What is the critical pH range listed in the blood gas critical values?

• A. 6.8-7.0
• B. 7.2-7.6
• C. 7.0-7.4
• D. 7.4-7.6

Answer: (B)

Understanding critical values helps you see how labs signal urgent patient needs. pH measures hydrogen ion concentration and reflects acid–base balance. Normal arterial pH is about 7.35–7.45. Laboratories often designate a pH range of 7.2–7.6 as a critical value because disturbances in that window indicate a significant life-threatening shift (acidemia if it’s below 7.2, or alkalemia if it’s above 7.6) that requires immediate clinical action. Values outside this range are even more severe and typically prompt even more urgent intervention, while values inside the 7.2–7.6 span may still be serious but are not the standard critical cutoffs used for rapid escalations. Therefore, 7.2–7.6 is the range used for critical reporting in this context.