[Propofol anesthesia for ambulatory surgery in adults]

We reported 131 cases of ambulatory surgery in adults mainly anaesthetized with propofol infusion. Without any premedication, anesthesia was induced with propofol and fentanyl. A laryngeal mask airway was inserted using intravenous injection of vecuronium. Anesthesia was maintained with continuous infusion of propofol and intermittent fentanyl administrations, and local anesthetic infiltration was combined. All patients received air and oxygen mixture (FIO2 0.4) throughout the procedure. During surgery, metoclopramide and flurbiprofen axetil were given to prevent postoperative pain, nausea and vomiting. After surgery, patients were observed at the daycare unit in ward. Average age was 42 years and ASA risk was 1.3. Operation time and anesthesia time and hospital stay were 43.4 minutes, 70.6 minutes and 332 minutes, respectively. In 25 patients (19%) analgesics were needed for postoperative pain. Although 3 patients (2.3%) were unsuccessful as ambulatory surgery due to excessive pain, all patients including these three could be discharged within 24 hours after surgery. We conclude that combined anesthesia with propofol, fentanyl and local anesthetic is suitable for ambulatory surgery in adults.

No effect of preoperative paracetamol and codeine suppositories for pain after termination of pregnancies in general anaesthesia

Outpatient surgery demands rapid recovery and satisfied patients. The purpose of the study was to investigate whether rectal premedication with paracetamol and codeine would reduce the need of rescue analgesics, reduce the postoperative pain experience and result in faster eligibility for discharge. Ninety pregnant patients scheduled for day-case surgery with evacuation of the uterine cavity were randomly assigned into two groups. The paracetamol and codeine group was given a suppository with 60 mg of codeine and 800 mg of paracetamol together with standard premedication of intramuscular midazolam 0.08 mg/kg. The placebo group was given a placebo suppository and midazolam. All patients underwent the surgical procedure under general anaesthesia with alfentanil 15 microg/kg and propofol 1.5-2 mg/kg. There were no statistically significant differences between the groups in the postoperative pain experience as judged by Visual Analogue Scale (VAS-scale), verbal scale or the need for rescue analgesic medication with ketobemidone. Most of the patients experienced little postoperative pain with more than 70% scoring less than 20 mm on a VAS-scale from 0-100 mm at any time during the postoperative period. The paracetamol and codeine patients were significantly more sleepy at 30 min postoperatively. There were no differences between the groups in postoperative nausea or vomiting and no difference in discharge eligibility. The use of pre-operative suppository with paracetamol 800 mg and codeine 60 mg is unnecessary in this group of patients.

Propofol versus midazolam for conscious sedation guided by processed EEG during endoscopic retrograde cholangiopancreatography: a prospective, randomized, double-blind study

BACKGROUND AND STUDY AIMS

Endoscopic retrograde cholangiopancreatography (ERCP) is a complex procedure, which requires appropriate sedation. The aim of this prospective, randomized, double-blind study was to compare the quality and characteristics of sedation with midazolam or propofol in patients undergoing ERCP.

PATIENTS AND METHODS

A total of 32 patients undergoing ERCP were randomly allocated for sedation with propofol (n = 15) or midazolam (n = 17). Blood pressure, heart rate, and O2 saturation were monitored. Sedation was maintained at near constant levels by use of the spectral edge frequency (SEF) technique, an EEG-based method for measuring the depth of sedation. Clinical variables, patient cooperation, time to recovery, and amnesia served as outcome variables.

RESULTS

There was no significant difference between the two study groups in patient characteristics. The "target SEF" was 13.6 +/- 0.7 Hz for the propofol group and 14.8 +/- 1.1 Hz for the midazolam group (n.s.). The only clinical parameter with a significant difference between the groups was the percent of time in which the heart rate deviated more than 20% from baseline for at least 2 minutes, i.e. 14.6 +/- 2.0 % for propofol and 48.2 +/- 38.0% for midazolam (P<0.01). Patient cooperation was better in the propofol group than in the midazolam group (full cooperation, 13/15 vs. 1/17, respectively; P<0.001). Patient recovery was significantly quicker in the propofol group (P<0.001). The degree of amnesia was similar in both groups; no patient in either group remembered details of the procedure.

CONCLUSIONS

ERCP is better tolerated by patients sedated with propofol compared with midazolam, with a shorter recovery time and lesser hemodynamic side effects. Propofol should be considered to be the sedative drug of choice for ERCP.

