Normal aging: definition and physiologic changes

Aging is a process of the progressive functional decline with time, leading to disability, dependence, morbidity, and mortality. While the organ function in the elderly is relatively uncompromised under basal conditions, their ability to tolerate increased physiologic stress is reduced. And the extent and onset of the deterioration in functional reserve is quite diverse from patient to patient. The aging population is rapidly growing and their medical management is becoming one of the greatest challenges to anesthesiologists. The understanding of the normal physiologic changes with aging is essential to frame any discussion of perioperative management in the elderly. In this review, we will focus on the physiologic changes in neurologic, cardiac, pulmonary, renal, and hepatic function, and thermoregulation.

Thrombus entrapped by patent foramen ovale in a patient with pulmonary embolism: a case report / 대한마취과학회지

Thrombus-in-transit appears to increase the risk of mortality compared to pulmonary embolism alone and can require alteration in therapeutic plan. We present the case of a biatrial thromboembolus caught in transit across a patent foramen ovale diagnosed by intraoperative transesophageal echocardiogram in a 69-year-old female with acute pulmonary embolism and subsequent acute cerebral infarction. We suggest that echocardiography should be performed in a patient with suspected pulmonary thromboembolism to evaluate right heart function and diagnose emboli in transit.

Incidence and Risk Factors of Postoperative Nausea and Vomiting in Patients with Fentanyl-Based Intravenous Patient-Controlled Analgesia and Single Antiemetic Prophylaxis

PURPOSE: We evaluated the incidence and risk factors of postoperative nausea and vomiting (PONV) in patients with fentanyl-based intravenous patient-controlled analgesia (IV-PCA) and single antiemetic prophylaxis of 5-hydroxytryptamine type 3 (5 HT3)-receptor antagonist after the general anesthesia. MATERIALS AND METHODS: In this retrospective study, incidence and risk factors for PONV were evaluated with fentanyl IV-PCA during postoperative 48 hours after various surgeries. RESULTS: Four hundred-forty patients (23%) of 1878 had showed PONV. PCA was discontinued temporarily in 268 patients (14%), mostly due to PONV (88% of 268 patients). In multivariate analysis, female, non-smoker, history of motion sickness or PONV, long duration of anesthesia (>180 min), use of desflurane and intraoperative remifentanil infusion were independent risk factors for PONV. If one, two, three, four, five, or six of these risk factors were present, the incidences of PONV were 18%, 19%, 22%, 31%, 42%, or 50%. Laparoscopic surgery and higher dose of fentanyl were not risk factors for PONV. CONCLUSION: Despite antiemetic prophylaxis with 5 HT3-receptor antagonist, 23% of patients with fentanyl-based IV-PCA after general anesthesia showed PONV. Long duration of anesthesia and use of desflurane were identified as risk factors, in addition to risk factors of Apfel's score (female, non-smoker, history of motion sickness or PONV). Also, intraoperative remifentanil infusion was risk factor independent of postoperative opioid use. As the incidence of PONV was up to 50% according to the number of risk factors, risk-adapted, multimodal or combination therapy should be applied.

Sugammadex versus neostigmine reversal of moderate rocuronium-induced neuromuscular blockade in Korean patients / 대한마취과학회지

BACKGROUND: Rapid and complete reversal of neuromuscular blockade (NMB) is desirable at the end of surgery. Sugammadex reverses rocuronium-induced NMB by encapsulation. It is well tolerated in Caucasian patients, providing rapid reversal of moderate (reappearance of T2) rocuronium-induced NMB. We investigated the efficacy and safety of sugammadex versus neostigmine in Korean patients. METHODS: This randomized, safety assessor-blinded trial (NCT01050543) included Korean patients undergoing general anesthesia. Rocuronium 0.6 mg/kg was given prior to intubation with maintenance doses of 0.1-0.2 mg/kg as required. Patients received sugammadex 2.0 mg/kg or neostigmine 50 microg/kg with glycopyrrolate 10 microg/kg to reverse the NMB at the reappearance of T2, after the last rocuronium dose. The primary efficacy endpoint was the time from sugammadex or neostigmine administration to recovery of the train-of-four (TOF) ratio to 0.9. The safety of these medications was also assessed. RESULTS: Of 128 randomized patients, 118 had evaluable data (n = 59 in each group). The geometric mean (95% confidence interval) time to recovery of the TOF ratio to 0.9 was 1.8 (1.6, 2.0) minutes in the sugammadex group and 14.8 (12.4, 17.6) minutes in the neostigmine group (P < 0.0001). Sugammadex was generally well tolerated, with no evidence of residual or recurrence of NMB; four patients in the neostigmine group reported adverse events possibly indicative of inadequate NMB reversal. CONCLUSIONS: Sugammadex was well tolerated and provided rapid reversal of moderate rocuronium-induced NMB in Korean patients, with a recovery time 8.1 times faster than neostigmine. These results are consistent with those reported for Caucasian patients.

