A 28-year-old obese woman (body mass index [BMI], 57 kg/m 2 ) 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 [SpO 2 ], 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 10 9 /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 noninvasive ventilation (NIV), was intubated and treated with mechanical ventilation (MV) with a fraction of inspired oxygen (FiO 2 ) of 1.0 and positive end-expiratory pressure (PEEP) of 20 cm H 2 O for the first 24 hours to maintain an SpO 2 > 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.
Patient 2A previously well 24-year-old man (BMI, 22 kg/m 2 ) was admitted to a regional hospital with a 1-week history of dry cough, fever, headache, abdominal pain, and vomiting. Thirty-six hours later, he was transferred to a metropolitan hospital because of worsening dyspnoea and hypoxia (SpO 2 , 88% on 15 L/min oxygen via face mask). He had tachycardia (110 beats/min), tachypnoea (respiratory rate, 34 breaths/min) and was febrile (39.9°C). He had a normal WCC (4.2 10 9 /L) but an elevated CRP level (256 mg/L).A chest x-ray showed unilateral lobar consolidation. He was transferred to the ICU and treated with oseltamivir, broad-spectrum antibiotics, and NIV with an FiO 2 of 1.0. After 96 hours, his hypoxia remained severe (partial pressure of arterial oxygen [PaO 2 ] to FiO 2 ratio, < 100), another chest x-ray showed bilateral alveolar infiltrates, and he was intubated and MV was commenced with an FiO 2 of 1.0 and high-level PEEP (20 cm H 2 O) for several days.Bacterial cultures and urine pneumococcal antigen test results were negative. Oseltamivir therapy was continued for 7 days, and MV for 15 days.
Patient 3A 26-year-old obese man (BMI, > 40 kg/m 2 ) with a history of mild asthma presented after 2 days of nausea without vomiting, and no fever or cough. On the day of admission, he developed shortness of breath. He was found to be hypoxic (SpO 2 , 90% on an FiO 2 of 1.0) with bilateral pulmonary infiltrates showing on a chest x-ray. His WCC was 5.6 10 9 /L and CRP level was 137 mg/L. Therapy with broad-spectrum antibiotics and oseltamivir was commenced. He was intubated, and MV was commenced with an FiO 2 of > 0.6 and high-...
