Case presentation: the trainee

A 56-year-old woman of South Indian origin presented with 2 weeks of cough, fever, malaise and dyspnoea ,with no response to amoxicillin. She was generally well with mild hypertension, type 2 diabetes controlled with metformin, hypothyroidism and vitamin D deficiency. There were no other relevant exposures, previous imaging, lung function or other investigations.

Initial observations: temperature 38.2°C, blood pressure 112/76 mm Hg, RR 24, SpO₂ 94% on 3 L/min of O₂ via nasal cannulae. Examination of the chest revealed bilateral crackles.

Chest X-ray on admission showed bilateral patchy consolidation to the mid zones (figure 1A).

Initial test results are shown below:

White cell count 8.8×10⁹/L (4–10).

C-reactive protein 141 (<5).

HIV negative.

Throat swab PCR negative for respiratory viruses.

With a working diagnosis of community-acquired pneumonia, treatment was initiated promptly with intravenous amoxicillin/clavulanic acid and clarithromycin, O₂ via nasal cannulae, intravenous crystalloids and paracetamol, and the patient was admitted to the acute admissions unit. Despite this, the patient failed to improve. Amoxicillin/clavulanic acid was changed to piperacillin/tazobactam, and she was transferred to the high dependency unit (HDU) 4 days after admission due to increasing O₂ requirements. Sputum examination was positive for Candida sp only.

Intensive care assessment

This patient deteriorated despite appropriate medical therapy. She was initially managed on HDU with high flow nasal O₂. However, her respiratory failure progressed rapidly, requiring invasive mechanical ventilation 5 days after admission. CT scan of the chest showed features consistent with ARDS (Acute Respiratory Distress Syndrome) (figure 1B).

There was little change over the following 4 days despite treatment with meropenem, clarithromycin and fluconazole. Ten days after admission, on day 5 of mechanical ventilation, gas exchange and lung mechanics rapidly deteriorated with a severe hypoxaemic respiratory acidosis (FiO_{2 …}