintained? The study by the Collaborative Study Group (CSG) is important because it sets out to address some of these key questions. The value of ScvO2in any given patient reflects not only oxygen delivery but also oxygen consumption. Reductions in ScvO2may therefore reflect a large number of acute changes in physiology including hypoxia, shivering, anaesthesia, haemorrhage and myocardial ischaemia [3]. The therapeutic approach to achieving the target value may need to include more than simply intravenous fluids and inotropic therapy. If a period of post-operative sedation and invasive ventilation is required to control oxygen consumption, would such an intervention be

Commentary

Should we use central venous saturation to guide management in high-risk surgical patients?

Rupert M Pearse and Charles J Hinds

Barts and The London School of Medicine and Dentistry, Queen Mary’s University of London, 5th floor, 38 Little Britain, St. Bartholomew’s Hospital, London EC1A 7BE, UK

Corresponding author: Rupert Pearse, rupert.pearse@https://www.wendangku.net/doc/3f7074773.html,

Published: 15 December 2006Critical Care2006, 10:181 (doi:10.1186/cc5122)

This article is online at https://www.wendangku.net/doc/3f7074773.html,/content/10/6/181

? 2006 BioMed Central Ltd

See related research by The Collaborative Study Group on Perioperative ScvO2

Monitoring, https://www.wendangku.net/doc/3f7074773.html,/content/10/6/R158

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Critical Care Vol 10 No 6Pearse and Hinds

valid? Although the normal value of ScvO2is often quoted as 70%, there are in fact few published data to confirm this, either in healthy volunteers or in surgical patients [3]. Previous observational work shows that considerable variations in ScvO2may occur depending on the nature and severity of the acute physiological disturbance. It would be naive simply to accept this ‘normal’ value as being optimal in every clinical situation.

The CSG researchers explored the relationship between ScvO2and post-operative complication rates. Their findings suggest that a higher target value of 75% would be more appropriate in patients undergoing major abdominal surgery. This finding is consistent with the analysis of ScvO2data from a recent interventional trial of post-operative GDT [2].

H owever, both these studies have shown that large decreases in ScvO2occur immediately after surgery. It is unclear whether such changes, which are more marked in those patients who develop complications, relate pre-dominantly to an increase in oxygen consumption, a decrease in oxygen delivery or, more probably, a failure to increase delivery to match increased consumption. What is more, these observations raise the possibility that the most appropriate goal for ScvO2may vary during and after surgery. The question of how long GDT should be continued remains unanswered. Several recent successful GDT trials have opted for short periods of early treatment lasting between 4 and 8hours [4,6,7]. H owever, GDT has also been effective when administered for periods of up to 24hours [5,8].

As with any monitoring technology, ScvO2is a double-edged sword. Anecdotal evidence suggests that clinicians have a limited understanding of the pitfalls associated with ScvO2 measurement, which may lead to a number of problems in practice. For example, the aggressive targeting of too high a value for ScvO2may be harmful, particularly in the elderly. The authors make an important point in suggesting that the targeted value for ScvO2should be modified for different patient groups. In particular, the presence of cytopathic hypoxia in septic patients may result in a high value of ScvO2 despite low oxygen delivery. Another consideration is that of sampling site. Venous oxygen saturation differs between the superior vena cava and the right atrium, and the value of ScvO2may therefore vary according to the position of the catheter tip [3]. Despite the promising findings of this most recent work, the routine peri-operative use of ScvO2-guided GDT cannot be recommended until a large randomised trial has confirmed the value of this approach.

Competing interests

The authors declare that they have no competing interests. References

1.The Collaborative Study Group on Perioperative ScvO2Monitoring:

Multicentre study on peri- and postoperative central venous oxygen saturation in high-risk surgical patients.Cr i t Care 2006, 10:R158.2.Pearse RM, Dawson D, Fawcett J, Rhodes A, Grounds RM,

Bennett ED: Changes in central venous saturation after major surgery, and association with outcome.Cr t Care2005, 9: R694-R699.

3.Pearse RM, Rhodes A: Mixed and central venous oxygen satu-

ration.In Yearbook of Intensive Care and Emergency Medicine.

Edited by Vincent JL. Berlin: Springer; 2005:592-602.

4.Rivers E, Nguyen B, Havstad S, Ressler J, Muzzin A, Knoblich B,

Peterson E, Tomlanovich M: Early goal-directed therapy in the treatment of severe sepsis and septic shock.N Engl J Med 2001, 345:1368-1377.

5.Boyd O, Grounds RM, Bennett ED: A randomized clinical trial of

the effect of deliberate perioperative increase of oxygen delivery on mortality in high-risk surgical patients.JAMA 1993, 270:2699-2707.

6.McKendry M, McGloin H, Saberi D, Caudwell L, Brady AR, Singer

M: Randomised controlled trial assessing the impact of a nurse delivered, flow monitored protocol for optimisation of circulatory status after cardiac surgery.BMJ2004, 329:258. 7.Pearse RM, Dawson D, Fawcett J, Rhodes A, Grounds RM,

Bennett ED: Early goal-directed therapy after major surgery reduces complications and duration of hospital stay. A ran-domised, controlled trial.Crit Care2005, 9:R687-R693.

8.Polonen P, Ruokonen E, Hippelainen M, Poyhonen M, Takala J: A

prospective, randomized study of goal-oriented hemody-namic therapy in cardiac surgical patients.Anesth Analg2000, 90:1052-1059.

9.Gattinoni L, Brazzi L, Pelosi P, Latini R, Tognoni G, Pesenti A,

Antonio, Fumagalli, Roberto, The SvO2Collaborative Group: A trial of goal-oriented hemodynamic therapy in critically ill patients.N Engl J Med1995, 333:1025-1032.

10.Hayes MA, Timmins AC, Yau EH, Palazzo M, Hinds CJ, Watson D:

Elevation of systemic oxygen delivery in the treatment of criti-cally ill patients.N Engl J Med1994, 330:1717-1722.

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Research

Impact of emergency intubation on central venous oxygen saturation in critically ill patients: a multicenter observational study

Glenn Hernandez 1, Hector Pe?a 2, Rodrigo Cornejo 3, Maximiliano Rovegno 1, Jaime Retamal 1, Jose Luis Navarro 3, Ignacio Aranguiz 1, Ricardo Castro 1 and Alejandro Bruhn 1

1Pontificia Universidad Católica de Chile, Departamento de Medicina Intensiva, Marcoleta 367, Santiago, Chile

2Instituto Nacional de Cardiología Ignacio Chávez, UTI de Cardio-Neumología, Juan Badiano No. 1 C.P. 14080, Ciudad de México, México 3Hospital Clínico Universidad de Chile, Unidad de Pacientes Críticos, Santos Dumont 999, Santiago, Chile

Corresponding author: Glenn Hernandez,glennguru@https://www.wendangku.net/doc/3f7074773.html,

Received: 29 Dec 2008Revisions requested: 9 Feb 2009Revisions received: 17 Apr 2009Accepted: 4 May 2009Published: 4 May 2009Critical Care 2009, 13:R63 (doi:10.1186/cc7802)

This article is online at: https://www.wendangku.net/doc/3f7074773.html,/content/13/3/R63? 2009 Hernandez et al .; licensee BioMed Central Ltd.

This is an open access article distributed under the terms of the Creative Commons Attribution License (https://www.wendangku.net/doc/3f7074773.html,/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction Central venous oxygen saturation (ScvO 2) has emerged as an important resuscitation goal for critically ill patients. Nevertheless, growing concerns about its limitations as a perfusion parameter have been expressed recently,including the uncommon finding of low ScvO 2 values in patients in the intensive care unit (ICU). Emergency intubation may induce strong and eventually divergent effects on the physiologic determinants of oxygen transport (DO 2) and oxygen consumption (VO 2) and, thus, on ScvO 2. Therefore, we conducted a study to determine the impact of emergency intubation on ScvO 2.

Methods In this prospective multicenter observational study, we included 103 septic and non-septic patients with a central venous catheter in place and in whom emergency intubation was required. A common intubation protocol was used and we evaluated several parameters including ScvO 2 before and 15

minutes after emergency intubation. Statistical analysis included chi-square test and t test.

Results ScvO 2 increased from 61.8 ± 12.6% to 68.9 ± 12.2%,with no difference between septic and non-septic patients.ScvO 2 increased in 84 patients (81.6%) without correlation to changes in arterial oxygen saturation (SaO 2). Seventy eight (75.7%) patients were intubated with ScvO 2 less than 70% and 21 (26.9%) normalized the parameter after the intervention.Only patients with pre-intubation ScvO 2 more than 70% failed to increase the parameter after intubation.

Conclusions ScvO 2 increases significantly in response to emergency intubation in the majority of septic and non-septic patients. When interpreting ScvO 2 during early resuscitation, it is crucial to consider whether the patient has been recently intubated or is spontaneously breathing.

