Extravascular lung water index improves the diagnostic accuracy of lung injury in patients with shock

Introduction: The diagnosis of acute lung injury (ALI) may be more robust if more accurate physiological markers can be identified. Extravascular lung water (EVLW) is one possible marker, and it has been shown to correlate with respiratory function and mortality in patients with sepsis. Whether EVLW confers diagnostic value in a general population with shock, as well as which index performs best, is unclear. We investigated the diagnostic accuracy of various EVLW indices in patients with shock. Methods: We studied a prospective, observational cohort of 51 patients with shock admitted to a tertiary ICU. EVLW was measured within 6 hours of ICU admission and indexed to actual body weight (EVLW/ABW), predicted body weight (EVLW/PBW) and pulmonary blood volume (EVLW/PBV). The relationship of these indices to the diagnosis and severity of lung injury and ICU mortality were studied. Positive and negative likelihood ratios, pre- and posttest odds for diagnosis of lung injury and mortality were calculated. Results: All EVLW indices were higher among patients with lung injury and significantly correlated with respiratory parameters. Furthermore, all EVLW indices were significantly higher in nonsurvivors. The use of EVLW improves the posttest OR for the diagnosis of ALI, acute respiratory distress syndrome (ARDS) and severe lung injury (sLI) by up to eightfold. Combining increased EVLW and a diagnosis of ALI, ARDS or sLI increases the posttest odds of ICU mortality. EVLW/ABW and EVLW/PBV demonstrated the best diagnostic performance in this population. Conclusions: EVLW was associated with degree of lung injury and mortality, regardless of the index used, confirming that it may be used as a bedside indicator of disease severity. The use of EVLW as a bedside test conferred added diagnostic value for the identification of patients with lung injury

Assessing left ventricular systolic function in shock: evaluation of echocardiographic parameters in intensive care

Introduction: Assessing left ventricular (LV) systolic function in a rapid and reliable way can be challenging in the critically ill patient. The purpose of this study was to evaluate the feasibility and reliability of, as well as the association between, commonly used LV systolic parameters, by using serial transthoracic echocardiography (TTE). Methods: Fifty patients with shock and mechanical ventilation were included. TTE examinations were performed daily for a total of 7 days. Methods used to assess LV systolic function were visually estimated, "eyeball" ejection fraction (EBEF), the Simpson single-plane method, mean atrioventricular plane displacement (AVPDm), septal tissue velocity imaging (TDIs), and velocity time integral in the left ventricular outflow tract (VTI). Results: EBEF, AVPDm, TDIs, VTI, and the Simpson were obtained in 100%, 100%, 99%, 95% and 93%, respectively, of all possible examinations. The correlations between the Simpson and EBEF showed r values for all 7 days ranging from 0.79 to 0.95 (P < 0.01). the Simpson correlations with the other LV parameters showed substantial variation over time, with the poorest results seen for TDIs and AVPDm. The repeatability was best for VTI (interobserver coefficient of variation (CV) 4.8%, and intraobserver CV, 3.1%), and AVPDm (5.3% and 4.4%, respectively), and worst for the Simpson method (8.2% and 10.6%, respectively). Conclusions: EBEF and AVPDm provided the best, and Simpson, the worst feasibility when assessing LV systolic function in a population of mechanically ventilated, hemodynamically unstable patients. Additionally, the Simpson showed the poorest repeatability. We suggest that EBEF can be used instead of single-plane Simpson when assessing LV ejection fraction in this category of patients. TDIs and AVPDm, as markers of longitudinal function of the LV, are not interchangeable with LV ejection fraction

Changes in blood lactate predict outcome better than absolute values in severe SIRS

Introduction: Serum lactate is considered to be a marker of tissue hypoxia (1) Cut-off values >4 mM predict poor outcome, yet many patients after resuscitation according Surviving Sepsis Campaign guidelines (SSCG) (2) have high mortality despite decreases in blood lactate. Our hypothesis was that dynamic, rather than absolute blood lactate concentrations predict survival. Further we tested the ability of microdialysis lactate (MD-lac) to follow dynamic changes in blood levels, and whether this was also predictive of survival. Methods: Prospective, observational, single-centre cohort study in a mixed-bed university hospital ICU. About 53 consecutive patients with SIRS and circulatory failure despite adequate fluid resuscitation according to the SSCG were included. Arterial blood lactate (B-lac) was measured 6- hourly and MD-lac in subcutaneous tissue measured 4- hourly. Changes in B- and MD-lac from baseline were also calculated. Results: There were no differences in absolute values of B- lac or MD-lac between survivors and non-survivors during the first 24 h, nor were there differences in the change in MD-lac. In contrast changes in B-lac were greater in survivors. Among patients who reached P-lac > 4 mM during the study period of 7 days, the mortality rate was 37% as compared to 21% in the others, although this did not reach statistical significance. Conclusions: Survivors of severe SIRS were characterized by greater changes in B-lac compared to baseline. This supports the concept of lactate clearance, rather than absolute values, as a useful end point for fluid resuscitation, as opposed to the traditional endpoints used in the SSCG. In contrast MD- lac was not a useful predictor of mortality in this population