Sedation with propofol plus midazolam versus propofol alone for interventional endoscopic procedures: a prospective, randomized study

AIM

Adequate patient sedation is mandatory for most interventional endoscopic procedures. Recent anaesthesiologic studies indicates that propofol and midazolam act synergistically in combination and therefore may be superior to sedation with propofol alone in terms of sedation efficacy, recovery and costs (due to a presumed lower total dose of propofol needed).

METHODS

A total of 239 consecutive patients undergoing therapeutic EGD or ERCP (EGD/ERCP-ratio, 1:1) randomly received either propofol alone (n=120, group A, loading dose 40-60 mg intravenously, followed by repeated doses of 20 mg) or propofol plus midazolam (n=119, group B, initial midazolam dose of 2. 5-3.5 mg intravenously, followed by repeated doses of 20 mg of propofol) for sedation. Vital signs (heart rate, blood pressure, oxygen saturation, electrocardiogram) were continuously monitored. Procedure-related parameters, the recovery time and quality (post-anaesthesia recovery score) as well as the patient's co-operation and tolerance to the procedure (visual analogue scale) were prospectively assessed.

RESULTS

Patients of group A and B were well matched with respect to demographic and clinical data, endoscopic findings, and the type of associated procedures. In group A, a mean dose of 0.25 +/- 0.13 mg.min/kg propofol was used compared to 0.20 +/- 0.09 mg.min/kg of propofol in group B (P < 0.01, plus additional 2.9 +/- 0.5 mg of midazolam). Clinically relevant changes in vital signs were observed at comparable frequencies with a lowering of the systolic blood pressure < 90 mmHg in six out of 119 patients in group B and one out of 120 patients in group A (P=0.07). The sedation efficacy was rated similarly in both groups, whereas the mean recovery time (group A, 19 +/- 7 min vs. group B, 25 +/- 8 min, P < 0.05) as well as the recovery score (post-anaesthesia recovery score group A, 8.0 +/- 1.1 vs. post-anaesthesia recovery score group B, 7.3 +/- 1.2, P < 0.001) were significantly better with propofol alone than with propofol plus midazolam.

CONCLUSION

During therapeutic endoscopy, sedation with propofol and midazolam requires a lower total dose of propofol, but otherwise has no superior sedation efficacy and is associated with a slower post-procedure recovery than sedation with propofol alone.

[Comparison between total intravenous anesthesia and inhalation anesthesia in the surgery of acute cholecystitis]

We investigated retrospectively the influence of anesthetic methods on the intraoperative managements and postoperative outcomes in 26 patients receiving emergency or early surgery for acute cholecystitis. Fourteen of the 26 patients received total intravenous anesthesia with propofol, fentanyl, and ketamine (PFK group), while the remainder received nitrous oxide and isoflurane or sevoflurane anesthesia (GO group). There were no significant differences between the groups with respect to demographic data. We found no significant differences between the groups in duration of operation and anesthesia, the incidence of intraoperative hypotension, and the use of ephedrine and dopamine during induction and maintenance of anesthesia. After surgery, the PFK group had significantly earlier bowel function than the GO group, with earlier starting of oral intake (54.0 +/- 25.1 vs 89.3 +/- 31.9 hours after surgery; P = 0.026). These data suggest that total intravenous anesthesia by propofol, fentanyl, and ketamine may provide the earlier recovery of bowel function than inhaled anesthesia after emergency or early surgery for acute cholecystitis.

Continuous propofol anaesthesia for patients with myotonic dystrophy

Myotonic dystrophy, a rare genetic disorder, may pose a serious problem to the anaesthesiologist due to muscular and extramuscular involvement. Thirteen patients, median age 21 yr were anaesthetized by continuous propofol infusion, fentanyl, atracurium and N2O to evaluate this combination in myotonic dystrophy. Intraoperatively, neither exaggerated reactions nor haemodynamic instability was observed. Recovery was smooth and quick. Although there was a significant decrease in mean postoperative vital capacity (965 (349) ml) from the preoperative value (1664 (566) ml, P = 0.0028), there was no change in mean postoperative SpO2 and there were no perioperative respiratory complications. Only two patients complained of nausea and vomiting. Similarly, muscular hypertonia and shivering were not observed. We conclude that the combination of continuous propofol infusion and fentanyl was a successful anaesthetic technique in these young myotonic dystrophy patients undergoing peripheral surgery.

