Human Metapneumovirus Pneumonia Precipitating Acute Respiratory Distress Syndrome in an Adult Patient

Acute respiratory distress syndrome (ARDS) is often due to direct lung injury, trauma, surgery, or infection. Making a definitive diagnosis may be difficult initially, as clinical manifestations are nonspecific until the disease progresses. We present a case of human metapneumovirus (hMPV) pulmonary infection precipitating ARDS. A 51-year-old woman presented with one week of pleuritic chest pain, dyspnea, wheezing, subjective fever, and productive cough prior to presentation. Her medical history was significant for human immunodeficiency virus (HIV) with an unknown CD4 count and viral load, pulmonary sarcoidosis, asthma, and being an active smoker. On admission, the patient was dyspneic and using accessory muscles to breathe. She was afebrile and hypotensive. Physical examination revealed bilateral diffuse crackles. Her white blood cell (WBC) count was 7.7 K/mcL. A chest radiograph demonstrated bilateral lung opacifications suggestive of pneumonia, possibly Pneumocystis jiroveci pneumonia (PJP). Broad-spectrum antibiotics, including PJP treatment, corticosteroids, and fluids, were started. The patient received approximately 4 liters of intravenous fluids; yet, she remained hypotensive and required norepinephrine. Chest computed tomography (CT) demonstrated bilateral consolidations. Arterial blood gas (ABG) showed a partial pressure of oxygen (PaO(2)) of 55 mmHg. The patient was intubated for acute hypoxemic respiratory failure and had a PaO(2)/fraction of inspired oxygen (FiO(2)) < 100. Repeat ABG within 12 hours showed a potential of hydrogen (pH) of 7.34, partial pressure of carbon dioxide (pCO(2)) of 42 mmHg, and a PaO(2) of 130 mmHg. Bronchoalveolar lavage revealed only hMPV. The patient was managed supportively and extubated three days later. She was discharged home without oxygen requirement. hMPV causes respiratory infections, most commonly in the extremes of age and immunocompromised patients. The treatment is supportive. Our patient developed acute hypoxemic respiratory failure secondary to an hMPV infection. hMPV pneumonia should be considered as a differential diagnosis in patients with severe respiratory illness and ARDS in order to promote antibiotic stewardship.