Abstract : Mechanical ventilation in ICU patients may induce acute kidney injury (AKI). We aimed to describe the effect of mechanical ventilation (MV) settings, on AKI worsening, as well as the potential role of mean perfusion pressure (MPP).We included from the MIMIC-III database adult patients admitted for the first time in the ICU. We excluded patients with known chronic kidney disease, no KDIGO information and who suffered KDIGO3 AKI at day-1. The main outcome was one-KDIGO category AKI worsening (compared to the day before) and included as a categorical variable : discharged alive without AKI worsening and death before AKI worsening. We used a multinomial logistic regression at day 1 and day 2 according to a landmark-approach, with a two-days sliding perspective.26,884/61,051 patients met the inclusion criteria (15,046 male, 56.0%; median age 65 [iqr 52, 78]). ICU and hospital mortality were 7.4 and 10.7%, respectively. Between day 1 and day 3, 529 patients died without AKI worsening, 11,230 were discharged alive and 1,656 suffered an AKI worsening. Between day 2 and day 4, 128 patients suffered an AKI worsening, 5,686 were discharged alive and 313 died.
In multivariable analysis, using the no MV modality as a reference (n=19,666), MV at day 1 was associated with AKI worsening at day 3 (relative risk ratio [RRR] 15.7 [7.7, 32], 23.2 [17.6, 30.6] and 55.6 [29, 106.4] for MV with PEEP < 5 (n=283), PEEP between 5 and 8 (n=4,153) and PEEP > 8cmH2O (n=1,134)).
RRR of AKI worsening at day-4 were 2.3 [0.3, 19.4], 13.3 [5.8, 30.6] and 44.9 [17.2, 117.2] for MV with PEEP < 5 (n=254), PEEP between 5 and 8 (n=2,751) and PEEP > 8cmH2O (n=1,088) at day 2 compared to no MV (n=16,397).
Hemodynamic parameters are shown on Figure. MPP significantly differed across MV groups (67, 70, 68 and 64mmHg in patients receiving no MV, MV with PEEP <5, PEEP 5-8 and PEEP >8cmH2O, p<0.001).
Mechanical ventilation was associated with AKI worsening in an increasing PEEP dependent manner at the early phase of ICU management in a large cohort of patients. Interaction between MPP and mechanical ventilation should be explored further.