H1N1 infection and the kidney in critically ill patients

Background: Acute renal failure due to viral infections is rare. We assessed the development of acute kidney injury (AKI) in critically compromised patients due to the H1N1 influenza virus. Methods: All patients with a PCR-confirmed diagnosis of H1N1 influenza infection admitted to the intensive care unit between May and July 2009 were retrospectively studied. Thereafter, the risk factors associated with the development of acute renal injury, the requirements of acute hemodialysis (HD) and death were analyzed. Results: Twenty-two patients with H1N1 pneumonia were included: age: 52.91 +/- 18.89 years; gender: males 11 (50%); chronic airway disease: 9 (41%); oncohematological disease: 8 (36.7%); cardiovascular disease 5 (22.7%); chronic renal insufficiency: 4 (18.2%); obesity 3 (13.6%); concomitant pregnancy: 2 (9.1%); diabetes mellitus: 2 (9.1%); previous influenza A vaccination: 9 (41%). All patients received oseltamivir within 48 hours of presumed diagnosis. Seventeen patients (77.3%) developed fever initially. Six patients (27.3%) required non-invasive ventilation assistance and 15 patients (68.2%) received invasive ventilatory support. Mean days on mechanical respiratory assistance: 11 +/- 10.35. Arterial partial pressure of oxygen/fraction of inspired oxygen ratio: 140.11 +/- 83.03 mmHg. Inotropic drugs were administered to 15 patients (68.2%). Fourteen patients (63.6%) developed AKI. Mean highest creatinine levels: 2.74 +/- 2.83 mg/dl. Four patients (18.2%) needed renal replacement therapy with a mean duration of 15 +/- 12 days. Six patients (42.9%) recovered renal function. AKI was associated with pregnancy, immunosuppression, high APACHE, SOFA and MURRAY scores, and less time on mechanical ventilation assistance, hemodynamical instability and thrombocytopenia. HD requirements were associated with elevated SOFA scores (12.25 +/- 1.75 vs. 6.22 +/- 0.8, p<0.05), elevated creatine phosphokinase (933 +/- 436.6 vs. 189.9 +/- 79.3 U/L, p<0.05) and alanine transferase levels (843.3 +/- 778.8 vs. 85.33 +/- 17.4 U/L, p<0.05). Twelve patients died (54.6%), 10 of whom had acute renal failure (83.3%) and 3 had been on acute HD (25%). Mortality was associated with higher APACHE, SOFA and Murray scores, a higher oseltamivir dose (253.1 +/- 25.8 vs. 183.8 +/- 27.6 mg, p<0.05), lower oxygen inspired fraction/alveolar pressure ratio (99.3 +/- 12.2 vs. 196.3 +/- 33.9 mmHg, p<0.01), thrombocytopenia (88966 +/- 22977 vs. 141200 +/- 17282 mm(3), p<0.05), hypoalbuminemia (1.82 +/- 0.1 vs. 2.61 +/- 0.2 g/dl, p<0.01), acute renal failure (10 vs. 4, p<0.05), oligoanuria (5 vs. 0, p<0.05) and lack of recovery of renal function (2 vs. 4, p<0.01). Three out of 4 (75%) of the hemodialyzed patients died. Conclusions: In the critically ill due to H1N1 pneumonia, renal insufficiency was a frequent complication, demanding renal replacement therapy in 18% of cases. The need for HD was associated with an elevated risk of death. Mortality was mainly associated with multiple organ failure, oligoanuria, acute renal injury and a lack of recovery of renal function.