ABSTRACT
Background: Acute kidney injury (AKI) is a common complication of COVID-19 ARDS and is associated with greater risk of mortality (1)). In addition to the direct tubular injury mediated by the virus, indirect mechanisms play a role in AKI development. Positive pressure ventilation, by increasing intrathoracic pressure, leads to a decreased venous return to the heart and to a reduced cardiac output (2). In addition, elevated central venous pressure (CVP) may result in elevated tubular hydrostatic pressure in the encapsulated kidney, which reduces glomerular filtration rate and oxygen delivery (3). We hypothesized that elevated intrathoracic pressure, determined by positive pressure ventilation is associated with an increased risk of AKI. The aim of the study is to assess the association between hemodynamics and ventilatory parameters set during mechanical ventilation and AKI in patients with COVID-19 ARDS. Method(s): This is single center retrospective observational study performed at Papa Giovanni XXIII Hospital Bergamo (Italy). Consecutive patients were enrolled with a diagnosis of COVID-19 and ARDS managed with invasive mechanical ventilation. If patients developed AKI (defined according to KDIGO definition) within 14 days of ICU stay were included in "AKI group", otherwise were classified in "non-AKI group". Demographic characteristics, lab tests and hemodynamic [mean arterial pressure (MAP) and central venous pressure (CVP), fluid balance] and ventilatory parameters [positive end-expiratory pressure (PEEP), plateau pressure (PPlat)] were compared between group using Mann Whitney test. Data are presented as median and 95% CI. Only data registered until the day of the AKI occurrence, in patients in AKI group, or until the day corresponding to the median days between ICU admission and the AKI occurrence calculated before for patients in non-AKI group, were considered for the statistical analysis. Result(s): Among the 140 patients included in the analysis, AKI occurred in 70 (48%) patients and 27 (19%) required continuous renal replacement therapy (CRRT). Table 1 shows comparison between the two groups. Patients in AKI group were older, had higher prevalence of obesity, hypertension and diabetes, had lower MAP and received a greater amount of fluid and furosemide compared to patients in non-AKI group (p<0.05). Only a trend toward a greater CVP was observed in patients with AKI, without reaching a significant difference. Both PEEP and Pplat were set higher in patients with AKI, while the severity of lung disease, measured by PaO2/FiO2 were not different between the two groups. Conclusion(s): In our cohort, higher pressure ventilation was associated with an increased risk of AKI.