Role of vasopressin in current anesthetic practice / 대한마취과학회지

Arginine vasopressin (AVP), also known as antidiuretic hormone, is a peptide endogenously secreted by the posterior pituitary in response to hyperosmolar plasma or systemic hypoperfusion states. When administered intravenously, it causes an intense peripheral vasoconstriction through stimulation of V₁ receptors on the vascular smooth muscle. Patients in refractory shock associated with severe sepsis, cardiogenic or vasodilatory shock, or cardiopulmonary bypass have inappropriately low plasma levels of AVP (‘relative vasopressin deficiency’) and supersensitivity to exogenously-administered AVP. Low doses of AVP and its synthetic analog terlipressin can restore vasomotor tone in conditions that are resistant to catecholamines, with preservation of renal blood flow and urine output. They are also useful in the treatment of refractory arterial hypotension in patients chronically treated with renin-angiotensin system inhibitors, cardiac arrest, or bleeding esophageal varices. In the perioperative setting, they represent attractive adjunct vasopressors in advanced shock states that are unresponsive to conventional therapeutic strategies.

Effects of intravenously administered indocyanine green on near-infrared cerebral oximetry and pulse oximetry readings / 대한마취과학회지

BACKGROUND: Intravenously administered indocyanine green (ICG) may cause misreadings of cerebral oximetry and pulse oximetry in patients undergoing carotid endarterectomy under general anesthesia. The present study determined the effects of two different doses (12.5 mg vs. 25 mg) of ICG on regional cerebral tissue oxygen saturation (SctO2) and percutaneous peripheral oxygen saturation (SpO2). METHODS: Twenty-six patients receiving ICG for videoangiography were divided into two groups according to the dosage (12.5 mg and 25 mg, n = 13 in each group). Heart rate, arterial blood pressure, SctO2, and SpO2 were measured before and after an intravenous bolus administration of ICG. RESULTS: Following the dye administration, no changes in heart rate or arterial blood pressure were noted in either group. SctO2 was increased in both groups; however, the magnitude of the increase was greater (21.6 +/- 5.8% vs. 12.6 +/- 4.1%, P < 0.0001) and more prolonged (28.4 +/- 9.6 min vs. 13.8 +/- 5.2 min, P < 0.0001) in the 25 mg group than in the 12.5 mg group. In contrast, SpO2 was decreased in both groups; the magnitude of the decrease was greater in the 25 mg group than in the 12.5 mg group (4.0 +/- 0.8% vs. 1.6 +/- 1.0%, P < 0.0001). There were no differences in the time to reach the peak SctO2 or to reach the nadir SpO2 between the two groups. CONCLUSIONS: In patients given ICG for videoangiography, a 25 mg bolus results in a greater and more prolonged increase in SctO2 and a greater reduction in SpO2 than a 12.5 mg bolus, with no differences in the time to reach the peak SctO2 or to reach the nadir SpO2.

Vasopressin ameliorates hypotension induced by beach chair positioning in a dose-dependent manner in patients undergoing arthroscopic shoulder surgery under general anesthesia / 대한마취과학회지

BACKGROUND: The beach chair position (BCP) is associated with hypotension that may lead to cerebral ischemia. Arginine vasopressin (AVP), a potent vasoconstrictor, has been shown to prevent hypotension in BCP. It also improves cerebral oxygenation in different animal models. The present study examined the effect of escalating doses of AVP on systemic hemodynamics and cerebral oxygenation during surgery in BCP under general anesthesia. METHODS: Sixty patients undergoing arthroscopic shoulder surgery in BCP under general anesthesia were randomly allocated to receive either saline (control, n = 15) or three different doses of AVP (0.025, 0.05, or 0.075 U/kg; n = 15 each) 2 minutes before BCP. Mean arterial pressure (MAP), heart rate (HR), regional cerebral oxygen saturation (SctO2), and jugular venous oxygen saturation (SjvO2) were measured after induction of anesthesia and before (presitting in supine position) and after BCP. RESULTS: AVP per se given before BCP increased MAP, and decreased SjvO2, SctO2, and HR in all patients (P 20% SctO2 decrease from the baseline value) with no differences in SjvO2 and the incidence of SjvO2 < 50% or SjvO2 < 40% among the groups. CONCLUSIONS: AVP ameliorates hypotension associated with BCP in a dose-dependent manner in patients undergoing shoulder surgery under general anesthesia. However, AVP may have negative effects on SctO2 before and after BCP and on SjvO2 before BCP.

