A comparison of central and mixed venous oxygen saturation in circulatory failure

Central Venous Oxygen Saturation for Estimating Mixed Venous Oxygen Saturation and Cardiac Index in the ICU: A Systematic Review and Meta-Analysis

OBJECTIVES

The objectives of our systematic review and meta-analyses were to determine the diagnostic accuracy of central venous oxygen saturation (Scvo2) in estimating mixed venous oxygen saturation (Svo2) and cardiac index in critically ill patients.

DATA SOURCES

A systematic search using MEDLINE, Cochrane Central Register of Controlled Trials, and Embase was completed on May 6, 2024.

STUDY SELECTION

Studies of patients in the ICU for whom Scvo2 and at least one reference standard test was performed (thermodilution and/or Svo2) were included.

DATA EXTRACTION

Individual patient data were used to calculate the pooled intraclass correlation coefficient (ICC) for Svo2 and Spearman correlation for cardiac index. The Quality Assessment of Diagnostic Accuracy Studies-2 and Grading Recommendations Assessment, Development, and Evaluation tools were used for the risk of bias and certainty of evidence assessments.

DATA SYNTHESIS

Of 3427 studies, a total of 18 studies with 1971 patients were identified. We meta-analyzed 16 studies (1335 patients) that used Svo2 as a reference and three studies (166 patients) that used thermodilution as reference. The ICC for reference Svo2 was 0.83 (95% CI, 0.75-0.89) with a mean difference of 2.98% toward Scvo2. The Spearman rank correlation for reference cardiac index is 0.47 (95% CI, 0.46-0.48; p < 0.0001).

CONCLUSIONS

There is moderate reliability for Scvo2 in predicting Svo2 in critical care patients with variability based on sampling site and presence of sepsis. There is limited evidence on the independent use of Scvo2 in predicting cardiac index.

Central venous oxygen saturation changes as a reliable predictor of the change of CI in septic shock: To explore potential influencing factors

PURPOSE

Assessing fluid responsiveness relying on central venous oxygen saturation (ScvO2) yields varied outcomes across several studies. This study aimed to determine the ability of the change in ScvO2 (ΔScvO2) to detect fluid responsiveness in ventilated septic shock patients and potential influencing factors.

METHODS

In this prospective, single-center study, all patients conducted from February 2023 to January 2024 received fluid challenge. Oxygen consumption was measured by indirect calorimetry, and fluid responsiveness was defined as an increase of cardiac index (CI) ≥ 10% measured by transthoracic echocardiography. Multivariate linear regression analysis was conducted to evaluate the impact of oxygen consumption, arterial oxygen saturation, CI, and hemoglobin on ScvO2 and its change before and after fluid challenge.

RESULTS

Among 49 patients (31 men, aged (59 ± 18) years), 27 were responders. The patients had an acute physiology and chronic health evaluation II score of 24 ± 8, a sequential organ failure assessment score of 11 ± 4, and a blood lactate level of (3.2 ± 3.1) mmol/L at enrollment. After the fluid challenge, the ΔScvO2 (mmHg) in the responders was greater than that in the non-responders (4 ± 6 vs. 1 ± 3, p = 0.019). Multivariate linear regression analysis suggested that CI was the only independent influencing factor of ScvO2, with R2 = 0.063, p = 0.008. After the fluid challenge, the change in CI became the only contributing factor to ΔScvO2 (R2 = 0.245, p < 0.001). ΔScvO2 had a good discriminatory ability for the responders and non-responders with a threshold of 4.4% (area under the curve = 0.732, p = 0.006).

CONCLUSION

ΔScvO2 served as a reliable surrogate marker for ΔCI and could be utilized to assess fluid responsiveness, given that the change of CI was the sole contributing factor to the ΔScvO2. In stable hemoglobin conditions, the absolute value of ScvO2 could serve as a monitoring indicator for adequate oxygen delivery independent of oxygen consumption.

Inferior and Superior Vena Cava Saturation Monitoring After Neonatal Cardiac Surgery

OBJECTIVES

Superior vena cava oxygen saturation (SVC O 2 ) monitoring is well described for early detection of hemodynamic deterioration after neonatal cardiac surgery but inferior vena cava vein oxygen saturation (IVC O 2 ) monitoring data are limited.

DESIGN

Retrospective cohort study of 118 neonates with congenital heart disease (52 single ventricle) from February 2008 to January 2014.

SETTING

Pediatric cardiac ICU.

