Anesthetic Requirements in Chronic Cord-injured Patients Undergoing Surgery below the Level of Injury / 대한마취과학회지

BACKGROUND: We determined the effect of spinal cord injury (SCI) on sevoflurane requirements and stress hormone responses, and sevoflurane concentration to block autonomic hyperreflexia (AHR) in SCI patients. METHODS: In the first series, sevoflurane concentrations to maintain bispectral index score (BIS) at 40-50 and stress hormone response were examined in 27 SCI patients undergoing surgery below the level of injury.Fifteen patients without SCI served as control.Measurements included end-tidal sevoflurane concentrations (ET(SEVO)), systolic blood pressure (SBP), heart rate (HR), catecholamines, vasopressin, and cortisol concentrations.In the second series, sevoflurane concentration to block AHR was examined in 31 SCI patients undergoing transurethral litholapaxy.When a patient developed an episode of AHR, the target sevoflurane concentration was maintained for 10 min, and then the procedure was repeated.Each target concentration was determined by up-down method based on SBP. RESULTS: During surgery, SBP, HR, and BIS were comparable between SCI and control.However, ETSEVO was significantly smaller in the SCI than the control.Plasma concentrations of norepinephrine, epinephrine and cortisol were significantly lower in the SCI than the control.SBP rose by 67 +/- 31 mmHg, whereas HR fell by 13 +/- 8 bpm during the 1st trial in the SCI (P < 0.01).Hypertensive events were associated with increases of norepinephrine concentrations.ETSEVO required to prevent AHR were 3.12% in 50% of patients, 3.83% in 95% of patients. CONCLUSIONS: SCI reduces the anesthetic requirement by 39%, and decreases stress hormone responses during surgery below the level of injury.To prevent AHR in 95% of SCI patients undergoing litholapaxy, ETSEVO 3.83% may be required.

Effects of Nitrous Oxide and Desflurane on Cardiovascular Responses to Endotracheal Intubation / 대한마취과학회지

BACKGROUND: Endotracheal intubation often results in hypertension and tachycardia. Desflurane and nitrous oxide (N2O) are known to augment the sympathetic nervous activity. We examined whether N2O and desflurane affect the cardiovascular responses to the intubation. METHODS: One hundred-fifty patients were assigned randomly to receive one of six treatment regimens (n = 25 each): 2% sevoflurane (control), 6% desflurane or 12% desflurane with and without 75% N2O, respectively. General anesthesia was induced with intravenous thiopental (5-7 mg/kg), and tracheal intubation was facilitated with intravenous vecuronium (0.12 mg/kg). N2O was started 3 min before and desflurane soon after the intubation. Systolic arterial blood pressure (SAP), heart rate (HR), and plasma catecholamine concentrations were determined. RESULTS: The intubation increased SAP and HR in all groups within 1 min. A second increase was noted with 12% desflurane at 3 to 5 min after the intubation. N2O did not affect the tachycardiac response, but attenuated the pressor response to both intubation and 12% desflurane. The plasma concentrations of norepinephrine increased significantly at 1 min after the intubation in all groups with more pronounced rise in N2O groups, and increased further at 5 min in the 12% desflurane groups. CONCLUSIONS: A biphasic increase of SAP and HR was noted with 12% desflurane. The first increase may be related with the mechanical stimulus of the tracheal intubation and the second with the desflurane itself. Although N2O did not affect the tachycardiac responses and augmented norepinephrine release, it suppressed the pressor responses.