Hemodynamic monitoring in shock and implications for management. International Consensus Conference, Paris, France, 27-28 April 2006

In-vitro evaluation of the PediaSat continuous central venous oxygenation monitoring system

BACKGROUND AND OBJECTIVE

In-vitro performance of the PediaSat system for continuous monitoring of central venous oxygen saturation by spectrophotometry has been evaluated.

METHODS

PediaSat continuous fibre-optic oximetry catheters were inserted in a black testing chamber, connected with an extracorporeal circuit and filled with human whole blood. Oxygen inflow into the cardiopulmonary bypass system was varied, and the testing chamber was perfused with blood flow of 1000 ml min(-1). Oxygen saturation values measured by PediaSat (S PediaSat O2) were compared with cooximetry (S CO-OX O2) values from simultaneously taken blood samples by Bland-Altman and simple regression analyses.

RESULTS

Fifty data pairs were obtained. S PediaSat O2 and S CO-OX O2 values ranged between 28-98 and 24.9-99.5%, respectively. Correlation between S PediSat O2 and S CO-OX O2 was high with an r2 value equal to 0.96 (P < 0.0001). Overall, S PediaSat O2 only slightly overestimated S CO-OX O2 (mean bias +2.9%), and limits of agreement (+/-2 SD of bias) were acceptable (-6.8/+12.6%). Sensitivity and specificity of the first differences of S PediaSat O2 and S CO-OX O2 were 1.0 and 0.92, respectively. Subgroup analysis of S CO-OX O2 values below 70% resulted in an overestimation by S PediaSat O2, with a mean bias of +5.2% and limits of agreement of -4.7 and +15.1%.

CONCLUSION

The current version of the PediaSat system does not reliably reflect S CO-OX O2 values below 70%, but it seems to be a useful tool providing an accurate trend of continuous central venous oxygen saturation.

Cardiac function index provided by transpulmonary thermodilution behaves as an indicator of left ventricular systolic function

OBJECTIVE

To test whether cardiac function index could actually behave as an indicator of left ventricular systolic function by testing if 1) it increased with inotropic stimulation; 2) it was not altered by fluid loading; 3) it correlated with the echographic left ventricular ejection fraction, considered as the clinical gold standard for measuring left ventricular systolic function, and it reliably tracked the changes in left ventricular ejection fraction during therapeutic intervention. The transpulmonary thermodilution calculates the cardiac function index, which is the ratio of cardiac output over global end-diastolic volume.

DESIGN

Prospective study.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

Thirty-nine patients (n = 48 cases) with acute circulatory failure.

INTERVENTION

A 500-mL saline administration (n = 24 cases) and a dobutamine infusion (n = 24 cases).

MEASUREMENTS AND MAIN RESULTS

We simultaneously measured left ventricular ejection fraction (monoplane or biplane Simpson method) and cardiac function index at baseline and after saline and dobutamine administration. As volume expansion altered neither left ventricular ejection fraction (47 +/- 11% to 47 +/- 11%) nor cardiac function index (4.5 +/- 2.2 to 4.5 +/- 2.1 min(-1)), dobutamine infusion significantly increased left ventricular ejection fraction by 32 +/- 28% and cardiac function index by 29 +/- 22%. Considering the 96 cardiac function index:left ventricular ejection fraction pairs of measurements, cardiac function index and left ventricular ejection fraction were correlated significantly (r = .67, p < .05). A cardiac function index <3.2 min(-1) predicted a left ventricular ejection fraction of <35% with a sensitivity of 81% and a specificity of 88%. Importantly, the changes in left ventricular ejection fraction and in cardiac function index during fluid and dobutamine administration were correlated significantly (r = .79, p < .05).

CONCLUSIONS

Cardiac function index fulfilled the criteria required from a clinical indicator of left ventricular global systolic function. Thus, it could serve as an easy bedside detection of the alteration in left ventricular ejection fraction that should alert the physician and incite to perform an echocardiography. Furthermore, cardiac function index tracked accurately the effects of an inotropic therapy.

Blood lactate monitoring in critically ill patients: a systematic health technology assessment

OBJECTIVE

To decide whether the use of blood lactate monitoring in critical care practice is appropriate. We performed a systematic health technology assessment as blood lactate monitoring has been implemented widely but its clinical value in critically ill patients has never been evaluated properly.

DATA SOURCE

PubMed, other databases, and citation review.