Spontaneous recovery profile of rapacuronium during desflurane, sevoflurane, or propofol anesthesia for outpatient laparoscopy

We evaluated the spontaneous recovery characteristics of rapacuronium during desflurane-, sevoflurane-, or propofol-based anesthesia in 51 consenting women undergoing laparoscopic tubal ligation procedures. After the induction of the anesthesia with standardized doses of propofol and fentanyl, 1.5 mg/kg IV rapacuronium was administered to facilitate tracheal intubation. Patients were randomized to receive either 1 minimum alveolar anesthetic concentration of desflurane, 1 minimum alveolar concentration of sevoflurane, or 100 microg. kg(-1). min(-1) propofol infusion in combination with 66% nitrous oxide in oxygen for maintenance of anesthesia. Neuromuscular blockade was monitored at the wrist by using electromyography. The degree of maximum blockade and the times for first twitch recovery (T(1)) to 5%, 25%, 50%, 75%, and 90%, as well as the recovery index, were similar in all three anesthetic groups. However, recovery times for the train-of-four ratio to achieve 0.7 and 0.8 were significantly longer with desflurane (44.4 +/- 18.9 and 53.5 +/- 22.4 min) and sevoflurane (44.8 +/- 15.1 and 53.2 +/- 15.8 min) compared with propofol (31.8 +/- 5.3 and 36.5 +/- 6.5 min). Eight patients (16%) required a maintenance dose of 0.5 mg/kg rapacuronium and reversal of rapacuronium residual block occurred in three (6%) patients. We conclude that spontaneous recovery after an intubating dose of 1.5 mg/kg rapacuronium was significantly prolonged by both desflurane and sevoflurane compared with propofol-based anesthesia. Routine monitoring of neuromuscular activity is recommended even when a single bolus dose of rapacuronium is administered during ambulatory anesthesia.

IMPLICATIONS

When administered for laparoscopic surgery, the duration of action of an intubating dose of rapacuronium was prolonged 40%-50% by desflurane and sevoflurane, respectively, (versus propofol). Monitoring recovery of neuromuscular blockade produced by rapacuronium is particularly important when desflurane or sevoflurane is administered to ensure that an adequate recovery (train-of-four > or = 0.8) is achieved by the end of anesthesia.

The effects of nicardipine on dynamic cerebral autoregulation in patients anesthetized with propofol and fentanyl

We investigated the effects of nicardipine on dynamic cerebral pressure autoregulation in 13 normal adult patients undergoing gynecologic or orthopedic surgery. Anesthesia was induced and maintained with propofol and fentanyl. Hypotension to a mean arterial pressure of 60-65 mm Hg was induced and maintained with a continuous infusion of nicardipine. Time-averaged mean blood flow velocity in the right middle cerebral artery was measured continuously by using transcranial Doppler ultrasonography. The cerebral autoregulatory responses were activated by releasing thigh cuffs. The actual blood flow velocity in the right middle cerebral artery response to acute change in mean arterial pressure was fitted to 1 of 10 computer-generated curves to determine the dynamic rate of cerebral autoregulation (dRoR), and the best fitting curve was used. The autoregulation test was repeated until two values of dRoR were obtained at baseline and during induced hypotension. Nicardipine significantly reduced dRoR values of 13.1% +/- 3.6%/s at baseline to 8.3% +/- 2.6%/s during hypotension (P: < 0.01). During deliberate hypotension induced by nicardipine, the cerebral dynamic autoregulatory response is impaired in normal adult patients.

IMPLICATIONS

During deliberate hypotension induced by nicardipine, the cerebral dynamic autoregulatory response is impaired in normal adult patients.

Postoperative recovery after desflurane, propofol, or isoflurane anesthesia among morbidly obese patients: a prospective, randomized study

