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ARDS — FRCA Final MCQ

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ModerateIntensive Care MedicineARDSFRCA Final

A 62-year-old man with ischaemic heart disease is on day 3 following an emergency laparotomy for a perforated duodenal ulcer. He remains intubated in ICU with new bilateral pulmonary opacities that are not explained by effusions, lobar collapse or nodules. Clinical assessment and echocardiography indicate that cardiac failure or fluid overload does not explain his respiratory failure. Ventilator settings are FiO2 0.60, PEEP 12 cmH2O, tidal volume 420 mL (6 mL/kg predicted body weight), respiratory rate 22 breaths/min and plateau pressure 28 cmH2O. Arterial blood gas analysis shows pH 7.22, PaCO2 7.8 kPa, PaO2 8.5 kPa, bicarbonate 18 mmol/L and lactate 3.8 mmol/L. According to the Berlin definition, what is the severity of his ARDS?

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Correct answer: E — Moderate

The correct answer is E, moderate ARDS. The clinical insult occurred within one week, imaging shows qualifying bilateral opacities, and hydrostatic pulmonary oedema has been excluded. PaO2 8.5 kPa is approximately 64 mmHg; therefore, PaO2/FiO2 = 64/0.60 = approximately 106 mmHg. With PEEP well above the required 5 cmH2O, this lies in the Berlin moderate range of >100 to <=200 mmHg. Mild ARDS requires a ratio >200 to <=300 mmHg. Severe ARDS requires a ratio <=100 mmHg, so this patient is close to, but does not meet, that boundary. He meets the diagnostic criteria, excluding no ARDS or merely being at risk.

Reference: ARDS Definition Task Force. Acute respiratory distress syndrome: the Berlin Definition. JAMA. 2012;307(23):2526-2533. https://pubmed.ncbi.nlm.nih.gov/22797452/