Anesthetic Requirement and Stress Hormone Response During Surgery in Spinal Cord-injured Patients

Nitrous oxide (N2O) is often used for anesthetic adjuvant, but may be associated with side effects and toxicities. Remifentanil shares characteristics with N2O, including anesthetic-reducing and antinociceptive effects and a rapid recovery. Anesthetic requirements and stress hormone response in SCI patients undergoing anesthesia with sevoflurane supplemented with clinically equivalent doses of either N2O or remifentanil. Forty-five SCI patients scheduled to undergo pressor sore surgery below the level of the injury are randomly allocated to receive either sevoflurane alone (control, n=15), or combined with 67% N2O (n=15) or target-controlled infusions of 1.37 ng/mL remifentanil (n=15). Sevoflurane concentration is titrated to maintain a Bispectral Index (BIS) value of 40-50. Measurements include end-tidal sevoflurane concentrations, mean arterial blood pressure (MAP), heart rate (HR), and plasma catecholamine and cortisol concentrations.

Inclusion criteria

• ASA physical status II, with chronic, clinically complete cord injuries scheduled for a surgery for pressure sore below the level of the neurologic lesion under general anesthesia.

Exclusion criteria

• Cardiovascular, pulmonary, or metabolic diseases. Patients who took medications that would influence autonomic or cardiovascular responses to the surgery