Introduction

Central venous oxygen saturation (ScvO 2), a complex physio-logic parameter, is being widely used as a resuscitation goal in critically ill patients [1-3], although several limitations may pre-clude a clear interpretation of its changes [4]. Early therapeu-tic interventions applied rather simultaneously after hospital or intensive care unit (ICU) admission, may affect the oxygen transport (D O 2)/oxygen consumption (VO 2) balance and ScvO 2 in an unpredictable direction. The uncommon finding of

low ScvO 2 values in critically ill ICU patients may be explained by the predominately positive impact of these early interven-tions [5,6].

More than 70% of critically ill patients undergo emergency intubation during ICU stay [6-8], a maneuver with strong and eventually divergent effects on the physiologic determinants of DO 2 and VO 2. The final impact of emergency intubation on ScvO 2 may be unpredictable since it could potentially increase

ALI: acute lung injury; APACHE: Acute Physiology and Chronic Health Evaluation; ARDS: acute respiratory distress syndrome; DO 2: oxygen trans-port; EGDT: early goal directed therapy; FiO 2: fraction of inspired oxygen; HR: heart rate; ICU: intensive care unit; MAP: mean arterial pressure; O 2ER: oxygen extraction ratio; PEEP: positive end expiratory pressure; RR: respiratory rate; SaO 2: arterial oxygen saturation; ScvO 2: central venous oxygen saturation; SOFA: Sequential Organ Failure Assessment; VO 2: oxygen consumption.

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ScvO 2 by blunting regional VO 2, or eventually decrease it, par-ticularly in hemodynamically unstable or hypovolemic patients,due to the negative effects of sedation and positive intra-tho-racic pressure on cardiac output. Of note, 53% of septic patients were intubated during the study period in the early-goal directed therapy (EGDT) trial [1], but the impact of this intervention on ScvO 2 was not reported, nor has it been stud-ied thereafter.

Our aim was to study the specific impact of this isolated maneuver on ScvO 2 in critically ill septic and non-septic patients subjected to emergency intubation.

Materials and methods

This prospective observational multicenter study was per-formed in three university-affiliated hospitals between Decem-ber 2006 and March 2008. The study was approved by the corresponding institutional review boards. Surrogates signed an informed consent for ICU treatment including the intubation procedure.

Inclusion and exclusion criteria

Adult patients with arterial and central venous catheters in place with a confirmed tip position in the superior vena cava,and in whom emergency intubation was required, were enrolled. Patients with acute neurological conditions and post-cardiac arrest were excluded.

Study protocol

The intubation protocol started as soon as the intubation was decided. It included pre-oxygenation with 100% oxygen, eto-midate (0.1 to 0.3 mg/kg) or propofol (0.5 to 2 mg/kg) for unconsciousness induction. Fentanyl (1 to 5 μg/kg), mida-zolam (0.01 to 0.1 mg/kg), and rocuronium (0.6 to 1.2 mg/kg)were used for sedation and neuromuscular paralysis. Mechan-ical ventilation was started in all patients with the following ini-tial settings: fraction of inspired oxygen (FiO 2) 100%,respiratory rate (RR) 15 breaths/minute, tidal volume of 8 ml/kg and positive end expiratory pressure (PEEP) 5 cmH 2O. If hypotension developed during intubation, a bolus of 250 ml of saline solution was infused and vasopressors were adminis-tered as required.

The study period was 15 minutes. Arterial and central venous samples were drawn for blood gases analysis immediately before and 15 minutes after intubation. Simultaneously, the fol-lowing clinical variables were recorded: arterial pressure, heart rate (HR), and RR. After the second blood gas samples, venti-lator parameters were adjusted according to the particular patients requirements and current recommendations [2].Blood samples were placed in ice cold water and transferred to the central laboratory to be analyzed by co-oximetry (ABL 725; Radiometer, Copenhagen, Denmark). Oxygen extraction ratio (O 2ER) was calculated as O 2ER = 100 × (SaO 2 -ScvO 2)/SaO 2, where SaO 2 is arterial oxygen saturation.

The clinical characteristics of the patients, demographic varia-bles, cause of intubation, use of vasoactive drugs, and severity scores (Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA)) were recorded at baseline. After the emergency,patients were classified as septic or non-septic, according to the predominant condition that led to the cardio-respiratory failure. Changes in ScvO 2 were analyzed for the whole popu-lation and also individually for septic and non-septic sub-groups.

Statistical analysis

Numerical variables were compared using Student's t test,and categorical variables were compared by chi-square or Fisher's exact test. Changes in variables (ScvO 2, O 2ER) were analyzed by a paired Student's t test. Correlation between changes in ScvO 2 and SaO 2 was performed with linear regres-sion analysis. The SPSS 17.0 software (Chicago, IL, USA)was used for statistical calculations. Results are expressed as percentages or mean (± standard deviation). A P < 0.05 was considered as statistically significant. All reported P values are two-sided.

Results

A total of 108 critically ill patients requiring emergency intuba-tion were included in this study. Forty-two patients (40.8%)were intubated for respiratory failure, 17 (16.5%) for circula-tory failure, and the remaining 44 (42.7%) for mixed causes.Five patients were excluded from analysis because measure-ments could not be obtained in due time: two with difficult intu-bation and three for severe cardiovascular instability during the procedure. In these patients, samples were taken only after 35to 50 minutes, and ScvO 2 ranged from 59 to 65% with no improvement compared with pre-intubation values.

Baseline characteristics of the remaining 103 patients are shown in Table 1. Forty-eight patients (46.6%) had severe sepsis (more frequently respiratory (43%) and abdominal (40%) sources). These patients had septic shock, community-acquired pneumonia, pancreatitis, and postoperative sepsis,with different organ dysfunction profiles including acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) in 20(42%). Fifty (91%) of the non-septic patients were of cardio-genic origin (including acute circulatory failure, acute coronary syndromes, pulmonary edema, pulmonary thromboembolism,life-threatening arrhythmias, and congestive heart failure).At intubation, 41 patients were macro-hemodynamically stable without vasoactive drugs, and the others used either vasopres-sors or inotropes as shown in Table 1. Basal arterial lactate was 2.27 ± 1.77 mmol/L. Severe septic patients had been previously resuscitated according to Surviving Sepsis Cam-paign guidelines [2] including fluid challenge in all and vaso-pressors in 25 patients, mostly norepinephrine (Table 1).Source control was ongoing in all. In the cardiogenic patients,

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24 were receiving inotropic support with dobutamine, milri-none, or levosimendan (Table 1). Only nine patients were under vasodilator therapy. Hospital mortality for the whole group was 22%.

No severe adverse events such as arrhythmias or cardiac arrest during intubation were registered. Thirty-three patients used vasopressors before intubation (Table 1), of whom 14required a transitory increase in norepinephrine dose. Of the reminder 70 patients, 17 required one or two 8 mg ephedrine bolus plus an additional 250 ml normal saline bolus during the study protocol.

In the whole group, ScvO 2 increased after intubation in 84 of 103 patients (81.6%) from 61.8 ± 12.6% to 68.9 ± 12.2% (P < 0.0001; Table 2 and Figure 1). ScvO 2 increased also signif-

icantly in both septic and non-septic patients (Table 2).Changes in ScvO 2 were independent from changes in SaO 2as demonstrated by a non-significant correlation between both (r 2 = 0.014, P = 0.242; Figure 2). As a whole, 78 (75.7%)patients were intubated with a ScvO 2 less than 70% and 21(26.9%) normalized the parameter after this sole intervention.We also explored the impact of the maneuver over ScvO 2according to pre-intubation values of ScvO 2 and SaO 2. We found a significant increase in ScvO 2 in patients with baseline ScvO 2 less than 70% independent of baseline SaO 2. Only patients with ScvO 2 more than 70% failed to increase the parameter after intubation (Table 3).

As a whole, oxygen extraction decreased in 56 patients (54.4%) by more than 2.5%, but increased more than 2.5% in 32 patients (31%) compared with baseline. As expected,patients who decreased O 2ER after intubation, exhibited higher pre-intubation respiratory rates (30.7 ± 6.3 vs . 25.3 ±4.0; P = 0.047). Mean arterial pressure (MAP), HR, and RR decreased also significantly after intubation (Table 2).Septic and non-septic subgroups showed the same trends in physiologic variables after intubation, except for a higher decrease in O 2ER in septic patients, and in MAP in the non-septic subgroup.

Discussion

Our study demonstrates that emergency intubation markedly improves ScvO 2 in both septic and non-septic patients.Changes in ScvO 2 were consistent across the studied sub-groups, regardless of the cause of intubation and baseline arterial oxygen saturation. In contrast, the effects on oxygen extraction were more variable. In almost 30% of the patients this sole maneuver increased ScvO 2 over 70%, a level consid-ered as a resuscitation goal by current guidelines [2].The role of ScvO 2 as a reliable marker of global dysoxia has been widely accepted [1,2]. Nevertheless, no study has repli-cated the very low ScvO 2 values of the EGDT trial [1]. Low ScvO 2 values are present in less than 21% of ICU patients with septic shock or respiratory failure [5,6]. Interestingly, the study by van Beest and colleagues 83% of patients were already intubated before the first ScvO 2 sampling [6]. In fact,our low pre-intubation ScvO 2 values in septic patients closely resemble baseline data from the EGD T trial [1], although ScvO 2 values after intubation are quite similar to those previ-ously reported in the ICU setting [5,6,9].