Heart rate variability predicts the extent of corrected QT interval prolongation after tracheal intubation

BACKGROUND: Corrected QT (QTc) interval can be modulated by sympathetic and parasympathetic balance. Tracheal intubation causes significant prolongation of the QTc interval due to sympathetic stimulation. This study was designed to elucidate the relationship between baseline autonomic nervous system activity and QTc prolongation after endotracheal intubation using heart rate variability (HRV). METHODS: Sixty-six healthy patients were included and the baseline HRV data were recorded for 5 min before anesthesia. Power spectrum densities were calculated for low frequencies (LF, 0.04-0.15 Hz) and high frequencies (HF, 0.15-0.4 Hz), defined as either LF's or HF's relative part of the total power. Anesthesia was induced with sevoflurane and vecuronium was given. The QTc interval, heart rate (HR) and mean arterial pressure (MAP) were measured before induction (baseline), before laryngoscopy (pre-intubation) and immediately after the intubation (post-intubation). RESULTS: The QTc interval change at post-intubation from baseline (DeltaQTc) showed a significant negative correlation with the HF (r = 0.34, P = 0.006) and positive correlation with LF/HF ratio (r = 0.37, P = 0.005). Patients were retrospectively divided into low-HF/LF (2.5, n = 22). The DeltaQTc was statistically higher in the high-LF/HF group compared to that in the low-LF/HF group (P = 0.048). The HR and MAP at baseline, pre-intubation and post-intubation were not different between two groups. CONCLUSIONS: The QTc interval prolongation after endotracheal intubation is influenced by baseline autonomic conditions and can be exaggerated in patients with activated sympathetic activity or depressed parasympathetic activity.

Low-dose remifentanil to modify hemodynamic responses to tracheal intubation: comparison in normotensive and untreated/treated hypertensive Korean patients / 대한마취과학회지

BACKGROUND: Remifentanil has been shown to be effective at treating potentially adverse hemodynamic responses to tracheal intubation even at low doses (< 1 microg/kg/min), which needs to be evaluated in patients with diverse cardiovascular conditions. METHODS: A low-dose regimen of remifentanil (continuous infusion of 0.1 microg/kg/min, preceded by 0.5 microg/kg bolus) was given before induction with bolus propofol and rocuronium, and heart rate as well as systolic, diastolic, and mean arterial pressures were measured at 1 min intervals from before induction to 5 min after tracheal intubation in normotensive patients, untreated hypertensive patients, and patients with known hypertension. RESULTS: The low-dose regimen of remifentanil resulted in parallel hemodynamic responses in all three groups, and was effective at limiting hemodynamic responses to tracheal intubation without excessive cardiovascular depression. Hemodynamic responses in our study showed a similar pattern to that reported in previous investigations, except for elevations in heart rate and arterial pressures over the baseline values immediately after intubation. CONCLUSIONS: We suggest that the low-dose regimen of remifentanil in our study could be routinely used to modify hemodynamic responses to tracheal intubation in patients with diverse hemodynamic characteristics. However, the development of supplementary regimens is still needed to control the brief, but exaggerated responses to tracheal intubation, especially in untreated hypertensive patients.

Comparison of the trapezius squeezing test and jaw thrust as indicators for laryngeal mask airway insertion in adults / 대한마취과학회지

BACKGROUND: The purpose of this study was to compare the effectiveness of the trapezius squeezing test with that of the jaw thrust maneuver as clinical indicators of adequate conditions for laryngeal mask airway (LMA) insertion in adults under sevoflurane anesthesia. METHODS: One hundred adult patients of ASA physical status 1 or 2 undergoing minor surgical procedures were randomly allocated to the T (trapezius squeezing, n = 50) group or the J (jaw thrust, n = 50) group. The LMA was inserted immediately after the loss of response to trapezius squeezing or jaw thrust. Successful and unsuccessful attempts were recorded. An unsuccessful attempt was defined as the occurrence of coughing, gagging, gross purposeful movements, breath-holding, laryngospasm, or an SpO2 < 90% during LMA insertion. Insertion time, end-tidal sevoflurane concentration, mean arterial pressure, and heart rate were recorded. RESULTS: The incidence of successful attempts was significantly higher in the T than in the J group (48/50 vs. 36/50, respectively). CONCLUSIONS: The trapezius squeezing test is a superior indicator of an adequate condition for LMA insertion compared to the jaw thrust maneuver in adults under sevoflurane anesthesia.

