Association Between the Severity of Early Acute Kidney Injury and Subsequent in-Hospital Complications and 90-Day Mortality in Geriatric Patients Receiving Invasive Mechanical Ventilation

Purpose: Acute kidney injury (AKI) in elderly patients is associated with higher hospital mortality. However, the relationship between AKI and peri-intubation complications is unclear. Methods: This retrospective, observational, multicenter cohort study enrolled 3271 consecutive elderly patients (>75 years) who received invasive mechanical ventilation (MV) in four medical centers of Chinese PLA General Hospital from 2008 to 2020. AKI was diagnosed according to the 2012 KDIGO criteria by an absolute increase in serum creatinine of >26.5 mu mol/L within the first 48 hours of MV. We recorded subsequent in-hospital complications, including incident gastrointestinal bleeding, new-onset electrolyte imbal-ances, severe hypoxemia, hypoalbuminemia, cardiovascular instability and all-cause 90-day mortality. Results: A total of 1292 patients were included in the final evaluation, with 29.1% presenting AKI (stage 1: 31.4%, stage 2: 35.1%, stage 3: 33.5%). Multiple regression analyses show that more advanced AKI increased the risk of MAP <65 mmHg (stage 1: OR=1.833, P=0.002; stage 2: OR= 4.653, P<0.001; stage 3: OR=4.834, P<0.001) and SBP <90 mmHg (stage 1: OR=1.644, P=0.014; stage 2: OR=3.701, P<0.001; stage 3: OR=5.750, P<0.001), a new need for or requiring an increased dose of vasopressors (stage 1: OR=1.623, P=0.014; stage 2: OR=3.250, P<0.001; stage 3: OR=12.132, P<0.001), gastrointestinal bleeding (stage 1: OR=1.102, P=0.669; stage 2: OR=1.471, P=0.060; stage 3: OR=2.377, P<0.001), severe hypoxia (stage 1: OR=1.213, P=0.399; stage 2: OR=1.449, P=0.077; stage 3: OR=2.214, P<0.001) and all-cause 90-day mortality (stage 1: OR =0.935; P=0.741; stage 2: OR=1.888; P=0.001; stage 3: OR=12.584; P<0.001). Conclusion: Our study suggests that the presence of AKI within the first 48 hours of MV in geriatric patients is associated with a higher risk for postintubation complications and 90-day mortality. Moreover, the risk of complications was greater for patients with more severe AKI.