Lipid Emulsion in the Successful Resuscitation of Local Anesthetic Toxicity after Ankle Block / 대한구급학회지

Unexpected occurrence of local anesthetic toxicity is not rare and can cause fatal complications that do not respond to any known drug of intervention. Recently, the successful use of lipid emulsion for local anesthetic toxicity has been reported and recommended as a rescue method for cardiac or neurologic complications. We report a case of seizure attack and respiratory arrest successfully recovered with the use of intravenous lipid emulsion. Clinicians must be aware of the beneficial role of lipid emulsion in cases of local anesthetic toxicity.

Blood pressure management and regional cerebral oxygen saturation during surgery in beach chair position / 대한마취과학회지

No abstract available.

Anesthetic requirements and stress hormone responses in chronic spinal cord-injured patients undergoing surgery below the level of injury: nitrous oxide vs remifentanil / 대한마취과학회지

BACKGROUND: Nitrous oxide (N2O) and remifentanil both have anesthetic-reducing and antinociceptive effects. We aimed to determine the anesthetic requirements and stress hormone responses in spinal cord-injured (SCI) patients undergoing surgery under sevoflurane anesthesia with or without pharmacodynamically equivalent doses of N2O or remifentanil. METHODS: Forty-five chronic, complete SCI patients undergoing surgery below the level of injury were randomly allocated to receive sevoflurane alone (control, n = 15), or in combination with 67% N2O (n = 15) or target-controlled infusion of 1.37 ng/ml remifentanil (n = 15). Sevoflurane concentrations were titrated to maintain a Bispectral Index (BIS) value between 40 and 50. Measurements included end-tidal sevoflurane concentrations, mean arterial blood pressure (MAP), heart rate (HR), and plasma catecholamine and cortisol concentrations. RESULTS: During surgery, MAP, HR, and BIS did not differ among the groups. Sevoflurane concentrations were lower in the N2O group (0.94 +/- 0.30%) and the remifentanil group (1.06 +/- 0.29%) than in the control group (1.55 +/- 0.34%) (P < 0.001, both). Plasma concentrations of norepinephrine remained unchanged compared to baseline values in each group, with no significant differences among groups throughout the study. Cortisol levels decreased during surgery as compared to baseline values, and returned to levels higher than baseline at 1 h after surgery (P < 0.05) without inter-group differences. CONCLUSIONS: Remifentanil (1.37 ng/ml) and N2O (67%) reduced the sevoflurane requirements similarly by 31-39%, with no significant differences in hemodynamic and neuroendocrine responses. Either remifentanil or N2O can be used as an anesthetic adjuvant during sevoflurane anesthesia in SCI patients undergoing surgery below the level of injury.

Effects of inspired oxygen fraction in discriminating venous from arterial blood in percutaneous central venous catheterization under general anesthesia / 대한마취과학회지