PATIENTS

Neonates (< 30 d) with concurrent admission IVC O 2 and SVC O 2 measurements after cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary aim was to correlate admission IVC O 2 and SVC O 2 . Secondary aims included: correlate flank or cerebral near-infrared spectroscopy with IVC O 2 and SVC O 2 , respectively, and exploratory analysis to evaluate associations between oximetry data and a composite adverse outcome defined as any of the following: increasing serum lactate or vasoactive support at 2 hours post-admission, cardiac arrest, or mortality. Admission IVC O 2 and SVC O 2 correlated ( r = 0.54; p < 0.001). However, IVC O 2 measurements were significantly lower than paired SVC O 2 (mean difference, -6%; 95% CI, -8% to -4%; p < 0.001) with wide variability in sample agreement. Logistic regression showed that each 12% decrease in IVC O 2 was associated with a 12-fold greater odds of the composite adverse outcome (odds ratio [OR], 12; 95% CI, 3.9-34; p < 0.001). We failed to find an association between SVC O 2 and increased odds of the composite adverse outcome (OR, 1.8; 95% CI, 0.99-3.3; p = 0.053). In an exploratory analysis, the area under the receiver operating curve for IVC O 2 and SVC O 2 , and the composite adverse outcome, was 0.85 (95% CI, 0.77-0.92) and 0.63 (95% CI, 0.52-0.73), respectively. Admission IVC O 2 had strong correlation with concurrent flank near-infrared spectroscopy value ( r = 0.74; p < 0.001). SVC O 2 had a weak association with cerebral near-infrared spectroscopy ( r = 0.22; p = 0.02).

CONCLUSIONS

In postoperative neonates, admission IVC O 2 and SVC O 2 correlate. Lower admission IVC O 2 may identify a cohort of postsurgical neonates at risk for low cardiac output and associated morbidity.

Optimal Perfusion Targets in Cardiogenic Shock

Cardiology shock is a syndrome of low cardiac output resulting in end-organ dysfunction. Few interventions have demonstrated meaningful clinical benefit, and cardiogenic shock continues to carry significant morbidity with mortality rates that have plateaued at upwards of 40% over the past decade. Clinicians must rely on clinical, biochemical, and hemodynamic parameters to guide resuscitation. Several features, including physical examination, renal function, serum lactate metabolism, venous oxygen saturation, and hemodynamic markers of right ventricular function, may be useful both as prognostic markers and to guide therapy. This article aims to review these targets, their utility in the care of patients with cardiology shock, and their association with outcomes.

Relationship Analysis of Central Venous-to-arterial Carbon Dioxide Difference and Cardiac Index for Septic Shock

To analyze the relationship of the central venous-to-arterial carbon dioxide difference (p(cv-a)CO₂) and cardiac index (CI) in patients with septic shock, an observational study was conducted in intensive care unit (ICU). 66 consecutive patients with septic shock and central venous oxygen saturation (ScvO₂) ≥ 70% were included after early fluid resuscitation. Measurements were taken at a 6 h interval (T0, T6, T12, T18, T24) during first 24 h after their admission into ICU, including heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), p(cv-a)CO₂, cardiac index(CI, L/(min•m²)) and ScvO₂. Patients were divided into low p(cv-a)CO₂ group (n = 35) and high p(cv-a)CO₂ group (n = 31) according to a threshold of 6 mmHg for p(cv-a)CO₂ at T0. As a result, at T0, T6, T12, T18 and T24, there were respectively significant differences between low and high p(cv-a)CO₂ groups for CI (4.1 ± 1.4 vs 2.4 ± 0.6, 4.4 ± 0.9 vs 2.8 ± 0.7, 4.1 ± 1.3 vs 2.9 ± 0.6, 4.0 ± 1.3 vs 2.7 ± 0.8, 4.2 ± 1.4 vs 2.9 ± 0.8, p < 0.001 at each time point), 28-day mortality rate was 38.7%(12/31) for high p(cv-a)CO₂ group and 22.8% (8/35) for low p(cv-a)CO₂ group (p > 0.05), there were significant differences for p(cv-a)CO₂ (p < 0.05) between low and high p(cv-a)CO₂ groups, no differences for HR, MAP, CVP, ScvO₂ (p > 0.05). CI was inversely correlated with p(cv-a)CO₂ value (r = −0.804, p < 0.001), but not for ScvO₂(r = 0.08, p > 0.05). Receiver operating characteristic curve analysis confirmed the correlation of p(cv-a)CO₂ with CI (AUC: 0.782;p < 0.001; 95% confidence interval: 0.710–0.853). The cut-off value for the best predictive value of CI ≥ 2.2 L/(min·m²) was p(cv-a)CO₂ of 5.55 mmHg or lower with a sensitivity of 85.7% and specificity of 66.8%. Hence CI measured with USCOM is inversely correlated with p(cv-a)CO₂ values in guiding the resuscitation of patients with septic shock.

