Life-threatening respiratory failure from H1N1 influenza 09  (human swine influenza)

We present the first six cases of H1N1 influenza 09 (confirmed by a polymerase chain reaction test from nasopharyngeal swabs) in patients requiring admission to intensive care in Australia (in three hospitals in the north-western suburbs of Melbourne). These cases highlight the small but significant risk of life-threatening respiratory failure associated with H1N1 influenza 09 infection.

A 28-year-old obese woman (body mass index [BMI], 57 kg/m2) presented to the emergency department (ED) with a history of 5 days of sore throat, lethargy and myalgias, and a clear chest x-ray, followed by 2 days of dyspnoea, productive cough, and pleuritic chest pain. She was febrile (40°C), and had tachypnoea (respiratory rate, 36 breaths/min) and hypoxia (oxygen saturation measured by pulse oximetry [Spo2], 87% on 15 L/min oxygen via face mask). Her admission chest x-ray showed widespread alveolar infiltrates. She had a normal white cell count (WCC) of 6.3 × 109/L, but an elevated serum C-reactive protein (CRP) level of 221 mg/L (reference ranges shown in Box 1). She was admitted to the intensive care unit (ICU) and, after a brief trial of non-invasive ventilation (NIV), was intubated and treated with mechanical ventilation (MV) with a fraction of inspired oxygen (Fio2) of 1.0 and positive end-expiratory pressure (PEEP) of 20 cm H2O for the first 24 hours to maintain an Spo2 > 89%. She was treated with inotropes for septic shock and with renal replacement therapy for acute renal failure. Therapy with oseltamivir in addition to empiric broad-spectrum antibiotics was commenced. Bacterial cultures of blood, urine and tracheal aspirate were negative. The result of a test for urine pneumococcal antigen was negative. The patient was successfully weaned from ventilatory support on Day 14.