BACKGROUND: A low fraction of inspired oxygen (FiO2) increases venous deoxygenated hemoglobin concentrations, making the color of the blood darker. The present study was aimed to determine the effects of FiO2 on the ability to discriminate venous from arterial blood. METHODS: One-hundred and sixty surgical patients undergoing percutaneous central venous access of the internal jugular vein were randomly assigned to receive an FiO2 of 0.2, 0.4, 0.6, or 1.0 (n = 40 each) for at least 20 min prior to central line placement under general anesthesia. Vascular access was achieved with a 22-gauge needle; 2 ml of blood was withdrawn and shown to three physicians including the operator. Each of them was asked to identify the blood as 'arterial', 'venous' or 'not sure'. Simultaneous blood gas analysis of the samples was performed on blood taken from the puncture site and the artery after visual comparison to confirm blood's origin and hemodynamic measurements. RESULTS: Lowering FiO2 progressively increased venous deoxygenated hemoglobin concentrations (2.24 +/- 1.12, 3.30 +/- 1.08, 3.66 +/- 1.15, and 3.71 +/- 1.33 g/dl) in groups having an FiO2 of 1.0, 0.6, 0.4 and 0.2, respectively (P < 0.001), thereby facilitating the 'venous' blood identification (P < 0.001). Neither heart rate nor mean arterial pressure differed among the groups. None developed hypoxemia (percutaneous hemoglobin oxygen saturation < 90%) in any group during the study period. CONCLUSIONS: A low FiO2 increases venous deoxygenated hemoglobin levels, thereby facilitating the recognition by clinicians of its venous origin in percutaneous central venous catheterization under general anesthesia.

Protective Effect of Sauchinone Against Regional Myocardial Ischemia/Reperfusion Injury: Inhibition of p38 MAPK and JNK Death Signaling Pathways

Sauchinone has been known to have anti-inflammatory and antioxidant effects. We determined whether sauchinone is beneficial in regional myocardial ischemia/reperfusion (I/R) injury. Rats were subjected to 20 min occlusion of the left anterior descending coronary artery, followed by 2 hr reperfusion. Sauchinone (10 mg/kg) was administered intraperitoneally 30 min before the onset of ischemia. The infarct size was measured 2 hr after resuming the perfusion. The expression of cell death kinases (p38 and JNK) and reperfusion injury salvage kinases (phosphatidylinositol-3-OH kinases-Akt, extra-cellular signal-regulated kinases [ERK1/2])/glycogen synthase kinase (GSK)-3beta was determined 5 min after resuming the perfusion. Sauchinone significantly reduced the infarct size (29.0% +/- 5.3% in the sauchinone group vs 44.4% +/- 6.1% in the control, P < 0.05). Accordingly, the phosphorylation of JNK and p38 was significantly attenuated, while that of ERK1/2, Akt and GSK-3beta was not affected. It is suggested that sauchinone protects against regional myocardial I/R injury through inhibition of phosphorylation of p38 and JNK death signaling pathways.

Cardiovascular and arousal responses to single-lumen endotracheal and double-lumen endobronchial intubation in the normotensive and hypertensive elderly / 대한마취과학회지

BACKGROUND: Endotracheal intubation usually causes transient hypertension and tachycardia. The cardiovascular and arousal responses to endotracheal and endobronchial intubation were determined during rapid-sequence induction of anesthesia in normotensive and hypertensive elderly patients. METHODS: Patients requiring endotracheal intubation with (HT, n = 30) or without hypertension (NT, n = 30) and those requiring endobronchial intubation with (HB, n = 30) or without hypertension (NB, n = 30) were included in the study. Anesthesia was induced with intravenous thiopental 5 mg/kg followed by succinylcholine 1.5 mg/kg. After intubation, all subjects received 2% sevoflurane in 50% nitrous oxide and oxygen. Mean arterial pressure (MAP), heart rate (HR), plasma catecholamine concentration, and Bispectral Index (BIS) values, were measured before and after intubation. RESULTS: The intubation significantly increased MAP, HR, BIS values and plasma catecholamine concentrations in all groups, the peak value of increases was comparable between endotracheal and endobronchial intubation. However, pressor response persisted longer in the HB group than in the HT group (5.1 +/- 1.6 vs. 3.2 +/- 0.9 min, P < 0.05). The magnitude of increases in MAP and norepinephrine from pre-intubation values was greater in the hypertensive than in the normotensive group (P < 0.05), while there were no differences in those of HR and BIS between the hypertensive and normotensive groups. CONCLUSIONS: Cardiovascular response and arousal response, as measured by BIS, were similar in endobronchial and endotracheal intubation groups regardless of the presence or absence of hypertension except for prolonged pressor response in the HB group. However, the hypertensive patients showed enhanced cardiovascular responses than the normotensive patients.