Cardioprotection and ageing / 대한마취과학회지

With an increase in the elderly population and an increase in the prevalence of age-related cardiovascular disease, anesthesiologists are increasingly being faced with elderly patients with known or suspected ischemic heart disease in the perioperative period. Although early reperfusion remains the best strategy to reduce ischemic injury, reperfusion may damage the myocardium. Adjuvant therapy to revascularization is therefore necessary. To develop better strategies to prevent ischemia-reperfusion injury in older patients, we need to understand the aged myocardium, which has undergone structural and functional changes relative to the normal myocardium, resulting in reduced functional capacity and vulnerability to ischemia-reperfusion injury. In addition, innate or acquired cardioprotection deteriorates with aging. These changes in the aged myocardium might explain why there is poor translation of basic research findings from young animals to older patients. In this review, I discuss changes in intracellular signaling associated with myocardial ageing that have an effect on ischemia-reperfusion injury, and I discuss the efficacy of cardioprotection afforded by ischemic and pharmacologic pre-and post-conditioning in the aged myocardium. Finally, I outline strategies to restore protection in the aged myocardium.

Mitochondrial Permeability Transition Pore and Cardioprotection Against Ischemia-reperfusion Injury

Opening of mitochondrial permeability transition pore (mPTP) was found to have a critical role in cell death from ischemia/reperfusion (I/R) injury experimentally in the late 1980's. Thereafter, tremendous efforts have been made to define the molecular composition of mPTP and underlying mechanisms of its opening. mPTP opening, so far, has been demonstrated with the conformational changes of the mitochondrial protein components including cyclophilin-D, adenine nucleotide translocase, and voltage-dependent anion channel, which were induced by the modification of the levels of Ca2+, phosphate, mitochondrial membrane potential, intracellular pH and adenine nucleotide. At present, genetic modulation of the expression of protein components are being used in the investigation of its properties, presenting novel mechanisms of mPTP opening, including phosphate carrier. For therapeutic intervention, cyclosporin A and its analogues were first to be demonstrated to inhibit the opening of mPTP, affecting cyclophilin-D. There are numerous pharmacological substances that have direct or indirect effects on mPTP opening, including bongkrekic acid, reactive oxygen species scavengers, calcium channel blockers, and Na+/H+ exchanger-1 inhibitors, but only cyclosporin A was clinically tried to limit the myocardial infarction. Conditioning interventions, ischemic or anesthetic, have also been shown to be effective in limiting the detrimental effects of I/R injury. These interventions are commonly related to specific receptors on cell membrane and then signal transduction pathway consisting of many protein kinases, which eventually lead to mitochondria. And being presented are experimental evidences that inhibition of mPTP opening is a primary mechanism of these conditioning interventions. In conclusion, mPTP opening is now presented as primary mechanism and therapeutic target of I/R injury, but precise mechanism and standardized treatment method are needed to be clarified.

Cariopulmonary Resuscitation / 대한마취과학회지

No abstract available.

The CobraPLA(TM) During Anesthesia with Controlled Ventilation: A Clinical Trial of Efficacy

The CobraPLA(TM) (CPLA) is a relatively new supraglottic airway device that has not been sufficiently investigated. Here, we performed a prospective observational study to evaluate the efficacy of the CPLA during controlled ventilation. In 50 anesthetized and paralyzed patients undergoing elective surgery a CPLA was inserted and inflated to an intracuff pressure of 60 cm H2O. The success rate of insertion upon the first attempt was 82% (41/50), with a mean insertion time of 16.3 +/- 4.5 seconds. The adequacy of ventilation was assessed by observing the end tidal CO2 waveform, movement of the chest wall, peak airway pressure (13.5 cm H2O), and leak fraction (4%). We documented the airway sealing pressure (22.5 cm H2O) and noted that the the site of gas leaks at that pressure were either at the neck (52%), the abdomen (46%), or both (2%). In 44 (88%) patients, the vocal cords were visible in the fiberoptic view through the CPLA. There was no gastric insufflation during the anesthesia. Respiratory and hemodynamic parameters remained stable during CPLA insertion. Postoperative blood staining of CPLA was minimal, occurring in 22% (11/50) of patients. Mild and moderate throat soreness was reported in 44% (22/50) and 4% (2/50) of patients, respectively. Lastly, mild dysphonia was observed in 6% (3/50) of patients and mild dysphagia in 10% (5/50) of patients. Our results indicated that the CPLA is both easy to place and allows adequate ventilation during controlled ventilation.

