Effect of acute kidney injury on weaning from mechanical ventilation in critically ill patients*

OBJECTIVES: Acute kidney injury (AKI) worsens outcome in various scenarios. We sought to investigate whether the occurrence of AKI has any effect on weaning from mechanical ventilation. DESIGN AND SETTING: Observational, retrospective study in a 23-bed medical/surgical intensive care unit (ICU) in a cancer hospital from January to December 2003. PATIENTS: The inclusion criterion was invasive mechanical ventilation for > or =48 hrs. AKI was defined as at least one measurement of serum creatinine of > or =1.5 mg/dL during the ICU stay. Patients were then separated into AKI and non-AKI patients (control group). The criterion for weaning was the combination of positive end-expiratory pressure of or =85% increase in baseline serum creatinine (hazard rate, 2.30; 95% confidence interval, 1.30-4.08), oliguria (hazard rate, 2.51; 95% confidence interval, 1.24-5.08), and the number of antibiotics (hazard rate, 2.64; 95% confidence interval, 1.51-4.63) predicted longer duration of weaning. The length of ICU stay and ICU mortality rate were significantly greater in the AKI patients. After adjusting for Simplified Acute Physiology Score II, oliguria (odds ratio, 30.8; 95% confidence interval, 7.7-123.0) remained as a strong risk factor for mortality. CONCLUSION: This study shows that renal dysfunction has serious consequences in the duration of mechanical ventilation, weaning from mechanical ventilation, and mortality in critically ill cancer patients.