To explore the incidence, pathogenetic and risk factors of acute kidney injury (AKI) complicated after mechanical ventilation (MV) in very elderly male inpatients.

A total of 260 very elderly male inpatients treated with MV at the geriatric ward of Chinese PLA General Hospital from January 2008 to June 2013 were selected as subjects, and divided into AKI group and non-AKI group according to whether AKI occurred after MV. Univariate analysis was used, taking out factors influencing the prognosis. Logistic regression analysis was used, taking the statistically significant factors as independent variables in order to determine the impact of various factors on AKI.

The median age was 89 years in the 260 very elderly inpatients treated with MV, among whom 125 patients (48.1%) suffered from AKI after MV. There was no significant difference in age and body mass index (BMI) between the two groups (P> 0.05). The percentages of patients with histories of coronary heart disease, chronic obstructive pulmonary disease, and/or hypertension were slightly higher in the AKI group than in the non-AKI group, but the difference was not statistically significant (P> 0.05). The percentage of patients with a history of chronic kidney disease (CKD) (67.2% vs 51.1%, t=6.937, P=0.008) or diabetes (51.2% vs 38.5%, t=4.224, P=0.040) was statistically higher in the AKI group than in the non-AKI group. Compared with the non-AKI group, the AKI group showed lower PaO₂ (58.2 vs 62.5 mmHg, t=2.729, P=0.006), lower level of PaCO₂ (46.2 vs 51.0 mmHg, t=2.075, P=0.038), and lower PaO₂/FiO₂, (122.5±46.0 vs 145.7±48.6 mmHg, t=3.944, P<0.001) in more patients, together with higher levels of serum uric acid (422.4 vs 265.0 μmol/L, t=7.438, P<0.001) and serum glucose (9.4 vs 7.7 mmol/L, t=3.505, P<0.001). The percentage of using high level of positive end-expiratory pressure (PEEP) (≥4 cmH₂O) was higher in the AKI group (21.6% vs 10.4%, t=16.816, P=0.013) than in the non-AKI group. Multivariate logistic regression analysis showed that a history of CKD (OR=1.976, P=0.027), high uric acid level (OR=1.006, P<0.001), low level of PaO₂/FiO₂ (OR=0.989, P=0.001), and high PEEP (≥4 cmH₂O, OR=3.146, P=0.004) were the main risk factors for the occurrence of AKI after MV in the very elderly male inpatients.

The incidence of AKI after MV in the very elderly inpatients was 48.1%. A history of CKD, high uric acid, low PaO₂/FiO₂, and using higher level of PEEP (≥4 cmH₂O) in treatment were the independent risk factors of AKI after MV in the very elderly inpatients.