Extravascular lung water levels are associated with mortality: a systematic review and meta-analysis

Abstract

Background The prognostic value of extravascular lung water (EVLW) measured by transpulmonary thermodilution (TPTD) in critically ill patients is debated. We performed a systematic review and meta-analysis of studies assessing the effects of TPTD-estimated EVLW on mortality in critically ill patients. Methods Cohort studies published in English from Embase, MEDLINE, and the Cochrane Database of Systematic Reviews from 1960 to 1 June 2021 were systematically searched. From eligible studies, the values of the odds ratio (OR) of EVLW as a risk factor for mortality, and the value of EVLW in survivors and non-survivors were extracted. Pooled OR were calculated from available studies. Mean differences and standard deviation of the EVLW between survivors and non-survivors were calculated. A random effects model was computed on the weighted mean differences across the two groups to estimate the pooled size effect. Subgroup analyses were performed to explore the possible sources of heterogeneity. Results Of the 18 studies included (1296 patients), OR could be extracted from 11 studies including 905 patients (464 survivors vs. 441 non-survivors), and 17 studies reported EVLW values of survivors and non-survivors, including 1246 patients (680 survivors vs. 566 non-survivors). The pooled OR of EVLW for mortality from eleven studies was 1.69 (95% confidence interval (CI) [1.22; 2.34], p < 0.0015). EVLW was significantly lower in survivors than non-survivors, with a mean difference of −4.97 mL/kg (95% CI [−6.54; −3.41], p < 0.001). The results regarding OR and mean differences were consistent in subgroup analyses. Conclusions The value of EVLW measured by TPTD is associated with mortality in critically ill patients and is significantly higher in non-survivors than in survivors. This finding may also be interpreted as an indirect confirmation of the reliability of TPTD for estimating EVLW at the bedside. Nevertheless, our results should be considered cautiously due to the high risk of bias of many studies included in the meta-analysis and the low rating of certainty of evidence. Trial registration the study protocol was prospectively registered on PROSPERO: CRD42019126985.

Which haemodynamic monitoring should we chose for critically ill patients with acute circulatory failure?

“…Recent literature contributed to the indirect validation of the TPTD-derived estimation of lung water and permeability. A recent metaanalysis highlighted that extravascular lung water is associated with mortality in critically ill patients [35], confirming its physiological value. Pulmonary permeability estimated by TPTD has also been investigated by an animal study showing its ability to detect the elevation of inflammatory cytokines during acute respiratory distress syndrome (ARDS) [36].…”

Capillary leak and endothelial permeability in critically ill patients: a current overview

“…Among more invasive diagnostic tools, the use of transpulmonary thermodilution not only presents an approach for hemodynamic monitoring, but also to approximate a patient’s fluid status [ 166 ]. Extravascular lung water is defined as the fluid volume outside the pulmonary vasculature, within the interstitial and alveolar spaces [ 166 , 167 ]. It was previously validated against the reference method of gravimetry in autopsy studies [ 167 – 169 ].…”

“…Transpulmonary thermodilution (e.g., with use of the PiCCO™ system) and can be helpful in bedside clinical diagnosis and decision-making. It has been observed that an elevated extravascular lung water is linked to a higher mortality risk in ICU patients [ 166 ]. This association held true for both acute respiratory distress syndrome patients and critically ill patients without acute respiratory distress syndrome, suggesting the broad applicability of extravascular lung water as an indicator of disease severity [ 166 ].…”

Fluid management in septic patients with pulmonary hypertension, review of the literature

“…Intravenous fluid (IVF) administration has long been termed the 'cornerstone of resuscitation' (60). EGDT targeting a specific CVP (>8 mmHg) to guide fluid administration was initially thought to improve survival outcomes in patients with severe sepsis but studies found that only about 50% of these patients were fluid responders (61).…”