Duration and recovery profile of cisatracurium after succinylcholine during propofol or isoflurane anesthesia

Study Objective: To determine the duration and recovery profile of maintenance doses of cisatracurium besylate following succinylcholine, and during propofol or isoflurane anesthesia.

Design: Randomized, open-label study.

Setting: Operating suite of a university-affiliated medical center.

Patients: Forty ASA physical status I and II adult patients having elective surgery with general anesthesia lasting longer than 90 minutes.

Interventions: Following a standardized induction sequence, a baseline electromyogram (EMG) was obtained. An intubating dose of intravenous (IV) succinylcholine 1.0 mg/kg was administered. Ventilation was maintained with a face mask until the first twitch (T₁) of the evoked train-of-four (TOF) reached 10% of control when tracheal intubation was performed. Spontaneous recovery from neuromuscular blockade was allowed to occur until the first twitch returned to 25% of control. Patients then were randomized to receive cisatracurium as follows. Group 1: 0.025 mg/kg [0.5 × 95% effective dose (ED₉₅)]; Group 2: 0.05 mg/kg (ED₉₅); Group 3: 0.05 mg/kg (ED₉₅); and Group 4: 0.1 mg/kg (2×ED₉₅). Anesthesia for Groups 1 and 2 were maintained with isoflurane 1% to 2%, 66% nitrous oxide (N₂O) in oxygen (O₂), and in Groups 3 and 4, anesthesia was maintained with propofol 80 to 160 μg/kg/min, 66% N₂O in O₂. The TOF-evoked EMG was recorded at 10-second intervals. The time for the evoked EMG to spontaneously return to 25%, 50%, and 75% of the original baseline was recorded.

Measurements and Main Results: There were 10 patients in each of the four groups. The duration of action of cisatracurium 0.05 mg/kg (ED₉₅) after an intubating dose of succinylcholine is 24.5 ± 10 minutes and 21.3 ± 9 minutes during anesthesia maintained with isoflurane and propofol, respectively. Doubling the dose of cisatracurium resulted in approximately twice the duration of action (40.2 ± 7 min) during propofol anesthesia. Following a dose of cisatracurium 0.025 mg/kg (0.5×ED₉₅), the T₁ of the EMG-evoked response did not decrease below 25% in 7 of 10 patients.

Conclusion: Following succinylcholine, the duration of action of a single dose of cisatracurium 0.05 mg/kg is 20 to 25 minutes during anesthesia maintained with propofol or isoflurane. The duration and recovery profile of cisatracurium is dose dependent during propofol and isoflurane anesthetics. Cisatracurium 0.025 mg/kg is an inadequate maintenance dose following recovery from succinylcholine and it fails to provide adequate surgical relaxation.     

Recovery following outpatient anesthesia: Use of enflurane versus propofol

Study Objective: To compare the intraoperative conditions and postoperative recovery of patients following the use of either propofol-nitrous oxide (N₂O) or enfurane-N₂O for maintenance of outpatient anesthesia.

Design: Randomized, single-blind study.

Setting: University hospital outpatient surgery center.

Patients: 61 ASA physical status I and II, healthy female outpatients undergoing laparoscopic surgery.

Interventions: Patients were randomly assigned to one of three anesthetic regimes. Group 1 (control) received thiopental sodium 4 mg/kg intravenously (IV), followed by 0.5% to 1.5% enfurane and 67% N₂0 in oxygen (O₂). Group 2 received propofol 2 mg/kg IV, followed by 0.5% to 1.5% enfurane and 67% N₂O in O₂. Group 3 received propofol 2 mg/kg IV, followed by propofol 50 to 160 μg/kg/min IV and 67% N₂O in O₂. All patients received succinylcholine 1 mglkg IV to facilitate tracheal intubation and atracurium 10 to 20 mg IV to provide adequate relaxation during the maintenance period.

Measurements and Main Results: Recovery from anesthesia was assessed by a research nurse who was unaware of the anesthetic technique used. The mean ± SD time to eye opening was significantly longer in the thiopental-enflurane-N₂O group (Group 1) than in the propofol-propofol-N₂0 group (Group 3) (6.1 ± 2.5 minutes vs. 3.5 ± 2.8 minutes, respectively). In addition, the mean time to respond to verbal commands was significantly shorter in the propofol induction groups compared with the thiopental induction group. However, the use of enfurane versus propofol for maintenance of anesthesia did not significantly prolong the time from arrival in the recovery room to sitting, tolerating oral fluids, walking, or being judged “fit for discharge.” There were no differences among the three groups with respect to postoperative pain or analgesic requirements. Finally, patients who received enfurane for maintenance of anesthesia had a significantly higher frequency of nausea and vomiting than the propofol maintenance group.