Is normalization of ScvO 2 after intubation a reliable indicator of a successful resuscitation? Our data show that ScvO 2, as expected, is highly sensitive to intubation. We believe that early normalization of this sole parameter after intubation should be interpreted with caution. Either an increase in SaO 2in some patients, or a decrease in cerebral and respiratory

Table 1

Baseline characteristics of the patients

All patients (n = 103)

Age (years)

58 ± 17

Gender male/female, n/(%)65 (63.1)/38 (36.9)APACHE II score 26 ± 7SOFA score 9 ± 4Hemoglobin (g/dl)10.3 ± 1.9

Presence of severe sepsis Yes, n (%)48 (46.6)No, n (%)

55 (53.4)Cardiogenic, n (%)50 (48.5)Vasoactive drug use None, n (%)41 (40)Vasopressors, n (%)33 (32)Norepinephrine 20 (19)Dopamine 5 (5)Inotropes, n (%)

29 (28)Dobutamine 17 (17)Milrinone 5 (5)Levosimendan 2 (2)Vasoactive dose

Norepinephrine, μg/kg/min 0.1 ± 0.1Dopamine, μg/kg/min 5.2 ± 2.6Dobutamine, μg/kg/min 4.6 ± 1.9Milrinone, μg/kg/min 0.42 ± 0.21Levosimendan, μg/kg/min

0.2 ± 0.1APACHE = Acute Physiology and Chronic Health Evaluation; SOFA = Sequential Organ Failure Assessment.

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muscles VO 2, may both increase ScvO 2, but not necessarily reflect an improvement in global perfusion. In concordance, a recent study challenged the sensitivity of a ScvO 2 more than 70% as a marker of an adequate D O 2/VO 2 balance after resuscitation in the ICU setting [10]. Therefore, we strongly believe that a multimodal approach including other parameters such as clinical perfusion, venous-arterial partial pressure of carbon dioxide gradient or lactate, must be used to assess perfusion, particularly after intubation.

Although the aim of our clinical observational study was to evaluate the specific impact of emergency intubation on ScvO 2 and not to explore the determinants of this response,some physiologic considerations are important. Several stud-ies have shown that sedation and connection to mechanical ventilation can decrease oxygen consumption in the brain and respiratory muscles, the principal determinants of VO 2 in the territories drained by the superior vena cava [11-17]. Support-ing this concept, and as expected, we found that patients with higher pre-intubation RR exhibited more pronounced decreases in O 2ER after the maneuver. Conversely, DO 2 can

Figure 1

Distribution of central venous oxygen saturation before and after intubation. ScvO 2

= central venous oxygen saturation.Figure 2

Correlation between changes in central venous oxygen saturation and arterial oxygen saturation after intubation. SaO 2 = arterial oxygen saturation; ScvO 2

= central venous oxygen saturation.

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also be affected by emergency intubation and mechanical ven-tilation either by increases in SaO 2 or changes in cardiac out-put. The increase in intra-thoracic pressure and decrease in sympathetic outflow induced by the maneuver favor a decrease in venous return, vasomotor tone, and cardiac out-put. Thus, sometimes divergent changes in DO 2 and VO 2 can be induced by emergency intubation and could probably explain the variable effect on oxygen extraction. Our results demonstrate that in the majority of patients subjected to emer-gency intubation, either septic or not, the predominant effect is to increase ScvO 2, although this cannot be predicted a pri-ori in individual cases. Therefore, an early measurement of ScvO 2 after intubation may facilitate interpretation of further changes during ScvO 2-guided resuscitation.

Our study has several limitations. To obtain a more compre-hensive physiologic interpretation of ScvO 2 changes, future studies should directly assess the effects of intubation on each of the determinants of ScvO 2. Unfortunately, we did not measure cardiac output due to the extreme emergency con-text. In addition, it should be confirmed if these short-term effects persist over time and if early normalization of ScvO 2after emergency intubation truly represents a correction of global hypoperfusion.

Our results should not be interpreted as a mandatory recom-mendation to intubate every patient presenting with low ScvO 2 during resuscitation. Some patients present severe hemodynamic instability after the maneuver. Clinicians must be aware of the inherent risks associated with emergency intu-bation, which should be balanced against the potential benefit.

Table 2

Study variables before vs. after intubation

Before intubation

After intubation P value SaO 2 (%)90.6 ± 7.597.0 ± 2.9< 0.001O 2ER (%)

32.1 ± 10.829.2 ± 11.60.002Heart rate (beats/min)103.7 ± 25.296.4 ± 23.10.020Respiratory rate (breaths/min)29.1 ± 6.215.2 ± 3.1< 0.001MAP (mmHg)

67.8 ± 19.6

57.5 ± 21.1

< 0.001

MAP = mean arterial pressure; O 2ER = oxygen extraction; SaO 2 = arterial oxygen saturation.P < 0.05 considered as significant.

Table 3

Changes in ScvO2 after intubation for different subgroups

ScvO 2 (%)Before intubation

After intubation P value All patients

61.8 ± 12.6

68.9 ± 12.2

< 0.001

Presence of severe sepsis Yes (n = 48)63.6 ± 11.971.1 ± 12.0< 0.001No (n = 55)

59.3 ± 13.1

65.6 ± 11.6

< 0.001

According to baseline ScvO 2

< 70% (n = 76)56 ± 8.464.8 ± 10.8< 0.001≥ 70% (n = 27)

78 ± 6.7

80.2 ± 8.1

0.181

According to baseline SaO 2

< 90% (n = 42)54.1 ± 8.061.5 ± 11.4< 0.001≥ 90% (n = 61)

67.1 ± 12.5

73.0 ± 10.0

< 0.001

SaO 2 = arterial oxygen saturation; ScvO 2 = central venous oxygen saturation.P < 0.05 considered as significant.

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Conclusions

ScvO 2 increases significantly in response to emergency intu-bation in critically ill septic and non-septic patients, although it is not clear if this truly represents an improvement in global dysoxia. Our findings may contribute to explain the discrep-ancy between EGDT trial and ICU reports concerning the inci-dence of low ScvO 2 values in heterogeneous critically ill patients. When interpreting ScvO 2 during early resuscitation,it is crucial to consider whether the patient has been https://www.wendangku.net/doc/3f7074773.html,peting interests

The authors declare that they have no competing interests.

Authors' contributions

GH conceived the study, and participated in its design and coordination and helped to draft the manuscript. AB con-ceived the study, and participated in its design and coordina-tion and helped to draft the manuscript. RC (Rodrigo Cornejo)conceived the study, and participated in its design and coor-dination and helped to draft the manuscript. RC (Ricardo Cas-tro) conceived of the study, and participated in its design and coordination and helped to draft the manuscript. MR per-formed the statistical analysis. JR, HP, JLN, and IA recruited patients. All authors read and approved the final manuscript.

Acknowledgements

The study was funded by an institutional grant of the Departmento de Medicina Intensiva de la Pontificia Universidad Católica de Chile.

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Key messages

? ScvO 2 increased significantly in response to emergency

intubation in critically ill septic and non-septic patients.? Changes in ScvO 2 were consistent across the studied

subgroups, regardless of the cause of intubation and baseline SaO 2.? In almost 30% of the patients, this sole maneuver

increased ScvO 2 to levels considered as a resuscitation goal by some current guidelines.

科技期刊

中国胸心血管外科临床杂志

CHINESE JOURNAL OF CLINICAL THORACIC

AND CARDIOVASCULAR SURGERY

1998年 第5卷 第4期 No.4 Vol.5 1998

术后血容量变化的比较

张耀频　孙培吾　童萃文　麦惠成

【摘要】　目的　比较中心静脉血氧饱和度(central venous oxygen saturation,ScvO2，经右心房)与混合静脉血

氧饱和度(mixed venous oxygen saturation,SvO2，经肺动脉)在监测心脏术后血容量(BV)变化时的意义。　方法　

24例心脏手术后患者，分别于术后进入ICU处于机械通气及睡眠状态(Ⅰ组)；术后6小时处于机械通气及清醒状

态(Ⅱ组)；术后20小时处于自主呼吸及清醒状态(Ⅲ组)；同时测定ScvO2，SvO2，BV和其他血流动力学指标并进

行相关分析。　结果　ScvO2与BV相关系数(r)分别为Ⅰ组0.5891(P＜0.01)，Ⅱ组0.5590(P＜0.01)，Ⅲ组0.6962(P＜

0.01)；SvO2与BV r分别为Ⅰ组0.7856，Ⅱ组0.7781(P＜0.01)，Ⅲ组0.7243(P＜0.01)；ScvO2与SvO2 r分别为Ⅰ组

0.8689，Ⅱ组0.8971，Ⅲ组0.9513(P＜0.01)。表明ScvO2与BV，SvO2在心脏术后不同状态下具有相关性。　结论　

ScvO2能代替SvO2作为反映心脏术后BV变化的一种监测指标。

【关键词】　中心静脉血氧饱和度 混合静脉血氧饱和度 血容量 心脏手术

A Comparison Between Central Venous and Mixed Venous Oxygen Saturation During Changes of Blood Volume in

Postoperative Period　Zhang Yaopin, Sun Peiwu, Tong Cuiwen, et al. Department of Cardiac and Thoracic Surgery, 3rd

Affiliated Hospital, Sun Yat-sen University of Medicine Science, Guangzhou 510630,P.R.China

【Abstract】　Objective　To compare central venous oxygen saturation (ScvO2,superior vena cava)with the mixed

venous oxygen saturation (SvO2,pulmonary artery) during changes of blood volume (BV) in postoperative cardiac surgery.

