Mathieu Jozwiak

Extravascular lung water is an independent prognostic factor in patients with acute respiratory distress syndrome.

Objective:Acute respiratory distress syndrome might be associated with an increase in extravascular lung water index and pulmonary vascular permeability index, which can be measured by transpulmonary thermodilution. We tested whether extravascular lung water index and pulmonary vascular permeability index are independent prognostic factors in patients with acute respiratory distress syndrome. Design:Retrospective study. Setting:Medical intensive care unit. Patients:Two hundred consecutive acute respiratory distress syndrome patients (age = 57 ± 17, Simplified Acute Physiology Score II = 57 ± 20, overall day-28 mortality = 54%). Measurements:Extravascular lung water index and pulmonary vascular permeability index were collected (PiCCO device, Pulsion Medical Systems) at each day of the acute respiratory distress syndrome episode. Main Results:The maximum values of extravascular lung water index and pulmonary vascular permeability index recorded during the acute respiratory distress syndrome episode (maximum value of extravascular lung water index and maximum value of pulmonary vascular permeability index, respectively) were significantly higher in nonsurvivors than in survivors at day-28 (mean ± SD: 24 ± 10 mL/kg vs. 19 ± 7 mL/kg of predicted body weight, p < 0.001 [t-test] for maximum value of extravascular lung water index and median [interquartile range]: 4.4 [3.3–6.1] vs. 3.5 [2.8–4.4], p = 0.001 for maximum value of pulmonary vascular permeability index, Wilcoxon’s test). In multivariate analyses, maximum value of extravascular lung water index or maximum value of pulmonary vascular permeability index, Simplified Acute Physiology Score II, maximum blood lactate, mean positive end-expiratory pressure, mean cumulative fluid balance, and the minimal ratio of arterial oxygen pressure over the inspired oxygen fraction were all independently associated with day-28 mortality. A maximum value of extravascular lung water index >21 mL/kg predicted day-28 mortality with a sensitivity of (mean [95% confidence interval]) 54% (44–63)% and a specificity of 73% (63–82)%. The mortality rate was 70% in patients with a maximum value of extravascular lung water index >21 mL/kg and 43% in the remaining patients (p = 0.0003). A maximum value of pulmonary vascular permeability index >3.8 predicted day-28 mortality with a sensitivity of (mean [95% confidence interval]) 67% (57–76)% and a specificity of 65% (54–75)%. The mortality rate was 69% in patients with a maximum value of pulmonary vascular permeability index >3.8 and 37% in the group with a maximum value of pulmonary vascular permeability index ⩽3.8 (p < 0.0001). Conclusions:Extravascular lung water index and pulmonary vascular permeability index measured by transpulmonary thermodilution are independent risk factors of day-28 mortality in patients with acute respiratory distress syndrome.

Lactate and Venoarterial Carbon Dioxide Difference/Arterial-Venous Oxygen Difference Ratio, but Not Central Venous Oxygen Saturation, Predict Increase in Oxygen Consumption in Fluid Responders*

Objectives:During circulatory failure, the ultimate goal of treatments that increase cardiac output is to reduce tissue hypoxia. This can only occur if oxygen consumption depends on oxygen delivery. We compared the ability of central venous oxygen saturation and markers of anaerobic metabolism to predict whether a fluid-induced increase in oxygen delivery results in an increase in oxygen consumption. Design:Prospective study. Setting:ICU. Patients:Fifty-one patients with an acute circulatory failure (78% of septic origin). Measurements:Before and after a volume expansion (500mL of saline), we measured cardiac index, o2- and Co2-derived variables and lactate. Main Results:Volume expansion increased cardiac index ≥15% in 49% of patients (“volume-responders”). Oxygen delivery significantly increased in these 25 patients (+32% ± 16%, p < 0.0001). An increase in oxygen consumption ≥15% concomitantly occurred in 56% of these 25 volume-responders (+38% ± 28%). Compared with the volume-responders in whom oxygen consumption did not increase, the volume-responders in whom oxygen consumption increased ≥15% were characterized by a higher lactate (2.3 ± 1.1 mmol/L vs. 5.5 ± 4.0 mmol/L, respectively) and a higher ratio of the veno-arterial carbon dioxide tension difference (P(v − a)Co2) over the arteriovenous oxygen content difference (C(a − v)o2). A fluid-induced increase in oxygen consumption greater than or equal to 15% was not predicted by baseline central venous oxygen saturation but by high baseline lactate and (P(v − a)Co2/C(a − v)o2 ratio (areas under the receiving operating characteristics curves: 0.68 ± 0.11, 0.94 ± 0.05, and 0.91 ± 0.06). In volume-nonresponders, volume expansion did not significantly change cardiac index, but the oxygen delivery decreased due to a hemodilution-induced decrease in hematocrit. Conclusions:In volume-responders, unlike markers of anaerobic metabolism, central venous oxygen saturation did not allow the prediction of whether a fluid-induced increase in oxygen delivery would result in an increase in oxygen consumption. This suggests that along with indicators of volume-responsiveness, the indicators of anaerobic metabolism should be considered instead of central venous oxygen saturation for starting hemodynamic resuscitation.