Recovery from anesthesia might be compromised in obese patients. Because of its pharmacological properties, desflurane might allow rapid postoperative recovery for these patients. We compared postoperative recovery for 36 obese patients randomized to receive either desflurane, propofol, or isoflurane to maintain anesthesia during laparoscopic gastroplasties. Anesthesia was induced with propofol and succinylcholine IV and was maintained with rocuronium, alfentanil, inhaled nitrous oxide, and the study drug. Immediate recovery (i.e., times from the discontinuation of anesthesia to tracheal extubation, eye opening, and the ability to state one's name) was measured. At the time of postanesthesia care unit (PACU) admission, arterial saturation and the ability of patients to move were recorded. In the PACU, intermediate recovery was measured by using sedation and psychometric evaluations, 30, 60, and 120 min postoperatively. Data were compared between groups by using the Kruskal-Wallis and chi(2) tests. Results were reported as means +/- SD. P: < 0.05, compared with desflurane, was considered significant. Immediate recovery occurred faster, and was more consistent, after desflurane than after propofol or isoflurane (times to extubation were 6 +/- 1 min, 13 +/- 8 min [P: < 0.05, compared with desflurane], and 12 +/- 6 min [P: < 0.05, compared with desflurane], respectively). At PACU admission, SpO(2) values were significantly higher and patient mobility was significantly better after desflurane than after isoflurane or propofol. Sedation was significantly less pronounced with desflurane at 30 and 120 min postoperatively. In morbidly obese patients, postoperative immediate and intermediate recoveries are more rapid after desflurane than after propofol or isoflurane anesthesia. This advantage of desflurane persists at least for 2 h after surgery and is associated with both an improvement in patient mobility and a reduced incidence of postoperative desaturation.

IMPLICATIONS

In morbidly obese patients, postoperative immediate and intermediate recoveries are more rapid and consistent after desflurane than after propofol or isoflurane anesthesia.

Surface vs intramuscular laryngeal electromyography

PURPOSE

To compare surface and intramuscular laryngeal electromyography (EMG) with adductor pollicis muscle EMG after 0.1 mgxkg(-1) cisatracurium.

METHODS

This prospective study included ten patients undergoing surgery with risk of damage to the recurrent laryngeal nerve (RLN). The tracheas were intubated after fentanyl/propofol without the aid of muscle relaxation. A surface laryngeal electrode was attached to the tube and placed amidst the vocal cords; two straight needles were inserted endoscopically into the left lateral cricoarytenoid muscle. Single twitch stimulation of the left RLN (0.1 Hz) was performed transcutaneously; skin EMG of the left adductor pollicis muscle was performed at 0.1 Hz. After supramaximal stimulation for 10 min, 0.1 mgxkg(-1) cisatracurium was injected. Lag, onset time and peak effect were measured and compared.

RESULTS

Good correlation (r = 0.9, 0.8, P < 0.005) and good comparability of the two methods of laryngeal EMG (mean difference and limits of agreement: 0 +/- 28 sec for lag time, -2 +/- 84 sec for onset time) was shown. The mean surface laryngeal lag and onset times were 67 +/- 22 sec and 198 +/- 72 sec, compared with the adductor pollicis muscle (98 +/- 30 sec and 242 +/- 59 sec) at P < 0.01. Peak effects at larynx (92 +/- 9%) and adductor pollicis muscle (95 +/- 3%) were similar.

CONCLUSION

Surface laryngeal EMG is comparable to intramuscular laryngeal EMG to determine degree and onset of the neuromuscular blockade. Increasing muscle relaxation does not cause the surface electrode to lose contact with the vocal cords and therefore underestimate onset time and peak effect.

[Comparison of propofol and isoflurane anesthesia on postoperative nausea, vomiting and pruritus induced by epidural morphine]

We compared propofol-nitrous oxide anesthesia (Group P) with isoflurane-nitrous oxide anesthesia (Group I) on the incidence of postoperative nausea, vomiting and pruritus induced by epidural morphine. Twenty-eight patients for thoracotomy for lung surgeries were randomly assigned either to Group P or Group I. All patients were administrated epidural morphine (4-7 mg.day-1) during and after the operation. The incidence of nausea, vomiting and pruritus was evaluated at the postoperative early (< 9 hour) and late (> 9 hour) periods. In the late postoperative period, in Group P the incidence of nausea and vomiting tended to be low compared with Group I, but the difference was not statistically significant. The incidence of pruritus was not different between the two groups in both early and late periods.

The effect of intravenous epinephrine on the bispectral index and sedation

Eight patients were given a propofol infusion until they no longer responded to loud verbal stimuli, a sedation score of two (modified Observer Assessment of Alertness and Sedation Scale). After receiving 15 microg of intravenous epinephrine, changes in sedation score and bispectral index (BIS) were observed. Mean pulse rate increased from 68 to 96 (SD 10) beat.min-1, mean blood pressure increased from 107/60 (SD 10/8) mmHg to 140/70 (SD 27/14) mmHg, and mean BIS level rose from 63 to 76 (p < 0.005). Sedation scores increased in six of the eight patients. Exogenous catecholamines seem to have an arousal effect on lightly anaesthetised patients. This could be due to changes in neurotransmitter levels in the brain, or due to the effects consequent on increased cardiac output.