Pitfalls in haemodynamic monitoring in the postoperative and critical care setting

Haemodynamic monitoring is a vital part of daily practice in anaesthesia and intensive care. Although there is evidence to suggest that goal-directed therapy may improve outcomes in the perioperative period, which haemodynamic targets we should aim at to optimise patient outcomes remain elusive and controversial. This review highlights the pitfalls in commonly used haemodynamic targets, including arterial blood pressure, central venous pressure, cardiac output, central venous oxygen saturation and dynamic haemodynamic indices. Evidence suggests that autoregulation in regional organ circulation may change either due to chronic hypertension or different disease processes such as traumatic brain injury, cerebrovascular ischaemia or haemorrhage; this will influence the preferred blood pressure target. Central venous pressure can be influenced by multiple pathophysiological factors and, unless central venous pressure is very low, it is rarely useful as a predictor for fluid responsiveness. Central venous oxygen saturation can be easily increased by a high arterial oxygen tension, making it useless as a surrogate marker of good cardiac output or systemic oxygen delivery in the presence of hyperoxaemia. Many dynamic haemodynamic indices have been reported to predict fluid responsiveness, but they all have their own limitations. There is also insufficient evidence to support that giving fluid until the patient is no longer fluid responsive can improve patient-centred outcomes. With the exception in the context of preventing contrast-induced nephropathy, large randomised controlled studies suggest that excessive fluid treatment may prolong duration of mechanical ventilation without preventing acute kidney injury in the critically ill.

Central Venous-to-Arterial Carbon Dioxide Gradient as a Marker of Occult Tissue Hypoperfusion after Major Surgery

The central venous-arterial carbon dioxide tension gradient (‘CO2 gap’) has been shown to correlate with cardiac output and tissue perfusion in septic shock. Compared to central venous oxygen saturation (SCVO2), the CO2 gap is less susceptible to the effect of hyperoxia and may be particularly useful as an adjunctive haemodynamic target in the perioperative period. This study investigated whether a high CO2 gap was associated with an increased systemic oxygen extraction (O2ER >0.3) or occult tissue hypoperfusion in 201 patients in the immediate postoperative period. The median CO2 gap of all patients was 8 mmHg (IQR 6 to 9), and a large CO2 gap was very common (>6 mmHg in 139 patients [69%], 95% CI 63 to 75; >5 mmHg in 170 patients [85%], 95% CI 79 to 89). A CO2 gap <5 mmHg had a higher sensitivity (93%) and negative predictive value (74%) than a CO2 gap <6 mmHg in excluding occult tissue hypoperfusion. Of the four variables that were predictive of an increased O2ER in the multivariate analysis—CO2 gap, arterial pH, haemoglobin and arterial lactate concentrations—the CO2 gap (odds ratio 4.41 per mmHg increment, 95% CI 1.7 to 11.2, P=0.002) was most important and explained about 34% of the variability in the risk of occult tissue hypoperfusion. In conclusion, a normal CO2 gap (<5 mmHg) had a high sensitivity and negative predictive value in excluding inadequate systemic oxygen delivery and may be useful as an adjunct to other haemodynamic targets in avoiding occult tissue hypoperfusion in the perioperative setting when high inspired oxygen concentrations are used.

Perioperative cardiovascular monitoring of high-risk patients: a consensus of 12

A significant number of surgical patients are at risk of intra- or post-operative complications or both, which are associated with increased lengths of stay, costs, and mortality. Reducing these risks is important for the individual patient but also for health-care planners and managers. Insufficient tissue perfusion and cellular oxygenation due to hypovolemia, heart dysfunction or both is one of the leading causes of perioperative complications. Adequate perioperative management guided by effective and timely hemodynamic monitoring can help reduce the risk of complications and thus potentially improve outcomes. In this review, we describe the various available hemodynamic monitoring systems and how they can best be used to guide cardiovascular and fluid management in the perioperative period in high-risk surgical patients.

