Relationship between transcutaneous and arterial carbon dioxide tension in adult patients anesthetized with nitrous oxide-fentanyl and nitrous oxide-enflurane.

The transcutaneous technique of measuring carbon dioxide tension (tcPCO2) was studied in 30 adult neurosurgery patients undergoing nitrous oxide-enflurane or nitrous oxide-fentanyl anesthesia to determine the relationship between tcPCO2 and PaCO2. tcPCO2 was an accurate (r = 0.9) and clinically useful trend indicator of PaCO2. The ability to detect trends was unaffected by the type of anesthetic agent used. The technique was less useful in predicting absolute values for PaCO2 (r = 0.64). This technique may be particularly useful in situations in which control PaCO2 is essential to patient management.