Correlation between extravascular lung water and oxygenation in ALI/ARDS patients in septic shock: Possible role in the development of atelectasis?

This study aimed to evaluate the relationship between PaO2/FiO2 ratio and extravascular lung water in septic shock- induced acute respiratory distress syndrome in a prospective observational clinical trial. Twenty-three patients suffering from sepsis induced acute respiratory distress syndrome were recruited. All patients were ventilated in pressure control/support mode. Haemodynamic parameters were determined by arterial thermodilution (PiCCO) eight hourly for 72 hours. At the same time blood gas analyses were done and respiratory parameters were also recorded. Data are presented as mean±SD. For statistical analysis Pearson’s correlation test, and analysis of variance (ANOVA) was used respectively. Significant negative correlation was found between extravascular lung water and PaO2/FiO2 (r= –0.355, P<0.001), and significant positive correlation was shown between extravascular lung water and PEEP (r=0.557, P<0.001). A post-hoc analysis was performed when “low” PEEP: <10 cmH2O and “high” PEEP: (10 cmH2O PEEP was applied, and neither the oxygenation, nor the driving pressure or the PaCO2 differed significantly, but the extravascular lung water showed significant difference when “high” or “low” PEEP was applied (13±5 vs 9±2 ml/kg respectively, P=0.001). This study found significant negative correlation between extravascular lung water and PaO2/FiO2. The mechanism by which extravascular lung water affects oxygenation is unknown but the significant positive correlation between PEEP and extravascular lung water shown in this trial suggests that the latter may have a role in the development of alveolar atelectasis

Microalbuminuria does not reflect increased systemic capillary permeability in septic shock

Objective To investigate the correlation between microalbuminuria and extravascular lung water in patients in septic shock who require mechanical ventilation for severe respiratory failure. Design and setting Prospective, observational, clinical study in the 20-bed intensive care unit of a university hospital. Patients and participants 25 consecutive patients in septic shock and also in severe respiratory failure requiring mechanical ventilation. Interventions Hemodynamic parameters and extravascular lung water were determined by single arterial thermodilution. Together with each hemodynamic measurement the PaO2/FIO2 ratio and urinary microalbumin to creatinine ratio (M:Cr) was measured. Serum C-reactive protein (CRP) and procalcitonin (PCT) levels were also determined daily. Measurements and results The EVLW index was significantly higher than normal throughout the study. Microalbuminuria was in the normal range on entry and remained so for the rest of the study period. Serum PCT and CRP levels were significantly higher than normal at every assessment points. No significant correlation was found between M:Cr and either EVLW or PaO2/FIO2 . Conclusions In this study patients in septic shock with significantly elevated EVLW had normal urinary M:Cr, and there was no correlation between M:Cr and EWLV, and PaO2/FIO2. Therefore based on the current results routine measurements of microalbuminuria to determine endothelial permeability cannot be recommended in critically ill patients