　Methods　Blood samples of 24 patients were taken:(Ⅰ) Immediately after entering to ICU(with mechanical ventilation);

(Ⅱ) 6 hours after operations(with mechanical ventilation but consciousness) and (Ⅲ) 20 hours later (self-breathing and consciousness).　Results　The correlation coefficient(r) between ScvO2 and BV were (Ⅰ) 0.5891(P＜0.01),(Ⅱ) 0.5590(P

＜0.01),(Ⅲ) 0.6962(P＜0.01) respectively; and the ones between SvO2 and BV were (Ⅰ) 0.7856,(Ⅱ)0.7781,(Ⅲ)0.7243(P＜

0.01) respectively; and the ones between ScvO2 and SvO2 were (Ⅰ)0.8689,(Ⅱ)0.8971 and (Ⅲ) 0.9513(P＜0.01)

respectively. These results showed that there was a clear linear correlation between ScvO2 and BV or SvO2 postoperatively.　Conclusion　ScvO2 can substitute for SvO2 as a BV monitoring method for postoperative cardiac patients.

【Key words】　Central venous oxygen saturation Mixed venous oxygen saturation Blood volume

Cardiac operation

混合静脉血氧饱和度(mixed venous oxygen saturation,SvO2)作为心排血量(CO)及失血量变化的一种指标，分

别由Boyd［1］和Scalea提出［2］，认为它有利于监测危重患者。但肺动脉导管对患者有一定的危险性，而中心静

脉导管(经上腔静脉入右心房)对患者危险性小、并发症少，而且费用低。有作者对中心静脉血氧饱和度(central

venous oxygen saturation,ScvO2)与SvO2在氧供需过程中进行比较，证实两者存在显著的相关性。但作为监测心脏

术后血容量(blood volume,BV)变化，两者有何意义，目前尚未见报道。由此，我们采用113m Incl(铟-113m)直接测

定BV［3］，对心脏术后患者的ScvO2与SvO2在BV变化时的相关性作一探讨。

1　材料与方法

1.1　临床资料

本组心脏术后患者24例，男16例，女8例。年龄7～53岁，平均32.2±11.6岁。体重37～65kg，平均50.4

±7.4kg。先天性心脏病畸形矫治术6例，单、双瓣替换术18例，术后均用血管活性药物。

1.2　测定方法和分组

1.2.1　测定条件　患者术毕入ICU处于机械通气及睡眠状态(Ⅰ组)；术后6小时处于机械通气及清醒状态(Ⅱ

组)；术后20小时处于自主呼吸及清醒状态(Ⅲ组)。吸氧浓度均为50%，体温控制在37±0.3℃。

1.2.2　BV测定　113m Incl核素稀释法，按BV＝血浆容量/(1-Hct×0.96×0.91)计数，0.96为细胞容积“粘附血浆”校正值，0.91为中心静脉与周围静脉红细胞压积校正值。

1.2.3　血气测定　经颈内静脉穿刺插管达右心房，经左上肢贵要静脉插入Swan-Ganz导管达肺动脉远端，经左桡动脉插管，分别采集中心静脉、混合静脉和动脉血标本。经血气分析仪(HP782050)自动测试。

1.2.4　CO测定　采用热稀释法及CO计算机(EDWARD9520A)，经Swan-Ganz导管直接测得，结果按体表面积计算心排血指数(CI)。

1.2.5　其他　心率(HR)，平均动脉压(MAP)，平均肺动脉压(MPAP)中心静脉压(CVP)，肺毛细血管嵌压(PCWP)及尿量(UV)。

1.3　统计学处理

同一病例术后不同条件下采用线性回归及相关分析。

2　结 果

2.1　BV与其他反映BV指标相关分析

BV与PCWP，CI和UV在心脏术后不同组别均存在相关关系(表1)。

表1　BV与血流动力学指标相关分析

组别CVP PCWP MAP CI HR UV

Ⅰ组-0.09110.4924*0.38880.3936*-0.2993-

Ⅱ组-0.19770.5358**0.34400.5598**-0.27970.4514**

Ⅲ组-0.15700.3700*0.28300.5751**-0.22390.5343**

注：*P＜0.05，**P＜0.01

2.2　ScvO2与血流动力学指标相关分析

ScvO2与BV(P＜0.01)，CI(P＜0.01)，UV(Ⅱ组和Ⅲ组)，CVP(Ⅰ组和Ⅱ组)和PCWP(Ⅱ和Ⅲ组)均存在相关关系(表2)。

表2　ScvO2与血流动力学指标相关分析

组别CVP PCWP CI HR BV UV

Ⅰ组-0.4320*-0.25210.7971**-0.30380.5891**-

Ⅱ组-0.5638**-0.5038*0.8751**-0.50620.5590**0.4243*

Ⅲ组-0.4062-0.4534*0.8613**-0.21870.6962**0.5068*

注：*P＜0.05，**P＜0.01

2.3　SvO2与血流动力学指标相关分析

SvO2与CI，BV以及MPAP(Ⅱ组和Ⅲ组)在心脏术后均存在相关关系(P＜0.01，表3)。

表3　SvO2与血流动力学指标相关分析

组别MPAP PCWP CI HR BV

Ⅰ组-0.24540.00380.8040-0.23750.7856

Ⅱ组-0.55180.06730.8815-0.25070.7781

Ⅲ组-0.47790.06380.8533-0.31600.7243

2.4　ScvO2与SvO2和动脉与混合静脉血氧含量差(Ca-vO2)相关分析

ScvO2与SvO2和Ca-vO2在心脏术后不同组别均有相关关系(P＜0.01，表4)。

表4　ScvO2与SvO2，Ca-vO2相关分析

组别Ca-vO2SvO2

混合静脉血氧饱和度

混合静脉血氧饱和度 拉丁学名：Oxygen Saturation of Mixed Venose Blood；SvO2 相关疾病：循环衰竭；败血症；心源性休克；甲亢；贫血及变性血红蛋白症；脓毒症 【参考值】 68%～77%；平均75% 【临床意义】 通过测定混合静脉血氧饱和度（SvO2）来计算动静脉血氧含量差，能较准确反映心排出量。Waller等曾指出SvO2和心脏指数、每搏指数及左心室每搏指数之间有很高的相关性。SvO2下降，而动脉血氧饱和度和耗氧量尚属正常时，则可证明心排血量也是低的。因此现在认为混合静脉血的氧饱和度检查对严重心肺疾患的监测具有重要价值。 SvO2增高的常见原因是脓毒症，此外氰化物中毒及低温也可使SvO2增高。 SvO2降低的原因有：心输出量下降导致的血循环量不足、周围循环衰竭、败血症、心源性休克、甲亢、贫血及变性血红蛋白症、肺部疾患等各种原因导致的氧合功能减低者。SvO2低于60%时，通常提示组织耗氧增加或心肺功能不佳。 临床上连续测定SvO2对危重患者的监测起到重要作用，并对治疗方法及药物使用也有一定的指导作用 Nuclear factor kB (NF-kB) is a nuclear transcription factor that regulates expression of a large number of genes that are critical for the regulation of apoptosis, viral replication, tumorigenesis, inflammation, and various autoimmune diseases. The activation of NF-kB is thought to be part of a stress response as it is activated by a variety of stimuli that include growth factors, cytokines, lymphokines, UV, pharmacological agents, and stress. In its inactive form, NF-kB is sequestered in the cytoplasm, bound by members of the IkB family of inhibitor proteins, which include IkBa, IkBb, IkBg, and IkBe. The various stimuli that

血氧饱和度测量仪的设计要点

血氧饱和度测量仪 的设计

目录 摘要 (3) 第一章绪论 (4) 1.1血氧饱和度的基本概念 (4) 1.2血氧饱和度测量仪课程设计的意义 (3) 1.3血氧饱和度测量仪课程设计的技术要求 (4) 1.4基本步骤 (5) 1.4.1 理论依据 (5) 1.4.2 硬件电路的设计 (6) 1.4.3 软件设计 (6) 1.4.4 仿真及数值定标 (6) 第二章实验方案设计及论证 (6) 2.1 设计理论依据 (6) 2.2. 双波长法的概念 (6) 2.3 光电脉搏传感器 (7) 2.4 传感器可能受到的干扰 (9) 2.5实验方案设计 (10) 第三章硬件电路的设计 (10) 3.1硬件原理框图 (10) 3.2各部分电路的设计 (11) 第四章软件模块设计 (13) 4.1主程序流程图 (14) 4.2子程序流程图 (14) 4.3硬件调试 (16) 第五章设计收获及心得体会 (17) 第六章参考文献 (19) 附录程序清单 (20)