[Core and cutaneous thermal changes in the upper limb after anesthesia induction]

OBJECTIVES

To describe and compare the core-cutaneous thermal and photoplethysmographic time-course effects after induction of general anesthesia with propofol, fentanyl and vecuronium.

PATIENTS AND METHODS

We measured digital blood flow, core temperature and skin temperature in the upper limb (fingertip, forearm and upper arm) in 20 patients (10 men and 10 women, ASA-I) before anesthetic induction and 5, 10, 15 and 20 min after induction. Skin temperature changes were recorded with disposable thermocouples. Blood flow was recorded by digital photoplethysmography (PhPl) in the thumb. Anesthesia was provided without premedication, using propofol (3 mg.kg-1), fentanyl (0.1 mg) and vecuronium (0.1 mg.kg-1). After endotracheal intubation, anesthesia was maintained with oxygen-nitrous oxide and 0.1 mg of intravenous fentanyl at the tenth minute, without inhaled anesthetics.

RESULTS

All patients showed intense, abrupt vasodilatation in the thumb with marked increases in PhPl (PhPl = 10.4 +/- 5.0 mV/V, at 5 min, p < 0.001) and fingertip temperature (TFingertip = 6.2 +/- 2.0 C, at 10 min, p < 0.001). However, skin temperature changes in the upper arm and forearm were moderate and slower (TForearm = 2.1 +/- 1.4 C, p < 0.01 and TUpper arm = 1.1 +/- 1.2 C, p < 0.01; at 20 min in both cases). A significant correlation was found only between PhPl and TFingertip (r = 0.55, p < 0.001).

CONCLUSIONS

Anesthetic induction with propofol, fentanyl and vecuronium produces cutaneous vasodilatation in the upper limb unequally: the greatest increase in skin temperature occurs at the fingertip, while forearm and upper arm temperatures increase less. We think that skin vasodilatation in peripheral distal areas may play an important role in redistributing core heat during anesthesia.

A comparison of anaesthesia using remifentanil combined with either isoflurane, enflurane or propofol in patients undergoing gynaecological laparoscopy, varicose vein or arthroscopic surgery

BACKGROUND

Anaesthesia comprising remifentanil plus isoflurane, enflurane or propofol was randomly evaluated in 285, 285 and 284 patients, respectively, undergoing short-procedure surgery.

METHODS

Anaesthesia was induced with propofol (0.5 mg x kg(-1) and 10 mg x 10 s(-1)), and a remifentanil bolus (1 microg x kg(-1)) and infusion at 0.5 microg x g(-1) x min(-1). Five minutes after intubation, remifentanil infusion was halved and 0.5 MAC of isoflurane or enflurane, or propofol at 100 microg x kg(-1) x min(-1) were started and titrated for maintenance.

RESULTS

Patient demography and anaesthesia duration were similar between the groups. Surgery was performed as daycases (52%) or inpatients (48%). The median times (5-7 min) to extubation and postoperative recovery were similar between the groups. Responses to tracheal intubation (15% vs 8%) and skin incision (13% vs 7%) were significantly greater in the total intravenous anaesthesia (TIVA) group (P<0.05). Fewer patients given remifentanil and isoflurane (21%) or enflurane (19%) experienced > or =1 intraoperative stress response compared to the TIVA group (28%) (P<0.05). Median times to qualification for and actual recovery room discharge were 0.5-0.6 h and 1.1-1.2 h, respectively. The most common remifentanil-related symptoms were muscle rigidity (6-7%) at induction, hypotension (3-5%) and bradycardia (1-4%) intraoperatively and, shivering (6-7%), nausea and vomiting postoperatively. Nausea (7%) and vomiting (3%) were significantly lower with TIVA compared with inhaled anaesthetic groups (14-15% and 6-8%, respectively; P<0.05).

CONCLUSION

Anaesthesia combining remifentanil with volatile hypnotics or TIVA with propofol was effective and well tolerated. Times of extubation, postanaesthesia recovery and recovery room discharge were rapid, consistent and similar for all three regimens.