Fatal pulmonary embolism caused by thrombosis of contralateral axillary vein after arthroscopic right rotator cuff repair: A case report / 대한마취과학회지

A clinically apparent thromboembolism associated with arthroscopic shoulder surgery is extremely rare. We report a case of a fatal pulmonary embolism developed after an arthroscopic rotator cuff repair in a 45-year-old woman. On the first day after surgery, she experienced syncope that was complicated by cardiac arrest. No hemostasis impairment was noted. A computed tomography scan revealed a pulmonary embolism, and Doppler ultrasound revealed thrombosis of the axillary vein on the contralateral shoulder. She died from multiple organ failure 13 days after surgery. This case shows that clinicians must be aware of the potential occurrence of a pulmonary thromboembolism in patients undergoing prolonged arthroscopic shoulder surgery.

Comparison of intubating conditions and hemodynamic responses to tracheal intubation with different effect-site concentrations of remifentanil without muscle relaxants during target-controlled infusion of propofol / 대한마취과학회지

BACKGROUND: We compared the effects of different remifentanil effect-site concentrations on intubating conditions, and cardiovascular and bispectral index score (BIS) responses to intubation at a fixed effect-site concentration of propofol without muscle relaxants. METHODS: Sixty-four patients were randomly assigned to one of three groups: remifentanil 2 (group R2, n = 22), 4 (group R4, n = 21), or 6 ng/ml (group R6, n = 21). Anesthesia was induced using target-controlled infusion of propofol 5 microgram/ml and each concentration of remifentanil. Laryngoscopy and intubation was attempted at 2.5 min following induction. Intubating conditions were assessed as excellent, good or poor using a standard scoring system. Mean arterial pressure (MAP), heart rate (HR), and BIS values were assessed. RESULTS: Excellent or good intubating conditions were obtained in 91% of group R4 and 95% of R6, both of which are higher compared with 32% of R2 (P < 0.01). MAP and HR decreased significantly after induction in all groups. After intubation, they recovered to baseline value in group R2 and R4 but were significantly less than baseline values in R6. BIS response to intubation was attenuated in group R4 and R6 but not R2. Hypotension was more frequent in group R6 than R2. CONCLUSIONS: Remifentanil target concentrations of 4 or 6 ng/ml combined with 5 microgram/ml propofol provided good or excellent conditions for tracheal intubation and prevented cardiovascular and BIS response during induction without muscle relaxants. However, the use of 6 ng/ml dose was associated with frequent occurrence of hypotension and bradycardia requiring treatment.

Maternal and neonatal effects of remifentanil used during induction of general anesthesia in preeclamptic patients undergoing cesarean delivery / 대한마취과학회지

BACKGROUND: Endotracheal intubation elicits cardiovascular and arousal responses. The present study was aimed to determine whether remifentanil affects these responses in patients with preeclampsia. METHODS: Thirty preeclamptic women who were scheduled to undergo cesarean delivery under general anesthesia were randomly assigned to receive either remifentanil 1 microgram/kg (n = 15) or saline (n = 15) before induction of anesthesia. Systolic arterial pressure (SBP), heart rate (HR) and bispectral index (BIS) value as well as plasma catecholamine concentrations were measured. Neonatal effects were assessed using Apgar score and umbilical cord blood gas analysis. RESULTS: Induction with thiopental caused a reduction in SBP and BIS (P < 0.01) in both groups. Following the tracheal intubation SBP and HR increased in both groups, the magnitude of which was lower in the remifentanil group. BIS values also increased, of which magnitude did not differ between the groups. Norepinephrine concentrations increased significantly following the intubation in the control, while remained unaltered in the remifentanil group. The neonatal Apgar scores (5 min), and umbilical gas values were similar in the two groups except for higher incidence of Apgar score < 7 at 1 min in the remifentanil group. CONCLUSIONS: Remifentanil 1 microgram/kg effectively attenuates hemodynamic and catecholamine but not BIS responses to tracheal intubation in preeclamptic patients undergoing cesarean delivery. However, remifentanil may cause mild neonatal depression and thus should be used when adequate facilities for neonatal resuscitation are available.