STUDY SELECTION

We searched for lactate combined with critically ill patients as the target patient population. Two reviewers independently selected studies based on relevance for the following questions: Does lactate measurement: 1) perform well in a laboratory setting? 2) provide information in a number of clinical situations? 3) relate to metabolic acidosis? 4) increase workers' confidence? 5) alter therapeutic decisions? 6) result in benefit to patients? 7) result in similar benefits in your own setting? 8) result in benefits which are worth the extra costs?

DATA EXTRACTION AND SYNTHESIS

We concluded that blood lactate measurement in critically ill patients: 1) is accurate in terms of measurement technique but adequate understanding of the (an)aerobic etiology is required for its correct interpretation; 2) provides not only diagnostic but also important prognostic information; 3) should be measured directly instead of estimated from other acid-base variables; 4) has an unknown effect on healthcare workers' confidence; 5) can alter therapeutic decisions; 6) could potentially improve patient outcome when combined with a treatment algorithm to optimize oxygen delivery, but this has only been shown indirectly; 7) is likely to have similar benefits in critical care settings worldwide; and 8) has an unknown cost-effectiveness.

CONCLUSIONS

The use of blood lactate monitoring has a place in risk-stratification in critically ill patients, but it is unknown whether the routine use of lactate as a resuscitation end point improves outcome. This warrants randomized controlled studies on the efficacy of lactate-directed therapy.

Alcohol consumption and development of acute respiratory distress syndrome: a population-based study

This retrospective population-based study evaluated the effects of alcohol consumption on the development of acute respiratory distress syndrome (ARDS). Alcohol consumption was quantified based on patient and/or family provided information at the time of hospital admission. ARDS was defined according to American-European consensus conference (AECC). From 1,422 critically ill Olmsted county residents, 1,357 had information about alcohol use in their medical records, 77 (6%) of whom developed ARDS. A history of significant alcohol consumption (more than two drinks per day) was reported in 97 (7%) of patients. When adjusted for underlying ARDS risk factors (aspiration, chemotherapy, high-risk surgery, pancreatitis, sepsis, shock), smoking, cirrhosis and gender, history of significant alcohol consumption was associated with increased risk of ARDS development (odds ratio 2.9, 95% CI 1.3–6.2). This population-based study confirmed that excessive alcohol consumption is associated with higher risk of ARDS.

Precision of transpulmonary thermodilution: how many measurements are necessary?

BACKGROUND AND OBJECTIVES

To analyse the precision of transpulmonary thermodilution from the PiCCO technique (Pulsion Medical System, Munich, Germany) in everyday intensive care practice in order to ascertain the minimum number of measurements necessary for scientific precision.

METHODS

An observational study in the medical-surgical ICU of a teaching hospital was performed. Thirty consecutive patients from a mixed intensive care population using the PiCCO haemodynamic monitor were included. Five thermodilution measurements were repeated at 2 min intervals. The variability of the cardiac index and the global end-diastolic volume index was analysed with respect to the five consecutive measurements and the mean of the first two, first three, first four and all five measurements.

RESULTS

There was similar distribution among the different measurements and means. The variability of the cardiac index and global end-diastolic volume index, represented by the standard error of means, the coefficient of errors and the confidence intervals, revealed a similar precision in separate measurements and in the different averaging techniques. The coefficient of errors was less than 5% even when calculating the mean of the first two measurements, meeting the criterion of scientific precision, and including patients with arrhythmia and varying blood pressure.

CONCLUSION

Calculating the mean of two good-quality transpulmonary thermodilution measurements is equivalent to the other averaging techniques (three to five measurements) for the cardiac index and global end-diastolic volume index. Any further repeated measurements may be unnecessary and may contribute to volume overloading.

Transpulmonary thermodilution-derived cardiac function index identifies cardiac dysfunction in acute heart failure and septic patients: an observational study

INTRODUCTION

There is limited clinical experience with the single-indicator transpulmonary thermodilution (pulse contour cardiac output, or PiCCO) technique in critically ill medical patients, particularly in those with acute heart failure (AHF). Therefore, we compared the cardiac function of patients with AHF or sepsis using the pulmonary artery catheter (PAC) and the PiCCO technology.