摘要 氧是维持人体组织细胞正常功能，生命活动的基础。人体的绝大多数组织细胞的能量装换均需要氧的参加。所以，实时监护人体组织中氧的代谢具有重要的意义。 人体的新陈代谢过程是生物氧化过程。氧通过呼吸系统进入人体血液，与血液红细胞中的血红蛋白(Hb)结合成氧合血红蛋白(2HbO )，再输送到人体各部分组织细胞中去。在全部血液中，被氧结合的2HbO 容量占全部可结合容量的百分比称为血氧饱和度2O Sa 。许多临床疾病会造成氧供给的缺乏，这将直接影响细胞的正常新陈代谢，严重的还会威胁人的生命，所以动脉血氧浓度即2O Sa 。 的实时监测在临床救护中非常重要。 在本次关于血氧饱和度测量仪的设计中，是基于MCS —51单片机的设计，需要选测合适的光电脉搏传感器采集数据，并利用4为LED 数码显示测量值，利用键盘切换显示脉搏跳动的频率。 关键词：51单片机 血氧饱和度 比尔—朗伯定理

中心静脉压监测技术

中心静脉压监测技术 目的：中心静脉压是监测循环系统功能的重要指标之一，它代表靠近上、下腔静脉内和右心房内的压力。常选择颈静脉、锁骨下静脉、股静脉作为穿刺部位，中心静脉压可反映体内血容量、静脉回心血量、右心室充盈压力或右心功能的变化。对指导补血补液的量及速度，防止心脏过度负荷及指导利尿药的应用等都具有重要的参考意义。 操作程序准备用物：0.9%NS 250ml 2瓶、肝素钠1支、输液器、标尺、三通管、输液架、胶布、记号笔棉签、5ml注射器2个、安尔碘、弯盘、洗手液、锐器盒、医疗垃圾桶等。 病人安全与舒适：核对医嘱、床号、姓名、腕带。 与患者沟通，做好解释，评估患者病情，告知测量中心静脉压的目的及配合方法，取得患者的配合。 协助患者取平卧体位，检查患者中心静脉穿刺部位处皮肤及敷料固定情况。 消毒中心静脉装置，连接输液器与生理盐水，排气后连接中心静脉装置，用5ml注射器回抽回血，确定通路通畅，开放测压管通路，使测压管与中心静脉导管相通，测压管上端茂菲滴管调节孔与大气压相通。 选择标准的测压零点：输液器置于腋中线第4肋间（右心房水平）。 待测压管内液面自然下降至有轻微波动而不再下降时，用标尺测压管上的数值即为中心静脉压（正常值5-12cmH2O，如小于5cmH2O说明血容量不足，遵医嘱予补液，大于12cmH2O说明血容量过多，心功能不全，控制补液量和速度）。 测压结束，予肝素盐水封管。 整理床单位，患者取舒适体位，向患者及家属交待注意事项；将测量结果报告医生。 注意事项：1、操作时严格遵守无菌原则，防止感染。2、避免打折扭曲，保持测压管通畅，各接头连接紧密，防止进气。3、开放式测压装置每次更换一次。4、每次测压前保持测压管零点与右心房同一水平，体位变动时应重新调整两者关系。测量时，患者尽可能平卧，床头抬高不超过30°，标尺零点与选择测压零点处于同一水平。5、患者若躁动、咳嗽、呕吐或用力时，应在患者安静10—15分钟后再行测压。腹内压高的患者一般情况下测上腔静脉压力，监测数值有疑问时，应查找原因。6、测压管路不能输入血管活性药以防引起血压波动。

中心静脉穿刺置管操作常规

中心静脉穿刺置管操作常规 适应症 监测中心静脉压（CVP）； 快速补液、输血或给血管活性药物； 胃肠外营养； 插入肺动脉导管； 进行血液透析、滤过或血浆置换； 使用可导致周围静脉硬化的药物； 无法穿刺外周静脉以建立静脉通路； 特殊用途如心导管检查、安装心脏起搏器等； 禁忌证 出血倾向（禁忌行锁骨下静脉穿刺）； 局部皮肤感染（选择其他深静脉穿刺部位）； 胸廓畸形或有严重肺部疾患如肺气肿等，禁忌行锁骨下静脉穿刺； 术前准备 置管前应明确适应症，检查患者的出凝血功能。对清醒患者，应取得患者配合，并予适当镇静。准备好除颤器及有关的急救药品。 准备穿刺器具：包括消毒物品、深静脉穿刺手术包、穿刺针、引导丝、扩张管、深静脉导管（单腔、双腔或三腔）、缝合针线等，以及肝素生理盐水（生理盐水100ml+肝素6250U）和局麻药品（1%利多卡因或1%普鲁卡因）。 颈内静脉穿刺置管操作步骤 患者去枕仰卧位，最好头低15°~30°（Trendelenburg体位），以保持静脉充盈和减少空气栓塞的危险性，头转向对侧。 颈部皮肤消毒，术者穿无菌手术衣及手套，铺无菌单，显露胸骨上切迹、锁骨、胸锁乳突肌侧缘和下颌骨下缘。检查导管完好性和各腔通透性。 确定穿刺点：文献报道颈内静脉穿刺径路有13种之多，但常用中间径路或后侧径路（根据穿刺点与胸锁乳突肌的关系）。中间径路定位于胸锁乳突肌胸骨头、锁骨头及锁骨形成的三角顶点，环状软骨水平定位，距锁骨上3~4横指以上。后侧径路定位于胸锁乳突肌锁骨头后缘、锁骨上5cm或颈外浅静脉与胸锁乳突肌交点的上方。 确定穿刺点后局部浸润麻醉颈动脉外侧皮肤及深部组织，用麻醉针试穿刺，确定穿刺方向及深度。 左手轻柔扪及颈动脉，中间径路穿刺时针尖指向胸锁关节下后方，针体与胸锁乳突肌锁骨头内侧缘平行，针轴与额平面呈45°~60°角，如能摸清颈动脉搏动，则按颈动脉平行方向穿刺。后侧径路穿刺时针尖对准胸骨上切迹，紧贴胸锁乳突肌腹面，针轴与矢状面及水平面呈45°角，深度不超过5~7cm。穿刺针进入皮肤后保持负压，直至回抽出静脉血。 从注射器尾部导丝口插入引导丝（如用普通注射器则撤去注射器，从针头处插入引导丝），将穿刺针沿引导丝拔除。可用小手术刀片与皮肤平行向外侧（以免损伤颈动脉）破皮使之表面扩大。 绷紧皮肤，沿引导丝插入扩张管，轻轻旋转扩张管扩张致颈内静脉，固定好引导丝近端将扩张管撤出。 沿引导丝插入导管（成人置管深度一般以13~15cm为宜），拔除引导丝，用肝素生理盐水注射

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如对您有帮助，可购买打赏，谢谢脉搏血氧饱和度测量方法 导语：脉搏的血氧饱和度，对于身体的健康是特别有益处的，脉搏的血氧如果出现了问题，就会对自己的身体构成严重的影响，所以很多出现这种疾病的患 脉搏的血氧饱和度，对于身体的健康是特别有益处的，脉搏的血氧如果出现了问题，就会对自己的身体构成严重的影响，所以很多出现这种疾病的患者，就想全面了解脉搏血氧饱和度测量方法，下面的内容就做了介绍，你可以全面地来了解一下。 血氧饱和度(SaO2)是血液中被氧结合的氧合血红蛋白(HbO2)的容量占全部可结合的血红蛋白(Hb，hemoglobin)容量的百分比，即血液中血氧的浓度，它是呼吸循环的重要生理参数。而功能性氧饱和度为HbO2浓度与HbO2+Hb浓度之比，有别于氧合血红蛋白所占百分数。因此，监测动脉血氧饱和度(SaO2)可以对肺的氧合和血红蛋白携氧能力进行估计。正常人体动脉血的血氧饱和度为98% ，静脉血为75%。在临床上目前可以用取动脉血测量其中的氧分压来计算SaO2(不能连续监测)，也可以用脉搏血氧仪(PulseOximetr)，使用光电技术，在不用取血的情况下连续测量动脉血中的血氧饱和度。 测量方法 许多临床疾病会造成氧供给的缺乏，这将直接影响细胞的正常新陈代谢，严重的还会威胁人的生命，所以动脉血氧浓度的实时监测在临床救护中非常重要。 传统的血氧饱和度测量方法是先进行人体采血，再利用血气分析仪进行电化学分析，测出血氧分压PO2计算出血氧饱和度。这种方法比较麻烦，且不能进行连续的监测。 目前的测量方法是采用指套式光电传感器，测量时，只需将传感器预防疾病常识分享，对您有帮助可购买打赏

