COVID-19, permissive hypercapnia,and permissive hypoxemia

Q: 72 years old male is admitted to the ICU with pneumonia and requires 12 L/min of oxygen flow. Respiratory culture from admission shows COVID-19. Targeting PaO2 ≥60 mmHg rather than ≥90 mmHg may result in more days alive without ventilatory support.

A) True

B) False

Answer: A

Permissive hypoxemia appears to have benefit in patients with COVID-19 who require mechanical ventilation. The HOT-COVID Randomized Clinical Trial, published in JAMA in 2024 at the tail end of the COVID-19 pandemic, went relatively unnoticed. It was a very strong trial with an average of 350 patients in each arm, showing that though there may not be a mortality benefit, patients receiving at least 10 L/minute of oxygen or mechanical ventilation, targeting PaO2 ≥60 mmHg, were associated with more days alive without ventilatory support compared with a target ≥90 mmHg.

The underlying mechanism of action may be due to the Bohr Effect, in which permissive hypercapnia, and thus concomitant permissive hypoxemia, may cause more O₂ to be released in metabolically active tissues.

#pulmonary

#ventilation

#ID

Reference:

1. Nielsen FM, Klitgaard TL, Siegemund M, et al. Lower vs Higher Oxygenation Target and Days Alive Without Life Support in COVID-19: The HOT-COVID Randomized Clinical Trial. JAMA 2024; 331:1185.