Clinical Predictors of a Low Central Venous Oxygen Saturation after Major Surgery: A Prospective Prevalence Study

Optimising perioperative haemodynamic status may reduce postoperative complications. In this prospective prevalence study, we investigated the associations between standard haemodynamic parameters and a low central venous oxygen saturation (ScvO2) in patients after major surgery. A total of 201 patients requiring continuous arterial and central venous pressure monitoring after major surgery were recruited. Simultaneous arterial and central venous blood gases, haemodynamic and biochemical data and perfusion index were obtained from patients at a single time-point within 24 hours of surgery. A low ScvO2 (<70%) was observed in 109 patients (54%). Use of mechanical ventilation, mean arterial pressure, central venous pressure, haemoglobin concentrations, arterial pH and lactate concentrations, arterial oxygen (PaO2) and carbon dioxide tensions (PaCO2) were all associated with a low ScvO2 in the univariate analyses. In the multivariate analysis, only a higher perfusion index (odds ratio [OR] 0.87, 95% confidence interval [CI] 0.78 to 0.98), PaO2 (OR 0.98 per mmHg increment, 95% CI 0.97 to 0.99) and PaCO2 (OR 0.88 per mmHg increment, 95% CI 0.82 to 0.95) and a lower central venous pressure (OR 1.14 per mmHg increment, 95% CI 1.04 to 1.25) were significantly associated with a reduced risk of a low ScvO2, all in a linear fashion. In conclusion, PaO2, PaCO2, perfusion index and central venous pressure were significant predictors of a low ScvO2 in patients after major surgery including cardiac surgery, suggesting that ScvO2 should always be interpreted with the arterial blood gases and that liberal perioperative fluid therapy aiming at a high central venous pressure may be detrimental in optimising ScvO2.

Central venous oxygenation: when physiology explains apparent discrepancies

Central venous oxygen saturation (ScvO₂) >70% or mixed venous oxygen saturation (SvO₂) >65% is recommended for both septic and non-septic patients. Although it is the task of experts to suggest clear and simple guidelines, there is a risk of reducing critical care to these simple recommendations. This article reviews the basic physiological and pathological features as well as the metrological issues that provide clear evidence that SvO₂ and ScvO₂ are adaptative variables with large inter-patient variability. This variability is exemplified in a modeled population of 1,000 standard ICU patients and in a real population of 100 patients including 15,860 measurements. In these populations, it can be seen how optimizing one to three of the four S(c)vO₂ components homogenized the patients and yields a clear dependency with the fourth one. This explains the discordant results observed in large studies where cardiac output was increased up to predetermined S(c)vO₂ thresholds following arterial oxygen hemoglobin saturation, total body oxygen consumption needs and hemoglobin optimization. Although a systematic S(c)vO₂ goal-oriented protocol can be statistically profitable before ICU admission, appropriate intensive care mandates determination of the best compromise between S(c)vO₂ and its four components, taking into account the specific constraints of each individual patient.

Clinical utility of central venous saturation for the calculation of cardiac index in cardiac patients

BACKGROUND

Mixed venous saturation (MVS) obtained from the distal pulmonary artery (PA) during Swan-Ganz catheterization is the criterion standard for calculating cardiac output (CO) and cardiac index (CI) with the use of the Fick method. We think that calculating CI with the use of central venous saturation (CVS) instead of PA-MVS is both feasible and accurate. Earlier studies were small, enrolled heterogeneous patient populations, and resulted in inconsistent findings.

METHODS

All patients undergoing right heart catheterization from January 2011 to January 2012 in our catheterization lab with simultaneous measurements of MVS obtained from the distal PA and CVS obtained from the superior vena cava (SVC) or right atrium (RA) were included. Out of the 902 patients enrolled, we excluded patients (n = 50) who had known cardiac shunt or dialysis fistula, had duplicate medical records, or were septic. We calculated the CI with the use of the assumed Fick method using both MVS (criterion standard) and CVS (SVC or RA saturations) in the remaining 852 patients. We measured the correlation and the agreement between the 2 methods with the use of the Pearson correlation coefficient and Bland-Altman analysis.

RESULTS

Totals of 112 patients with simultaneous PA and RA saturation measurements (group I) and 740 patients with simultaneous PA and SVC saturation measurements (group II) were included. We found an excellent linear correlation between SVC and PA saturation (r = 0.928) and between RA and PA saturation (r = 0.95). There was also an excellent correlation between CI calculated with the use of PA saturation and CI calculated with the use of SVC (r = 0.87) or RA (r = 0.93) saturation. The mean bias of CVS-derived CI compared with MVS-derived CI (criterion standard) was -0.1 (95% limits of agreement [LOA] -1 to +0.77) in the SVC group and -0.006 (LOA -0.68 to +0.69) in the RA group. Patients with low CI had stronger correlation and smaller bias between the 2 methods compared with those with normal or high CI. The presence of baseline hypoxemia, valvular heart disease, or acute coronary syndrome had no significant effect on the correlation or the bias between the 2 methods.

