What is the typical pH target when implementing permissive hypercapnia?

• A. pH above 7.40.
• B. pH above approximately 7.25.
• C. pH above approximately 7.20.
• D. pH above 6.9.

Answer: (C)

Permissive hypercapnia lets CO2 rise and pH fall to reduce ventilator‑induced lung injury by using lower tidal volumes and pressures. The pH is allowed to drop only to a tolerable level, balancing lung protection with the risk of acidosis on the body. A typical target is to keep pH around 7.20 or higher, which provides enough acidosis to reap the lung‑protective benefits without causing severe systemic compromise. Going above 7.40 would undo the permissive approach by forcing near‑normal CO2 and pH, while dropping as low as 6.9 would introduce dangerous instability. Therefore, the best target is roughly 7.20.