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Permissive Hypercapnia ARDS — FRCA Final MCQ

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ModerateIntensive Care MedicinePermissive Hypercapnia ARDSFRCA Final

A 62-year-old man (ASA III) is being ventilated in ICU with ARDS. He is on FiO2 0.6, PEEP 12, VT 6 mL/kg IBW, RR 26. His ABG shows PaCO2 8.5 kPa and pH 7.22. What is the recommended approach to the hypercapnia?

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Correct answer: D — Administer IV sodium bicarbonate to correct the pH

Permissive hypercapnia is an accepted strategy in ARDS to maintain lung-protective ventilation (VT 6 mL/kg IBW, Pplat ≤30 cmH2O). Hypercapnia is tolerated provided the pH remains above approximately 7.15-7.20. At pH 7.22, this is borderline acceptable. Increasing tidal volume would worsen VILI. Increasing respiratory rate (up to 35/min, avoiding auto-PEEP) is the first step. If pH remains <7.15-7.20, a slow bicarbonate infusion may be considered, though this is controversial. Prone positioning should also be considered.

Reference: ARDSNet – 2000 – Low tidal volume protocol; ICS – 2024 – ARDS guidelines