Association between Acute Kidney Injury during Invasive Mechanical Ventilation and ICU Outcomes and Respiratory System Mechanics

Abstract

OBJECTIVES: Compare ICU outcomes and respiratory system mechanics in patients with and without acute kidney injury during invasive mechanical ventilation. DESIGNS: Retrospective cohort study. SETTINGS: ICUs of the University of California, San Diego, from January 1, 2014, to November 30, 2016. PATIENTS: Five groups of patients were compared based on the need for invasive mechanical ventilation, presence or absence of acute kidney injury per the Kidney Disease: Improving Global Outcomes criteria, and the temporal relationship between the development of acute kidney injury and initiation of invasive mechanical ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 9,704 patients were included and 4,484 (46%) required invasive mechanical ventilation; 2,009 patients (45%) had acute kidney injury while being treated with invasive mechanical ventilation, and the mortality rate for these patients was 22.4% compared with 5% in those treated with invasive mechanical ventilation without acute kidney injury (p < 0.01). Adjusted hazard of mortality accounting for baseline disease severity was 1.58 (95% CI, 1.22-2.03; p < 0.001]. Patients with acute kidney injury during invasive mechanical ventilation had a significant increase in total ventilator days and length of ICU stay with the same comparison (both p < 0.01). Acute kidney injury during mechanical ventilation was also associated with significantly higher plateau pressures, lower respiratory system compliance, and higher driving pressures (all p < 0.01). These differences remained significant in patients with net negative cumulative fluid balance. CONCLUSIONS: Acute kidney injury during invasive mechanical ventilation is associated with increased ICU mortality, increased ventilator days, increased length of ICU stay, and impaired respiratory system mechanics. These results emphasize the need for investigations of ventilatory strategies in the setting of acute kidney injury, as well as mechanistic studies of crosstalk between the lung and kidney in the critically ill.