METHODS

This retrospective observational study was conducted in the medical intensive care unit of a university hospital. Twelve patients with AHF and nine patients with severe sepsis or septic shock had four simultaneous hemodynamic measurements by PAC and PiCCO during a 24-hour observation period. Comparisons between groups were made with the use of the Mann-Whitney U test. Including all measurements, correlations between data pairs were established using linear regression analysis and are expressed as the square of Pearson's correlation coefficients (r2).

RESULTS

Compared to septic patients, AHF patients had a significantly lower cardiac index, cardiac function index (CFI), global ejection fraction, mixed venous oxygen saturation (SmvO2) and pulmonary vascular permeability index, but higher pulmonary artery occlusion pressure. All patients with a CFI less than 4.5 per minute had an SmvO2 not greater than 70%. In both groups, the CFI correlated with the left ventricular stroke work index (sepsis: r2 = 0.30, P < 0.05; AHF: r2 = 0.23, P < 0.05) and cardiac power (sepsis: r2 = 0.39, P < 0.05; AHF: r2 = 0.45, P < 0.05).

CONCLUSIONS

In critically ill medical patients, assessment of cardiac function using transpulmonary thermodilution technique is an alternative to the PAC. A low CFI identifies cardiac dysfunction in both AHF and septic patients.

[Volume status and central venous pressure]

Values of intramural or even transmural central venous pressure (CVP) as well as values of pulmonary artery occluded pressure do not correlate with the values of measured circulating blood volume or with responsiveness to fluid challenge. The veins contain approximately 70% of the total blood volume and are 30 times more compliant than arteries, therefore, changes in blood volume within the veins are associated with relatively small changes in venous pressure. The main reason for a lack of correlation between CVP values and blood volume is that the body does everything possible to maintain homeostasis and adequate transmural CVP is a must for cardiovascular function. The most accurate measurement of volume status would be the mean circulatory filling pressure (MCFP), which cannot be measured in a clinical setting. Stressed volume determines MCFP and directly affects venous return and cardiac output whereas unstressed volume is a reserve of blood that can be mobilized into circulation when needed. Both stressed and unstressed volume cannot be adequately measured. Therefore, considering the complexity of the physiologic feedback and clinical picture, robust reflexes and homeostatic mechanisms, CVP is insufficient as a surrogate parameter for assessing the volume status.

Tracking hypotension and dynamic changes in arterial blood pressure with brachial cuff measurements

BACKGROUND

Arterial cannulation is strongly recommended during shock. Nevertheless, this procedure is associated with significant risks and may delay other emergent procedures. We assessed the discriminative power of brachial cuff oscillometric noninvasive blood pressure (NIBP) for identifying patients with an invasive mean arterial blood pressure (MAP) below 65 mm Hg or increasing their invasive MAP after cardiovascular interventions.

METHODS

This prospective study, conducted in three intensive care units, included adults in circulatory failure who underwent 45 degrees passive leg raising, 300 mL fluid loading, and additional 200 mL fluid loading. The collected data were four invasive and noninvasive MAP measurements at each study phase.

RESULTS

Among 111 patients (50 septic, 15 cardiogenic, and 46 other source of shock), when averaging measurements of each study phase, NIBP measurements accurately predicted an invasive MAP lower than 65 mm Hg: area under the receiver operating characteristic curve 0.90 (95% CI: 0.71-1), positive and negative likelihood ratios 7.7 (95% CI: 5.4-11) and 0.31 (95% CI: 0.22-0.44) (cutoff 65 mm Hg). For identifying patients increasing their invasive MAP by more than 10%, the area under the receiver operating characteristic curve was 0.95 (95% CI: 0.92-0.96); positive and negative likelihood ratios (cutoff 10%) were 25.7 (95% CI: 10.8-61.4) and 0.26 (95% CI: 0.2-0.34).

CONCLUSIONS

NIBP measurements have a good discriminative power for identifying hypotensive patients and performed even better in tracking MAP changes, provided that one averages four NIBP measurements.

Intraoperative hemodynamic monitoring during organ transplantation: what is new?

PURPOSE OF REVIEW

To highlight the recent developments in hemodynamic monitoring during liver and lung transplantation.