The Effect of Milrinone on the Right Ventriclular Function in Patients with Reduced Right Ventricular Function Undergoing Off-pump Coronary Artery Bypass Graft Surgery

This investigation evaluated the effect of continuous milrinone infusion on right ventriclular (RV) function during off-pump coronary artery bypass graft (OPCAB) surgery in patients with reduced RV function. Fifty patients scheduled for OPCAB, with thermodilution RV ejection fraction (RVEF) <35% after anesthesia induction, were randomly allocated to either milrinone (0.5 microgram/kg/min) or control (saline) group. Hemodynamic variables and RV volumetric data measured by thermodilution method were collected as follows: after anesthesia induction (T1); 10 min after heart displacement for obtuse marginal artery anastomosis (T2); after pericardial closure (T3). Cardiac index and heart rate increased and systemic vascular resistance significantly decreased in milrinone group at T2. Initially lower RVEF of milrinone group was eventually comparable to control group after milrinone infusion. RVEF did not significantly change at T2 and T3 in both groups. RV end-diastolic volume in milrinone group consistently decreased from the baseline at T2 and T3. Continuous infusion of milrinone without a bolus demonstrated potentially beneficial effect on cardiac output and RV afterload in patients with reduced RV function during OPCAB. However, aggressive augmentation of intravascular volume seems to be necessary to maximize the effect of the milrinone in these patients.

Epinephrine-induced Metabolic Acidosis during Orthognatic Surgery: A case report / 대한마취과학회지

Epinephrine has a variety of clinical uses one is its use as a topical hemostatic agent on bleeding surfaces, such as in the mouth. We report a temporal association between the administration of topical epinephrine and the development of metabolic acidosis during general anesthesia. A 21 year-old patient, with facial asymmetry, had undergone orthognatic surgery. During the operation, serial blood gas analysis revealed the onset of a metabolic acidosis following the local infiltration (0.036 mg) and topical application of a high dose of epinephrine-Bosmin(R) (1:1,000 epinephrine). The metabolic acidosis resolved within 5 hours.

The Influence of Sevoflurane on the Antagonism Effect of Neostigmine for Rocuronium-induced Neuromuscular Blockade / 대한마취과학회지

BACKGROUND: Some volatile anesthetics prolong the spontaneous recovery from neuromuscular blockade, and decrease the effect of neostigmine administrated for neuromuscular recovery. In addition, these effects differ among each volatile anesthetic. The aim of this study was to examine the effect of sevoflurane on the antagonism effect of neostigmine during the recovery period after administering rocuronium. METHODS: Sixty-five adult patients were randomly allocated into 3 groups, using propofol and alfentanil, sevoflurane, and enflurane for the maintenance of anesthesia. Neuromuscular monitoring was performed using accelomyography. Tracheal intubation was performed at the maximum blockade after administering 0.6 mg/kg rocuronium. The infusion of rocuronium was initiated when a twitch was noticed and the infusion rate of rocuronium was determined to maintain a 15 +/- 5% twitch height. The acid-base balance was measured at a constant twitch height, and 20microgram/kg neostigmine injection. After neostigmine, the initial twitch height, the maximum twitch height, the onset and duration of neostigmine were measured, and the antagonism effect was calculated as a percentage of the pre-existing twitch depression immediately before administering the neostigmine. RESULTS: The maximum twitch heights and antagonism effects of the Sevoflurane and Propofol groups were larger than that of the Enflurane group and the durations of the neostigmine effect were longer. The rocuronium infusion rate was significantly higher in the Propofol group than in the other groups. CONCLUSIONS: The effects of sevoflurane on the antagonism effect and duration of neostigmine were less than enflurane, and there was no difference between sevoflurane and propofol.