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心电、脉搏血氧饱和度（S p O2）监测技术操作流程 1、操作者着装整齐、洗手、戴手套。 2、环境评估： 1）、操作者用手势示意（关闭门窗，遮挡病人）。 2）、大声说：“病房安静、室温22℃！” 3、病情判断、解释： 1）、核对病人，评估病情。大声说：＿床×××，＿疾病（疾病诊断），根据病情需要安置心电监护！ 2）、上前小声对病人说：您好，请问您是＿床×××吗？我是X护士，根据您的病情需要观察您的心电变化和机体组织缺氧状况，现在为您进行心电监护，这项操作没有什么痛苦，请您不要紧张，请您配合！ 4、准备病人： 1）、病人取水平仰卧位。 2）、解开衣扣，暴露胸部。 3）、清洁皮肤。 4）、同时使用安慰用语：“现在请您放松，平卧，我要在您的皮肤上贴上电极板。现在我帮您解开衣扣清洁皮肤，可能感觉有点凉，请不要紧张。” 5、连接： 1）、接通电源。 2）、开机，进入备用状态。 3）、将连接好导联线的5个电极板贴到病人胸壁的相应部位上。 RA（白色）：右锁骨中线锁骨下 LA（黑色）：左锁骨中线锁骨下 LL（红色）：胸骨左缘左锁骨中线第六肋间 RL（绿色）：胸骨右缘右锁骨中线第六肋间 Y（棕色）：剑突下方偏左心前区） 4）、将血氧饱和度导线与多功能参数监护仪相连接。 协助病人整理好上衣，盖好被子。 6、报告监护参数： 1）、监测心率： a、选择清楚的Ⅱ导联。 b、显示屏上出现心电图波，示窦性心律，律齐，心率110次/min。 c、大声说：心率110次/min！ 2）、监测血压： a、缠绕血压袖带。 b、告知用语：现在为您测量血压，测量时会感觉上臂发紧，请你不要紧张。 c、启动无创测压键，测量首次血压。 d、显示屏上显示血压为110/70mmHg。 e、大声说：血压为110/70mmHg！ 3）、监测S p O2： a、确认传感器性能（将探头夹在自己手指上，确认正常数值处于96%～98%）。 b、清洁指甲，把探头安放在患者左手示指上，指夹完全夹住左手示指末端，

血氧饱和度监测的常见问题及护理

血氧饱和度监测的常见问题及护理 主讲人： 参加时间： 参加人员： 血氧饱和度即SpO2被定义为氧合血红蛋白占血红蛋白的百分比值。常用动脉血氧定量技术，它测定的是从传感器光源一方发射的光线有多少穿过患者组织到达另一方接收器，这是一种无创伤测定血氧饱和度的方法。血氧饱和度读数变化是报告患者缺氧最及时、最迅速的警告。 一、血氧饱和度监测中的常见问题： 1、信号跟踪到脉搏，屏幕上无氧饱和度和脉率值。原因： （1）患者移动过度，过于躁动，使血氧饱和度参数找不到一个脉搏形式；（2）患者可能灌注太低，如肢体温度过低、末梢循环太差，使氧饱和度参数不能测及血氧饱和度和脉率; （3）传感器损坏； （4）传感器位置不准确（接头线应置手背，指甲面朝上）； （5）血液中有染色剂（如美蓝、荧光素）、皮肤涂色或手指甲上涂有指甲油，也会影响测量精度； （6）环境中有较强的光源。如手术灯、荧光灯或是其他光线直射时，会使探头的光敏元件的接受值偏离正常范围，因此需要避强光。必要时探头需遮光使用； (7)探头戴的时间过长以后，可能影响血液循环，使测量精度受影响； （8）另外，同侧手臂测血压时，会影响末梢循环而使测量值有误差。 2、氧饱和度迅速变化，信号强度游走不定可能由于患者移动过度或由于手术装置干扰操作性能。 3、氧饱和度显示传感器脱落 （1）传感器如在位且性能良好，应注意连接是否正常，临床最常出现此种情况即液体溅进传感器接头处； （2）血氧探头正常工作，开机自检后探头内发出较暗红光或红光较亮且闪烁不定。 二、血氧饱和度监测中常见问题的处理： 1、信号跟踪到脉搏，屏幕上无氧饱和度和脉率值时的处理 （1）密切观察患者病情； （2）使患者保持不动或将传感器移到活动少的肢体，使传感器牢固适当或进行健康人测试，必要时更换传感器； （3）必要时对所测患者注意保暖； （4）需要避强光； （5）时间过长可换另一手指测量； （6）尽量避免同侧手臂测血压。 2、氧饱和度迅速变化，信号强度游走不定时的处理尽量使患者保持安静少动，

中心静脉血氧饱和度监测技术资料

中心静脉血氧饱和度监测 技术资料 PCCI 飞利浦医疗保健 2011‐05‐25

目 录 1.参考文献 2.操作指南 附：CeVOX导管引导色标 CeVOX导管技术参数 CeVOX导管使用问答

Open Access Available online https://www.wendangku.net/doc/3f7074773.html,/content/10/6/R158 Page 1 of 8 (page number not for citation purposes) Research Multicentre study on peri- and postoperative central venous oxygen saturation in high-risk surgical patients Collaborative Study Group on Perioperative ScvO2 Monitoring Received: 5 Jul 2006Revisions requested: 27 Jul 2006Revisions received: 30 Aug 2006Accepted: 13 Nov 2006Published: 13 Nov 2006Critical Care 2006, 10:R158 (doi:10.1186/cc5094) This article is online at: https://www.wendangku.net/doc/3f7074773.html,/content/10/6/R158 ? 2006 Collaborative Study Group on Perioperative ScvO2 Monitoring; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (https://www.wendangku.net/doc/3f7074773.html,/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.For a complete list of authors and their affiliations, see Appendix. Corresponding author: Stephen M Jakob Abstract Introduction Low central venous oxygen saturation (ScvO 2) has been associated with increased risk of postoperative complications in high-risk surgery. Whether this association is centre-specific or more generalisable is not known. The aim of this study was to assess the association between peri- and postoperative ScvO 2 and outcome in high-risk surgical patients in a multicentre setting. Methods Three large European university hospitals (two in Finland, one in Switzerland) participated. In 60 patients with intra-abdominal surgery lasting more than 90 minutes, the presence of at least two of Shoemaker's criteria, and ASA (American Society of Anesthesiologists) class greater than 2,ScvO 2 was determined preoperatively and at two hour intervals during the operation until 12 hours postoperatively. Hospital length of stay (LOS) mortality, and predefined postoperative complications were recorded. Results The age of the patients was 72 ± 10 years (mean ±standard deviation), and simplified acute physiology score (SAPS II) was 32 ± 12. Hospital LOS was 10.5 (8 to 14) days,and 28-day hospital mortality was 10.0%. Preoperative ScvO 2decreased from 77% ± 10% to 70% ± 11% (p < 0.001)immediately after surgery and remained unchanged 12 hours later. A total of 67 postoperative complications were recorded in 32 patients. After multivariate analysis, mean ScvO 2 value (odds ratio [OR] 1.23 [95% confidence interval (CI) 1.01 to 1.50], p = 0.037), hospital LOS (OR 0.75 [95% CI 0.59 to 0.94], p = 0.012), and SAPS II (OR 0.90 [95% CI 0.82 to 0.99],p = 0.029) were independently associated with postoperative complications. The optimal value of mean ScvO 2 to discriminate between patients who did or did not develop complications was 73% (sensitivity 72%, specificity 61%). Conclusion Low ScvO 2 perioperatively is related to increased risk of postoperative complications in high-risk surgery. This warrants trials with goal-directed therapy using ScvO 2 as a target in high-risk surgery patients. Introduction Several randomised controlled clinical studies have shown improved morbidity and mortality in high-risk surgical patients with perioperative optimisation of haemodynamics using strict treatment protocols in the single-centre setting [1-3]. The haemodynamic endpoints in goal-directed studies have been based on values derived from the pulmonary artery catheter [1-4], oesophageal Doppler [5-10], or (very recently) lithium indi-cator dilution and pulse power analysis [11]. Central venous oxygen saturation (ScvO 2) and mixed venous oxygen satura-tion (SvO 2) have been proposed to be indicators of the oxygen supply/demand relationship. However, the relationship between SvO 2 and ScvO 2 remains controversial [12]. Venous oxygen saturations differ among organ systems because dif-ferent organs extract different amounts of oxygen. It is there-fore conceivable that venous oxygen saturation depends on the site of measurement [13]. Redistribution of blood flow and alterations in regional oxygen demand (for example, in shock,severe head injury, general anaesthesia, as well as microcircu-latory disorders) may affect the difference between ScvO 2 and SvO 2. Although ScvO 2 principally reflects the relationship of oxygen supply and demand, mainly from the brain and the upper part of the body [13], it correlates reasonably well with concomitantly measured SvO 2 [12,13], which is more dependent on changes in oxygen extraction in the gastrointes-tinal tract. HDC = high-dependency care; ICU = intensive care unit; LOS = length of stay; OR = odds ratio; ROC = receiver operator characteristic; SAPS II = simplified acute physiology score; ScvO 2 = central venous oxygen saturation; SvO 2 = mixed venous oxygen saturation.