Hemodynamic and Catecholamine Responses to Laryngoscopy and Endotracheal Intubation in Paraplegic Patients: Time Course and Relation to the Affected Level / 대한마취과학회지

BACKGROUND: We determined whether the cardiovascular responses to endotracheal intubation change as a function of the time elapsed after injury and the level of injury in patients with spinal cord injury. METHODS: One-hundred-eighty six patients with complete cord injury were grouped into 3 according to the level of injury:high- (T1-T4, n = 34), mid- (T5-T10, n = 47) and low paraplegics ( 10 yrs.Twenty-five patients with no cord injury served as controls.Systolic arterial blood pressure (SAP), heart rate (HR), and plasma catecholamine concentrations were measured. RESULTS: The intubation caused an increase of SAP and norepinephrine concentrations in every group.However, the magnitude of their peak increases was less in high paraplegics compared with all other groups (P < 0.05).HR was similarly increased in all groups (P < 0.01).Pressure but not either HR or norepinephrine response was enhanced in mid- and low-paraplegics whose injury elapsed more than 10 yrs compared with controls (P < 0.05).The incidence of arrhythmias did not differ among the groups. CONCLUSIONS: The pressure and plasma catecholamine changes associated with endotracheal intubation may be attenuated in high-paraplegics, and the pressure changes may be enhanced over time in mid- and low-paraplegics.

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.

Anesthetic Management for a Patient with Congenital Insensitivity to Pain with Anhidrosis (CIPA): A case report / 대한마취과학회지

Congenital insensitivity to pain with anhidrosis (CIPA) is a rare, autosomal-recessive disorder characterized by the clinical triad of indifference of pain, anhidrosis and heat intolerance.Because of their lack of autonomic response to noxious stimuli, the determination of adequate depth of anesthesia in the CIPA patient undergoing surgery is a major challenge.We experienced a patient with CIPA who had minor procedures three times under the general anesthesia, in which bispectral index (BIS) was maintained at 40-50 by adjusting sevoflurane concentrations with 50% nitrous oxide.The low end-tidal sevoflurane concentrations (<1.2 vol%) were required to keep the target BIS while vital signs remained stable throughout the surgery in each operation.BIS monitor may be a valuable tool to guide the depth of anesthesia in patients with CIPA.

Effects of Nitrous Oxide and Remifentanil on Cardiovascular Response to Endotracheal Intubation during Desflurane Anesthesia

BACKGROUND: Desflurane is known to causes hypertension and tachycardia when its inspired concentration is rapidly increased. We determined whether nitrous oxide (N2O) or remifentanil alters cardiovascular responses to intubation and/or inhalation of high concentrations of desflurane during induction of anesthesia. METHODS: Sixty patients were assigned randomly into three groups (n = 20 each). Anesthesia was induced with thiopental 5 mg/kg followed by saline (control and N2O groups) or remifentanil 1microg/kg (remifentanil group). Tracheal intubation was facilitated with intravenous vecuronium 0.12 mg/kg and 12% desflurane was given soon after the intubation. In addition, 75% N2O was given beginning 3 min before the intubation in the N2O group. Systolic arterial pressure (SAP), heart rate (HR), and plasma catecholamine concentrations were determined. RESULTS: The intubation resulted in an immediate increase and an additional second increase of SAP and HR at 3 to 5 min after intubation in all groups. SAP but not HR in the N2O group and both SAP and HR in the remifentanil group at first and second peak responses were lower than in the control group. Norepinephrine increased at 1 min after intubation and increased further at 5 min in the control and N2O groups but only increased at 5 min in the remifentanil group. CONCLUSIONS: A biphasic pressor and tachycardiac response in response to intubation and desflurane were noted. Although N2O did not affect tachycardiac response, it suppressed the pressor responses and augmented norepinephrine release. However, remifentanil significantly attenuated hemodynamic and catecholamine responses to endotracheal intubation and desflurane.