Precision of the transpulmonary thermodilution measurements

IntroductionWe wanted to determine the number of cold bolus injections that are necessary for achieving an acceptable level of precision for measuring cardiac index (CI), indexed global end-diastolic volume (GEDVi) and indexed extravascular lung water (EVLWi) by transpulmonary thermodilution.MethodsWe included 91 hemodynamically stable patients (age 59 (25% to 75% interquartile range: 39 to 79) years, simplified acute physiologic score (SAPS)II 59 (53 to 65), 56% under norepinephrine) who were monitored by a PiCCO2 device. We performed five successive cold saline (15 mL, 6°C) injections and recorded the measurements of CI, GEDVi and EVLWi.ResultsConsidering five boluses, the coefficient of variation (CV, calculated as standard deviation divided by the mean of the five measurements) was 7 (5 to 11)%, 7 (5 to 12)% and 7 (6 to 12)% for CI, GEDVi and EVLWi, respectively. If the results of two bolus injections were averaged, the precision (2 × CV/√ number of boluses) was 10 (7 to 15)%, 10 (7 to 17)% and 8 (7 to 14)% for CI, GEDVi and EVLWi, respectively. If the results of three bolus injections were averaged, the precision dropped below 10%, that is, the cut-off that is generally considered as acceptable (8 (6 to 12)%, 8 (6 to 14)% and 8 (7 to 14)% for CI, GEDVi and EVLWi, respectively). If two injections were performed, the least significant change, that is, the minimal change in value that could be trusted to be significant, was 14 (10 to 21)%, 14 (10 to 24)% and 14 (11 to 23)% for CI, GEDVi and EVLWi, respectively. If three injections were performed, the least significant change was 12 (8 to 17)%, 12 (8 to 19)% and 12 (9 to 19)% for CI, GEDVi and EVLWi, respectively, that is, below the 15% cut-off that is usually considered as clinically relevant.ConclusionsThese results support the injection of at least three cold boluses for obtaining an acceptable precision when transpulmonary thermodilution is used for measuring CI, GEDVi and EVLWi.

Effects of norepinephrine on mean systemic pressure and venous return in human septic shock

Objectives:Norepinephrine exerts venoconstriction that could increase both the mean systemic pressure and the resistance to venous return, but this has not yet been investigated in human septic shock. We examined the relative importance of both effects and the resulting effect on venous return when decreasing the dose of norepinephrine. Setting:Intensive care unit. Patients:Sixteen septic shock patients. Measurements:For estimating the venous return curve, we constructed the regression line between the pairs of cardiac index (pulse contour analysis) and central venous pressure values. These values were measured during 15-sec end-inspiratory and end-expiratory ventilatory occlusions performed at two levels of positive end-expiratory pressure, in view of widening the range of cardiac index:central venous pressure measurements and increasing the accuracy of the regression line. The x-axis intercept of the regression line was used to estimate the mean systemic pressure and the inverse of the slope of the regression line to quantify resistance to venous return. These measurements were obtained before and after decreasing the dose of norepinephrine. Passive leg raising was performed before and after decreasing the dose of norepinephrine. Main Results:Decreasing the dose of norepinephrine from 0.30 (0.10–1.40) to 0.19 (0.08–1.15) µg/kg/min decreased the mean systemic pressure from 33 ± 12 mm Hg to 26 ± 10 mm Hg (p = .0003). The slope of the multipoint cardiac index:central venous pressure relationship increased (p = .02). The resistance to venous return decreased, i.e., 1/slope decreased. Simultaneously, cardiac index decreased from 3.47 ± 0.86 L/min/m2 to 3.28 ± 0.76 L/min/m2 (p = .04), indicating a decrease in venous return. Passive leg raising increased cardiac index to a larger extent after (8% ± 4%) than before (1% ± 4%) decreasing norepinephrine (p = .001), suggesting an increase in unstressed blood volume at the lowest dose of norepinephrine. Conclusions:In septic shock patients, decreasing the dose of norepinephrine decreased the mean systemic pressure and, to a lesser extent, the resistance to venous return. As a result, venous return decreased.

