Failure of combination oral oseltamivir and inhaled zanamivir antiviral treatment in ventilator- and ECMO-treated critically ill patients with pandemic influenza A (H1N1)v.

Objective: The objective of this study was to describe the clinical course of severe and complicated pandemic (H1N1)v infection treated with oral oseltamivir and inhaled zanamivir in a series of intensive care patients.
Methods: We investigated a case series of patients with respiratory failure and a positive (H1N1)v real-time reverse transcriptase polymerase chain reaction (rRT-PCR). Treatment consisted of oseltamivir tablets 75 mg × 4 daily in a nasogastric tube plus zanamivir intravenous (i.v.) solution 25 mg × 4 daily as inhalation. Ventilator inspiratory plateau airway pressure in the ventilator was kept below 30 cmH₂O, PaO₂ above 8 kPa and pH above 7.30. If this could not be achieved, inhalational nitric oxide (NO) was added or extracorporeal membrane oxygenation (ECMO) was initiated.
Results: Twenty-one patients were admitted, with a median age of 50 y (range 6-69 y). Five patients (23.8%) died in the intensive care unit (ICU) and 1 patient died 2 weeks after ICU discharge. Nine patients received ECMO treatment, of whom 3 died during ECMO (33.3%; 3/9) and 1 at 2 weeks after. The mortality in patients not receiving ECMO treatment was 16.6% (2/12). Sixteen patients (76%) were influenza PCR-positive on day 7 after the start of antiviral treatment. Irreversible presumed lung fibrosis complicated with pneumothorax was common. A high Murray score at admission was significantly associated with a fatal outcome.
Conclusions: The mortality in these patients was high despite combined antiviral treatment with oseltamivir and zanamivir. Patients shed virus for a long time despite intensive therapy. Optimal management of patients with bilateral pneumonia and respiratory failure caused by (H1N1)v still needs to be determined.