RECENT FINDINGS

Even though a consensus on intraoperative hemodynamic monitoring is still lacking, the most frequently monitoring tool used is the pulmonary artery catheter (PAC). The filling pressures are widely accepted as not being able to accurately define cardiac preload. On the contrary, the use of transesophageal echocardiography (TEE), although it is operator dependent and requires a prolonged training, is increasing during the intraoperative period to directly evaluate the cardiovascular function. New frontiers have been opened by the transpulmonary thermodilution: intrathoracic blood volume has been shown to have a better correlation with preload than the filling pressures. The advanced modified PAC permits evaluation of the right heart function and preload. Recently, right ventricular end diastolic volume has been shown to correlate better with preload than the filling pressures and also the left ventricular end diastolic area.

SUMMARY

The PAC still represents the most used intraoperative hemodynamic monitoring technique. TEE is increasing in popularity. Recent studies demonstrate that volumetric monitoring conducted with transpulmonary thermodilution and advanced volumetric PAC give good definition of preload and should be implemented in clinical practice.

Innate immune responses to danger signals in systemic inflammatory response syndrome and sepsis

The systemic immune response induced by non-infectious agents is called systemic inflammatory response syndrome (SIRS) and infection-induced systemic immune response is called sepsis. The host inflammatory response in SIRS and sepsis is similar and may lead to multiple organ dysfunction syndrome (MODS) and ultimately death. The mortality and morbidity in SIRS and sepsis (i.e. critical illness) remain high despite advances in diagnostic and organ supporting possibilities in intensive care units. In critical illness, the acute immune response is organized and executed by innate immunity influenced by the neuroendocrine system. This response starts with sensing of danger by pattern-recognition receptors on the immune competent cells and endothelium. The sensed danger signals, through specific signalling pathways, activate nuclear transcription factor kappaB and other transcription factors and gene regulatory systems which up-regulate the expression of pro-inflammatory mediators. The plasma cascades are also activated which together with the produced pro-inflammatory mediators stimulate further the production of inflammatory biomarkers. The acute inflammatory response underlies the pathophysiological mechanisms involved in the development of MODS. The inflammatory mediators directly affect organ function and cause a decline in remote organ function by mediating the production of nitric oxide leading to mitochondrial anergy and cytopathic hypoxia, a condition of cellular inability to use oxygen. Understanding the mechanisms of acute immune responses in critical illness is necessary for the development of urgently needed therapeutics. The aim of this review is to provide a description of the key components and mechanisms involved in the immune response in SIRS and sepsis.

Serum concentration of chromogranin A at admission: an early biomarker of severity in critically ill patients

BACKGROUND

Chromogranin A (CGA), a stress marker released with catecholamines by the adrenal medulla, has never been associated with acute inflammation in critically ill patients.

AIM

To determine evidence for a link between serum concentration of CGA, biomarkers of inflammation, and outcome inpatients admitted with or without the systemic inflammatory response syndrome (SIRS).

METHODS

At admission, we measured in 53 patients and 14 healthy controls the serum concentrations of CGA,procalcitonin, and C-reactive protein. We also assessed the Simplified Acute Physiological Score (SAPS) in the patients.

RESULTS

Serum CGA concentrations were significantly increased in SIRS patients with a median value of 115 microg/L (68.0-202.8), when compared to healthy controls (PB0.001). In cases where infection was associated with SIRS, patients had the highest increase in CGA with a median value of 138.5 microg/L (65-222.3) (PB0.001). CGA concentrations positively correlated with inflammation markers (procalcitonin, C-reactive protein), but also with SAPS. Receiver operating characteristic (ROC) analysis showed that CGA is equivalent to SAPS as an indicator for 28-day mortality (area under curve (AUC) for both: 0.810).

CONCLUSIONS

Patients with CGA concentration superior to 71 microg/L have a significantly shorter survival. A Cox model confirmed that CGA and SAPS were independent predictors of outcome.

Near-infrared spectroscopy correlates with continuous superior vena cava oxygen saturation in pediatric cardiac surgery patients

BACKGROUND

Cerebral regional oxygen saturation (rSO(2)) measured with near-infrared spectroscopy (NIRS) has a well-proven clinical utility. A goal-oriented treatment based on the rSO(2) resulted in a significant reduction in major morbidity and in a shortening of postoperative hospital stay in patients undergoing coronary revascularization. In this study, we have compared the values of superior vena cava saturation (ScvO(2)) continuously measured with a Pediasat catheter and the corresponding NIRS rSO(2) values obtained during cardiac operations in pediatric patients.