Beneficial Hemodynamic Effects of Prone Positioning in Patients with Acute Respiratory Distress Syndrome

RATIONALE The effects of prone positioning during acute respiratory distress syndrome on all the components of cardiac function have not been investigated under protective ventilation and maximal alveolar recruitment. OBJECTIVES To investigate the hemodynamic effects of prone positioning. METHODS We included 18 patients with acute respiratory distress syndrome ventilated with protective ventilation and an end-expiratory positive pressure titrated to a plateau pressure of 28-30 cm H2O. Before and within 20 minutes of starting prone positioning, hemodynamic, respiratory, intraabdominal pressure, and echocardiographic data were collected. Before prone positioning, preload reserve was assessed by a passive leg raising test. MEASUREMENTS AND MAIN RESULTS In all patients, prone positioning increased the ratio of arterial oxygen partial pressure over inspired oxygen fraction, the intraabdominal pressure, and the right and left cardiac preload. The pulmonary vascular resistance decreased along with the ratio of the right/left ventricular end-diastolic areas suggesting a decrease of the right ventricular afterload. In the nine patients with preload reserve, prone positioning significantly increased cardiac index (3.0 [2.3-3.5] to 3.6 [3.2-4.4] L/min/m(2)). In the remaining patients, cardiac index did not change despite a significant decrease in the pulmonary vascular resistance. CONCLUSIONS In patients with acute respiratory distress syndrome under protective ventilation and maximal alveolar recruitment, prone positioning increased the cardiac index only in patients with preload reserve, emphasizing the important role of preload in the hemodynamic effects of prone positioning.

End-expiratory Occlusion Test Predicts Preload Responsiveness Independently of Positive End-expiratory Pressure During Acute Respiratory Distress Syndrome

Objective:A 15-second end-expiratory occlusion increases cardiac preload and allows detection of preload dependence. We tested whether the reliability of this test depends upon positive end-expiratory pressure. Design:Prospective study. Setting:Medical ICU. Patients:Thirty-four patients presenting with acute circulatory failure and acute respiratory distress syndrome ventilated with a tidal volume of 6.7 mL/kg (interquartile range, 6.3–7.1). Measurements:At positive end-expiratory pressure = 5 cm H2O, we measured the changes in cardiac index induced by end-expiratory occlusion and a passive leg raising test. Preload dependence was defined by a passive leg raising–induced increase in cardiac index greater than or equal to 10%. Positive end-expiratory pressure was increased to a plateau pressure of 30 cm H2O, and end-expiratory occlusion and passive leg raising were performed again. Main Results:At positive end-expiratory pressure = 5 cm H2O, 29% of patients were passive leg raising responders. An end-expiratory occlusion–induced increase in cardiac index greater than or equal to 5% detected a passive leg raising–induced increase in cardiac index greater than or equal to 10% with a sensitivity of 90% (95% CI, 56–100) and a specificity of 88% (95% CI, 68–97). At higher positive end-expiratory pressure (15 cm H2O [interquartile range, 13–15]), the plateau pressure – positive end-expiratory pressure difference did not change (15 mm Hg [14–17] vs 15 mm Hg [13–18] before the positive end-expiratory pressure increase). Increasing positive end-expiratory pressure significantly reduced cardiac index in passive leg raising responders (–27% [interquartile range, –6 to –56]) but not in other patients. At high positive end-expiratory pressure, passive leg raising increased cardiac index to a larger extent than at positive end-expiratory pressure = 5 cm H2O (19% [interquartile range, 15–34] vs 16% [interquartile range, 13–23], respectively). The proportion of passive leg raising responders significantly increased (34 vs 29%, respectively), meaning preload dependence had increased. At higher positive end-expiratory pressure, an end-expiratory occlusion–induced increase in cardiac index greater than or equal to 6% detected a passive leg raising–induced increase in cardiac index greater than or equal to 10% with a sensitivity of 100% (95% CI, 75–100) and a specificity of 90% (95% CI, 70–99). Conclusions:The end-expiratory occlusion test is reliable for detecting preload dependence whatever the positive end-expiratory pressure during acute respiratory distress syndrome.

Management of Myocardial Dysfunction in Severe Sepsis

Sepsis-induced cardiac dysfunction is a frequent and severe complication of septic shock. The mechanisms responsible for its development are complex and intricate. Echocardiography is the best method to make the diagnosis of cardiac dysfunction. Biomarkers (B-type natriuretic peptides and cardiac troponins) can alert clinicians of the possibility of cardiac dysfunction. Low plasma levels can serve to rule out a severe cardiac dysfunction. By contrast, high levels should prompt the performance of an echocardiographic examination. The transpulmonary thermodilution monitor and the pulmonary artery catheter can also be used to alert clinicians or to monitor the effects of inotropic therapy. Dobutamine is the first-line therapy. Its administration remains a matter of debate and should be carefully monitored in terms of efficacy and tolerance.