血氧饱和度测量仪的设计

血氧饱和度测量仪的设计

血氧饱和度测量仪 的设计

目录 摘要 (3) 第一章绪论 (4) 1.1血氧饱和度的基本概念 (4) 1.2血氧饱和度测量仪课程设计的意

义 (3) 1.3血氧饱和度测量仪课程设计的技术要求 (4) 1.4基本步骤 (5) 1.4.1理论依据 (5) 1.4.2硬件电路的设计 (6) 1.4.3软件设计 (6) 1.4.4仿真及数值定标 (6) 第二章实验方案设计及论证 (6)

2.1设计理论依据 (6) 2.2.双波长法的概念 (6) 2.3光电脉搏传感器 (7) 2.4传感器可能受到的干扰 (9) 2.5实验方案设计 (10) 第三章硬件电路的设计 (10) 3.1硬件原理框图 (10) 3.2各部分电路的设

计....................................................................................1 1 第四章软件模块设计.......................................................................................1 3 4.1主程序流程图..........................................................................................1 4 4.2子程序流程图..........................................................................................1 4 4.3硬件调试 (16) 第五章设计收获及心得体会 (17) 第六章参考文献 (19) 附录程序清单…………………………………………………

混合静脉血氧饱和度之欧阳光明创编

混合静脉血氧饱和度 欧阳光明（2021.03.07） 拉丁学名：Oxygen Saturation of Mixed Venose Blood；SvO2 相关疾病：循环衰竭；败血症；心源性休克；甲亢；贫血及变性血红蛋白症；脓毒症 【参考值】 68%～77%；平均75% 【临床意义】 通过测定混合静脉血氧饱和度（SvO2）来计算动静脉血氧含量差，能较准确反映心排出量。Waller等曾指出SvO2和心脏指数、每搏指数及左心室每搏指数之间有很高的相关性。SvO2下降，而动脉血氧饱和度和耗氧量尚属正常时，则可证明心排血量也是低的。因此现在认为混合静脉血的氧饱和度检查对严重心肺疾患的监测具有重要价值。 SvO2增高的常见原因是脓毒症，此外氰化物中毒及低温也可使SvO2增高。

SvO2降低的原因有：心输出量下降导致的血循环量不足、周围循 环衰竭、败血症、心源性休克、甲亢、贫血及变性血红蛋白症、肺部疾患等各种原因导致的氧合功能减低者。SvO2低于60%时，通常提示组织耗氧增加或心肺功能不佳。 临床上连续测定SvO2对危重患者的监测起到重要作用，并对治疗方法及药物使用也有一定的指导作用 Nuclear factor kB (NF-kB) is a nuclear transcription factor that regulates expression of a large number of genes that are critical for the regulation of apoptosis, viral replication, tumorigenesis, inflammation, and various autoimmune diseases. The activation of NF-kB is thought to be part of a stress response as it is activated by a variety of stimuli that include growth factors, cytokines, lymphokines, UV, pharmacological agents, and stress. In its inactive form, NF-kB is sequestered in the cytoplasm, bound by members of the IkB family of inhibitor proteins, which include IkBa, IkBb, IkBg, and IkBe. The various stimuli that activate NF-kB cause phosphorylation of IkB, which is followed by its ubiquitination and subsequent degradation. This results in the exposure of the nuclear localization signals (NLS) on NF-kB subunits and the subsequent translocation of the molecule to the nucleus. In the nucleus, NF-kB binds with a consensus sequence (5'GGGACTTTCC-3') of various genes and thus activates their transcription. IkB proteins are phosphorylated by IkB kinase complex consisting of at least three proteins; IKK1/IKKa,

血氧饱和度探头检测的基本原理

血氧饱和度探头检测的基本原理 氧是维系人类生命的基础，心脏的收缩和舒张使得人体的血液脉动地流过 肺部，一定量的还原血红蛋白(HbR)与肺部中摄取的氧气结合成氧和血红蛋白(HbO2)，另有约2%的氧溶解在血浆里。这些血液通过动脉一直输送到毛细血管，然后在毛细血管中将氧释放，以维持组织细胞的新陈代谢。血氧饱和度(血氧探头)(SO2)是血液中被氧结合的氧合血红蛋白(HbO2)的容量占全部可结合的血红 蛋白(Hb)容量的百分比，即血液中血氧的浓度，它是呼吸循环的重要生理参数。而功能性氧饱和度为HbO2浓度与HbO2 Hb浓度之比，有别于氧合血红蛋白所占百分数。因此，监测动脉血氧饱和度(血氧探头)(SaO2)可以对肺的氧合和血红 蛋白携氧能力进行估计。 1、血氧饱和度检测分类 血氧浓度的测量通常分为电化学法和光学法两类。 传统的电化学法血氧饱和度测量要先进行人体采血(最常采用的是取动脉血)，再利用血气分析仪进行电化学分析，在数分钟内测得动脉氧分压(PaO2)，并计算出动脉血氧饱和度(SaO2)。由于这种方法需要动脉穿刺或者插管，给病 人造成痛苦，且不能连续监测，因此当处于危险状况时，就不易使病人得到及 时的治疗。电化学法的优点是测量结果精确可靠，缺点是比较麻烦，且不能进 行连续的监测，是一种有损伤的血氧测定法。 光学法是一种克服了电化学法的缺点的新型光学测量方法，它是一种连续 无损伤血氧测量方法，可用于急救病房、手术室、恢复室和睡眠研究中。目前 采用最多的是脉搏血氧测定法(Pulse Oximetry)，其原理是检测血液对光吸收 量的变化，测量氧合血红蛋白(Hb02)占全部血红蛋白(Hb)的百分比，从而直接 求得SO2。该方法的优点是可以做到对人体连续无损伤测量，且仪器使用简单 方便，所以它已得到越来越普遍的重视。缺点是测量精度比电化学法低，非凡 是在血氧值较低时产生的误差较大。先后出现了耳式血氧计，多波长血氧计及 新近问世的脉搏式血氧计。最新的脉搏式血氧计的测量误差已经可以控制在1%

心电监护仪——血氧饱和度监测的注意事项

心电监护仪——血氧饱和度监测的注意事项 一、血氧饱和度的定义 血氧饱和度(SpO2)是血液中被氧结合的氧合血红蛋白(HbO2)的容量占全部可结合的血红蛋白(Hb)容量的百分比，即血液中血氧的浓度，它是呼吸循环的重要生理参数。常用动脉血氧定量技术，它测定的是从传感器光源一方发射的光线有多少穿过患者组织到达另一方接收器，这是一种无创伤测定血氧饱和度的方法。血氧饱和度读数变化是报告患者缺氧最及时、最迅速的警告。计算公式如下：SpO2 = HbO2/（HbO2+Hb）×100%。氧饱的正常值为95%-100%，氧饱与氧分压直接相关。 二、血氧饱和度的测定方法 血氧饱和度的测量通常分为电化学法和光学法两类。 1、电化学法即行人体采动脉血，再用血气分析仪测出血氧饱和度值，这是一种有创的测量方法，且不能进行连续的监测。 2、光学测量法是采用光电传感器的无创方法，是基于动脉血液对光的吸收量随动脉搏动而变化的原理进行测量的，该方法使用最多的就是脉搏血氧饱和度仪。仪器探头的一侧安装了两个发光管，分别发出红光和红外光，另一侧安装一个光电检测器，将检测到的透过手指动脉血管的红光和红外光转换成电信号。由于皮肤、肌肉、脂肪、静脉血、色素和骨头等对这两种光的吸收系数是恒定的，只有动脉血流中的HbO2和Hb浓度随着血液的动脉周期性的变化，从而引起光电检测器输出的信号强度随之周期性变化,将这些周期性变化的信号进行处理，就可测出对应的血氧饱和度，同时也计算出脉率。 三、SpO2报警值的设置 SpO2正常值，吸空气时SpO2测得值≥95％～97％。低氧血症:SpO2＜95％者为去氧饱和血症，SpO2＜90％为轻度低氧血症，SpO2＜85％为重度低氧血症。一般报警低限的设置应高于90％。 四、血氧饱和度监测中的常见问题 1、信号跟踪到脉搏，屏幕上无氧饱和度和脉率值。