METHODS

This was a prospective observational study enrolling fifteen pediatric patients (age: 6 days-7 years) undergoing cardiac operations. ScvO(2) data obtained with the Pediasat during the operation were compared with simultaneously recorded NIRS rSO(2) values.

RESULTS

One hundred and seventeen matched sets of data were obtained during the operation. ScvO(2) continuously measured with the Pediasat was significantly correlated with the corresponding NIRS rSO(2) values. However, there was a constant positive bias (ScvO(2) values were higher than NIRS rSO(2) values) of 5.6%, with a precision of 10.4%. Time-related percentage changes of NIRS rSO(2) were significantly correlated with the corresponding ScvO(2) percentage changes. A decrease in ScvO(2) is predictive for a decrease in rSO(2) with a sensitivity of 73.7% and a specificity of 85.7%.

CONCLUSIONS

The continuous measurement of ScvO(2) values obtained by the Pediasat may provide useful information about the metabolic conditions of the brain during cardiac operations in pediatric patients if considered as percentage changes. Absolute values of ScvO(2) tend to overestimate the correspondent rSO(2) values.

Nurses' prediction of volume status after aneurysmal subarachnoid haemorrhage: a prospective cohort study

Introduction

Patients who have suffered aneurysmal subarachnoid haemorrhage (SAH) often have derangements in blood volume, contributing to poor outcome. To guide fluid management, regular assessments of volume status must be conducted. We studied the ability of nursing staff to predict hypovolaemia or hypervolaemia, based on their interpretation of available haemodynamic data.

Methods

In a prospective cohort study, intensive care unit and medium care unit nurses, currently treating patients with recent SAH, were asked to predict present volume status. For their assessment they could use all available haemodynamic parameters (for example, heart rate, blood pressure, fluid balance). The nurses' assessments were compared with the actual circulating blood volume (CBV), as measured daily with pulse dye densitometry during the first 10 days after SAH. Normovolaemia was defined as a CBV of 60 to 80 ml/kg body weight; hypovolaemia as CBV under 60 ml/kg; severe hypovolaemia as CBV under 50 ml/kg and hypervolaemia as CBV above 80 ml/kg.

Results

A total of 350 combinations of volume predictions and CBV measurements were obtained in 43 patients. Prediction of hypovolaemia had a sensitivity of 0.10 (95% confidence interval [CI] = 0.06 to 0.16) and a positive predictive value of 0.37 (95% CI = 0.23 to 0.53) for actual hypovolaemia. The prediction of hypervolaemia had a sensitivity of 0.06 (95% CI = 0.01 to 0.16) and a positive predictive value of 0.06 (95% CI = 0.02 to 0.19) for actual hypervolaemia. Mean CBV was significantly lower in instances considered hypervolaemic than in instances considered normovolaemic.

Conclusions

Assessment of haemodynamic condition in patients with SAH by intensive care unit or medium care unit nurses does not adequately predict hypovolaemia or hypervolaemia, as measured using pulse dye densitometry. Fluid therapy after SAH may require guidance with more advanced techniques than interpretation of usual haemodynamic parameters.

Fetal outcomes of critically ill pregnant women admitted to the intensive care unit for nonobstetric causes

INTRODUCTION

The outcome of the fetus in critically ill mothers has been briefly reported as a part of descriptive studies focusing on maternal risk factors for admission to the intensive care unit. We evaluated the risk factors for adverse fetal outcomes in critically ill pregnant women admitted to the intensive care unit for nonobstetrical reasons.

DESIGN

Retrospective cohort study of all critically ill pregnant patients >18 yr; admitted to four (medical, surgical, trauma, and mixed medical-surgical) intensive care units at the Mayo Clinic in Rochester, MN; during the period of January 1995 to December 2005. Only pregnant women admitted to the intensive care unit in the antepartum period for nonobstetrical indications were included. Main predictors for fetal outcomes included: maternal comorbidities, obstetrical history, intensive care unit interventions, and intensive care unit complications. Fetal outcomes were defined as spontaneous abortions, neonatal mortality, fetal deaths, admission to the neonatal intensive care unit, neonatal intensive care unit length of stay, and neonatal intensive care unit complications.