Admission Hyperglycemia Aggravates the Prognosis of Critically Ill Patients / 대한구급학회지

BACKGROUND: Hyperglycemia is a common disease in critically ill patients, even those without diabetes. It has been recognized acute increase of blood glucose level would increase mortality in patients with and without diabetes in vascular disease such as acute myocardial infarct or acute stroke. However, there is not much data about hyperglycemic effects on the prognosis of patients with heterogenous disease in general intensive care unit (ICU). Aim of this study was to evaluate the effects of admission hyperglycemia on prognosis of critically ill patients with heterogenous disease. METHODS: We reviewed medical records of 712 patients admitted general ICU from July, 2000 to March, 2002 in teaching hospital. The patients who were not checked blood glucose level at ICU admission were excluded. We regarded diabetes patients who have been diagnosed diabetes before ICU admission. Hyperglycemia was defined as a fasting glucose level above 140 mg/dl or random glucose level above 200 mg/dl on 2 or more determinations. We measured hospital mortality, ICU stay, and hospital stay as well as blood glucose level. RESULT: Patients mortalities of diabetic hypergylcemia, nondiabetic hyperglycemia, diabetic normoglycemia, and nondiabetic normoglycemia were 17%, 19%, 26% and 10% respectively. CONCLUSIONS: Mortality of diabetic patients regardless of hyperglycemia at admission time and nondiabetic hyperglycemia patients were higher than nondiabetic normoglycemia patients in ICU.

The Effect of Hyperglycemia on the Prognosis of Critically Ill Patients Does Not Differ Diabetics from Nondiabetics / 대한마취과학회지

BACKGROUND: Hyperglycemia is common in critically ill patients, even in those without diabetes, and it is known to increase mortality in patients with or without diabetes in the settings of acute myocardial infarction or acute stroke. However, the clinical effects of admission hyperglycemia are uncertain, and no data is available that compares the prognosis in a heterogenous group of critically ill patients. The aim of this study was to evaluate the effect of hyperglycemia on prognosis in a heterogenous group of critically ill patients with or without diabetes. METHODS: The medical records of 858 consecutive adult patients admitted to a general intensive care unit (ICU) at a University Hospital over 21 months were reviewed. Patients with no records of blood glucose measurements and patients with normoglycemia during the first 3 days were excluded. The remaining 349 patients with hyperglycemia were divided into two groups according to a previous history of diabetes. Hyperglycemia was defined as a fasting blood glucose level of 140 mg/dl or more, or a random blood glucose level of 200 mg/dl or more on 2 or more determinations. The primary end-point of the study was ICU and in-hospital mortality, and its secondary end-point included length of stay in the ICU and hospital. RESULTS: There were no significant differences in ICU mortality (17.6/19.0%), in-hospital mortality (24.5/24.3%), ICU length of stay (6.6 +/- 11.9/6.6 +/- 10.4 days), and hospital length of stay (11.4 +/- 29.0/12.8 +/- 24.3 days) between diabetics and nondiabetics. CONCLUSIONS: Our results indicate that the effects of hyperglycemia on the prognosis of critically ill patients do not differ diabetics from nondiabetics.

Severe Hypotension Caused by Valve Malfunction in the Self-Inflating Bag-Valve Unit: A case report / 대한마취과학회지

Mishaps related to valve malfunction in a self-inflating bag-valve unit can lead to fatal complications. We report a case of severe hypotension that resulted from the locking of the Laerdal valve in the inspiratory position during transport in the operating room. A 36 year old man had undergone an off-pump coronary artery bypass graft. Immediately before leaving the operating room, severe hypotension developed abruptly. But an EKG showed only a reduction of heart rate. We started closed cardiac massage with an intravenous bolus injection of epinephrine 0.5 microgram and reconnected the anesthesia breathing circuit. The patient was manually ventilated using the anesthesia reservoir bag. Vital signs immediately recovered. At that time, the patient's abdomen was distended and we suspected an expiratory abnormality. The self-inflating bag-valve unit was tested with an anesthesia reservoir bag as a test lung. Expiration did not occur. Another self-inflating bag-valve unit was substituted and normal ventilation was restored. It is essential that before use, a self-inflating bag-valve unit should be tested for proper function during both expiration and inspiration using a test lung such as, an anesthesia reservoir bag.