经皮测血氧饱和度说明书

经皮测血氧饱和度（SPO2）说明书 1、血氧饱和度监护说明SpO2 监护的定义 SpO2容积描记参数测量动脉血氧饱和度，也就是氧合血红蛋白总数的百分比。例如，如在动脉血的红细胞中，占总数97%的血红蛋白分子与氧结合，则此血液就有97%SpO2血氧饱和度，监护仪上的SpO2值读数应为97%。SpO2值显示出形成氧合血红蛋白的携氧血红蛋白分子的百分率。SpO2容积描记参数还能提供脉率信号和容积描记波。 SpO2 容积描记参数测量原理 血氧饱和度用脉动血氧定量法测定。这是一种连续的、无创伤测定血红蛋白氧合饱和度 的方法。它测定的是从传感器光源一方发射的光线有多少穿过病人组织（如手指或者耳朵），到达另一方的接收器。传感器可测量的波长通常红色LED是660nm，红外线LED是940nm。LED的最大可选输出功率是4mＷ。 穿过的光线数量取决于多种因素，其中大多数是恒定的。但是，这些因素之一即动脉血 流随时间而变化，因为它是脉动的。通过测定脉动期间吸收的光线，就可能获得动脉血液的血氧饱和度。检测脉动本身就可给出一个“容积描记”波形和脉率信号。在主屏上可以显示“SpO2”值和“容积描记”波形。 本手册中的SPO2是指通过无创方法测得的人体功能血氧饱和度。 警告 如果存在着碳氧血红蛋白，高铁血红蛋白或染料稀释化学药品，则SpO2值会有偏差。 Sp02容积描记参数测量 ■在主屏上可以显示“Sp02”值和“容积描记”波形。 ■本手册中的SP02是指通过无创方法测得的人体功能血氧饱和度。 如果存在着碳氧血红蛋白，高铁血红蛋白或染料稀释化学药品，则Sp02值会有偏差。 血氧饱和度/脉搏监护 电外科设备的电缆不能与传感器电缆缠绕在一起。 不要把传感器放在有动脉导管或静脉注射管的肢体上。 不要将血氧探头与血压袖套血压测量放在同一肢体上，因为血压测量过程中血流闭塞会影响血氧饱和度读数。 ■确保指甲遮住光线。■探头线应该置于手背。 ■ Sp02值总显示在固定地方。■脉率仅在如下情况下显示： 1) 在ECG菜单中将“心率来源”设定为“SP02”或“全选”。 2) 在ECG菜单中将“心率来源”设定为“自动”，且此时没有ECG信号。 Sp02波形与脉搏量不成比例。 在开始监护以前，应先检查传感器电缆是否正常。当把Sp02传感器电缆从插口上拔去时，屏幕将显示“传感器脱落”的错误信息，并同时触发声音报警。 如果传感器包装或者传感器有受损的征象，则不要使用此Sp02传惑器，应把它退还给厂家。连续的，过长时间的监护可能会增加不希望发生的皮肤特征变化的危险，例如异常敏感、变红、起泡或压迫性坏死，特别是在新生儿或是在具有灌注障碍以及变化的或不成熟皮肤形态图的病人身上。特别要注意根据皮肤的质量变化，正确的光路对准和贴附方法来检查传感器安放位置。要定期地检查传感器贴附位置并在皮肤质量下降时改变贴附的位置。由于个别病人状态的不同，可能要求进行更频繁的检查。 2、血氧饱和度监护操作方法 Sp02容积描记测量 1) 打开监护仪； 2) 把传感器贴在病人手指的适当位置上；3) 把传感器电缆线一端的连接器插Sp02孔。

颈内静脉血氧饱和度监测

颈内静脉血氧饱和度监测 颈内静脉血氧饱和度监测 一、脑血流及脑代谢的生理 1．脑血流与代谢的关系 脑组织主要依靠葡萄糖在线粒体内的有氧氧化而获得能量，其中约有60％用于保持和恢复细胞膜除极和复极所必需的细胞内外离子浓度差，约40％用于维持细胞的完整性。虽然脑仅占体重的2%,但其代谢却需要15％心输出量。未麻醉的人CMRO约为 3.5ml 100g/min，CBF约为50ml 100g/min，其中80%的血量供应灰质，20%供应白质。 正常情况下，脑摄氧量为总氧供的25％，CBF和CMRO并不是始终保持不变，随着脑代谢活动的变化而变化。CBF受代谢需要的调节，这种现象被称为"代谢-血流偶联"，它是CBF自主调节过程的一部分，另一部分为压力－血流自主调节。调节CBF的压力变化范围很大，当CBF不随平均动脉压(在正常范围内)而变时，说明脑血流的压力－血流自主调节在起作用，当CBF随平均动脉压而变时，说明脑血流的压力－血流自主调节作用丧失。有许多生理因素可影响CBF 和/或CMRO，如：脑温度、PaCO2、PaO2、血液粘滞度、超出调节范围的平均动脉压、颅内压(ICP)、和中心静脉压(CVP)等。 2．脑血流与脑缺血 当CBF降低，以至不能满足脑的代谢需要时，即发生脑缺血。脑缺血的发生决定于CBF/CMRO平衡。CBF下降不一定发生脑缺血

(如果CMRO也同时下降);相反,CBF不低也可能会发生脑缺血(如果脑代谢高于血供时),所以,考察脑缺血应将CBF与CMRO结合起来才更有意义。CBF下降程度和脑缺氧时间决定了脑缺血性损伤的程度。在常温下脑缺血阈值。 在低温和麻醉下，CMRO降,这些阈值可发生变化，比如中低温CPB 时，CBF可降至10-20ml 100g/min，CMRO可降至0.5ml 100g/min,当灌注流量高于脑代谢需要时，临床上可由颈内静脉血氧饱和度反映出来。 二、颈内静脉血氧饱和度与CBF/CMRO的关系及临床意义 1．颈内静脉血氧饱和度与CBF/CMRO的关系 理论上：颈内静脉血氧饱和度(SjO2)为动脉血氧饱和度(SaO2)减脑氧代谢率(CMRO)与脑氧供(CDRO)之比，即：SjO 2＝SaO2－(CMRO/CDRO) 。CPB时SaO2约为１，CDRO可转变为CBF×CaO2(动脉血氧含量)，故上方程变为：SjO2＝１－CMRO/CBF×CaO2。由此可见：SjO2与CBF/CMRO有函数关系。通过SjO2可反映CBF/CMRO 的变化。 2．颈内静脉血氧饱和度监测的临床意义 目前脑缺血的监测主要指标为CBF及CMRO ，但这两项指标影响因素较多，在临床上进行有一定困难，而且单独监测CBF或CMRO 均不能反映脑氧代谢的供需平衡[j1]，所以人们在寻找临床上简单、实用的指标。从上述SjO2与CBF/CMRO的关系可看出通过SjO2变化可反映CBF/CMRO的变化。

混合静脉血氧饱和度监测在多脏器功能衰竭患者中的临床应用

混合静脉血氧饱和度监测在多脏器功能衰竭患者中的临床应用 混合静脉血氧饱和度(Mixed V enous OxygenSaturation,SvO2)是反映组织氧合程度、组织灌注水平的一个良好指标可动态反映氧平衡的变化[1]。1959 年Boyd 应用Sv02预测心脏术后病人心血管状态,1973年SvO2 连续监测应用于临床，随着SvO2 测定方法的不断改进，近年已广泛用于临床究当SvO2 降低时，反映机体氧供减少和(或)氧耗增加。近年研究表明，SvO2可用于心脏手术后、心力衰竭和呼吸衰竭及败血症休克中氧平衡的检测，有着重要临床意义。现对我院56例ICU患者的混合静脉血氧饱和度监测结果进行临床分析。探讨SvO2在ICU患者中的作用。 1、临床资料 病例：56例患者中男34例，女22例，年龄46-91岁。重症肺炎37例，冠脉搭桥术后9例，大手术后6例，心肺复苏术后4例。 2、结果 在混合静脉血氧饱和度监测中，显示脏器衰竭数目与平均混合静脉血氧饱和度的变化有相关性（见表1）。并且平均混合静脉血样饱和度与患者预后亦有一定的相关性，即混合静脉血氧饱和度越低，死亡率越高。 表一56例患者混合静脉血氧饱和度与脏器衰竭数目的关系 脏器衰竭数目（个）平均SvO2 2 3 4 大于等于5 小于等于0.700 1 小于等于0.600 7 2 1 1 小于等于0.500 8 8 4 1 小于等于0.400 2 1 2 3 表2 平均SVO2与患者预后的关系 脏器衰竭数目病例数平均SvO2 死亡例数病死率（％） 2 18 0.538 3 16.7 3 11 0.501 6 54.5 4 7 0.48 5 5 71.4 大于等于5 5 0.447 4 80.0 合剂41 0.487 18 43.9 3讨论 虽然MOF的首发衰竭脏器可以是心脏、胃肠，但更多的资料表明肺为最常见的首发衰季器官。本组的观察也表明，肺脏仍然是首发衰竭器官，是最容易受累的靶器官，感染、创伤、、大手术引起组织的低灌注，微循环障碍，组织细胞缺氧，细胞能量代谢受损，无氧代谢产物增多，中性粒细胞释放大量炎性介质，可损害重要脏器，从而产生MOF。而肺脏由于微血管调节功能障碍，输血中有形成分碎片的作用，引起微小血栓栓塞，使其顺应性降低，