RESULTS

A total of 153 adult women (>18 yr) with a diagnosis of pregnancy were admitted to the intensive care unit, of whom 93 pregnant women met the inclusion criteria. Median maternal age was 26 yr (interquartile range 22-33) and median gestational age was 25 wk (interquartile range 8-33). The median maternal Acute Physiologic and Chronic Health Evaluation III score was 27 (interquartile range 17-38). There were 32 fetal losses; 18 were spontaneous abortions and 14 were fetal deaths. Ten neonates required neonatal intensive care unit admission, five for respiratory distress syndrome; and only one neonate died. The median neonatal intensive care unit length of stay was 34 days (interquartile range 15-87). After multivariable logistic regression analysis, the risk factors associated with fetal loss were: presence of maternal shock, odds ratio 6.85 (95% confidence interval 1.16-58, p = 0.04); maternal transfusion of blood products, odds ratio 7.24 (95% confidence interval 1.4-49, p = 0.02); and gestational age, odds ratio 1.2 for every gestational week below 37 wk (95% confidence interval 1.1-1.3, p < 0.001).

CONCLUSIONS

Nonobstetrical critical illness in pregnant women significantly affects fetal and neonatal outcomes. Maternal shock, maternal requirement of allogenic blood product transfusion and lower gestational age were associated with an increased risk of fetal loss.

Monitoring the critically ill emergency department patient

Many critically ill patients are remaining in the emergency department for extended periods of time, and delays in diagnosis and/or therapy may increase patient morbidity and mortality. All emergency physicians use monitoring modalities in critically ill patients to detect early cardiovascular compromise and impaired oxygen delivery before disastrous collapse occurs. The authors hope the discussion in this article regarding the monitoring of oxygenation, ventilation, arterial perfusion pressure, intravascular volume, markers of tissue hypoxia, and cardiac output will help the EP provide optimal care for this complicated patient population.

Passive leg raising for predicting fluid responsiveness: importance of the postural change

OBJECTIVE

For predicting fluid responsiveness by passive leg raising (PLR), the lower limbs can be elevated at 45 degrees either from the 45 degrees semi-recumbent position (PLR(SEMIREC)) or from the supine position (PLR(SUPINE)). PLR(SUPINE) could have a lower hemodynamic impact than PLR(SEMIREC) since it should not recruit the splanchnic venous reservoir.

DESIGN

Prospective study

SETTING

A 24-bed medical intensive care unit.

PATIENTS AND PARTICIPANTS

A total of 35 patients with circulatory failure who responded to an initial PLR(SEMIREC) by an increase in cardiac index >/= 10%.

INTERVENTIONS

PLR(SEMIREC), a transfer from the semi-recumbent to the supine position and PLR(SUPINE) were performed in all patients in a random order before fluid expansion (500 mL saline).

MEASUREMENTS AND RESULTS

PLR(SEMIREC), supine transfer and PLR(SUPINE) significantly increased the pulse-contour derived cardiac index (PiCCOplus) by 22 (17-28)%, 9 (5-15)% and 10 (7-14)% (P < 0.05 vs. PLR(SEMIREC) for the latter two), respectively. These maneuvers significantly increased the right ventricular end-diastolic area (echocardiography) by 20 (14-29)%, 9 (5-16)% and 10 (5-16)% (P < 0.05 vs. PLR(SEMIREC) for the latter two) and the central venous pressure by 33 (22-50)%, 15 (10-20)% and 20 (15-29)% (P < 0.05 vs. PLR(SEMIREC) for the latter two), respectively. Volume expansion significantly increased cardiac index by 27 (21-38)% and all patients were responders to volume expansion. If an increase in cardiac index >/= 10% is considered as a positive response to PLR(SUPINE), 15 (43%) patients would have been unduly predicted as non-responders to fluid administration by PLR(SUPINE).

CONCLUSIONS

PLR(SEMIREC) induces larger increase in cardiac preload than PLR(SUPINE) and may be preferred for predicting fluid responsiveness.

Bench-to-bedside review: the initial hemodynamic resuscitation of the septic patient according to Surviving Sepsis Campaign guidelines--does one size fit all?