Wada testing in pediatric patients by use of propofol anesthesia

BACKGROUND AND PURPOSE

Wada testing may provide important information for surgical planning in pediatric patients with medically refractory epilepsy, but it is often not used because of the difficulties in performing the angiographic portion of the procedure in conscious children. We reviewed our experience using propofol, a short-acting IV administered anesthetic agent, for pediatric patients undergoing Wada testing.

METHODS

In a retrospective review of Wada tests performed on patients younger than 18 years, we identified 24 cases in which propofol anesthesia was used. We reviewed the medical records of these patients, with particular reference to dose of propofol, physiological parameters during anesthesia, and adequacy of neuropsychological testing after emergence from anesthesia.

RESULTS

Patients ranged in age from 6 to 16 years (mean age, 12.5 years). Propofol induced mild reductions in blood pressure (12.4% for systolic and 13.9% for diastolic blood pressure) and heart rate (mean reduction of 4.7%), which did not require specific treatment in any patient. Recovery from anesthesia was smooth and rapid, allowing initiation of Wada testing within 15 to 25 minutes of cessation of propofol. Wada testing was successfully accomplished in all patients.

CONCLUSION

Propofol provided rapid induction of anesthesia, was administered without endotracheal intubation, and did not cause substantial changes in cardiorespiratory parameters. Propofol anesthesia allowed controlled angiography among patients as young as 6 years and did not interfere with neuropsychological testing.

Comparison of two different anesthesia regimens in patients undergoing aortocoronary bypass grafting surgery: sufentanil-midazolam versus remifentanil-propofol

OBJECTIVE

To compare intraoperative hemodynamics and depth of anesthesia using sufentanil-midazolam (SM) versus remifentanil-propofol (RP) anesthesia.

DESIGN

Prospective, randomized study.

SETTING

Clinical investigation in an urban, university-affiliated hospital.

PARTICIPANTS

Forty patients undergoing elective first-time coronary artery bypass graft surgery.

INTERVENTIONS

Twenty patients were anesthetized using SM and 20 patients using RP.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic monitoring included a 5-lead electrocardiogram, a radial artery catheter, and a pulmonary artery catheter. Depth of anesthesia was assessed using bispectral index (BIS). Data were obtained after induction of anesthesia (T1), after sternotomy (T2), after pericardiotomy (T3), 5 minutes after cardiopulmonary bypass (CPB) (T4), after closure of thorax (T5), and at the end of surgery (T6). The 2 groups were comparable with regard to demographic and perioperative data. There were no significant differences of any hemodynamic parameter at any time between the 2 groups. In both groups, systemic vascular resistance increased at T2 and decreased at T4 from baseline value (p < 0.05). Cardiac index increased at T4 in both groups from baseline value (p < 0.05); 55% of the patients of both groups needed low-dose dobutamine after CPB. During CPB, 40% of the RP patients needed norepinephrine versus 35% of the SM patients. BIS was lower in the RP than in the SM group at T2 and T3 (p < 0.05). BIS values indicating intraoperative awareness were not noted.

CONCLUSION

Both anesthesia regimens provided stable hemodynamics and adequate anesthesia in patients undergoing coronary artery bypass graft surgery.

Omission of nitrous oxide from a propofol-based anesthetic does not affect the recovery of women undergoing outpatient gynecologic surgery

BACKGROUND

Although nitrous oxide (N2O) is used commonly during anesthesia, clinically relevant advantages-disadvantages of using this agent are not well established in the ambulatory setting. This study in women undergoing ambulatory gynecologic surgery compares outcomes in patients administered total intravenous anesthesia with propofol versus the propofol plus N2O. The primary outcome was the time to home readiness. Secondary outcomes included the incidence of postanesthetic adverse events.

METHODS

Women presenting for elective ambulatory termination of pregnancy or gynecologic laparoscopy were induced with an intravenous sleep dose of propofol and fentanyl. After induction, subjects were randomly allocated to maintenance anesthesia with propofol alone or propofol plus 65% N2O. Patients were assessed by a blinded observer in the postanesthetic care unit at 20-min intervals to determine home readiness. Postoperative pain and nausea were measured with visual analog scales. Postoperative analgesics and antiemetics were recorded. The incidence of adverse events occurring after hospital discharge was assessed by a telephone interview 24 h postoperatively.