Cardiac Output Estimations by Esophageal Doppler Cannot Replace Estimations by the Thermodilution Method in Off-pump Coronary Artery Bypass Surgery Patients / 대한마취과학회지

BACKGROUND: Esophageal doppler is discribed as a non-invasive alternative to cardiac output (CO) estimation by thermodilution, the current bedside "gold standard". This study was designed to evaluate the accuracy of CO estimations performed by esophageal doppler (EDCO), compared to those obtained using a continuous CO pulmonary flotation catheter (TDCO). METHODS: In 16 patients undergoing off-pump coronary artery bypass surgery, CO was measured simultaneously by the esophageal doppler and the thermodilution method, after induction (A), after sternotomy (B), after coronary revascularization (C), and after sternal closure (D). Agreement between the TDCO and EDCO estimations was assessed by analyzing their mean differences and the distribution of these differences. Relative CO changes (percentages of the previous value) was analyzed by the same method. RESULTS: Both absolute CO values and relative CO changes by esophageal doppler showed a considerable scatter compared to those obtained using the thermodilution method. The bias (EDCO-TDCO) between the two mehtods was -0.8 +/- 2.7 L/min for A, -0.9 +/- 2.5 L/min for B, -0.9 +/- 3.6 L/min for C, and -0.6 +/- 2.7 (mean +/- 2 SD) L/min for D. On analyzing changes in CO, no significant method bias was found but 2 SD of the bias were +/- 74% for A to B, +/- 100% for B to C, and +/- 83% for C to D. CONCLUSIONS: These results suggest that CO estimations by esophageal doppler cannot replace estimations by the thermodilution method in patients undergoing off-pump coronary artery bypass graft surgery.

Efficacy of the Laryngeal Tube in General Anesthesia / 대한마취과학회지

BACKGROUND: A prototype airway management device, a laryngeal tube, has been recently introduced in Korea. This study was designed to assess the efficacy of the laryngeal tube for airway management under general anesthesia. METHODS: We studied thirty-six ASA physical status I and II patients undergoing general anesthesia. Anesthesia was induced with sleep dose propofol 2.0 mg/kg i.v., supplemented with fentanyl 1 microgram/kg, and maintained with 50% nitrous oxide and propofol. After inserting the laryngeal tube, its cuff was inflated using a balloon cuff gauge until the intracuff pressure reached approximately 65 cmH2O. Adequacy of ventilation was assessed by observing the end tidal carbon dioxide wave form, chest wall movement and by stethoscope auscultation. Oropharyngeal leak pressure was also measured. Changes in heart rate, blood pressure, end-tidal carbon dioxide, airway pressure and oxygen saturation before induction, before insertion, 2, 5 and 10 minutes after insertion and 5 minutes after incision were recorded. RESULTS: The first time success rate at achieving an effective airway was 30 in 36 (83%). The mean leak pressure was 22.9+/-4.6 mmHg. Heart rate, blood pressure, oxygen saturation, end-tidal carbon dioxide and airway pressure values remained stable during laryngeal tube insertion and during the surgical procedure. CONCLUSIONS: We conclude that the laryngeal tube is easy to place, allows adequate ventilation and has a lower incidence of complications. It may offer an alternative device for the oxygenation of non-intubated patients undergoing general anesthesia.

Propofol for Ambulatory Laryngomicrosurgery Using Bispectral Index Monitoring: Nitrous Oxide Does Not Significantly Affect Postanesthetic Recovery and Emetic Sequelae / 대한마취과학회지

BACKGROUND: Although nitrous oxide (N2O) is used commonly during anesthesia, the roles of N2O in postanesthetic recovery and emetic sequelae are not well established in the ambulatory surgery. The goal of this study was to compare outcomes in patients anesthetized with propofol/air versus propofol/N2O using BIS. METHODS: Patients for ambulatory laryngomicrosurgery were randomly allocated to the group of anesthesia with propofol/air (Air, n = 44) or propofol/67% N2O (N2O, n = 44). The target concentration of propofol was controlled to maintain the BIS values between 35 and 40. By the end of surgery, anesthetics were discontinued and the time to eyes-open (TTEO) on verbal command was measured. The BIS values, effect site concentration (ESC), and total propofol doses were measured at eyes-open. Time to first drink (TTD), walk (TTW), and PONV were evaluated by blinded observers in the phase II recovery room. All data were analyzed using the student t-test and the Chi-Square Test. RESULTS: In the Air group, TTEO was significantly shorter than in the N2O group (7.6+/-3.1 min vs 9.5+/-2.3 min) despite the higher ESC of propofol (1.8+/-0.4 mcg/ml vs 1.5+/-0.3 mcg/ml). The propofol doses, BIS scores at eyes-open, TTD and TTW, and the incidence of PONV were no different in the two groups. Females showed faster emergence from anesthesia than males in the operating room, but showed slower recovery in the phase II recovery room. CONCLUSIONS: N2O does not affect significantly postanesthetic recovery and emetic sequelae. Since N2O has no effect on BIS values, propofol doses may be titrated accordingly.