The Surviving Sepsis Campaign guidelines for the management of severe sepsis and septic shock recommend that the initial hemodynamic resuscitation be done according to the protocol used by Rivers and colleagues in their well-known early goal-directed therapy (EGDT) study. However, it may well be that their patients were much sicker on admission than many other septic patients. Compared with other populations of septic patients, the patients of Rivers and colleagues had a higher incidence of severe comorbidities, a more severe hemodynamic status on admission (excessively low central venous oxygen saturation [ScvO₂], low central venous pressure [CVP], and high lactate), and higher mortality rates. Therefore, it may well be that these patients arrived to the hospital in late untreated hypovolemic sepsis, which may have been due, in part at least, to low socioeconomic status and reduced access to health care. The EGDT protocol uses target values for CVP and ScvO₂ to guide hemodynamic management. However, filling pressures do not reliably predict the response to fluid administration, while the ScvO₂ of septic patients is characteristically high due to decreased oxygen extraction. For all these reasons, it seems that the hemodynamic component of the Surviving Sepsis Campaign guidelines cannot be applied to all septic patients, particularly those who develop sepsis during their hospital stay.

Continuous monitoring of central venous oxygen saturation (Pediasat) in pediatric patients undergoing cardiac surgery: a validation study of a new technology

OBJECTIVE

Mixed venous oxygen saturation and central venous oxygen saturation are considered possible indicators of the adequacy of oxygen delivery with respect to the oxygen needs of critically ill adult and pediatric patients. The present study was aimed at validating the accuracy of a new technology (Pediasat central venous catheter) in providing a continuous measurement of the central venous oxygen saturation in pediatric patients.

DESIGN

A prospective observational study.

PARTICIPANTS

Thirty pediatric patients (age, 6 days-9 years) undergoing cardiac operations. Data obtained with the Pediasat during and after the operation were compared with simultaneously collected venous blood samples analyzed with standard laboratory techniques.

SETTING

A clinical research hospital.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A Bland and Altman analysis was performed on 30 matched sets of data collected before cardiopulmonary bypass, during cardiopulmonary bypass, and during the intensive care unit stay. Before cardiopulmonary bypass, there was a bias of 0.003, with lower and upper limits of agreement, -5.84 and 5.84 (percentage error, 17.3%). During cardiopulmonary bypass, the bias was 0.57 and lower and upper limits of agreement were -7.7 and 8.7 (percentage error, 23.2%). At 2 hours after the arrival in the intensive care unit, the bias was -0.6 and the lower and upper limits of agreement were -8 and 6.8 (percentage error, 20.3%).

CONCLUSIONS

Because of the minimal bias and the acceptable value of percentage error, the Pediasat may be considered as an accurate tool for the continuous measurement of the central venous oxygen saturation in neonates and pediatric patients during and after cardiac operations.

Passive leg raising

OBJECTIVE

To assess whether the passive leg raising test can help in predicting fluid responsiveness.

DESIGN

Nonsystematic review of the literature.

RESULTS

Passive leg raising has been used as an endogenous fluid challenge and tested for predicting the hemodynamic response to fluid in patients with acute circulatory failure. This is now easy to perform at the bedside using methods that allow a real time measurement of systolic blood flow. A passive leg raising induced increase in descending aortic blood flow of at least 10% or in echocardiographic subaortic flow of at least 12% has been shown to predict fluid responsiveness. Importantly, this prediction remains very valuable in patients with cardiac arrhythmias or spontaneous breathing activity.

CONCLUSIONS

Passive leg raising allows reliable prediction of fluid responsiveness even in patients with spontaneous breathing activity or arrhythmias. This test may come to be used increasingly at the bedside since it is easy to perform and effective, provided that its effects are assessed by a real-time measurement of cardiac output.

Liberal vs. conservative vasopressor use to maintain mean arterial blood pressure during resuscitation of septic shock: an observational study

OBJECTIVE

The optimal role of vasopressor therapy in septic shock is not known. We hypothesized that the variability in the use of vasopressors to treat hypotension is associated with subsequent organ failures.

DESIGN

Retrospective observational single-center cohort study.

SETTING

Tertiary care hospital.

PATIENTS AND PARTICIPANTS

Consecutive patients with septic shock.

MEASUREMENT AND RESULTS

Ninety-five patients were enrolled. Serial blood pressure recordings and vasopressor use were collected during the first 12h of septic shock. Median duration of hypotension that was not treated with vasopressors was 1.37h (interquartile range [IQR] 0.62-2.66). Based on the observed variability, we evaluated liberal (duration of untreated hypotension < median) vs. conservative (duration of untreated hypotensionn > median) vasopressor therapy. Compared with patients who received conservative vasopressor therapy, patients treated liberally had similar baseline organ impairment [median Sequential Organ Failure Assessment (SOFA) score 8 vs. 8, p = 0.438] were more likely to be younger (median age 70 vs. 77 years, p = 0.049), to require ventilator support (78 vs. 49%, p < 0.001), and to have progression of organ failures after 24h (59 vs. 37%, p = 0.032). When adjusted for age and mechanical ventilation, early therapy aimed at achieving global tissue perfusion [odds ratio (OR) 0.33, 95% confidence interval (CI) 0.11-0.88), and early adequate antibiotic therapy (OR 0.27, 95% CI 0.09-0.76), but not liberal vasopressor use (OR 2.13, 95% CI 0.80-5.84), prevented progression of organ failures.