RESULTS

A total of 740 patients received propofol alone, and 750 patients received propofol plus N2O. Mean home readiness times were not significantly different between treatment groups. There were no significant differences between groups in pain scores, nausea scores, analgesia administration, or antiemetic administration before discharge. There were no significant differences in the frequency of adverse events for 24 h after discharge from hospital.

CONCLUSIONS

Omission of N2O from a propofol-based anesthetic for ambulatory gynecologic surgery does not affect time to home readiness or the incidence of postoperative adverse events up to 24 h after discharge from hospital. (Key words: Awareness; outpatient surgery; total intravenous anesthesia.)

Total intravenous anesthesia with midazolam, remifentanil, propofol and cistracurium in morbid obesity

BACKGROUND

According to physical impairments of massive obesity, cardiac, respiratory and gastrointestinal physiology must be considered as much as pharmacokinetic behavior. Anesthetic management of morbidly obese patients has to be carefully planned, in order to minimize the increased risks of aspirative pneumonitis, hemodynamic instability and delay in recovery. The ideal anesthesia should provide a smooth and quick induction, allowing rapid airway control, prominent hemodynamic stability, and rapid emergence from anesthesia. To approach these ideal conditions, a Total Intravenous Anesthesia (TIVA) with midazolam, remifentanil, propofol and cisatracurium was designed and analyzed.

METHODS

10 consenting morbidly obese patients scheduled for elective Laparoscopic Adjustable Gastric Banding participated in the study. TIVA with midazolam, remifentanil, propofol and cisatracurium was used in all cases. Time to loss of consciousness, tracheal intubation, perianesthetic physiological parameters and complications, incidence of awareness with recall, recovery times, postoperative analgesia and costs of drugs were evaluated.

RESULTS

The analyzed data showed adequate time and physiological conditions for induction and tracheal intubation, stable maintenance with easy handling of deepness, low incidence of perianesthetic complications, excellent recovery performance and institutional efficiency.

CONCLUSIONS

TIVA with midazolam, remifentanil, propofol and cisatracurium was found to be effective, secure, predictable and economic for the anesthetic management of morbidly obese patients.

Electroencephalographic indices related to hypnosis and amnesia during propofol anaesthesia for cardioversion

Most previous studies which have assessed the depth of anaesthesia using the Bispectral Index (BIS) have used multi-agent anaesthetics with relatively slow induction and recovery times. Elevation of electroencephalographic (EEG) Beta/Alpha Ratio has been linked to onset of midazolam amnesia. Propofol anaesthesia for cardioversion in 19 patients enabled us to profile the changes in BIS and Beta/Alpha Ratio during a short, single-agent anaesthetic with a relatively rapid induction and recovery period. BIS values did not alter significantly through onset of amnesia and hypnosis as compared with awake values. Cardioversion occurred over a wide range of BIS values (38 to 94), with recovery at a median BIS value of 79. We observed the BIS to lag about 60 s behind the clinical situation (termed BIS60). The BIS60 more closely tracked the clinical level of consciousness, showing statistically significant differences from the uncorrected BIS. (amnesia (median BIS60 = 82, P = 0.02), hypnosis (median BIS60 = 67, P = 0.01), eye opening (median BIS60 = 90, P = 0.001)). An early EEG Beta/Alpha Ratio peak occurred at a mean of 4.6 s (SD = 16.6) after clinical amnesia onset and a late peak at a mean 58 s (SD = 144) after eye opening. There was no significant EEG response to cardioversion. We conclude that: (1) in rapidly changing conditions, the value of the BIS most accurately reflects the level of consciousness of the patient about 60 s in the past, and (2) the onset and offset of propofol-induced amnesia commonly corresponds to a peak in Beta/Alpha Ratio of the EEG.

Effect of bolus dose of remifentanil on haemodynamic response to tracheal intubation