Monitoring: from cardiac output monitoring to echocardiography.

Purpose of reviewHemodynamic exploration is mandatory in patients with shock to identify the type of shock, to select the best therapeutic strategy, and to assess the efficacy of the selected therapy. In this review, we summarize the characteristics of the main available hemodynamic monitoring systems and emphasize on how to select the most appropriate ones in patients with circulatory shock. Recent findingsOver the past decade, hemodynamic monitoring techniques have progressively evolved from intermittent toward real-time measurements and from invasive toward less invasive approaches. Nowadays, echocardiography is recommended as the first-line modality of hemodynamic evaluation in patients with shock. Current guidelines recommend reserving advanced hemodynamic monitoring systems for patients not responding to the initial therapy and/or for complex conditions such as combination of shock with acute respiratory distress syndrome. Invasive and noninvasive uncalibrated cardiac output monitors, as well as esophageal Doppler, could find their place in the perioperative context rather than in patients with shock. SummaryThe use of echocardiography should be encouraged at the initial period of shock to identify main involved mechanisms and to select the appropriate therapy. The use of more invasive monitoring systems should be discussed on an individualized basis.

Rifampin use in acute community-acquired meningitis in intensive care units: the French retrospective cohort ACAM-ICU study

IntroductionBacterial meningitis among critically ill adult patients remains associated with both high mortality and frequent, persistent disability. Vancomycin was added to treatment with a third-generation cephalosporin as recommended by French national guidelines. Because animal model studies had suggested interest in the use of rifampin for treatment of bacterial meningitis, and after the introduction of early corticosteroid therapy (in 2002), there was a trend toward increasing rifampin use for intensive care unit (ICU) patients. The aim of this article is to report on this practice.MethodsFive ICUs participated in the study. Baseline characteristics and treatment data were retrospectively collected from charts of patients admitted with a diagnosis of acute bacterial meningitis during a 5-year period (2004–2008). The ICU mortality was the main outcome measure; Glasgow Outcome Scale and 3-month mortality were also assessed.ResultsOne hundred fifty-seven patients were included. Streptococcus pneumoniae and Neisseria meningitidis were the most prevalent causative microorganisms. The ICU mortality rate was 15 %. High doses of a cephalosporin were the most prevalent initial antimicrobial treatment. The delay between admission and administration of the first antibiotic dose was correlated with ICU mortality. Rifampin was used with a cephalosporin for 32 patients (ranging from 8 % of the cohort for 2004 to 30 % in 2008). Administration of rifampin within the first 24 h of hospitalization could be associated with a lower ICU survival. Statistical association between such an early rifampin treatment and ICU mortality reached significance only for patients with pneumococcal meningitis (p=0.031) in univariate analysis, but not in the logistic model.ConclusionsWe report on the role of rifampin use for patients with community-acquired meningitis, and the results of this study suggest that this practice may be associated with lower mortality in the ICU. Nevertheless, the only independent predictors of ICU mortality were organ failure and pneumococcal infection. Further studies are required to confirm these results and to explain how rifampin use would reduce mortality.

Prospective assessment of a score for assessing basic critical-care transthoracic echocardiography skills in ventilated critically ill patients

BackgroundWe studied a score for assessing basic transthoracic echocardiography (TTE) skills exhibited by residents who examined critically ill patients receiving mechanical ventilation.MethodsWe conducted a prospective study in the 16 residents who worked in our medical-surgical ICU between 1 May 2008 and 1 November 2009. The residents received theoretical teaching (two hours) then performed supervised TTEs during their six-month rotation. Their basic TTE skills in mechanically ventilated patients were evaluated after one (M1), three (M3), and six (M6) months by two experts, who used a scoring system devised for the study. After scoring, residents gave their hemodynamic diagnosis and suggested a treatment.ResultsThe 4 residents with previous TTE skills obtained a significantly higher total score than did the 12 novices at M1 (18 (16 to 19) versus 13 (10 to 15), respectively, P = 0.03). In the novices, the total score increased significantly during training (M1, 13 (10 to 14); M3, 15 (12 to 16); and M6, 17 (15 to 18); P < 0.001) and correlated significantly with the number of supervised TTEs (r = 0.68, P < 0.0001). In the overall population, agreement with experts regarding the diagnosis and treatment was associated with a significantly higher total score (17 (16 to 18) versus 13 (12 to 16), P = 0.002). A total score ≥ 19/20 points had 100% specificity (95% confidence interval, 79 to 100%) for full agreement with the experts regarding the diagnosis and treatment.ConclusionsOur results validate the scoring system developed for our study of the assessment of basic critical-care TTE skills in residents.