CONCLUSIONS

In our retrospective study, early adequate antibiotics and achieving adequate global perfusion, but not liberal vasopressor therapy, were associated with improved organ failures after septic shock. Clinical trials which compare conservative vs. liberal vasopressor therapy are warranted.

Continuous and intermittent cardiac output measurement in hyperdynamic conditions: pulmonary artery catheter vs. lithium dilution technique

OBJECTIVE

This study aimed to assess the level of agreement of both intermittent cardiac output monitoring by the lithium dilution technique (CO(Li)) and continuous cardiac output monitoring (PulseCO(Li)) using the arterial pressure waveform with intermittent thermodilution using a pulmonary artery catheter (CO(PAC)).

DESIGN

Prospective, single-center evaluation.

SETTING

University Hospital Intensive Care Unit.

PATIENTS

Patients (n=23) receiving liver transplantation.

INTERVENTION

Pulmonary artery catheters were placed in all patients and CO(PAC) was determined using thermodilution. CO(Li) and PulseCO(Li) measurements were made using the LiDCO system.

MEASUREMENTS AND MAIN RESULTS

Data were collected after intensive care unit admission and every 8h until the 48th hour. A total of 151 CO(PAC), CO(Li) and PulseCO(Li) measurements were analysed. Bias and 95% limit of agreement were 0.11lmin(-1) and -1.84 to + 2.05 lmin(-1) for CO(PAC) vs. CO(Li) (r=0.88) resulting in an overall percentage error of 15.6%. Bias and 95% limit of agreement for CO(PAC) vs. PulseCO(Li) were 0.29 lmin(-1) and -1.87 to + 2.46 lmin(-1) (r=0.85) with a percentage error of 16.8%. Subgroup analysis revealed a percentage error of 15.7% for CO(PAC) vs. CO(Li) and 15.1% for CO(PAC) vs. PulseCO(Li) for data pairs less than 8 lmin(-1), and percentage errors of 15.5% and 18.5% respectively for data pairs higher than 8 lmin(-1).

CONCLUSION

In patients with hyperdynamic circulation, intermittent and continuous CO values determined using the LiDCO system showed good agreement with those obtained by intermittent pulmonary artery thermodilution.

Continuous monitoring of ScvO(2) by a new fibre-optic technology compared with blood gas oximetry in critically ill patients: a multicentre study

OBJECTIVE

The aim of this study was to compare the accuracy of the CeVOX monitor measuring continuous central venous saturation (ScvO(2)) with laboratory blood gas oximetry under clinical circumstances.

DESIGN

Prospective, multicentre, observational study.

SETTING

Five adult general intensive care units.

PATIENTS AND PARTICIPANTS

Fifty-three critically ill patients.

INTERVENTIONS

The fibre-optic probe was inserted into an ordinary central venous catheter's distal lumen. Blood samples were taken from this line via a Y-adapter every 8 h and ScvO(2) was measured with a laboratory co-oximeter. Patients were observed for a maximum of 5 days. Results were compared using linear regression and the Bland and Altman plots.

MEASUREMENTS AND RESULTS

The 526 matched pairs of ScvO(2) showed a significant correlation between the two methods (r = 0.79, p< 0.001). Bland-Altman plots showed an overall mean bias of -0.3% and moderate agreement (lower and upper levels of agreement: -13.2% and 12.5%). Correlation for the first time point, and for differences between the first two time points for each method revealed good correlation: (n = 53): r = 0.79, p< 0.001; (n = 50): r = 0.58, p< 0.001, respectively.

CONCLUSION

These results in a heterogeneous group of critically ill patients show that continuous ScvO(2) monitoring by the CeVOX technology yielded results comparable with those obtained by laboratory co-oximetry and therefore can be relied on in everyday clinical practice.