Anesthesia for Non-cardiac Surgery in the Patients with Cardiac Disease

Perioperative myocardial infarction is a major cause of morbidity and mortality in patients who undergo non-cardiac surgery, while an increasing number of patients with a coronary artery disease are presenting for surgery. In order to cope with this problem, one should first evaluate risk factors of these complications, and then manage the patient at risk to reduce or eliminate the risk factors. Risk assessment evaluates patients' co-morbidities and exercise tolerance, as well as the type of surgery to be performed, to determine the overall risk of perioperative cardiac complications. Previous or current cardiac disease, diabetes, and renal insufficiency all confer higher risks for perioperative cardiac complications. Poor exercise tolerance and high-risk surgical procedures (e.g., vascular, prolonged thoracic, or abdominal operations) also predict worse perioperative outcomes. Stress testing should be reserved for patients at moderate to high risk undergoing moderate- or high-risk surgery and those who have poor exercise capacity. After the assessment of the risk of cardiac complications, one should take measures to reduce it, including medical therapy and coronary intervention. Medical therapy using beta blockers, statins, and alpha-2 agonists may be effective to reduce perioperative risk and to obviate the need for more invasive procedures in high-risk patients. Coronary intervention should be performed for those patients who are indicated independent of the non-cardiac surgery. There appears to be no single best myocardium-protective anesthetic management, and therefore, the choice of anesthesia and intraoperative monitors is left at the discretion of the anesthesia care team.

Ischemic Reperfusion Injury and Anesthetics / 대한마취과학회지

No Abstract available.

Effects of Remifentanil and Alfentanil on Cardiovascular Responses to Laryngoscopy and Double-lumen Endobronchial Intubation / 대한마취과학회지

BACKGROUND: This study examined the cardiovascular responses to double-lumen endobronchial intubation during rapid sequence induction of anesthesia, and compared the effect of remifentanil and alfentanil in a randomized, double-blind, placebo-controlled study in three groups of 20 elderly patients each. METHODS: Anesthesia was induced with intravenous thiopental (4-6 mg/kg) immediately followed by either remifentanil 2 microgram/kg, alfentanil 30microgram/kg, or saline (placebo) given over 30 sec. Succinylcholine 1.5 mg/kg was given for neuromuscular block. The laryngoscopy and intubation were performed 60 sec later. RESULTS: The intubation significantly increased systolic arterial pressure (SAP) and heart rate (HR) in all groups. The maximum pressure changes in the remifentanil and alfentanil groups (36 +/- 26 and 33 +/- 30 mmHg, respectively) were significantly lower than the 83 +/- 35 mmHg in the control group. The maximum HR in the remifentanil (77 +/- 13 bpm) and alfentanil (80 +/- 13 bpm) groups was lower when compared to controls (93 +/- 11 bpm). The norepinephrine and epinephrine concentrations increased after intubation in the control group but remained unaltered in both the alfentanil and remifentanil groups. There were no significant differences between the remifentanil and alfentanil groups in HR, SAP or catecholamines at any time. Five patients in the remifentanil group and three in the alfentanil group received ephedrine for hypotension. CONCLUSIONS: Endobronchial intubation elicited a significant pressor response, and that both remifentanil and alfentanil similarly attenuated the pressor response. However, the incidence of hypotension confirms that both drugs should be used with caution in elderly patients.

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.