CONCLUSIONS

In cardiac patients, CVS can be used as a surrogate to true MVS in the calculation of CI. This method is readily available in patients who have central venous access, and may aid in early goal-directed treatment when cardiogenic shock is suspected.

Pilot study comparing sepsis management with and without electronic clinical practice guidelines in an academic emergency department

BACKGROUND

Sepsis is a potentially life-threatening condition that requires urgent management in an Emergency Department (ED). Evidence-based guidelines for managing sepsis have been developed; however, their integration into routine practice is often incomplete. Care maps may help clinicians meet guideline targets more often.

OBJECTIVES

To determine if electronic clinical practice guidelines (eCPGs) improve management of patients with severe sepsis and septic shock (SS/SS).

METHODS

The impact of an eCPG on the management of patients presenting with SS/SS over a 3-year period at a tertiary care ED was evaluated using retrospective case-control design and chart review methods. Cases and controls, matched by age and sex, were chosen from an electronic database using physician sepsis diagnoses. Data were compared using McNemar tests or paired t-tests, as appropriate.

RESULTS

Overall, 51 cases and controls were evaluated; the average age was 62 years, and 60% were male. eCPG patients were more likely to have a central venous pressure and central venous oxygen saturation measured; however, lactate measurement, blood cultures, and other investigations were similarly ordered (all p > 0.05). The administration of antibiotics within 3 h (63% vs. 41%; p = 0.03) and vasopressors (45% vs. 20%; p = 0.02) was more common in the eCPG group; however, use of corticosteroids and other interventions did not differ between the groups. Overall, survival was high and similar between groups.

CONCLUSION

A sepsis eCPG experienced variable use; however, physicians using the eCPG achieved more quality-of-care targets for SS/SS. Strategies to increase the utilization of eCPGs in Emergency Medicine seem warranted.

Central venous saturation is not an alternative to mixed venous saturation during cardiopulmonary bypass in coronary artery surgery patients

BACKGROUND

To evaluate the correlation and agreement between central venous saturation (ScvO(2)) and mixed venous saturation (SvO(2)) during cardiopulmonary bypass.

METHODS

Twenty-two consecutive patients scheduled for coronary artery surgery were prospectively included. Paired measurements of ScvO(2) and SvO(2) were performed 5 minutes after aortic cross-clamping, after each cardioplegia dose and after de-clamping of the aortic cross-clamp. ScvO(2) and SvO(2) were measured, respectively, by a fibreoptic catheter in the superior vena cava and on blood samples from the venous return line of the extracorporeal circuit, using a blood gas analyser

RESULTS

Ninety-five paired measurements of venous saturation were obtained. Correlation between the measurements was associated with an r = 0.55. The mean bias was 2.2 [Limits of agreement: -13.6%, +18%]. Changes in oxygen saturation over time showed an r = 0.4 and a mean bias of 0.2 [Limits of agreement: -17.9%, +18.3%]. Multivariate analysis identified the oxygen consumption index as the only factor explaining this variability.

CONCLUSIONS

Although mean biases between the measurements were low, limits of agreement were too large to provide a clinically acceptable estimation of SvO(2) by ScvO(2) in these conditions. Variations in regional oxygen consumption seem to be the main factor worsening the relationship.

Use of central venous oxygen saturation to guide therapy

The use of pulmonary artery catheters has diminished, so that other technologies are emerging. Central venous oxygen saturation measurement (ScvO₂) as a surrogate for mixed venous oxygen saturation measurement (SvO₂) is simple and clinically accessible. To maximize the clinical utility of ScvO₂ (or SvO₂) measurement, it is useful to review what the measurement means in a physiologic context,how the measurement is made, important limitations, and how this measurement may be helpful in common clinical scenarios. Compared with cardiac output measurement, SvO₂ is more directly related to tissue oxygenation. Furthermore,when tissue oxygenation is a clinical concern, SvO₂ is less prone to error compared with cardiac output, where small measurement errors may lead to larger errors in interpreting adequacy of oxygen delivery. ScvO₂ should be measured from the tip of a central venous catheter placed close to, or within, the right atrium to reduce measurement error. Correct clinical interpretation of SvO₂, or its properly measured ScvO₂ surrogate, can be used to (1) estimate cardiac output using the Fick equation, (2) better understand whether a patient's oxygen delivery is adequate to meet their oxygen demands, (3) help guide clinical practice, particularly when resuscitating patients using validated early goal directed therapy treatment protocols, (4) understand and treat arterial hypoxemia, and (5) rapidly estimate shunt fraction (venous admixture).