A randomized placebo-controlled double-blinded study was conducted in 40 ASA 1 and 2 patients to determine the dose response of remifentanil in attenuating the haemodynamic response to tracheal intubation. Patients were allocated to one of four groups: placebo, remifentanil 1 microgram.kg-1, remifentanil 2 micrograms.kg-1 and remifentanil 4 micrograms.kg-1. A propofol target-controlled infusion was started at 4 micrograms.ml-1 and incrementally titrated to loss of verbal contact. Muscle relaxation was provided by cisatracurium. The study drug was given three minutes later over 30 seconds, and 90 seconds later the patient's trachea was intubated under direct laryngoscopy. Baseline noninvasive blood pressure and heart rate recordings were made prior to starting target-controlled infusion, then at one-minute intervals after loss of verbal contact for the duration of the study. Demographic data and target-controlled infusion rate at intubation was similar for the groups. Following intubation, heart rate increased by 15% in the placebo group, 10% in 1 microgram.kg-1 group, with no changes in 2 micrograms.kg-1 and 4 micrograms.kg-1 groups. Systolic blood pressure following intubation increased by 30% in the placebo group, 10% in the 1 microgram.kg-1 group and remained unchanged in the 2 micrograms.kg-1 and 4 micrograms.kg-1 groups. Remifentanil 1 microgram.kg-1 attenuated the rise in heart rate and systolic blood pressure. Remifentanil 2 micrograms.kg-1 blocked the haemodynamic response completely: no further benefit was shown from increasing the dose to 4 micrograms.kg-1.

Use of the intubating laryngeal mask airway: are muscle relaxants necessary?

BACKGROUND

The intubating laryngeal mask airway (ILMA) is designed to facilitate blind tracheal intubation. The effect of a muscle relaxant on the ability to perform tracheal intubation through the ILMA device has not been previously evaluated. This randomized, double-blind, placebo-controlled study was designed to evaluate rocuronium, 0.2 or 0.4 mg/kg administered intravenously, on the success rate and incidence of complications associated with ILMA-assisted tracheal intubation.

METHODS

A total of 75 healthy patients were induced with propofol 2 mg/kg and fentanyl 1 microg/kg intravenously. After insertion of the ILMA device, patients were administered either saline, rocuronium 0.2 mg/kg, or rocuronium 0.4 mg/kg in a total volume of 5 ml. At 90 s after administration of the study drug, tracheal intubation was attempted using a disposable polyvinyl tube. If unsuccessful, a reusable silicone tube was tried. In addition to recording the time and number of attempts required to secure the airway, the incidence of complications during placement of the tracheal tube and removal of the ILMA were noted.

RESULTS

Tracheal intubation was successful in 76-96% of the patients. The overall success rates and times required to secure the airway were similar in all three treatment groups. The high-dose rocuronium group experienced less patient movement (8 vs. 28 and 48%) and coughing (12 vs. 20 and 52%) than the low-dose rocuronium and saline groups, respectively. Use of rocuronium was also associated with a dose-related decrease in the requirement for supplemental bolus doses of propofol during intubation and removal of the ILMA device.

CONCLUSIONS

Use of rocuronium did not significantly improve the success rate in performing tracheal intubation through the ILMA. However, it produced dose-related decreases in coughing and movement after tracheal intubation and reduced difficulties associated with removal of the ILMA device.

Renal effects of carprofen administered to healthy dogs anesthetized with propofol and isoflurane

OBJECTIVE

To evaluate renal effects of carprofen in healthy dogs following general anesthesia.

DESIGN

Randomized clinical trial.

ANIMALS

10 English hound dogs (6 females and 4 males).

PROCEDURE

Dogs were randomly assigned to control (n = 5) or carprofen (5) groups. Anesthesia was induced with propofol (6 to 8 mg/kg [2.7 to 3.6 mg/lb] of body weight, i.v.) and maintained with isoflurane (end-tidal concentration, 2.0%). Each dog underwent two 60-minute anesthetic episodes with 1 week between episodes, and mean arterial blood pressure was maintained between 60 and 90 mm Hg during each episode. Dogs in the carprofen group received carprofen (2.2 mg/kg [1 mg/lb], p.o.) at 9:00 AM and 6:00 PM the day before and at 7:00 AM the day of the second anesthetic episode. Glomerular filtration rates (GFR) were determined during each anesthetic episode by use of renal scintigraphy. Serum creatinine and BUN concentrations and the urine gamma-glutamyltransferase-to-creatinine concentration (urine GGT:creatinine) ratio were determined daily for 2 days before and 5 days after general anesthesia.

RESULTS

Significant differences were not detected in BUN and serum creatinine concentrations, urine GGT:creatinine ratio, and GFR either between or within treatment groups over time.

CONCLUSIONS AND CLINICAL RELEVANCE

Carprofen did not significantly alter renal function in healthy dogs anesthetized with propofol and isoflurane. These results suggest that carprofen may be safe to use for preemptive perioperative analgesia, provided that normal cardiorespiratory function is maintained.