Clinical review: use of venous oxygen saturations as a goal - a yet unfinished puzzle

Shock is defined as global tissue hypoxia secondary to an imbalance between systemic oxygen delivery and oxygen demand. Venous oxygen saturations represent this relationship between oxygen delivery and oxygen demand and can therefore be used as an additional parameter to detect an impaired cardiorespiratory reserve. Before appropriate use of venous oxygen saturations, however, one should be aware of the physiology. Although venous oxygen saturation has been the subject of research for many years, increasing interest arose especially in the past decade for its use as a therapeutic goal in critically ill patients and during the perioperative period. Also, there has been debate on differences between mixed and central venous oxygen saturation and their interchangeability. Both mixed and central venous oxygen saturation are clinically useful but both variables should be used with insightful knowledge and caution. In general, low values warn the clinician about cardiocirculatory or metabolic impairment and should urge further diagnostics and appropriate action, whereas normal or high values do not rule out persistent tissue hypoxia. The use of venous oxygen saturations seems especially useful in the early phase of disease or injury. Whether venous oxygen saturations should be measured continuously remains unclear. Especially, continuous measurement of central venous oxygen saturation as part of the treatment protocol has been shown a valuable strategy in the emergency department and in cardiac surgery. In clinical practice, venous oxygen saturations should always be used in combination with vital signs and other relevant endpoints.

Should We Monitor ScVO(2) in Critically Ill Patients?

Hemodynamic monitoring has become a real challenge in the intensive care unit. As an integrative parameter for oxygen supply/demand, venous oxygen saturation (SvO₂) provided by pulmonary artery catheterization is one of the most popular parameters to assess the adequacy of cardiac output. However, technical limitations and potential iatrogenic complications constitute important limits for a widespread use. Regular central venous catheters coupled with a fiberoptic lumen for central venous oxygen saturation (ScvO₂) monitoring have been proposed as a surrogate for SvO₂ monitoring. The purpose of the present article is to review the physiological backgrounds of circulation, the pathophysiology of circulatory failure and subsequent venous oxygen saturation alterations, and finally the merits and the limits of the use of ScvO₂ in different clinical situations.

No agreement of mixed venous and central venous saturation in sepsis, independent of sepsis origin

Introduction

Controversy remains regarding the relationship between central venous saturation (ScvO₂) and mixed venous saturation (SvO₂) and their use and interchangeability in patients with sepsis or septic shock. We tested the hypothesis that ScvO₂ does not reliably predict SvO₂ in sepsis. Additionally we looked at the influence of the source (splanchnic or non-splanchnic) of sepsis on this relationship.

Methods

In this prospective observational two-center study we concurrently determined ScvO₂ and SvO₂ in a group of 53 patients with severe sepsis during the first 24 hours after admission to the intensive care units in 2 Dutch hospitals. We assessed correlation and agreement of ScvO₂ and SvO₂, including the difference, i.e. the gradient, between ScvO₂ and SvO₂ (ScvO₂ - SvO₂). Additionally, we compared the mean differences between ScvO₂ and SvO₂ of both splanchnic and non-splanchnic group.

Results

A total of 265 paired blood samples were obtained. ScvO₂ overestimated SvO₂ by less than 5% with wide limits of agreement. For changes in ScvO₂ and SvO₂ results were similar. The distribution of the (ScvO₂ - SvO₂) (< 0 or ≥ 0) was similar in survivors and nonsurvivors. The mean (ScvO₂ - SvO₂) in the splanchnic group was similar to the mean (ScvO₂ - SvO₂) in the non-splanchnic group (0.8 ± 3.9% vs. 2.5 ± 6.2%; P = 0.30). O₂ER (P = 0.23) and its predictive value for outcome (P = 0.20) were similar in both groups.

Conclusions

ScvO₂ does not reliably predict SvO₂ in patients with severe sepsis. The trend of ScvO₂ is not superior to the absolute value in this context. A positive difference (ScvO₂ - SvO₂) is not associated with improved outcome.