Conclusion: Induction of anesthesia with propofol is associated with a more rapid emergence from anesthesia than induction with thiopental. Maintenance of anesthesia with enfurane did not prolong recovery compared with maintenance with propofol, but enfurane was associated with increased frequency of postoperative nausea and vomiting.     

Influence of thiopental and propofol on postoperative cognitive recovery in the elderly patient undergoing general anesthesia

Study Objective: To assess mental and psychomotor recovery following induction of anesthesia with thiopental or propofol in elderly patients undergoing general anesthesia.

Design: Randomized, prospective, double-blind study.

Setting: Large referral hospital.

Patients: 40 elderly patients ASA physical status I-III (>65 years) undergoing abdomino-pelvic surgery with an estimated surgical time of at least 90 minutes.

Interventions: All patients received combined epidural-general anesthesia. After establishing a T₆ sensory blockade, patients were randomized to receive either thiopental or propofol for induction of general anesthesia. The induction drug was slowly titrated until loss of eyelash reflex was noted. Thereafter, all patients received desflurane (2% to 3% end-tidal) and 70% nitrous oxide (N₂O) in oxygen for maintenance of general anesthesia. To facilitate tracheal intubation, intravenous alfentanil 10 μg/kg and atracurium 0.4 mg/kg were administered. Perioperative analgesia was maintained with epidural bupivacaine.

Measurements and Main Results: A digit substitution test (DSST) and shape-sorter test, as well as patient-generated 100-mm visual analog score (VAS; 0 = minimal and 100 = maximal) for anxiety, sleepiness, and coordination, were performed during the preanesthetic interview, on postanesthesia care unit admission, and at 15, 45, 90, and 120 minutes thereafter. To induce loss of consciousness, either thiopental 2.5 ± 1.0 mg/kg or propofol 1.6 ± 0.6 mg/kg was administered. The mean anesthetic time was 109 ± 30 minutes and 114 ± 38 minutes for the thiopental and propofol groups, respectively. Emergence, extubation, and orientation times, as well as time to follow commands, were unaffected by patient randomization. Similarly, the DSST and shape-sorter tests, in addition to the patient-generated VAS for pain, anxiety, and coordination, were similar among groups. However, irrespective of treatment modality, return to baseline digit substitution and shape-sorter scores were significantly delayed (p < 0.01).

Conclusion: When compared to thiopental, propofol does not facilitate improved cognitive recovery in geriatric patients undergoing prolonged surgery.     

Ketamine, Not Propofol, Attenuates Cerebrovascular Response to Carbon Dioxide in Humans With Isoflurane Anesthesia

Study Objectives: To investigate the effects of ketamine and propofol on the cerebrovascular response to carbon dioxide (CO₂) in humans during isoflurane anesthesia.

Design: Randomized clinical investigation.

Settings: University hospital of a medical school.

Patients: 30 ASA physical status I and II adult, elective surgical patients.

Interventions and Measurements: With each patient given air/oxygen/isoflurane anesthesia, the flow velocity in the middle cerebral artery (Vmca) and pulsatility index were measured using the transcranial Doppler method under hypocapnic [arterial CO₂tension (Pa ₂) 28–32 mmHg], normocapnic (Pa ₂ 38–42 mmHg), and hypercapnic conditions (Pa ₂ 48–52 mmHg). Pa ₂ was altered by supplementing the inspired gas with CO₂ without changing the respiratory conditions. Patients were then randomly assigned to receive either ketamine 1 mg · kg⁻¹ or propofol (2 mg · kg⁻¹followed by an infusion of 6–10 mg · kg⁻¹ · hr⁻¹) (n = 15 for each drug), and the measurements were repeated.

Main Results: Ketamine reduced both absolute and relative cerebrovascular reactivity to CO₂ significantly [2.9 ± 0.8 (control) vs. 2.6 ± 1.0 (ketamine) cm · sec⁻¹ · mmHg⁻¹: p < 0.05; and 3.5 ± 0.7 (control) vs. 2.8 ± 0.9 (ketamine) % · mmHg⁻¹: p < 0.01, respectively]. However, ketamine did not reduce Vmca during hypercapnic conditions (117 ± 29 cm · sec⁻¹) compared with controls (120 ± 28 cm · sec⁻¹). Although propofol decreased Vmca during all conditions, it did not cause any change in either absolute or relative CO₂ reactivity [2.5 ± 0.8 (control) vs. 2.5 ± 1.0 (propofol) cm · sec⁻¹ · mmHg⁻¹, and 3.3 ± 1.3 (control) vs. 4.1 ± 1.0 (propofol) % · mmHg⁻¹, respectively].

Conclusions: In humans given isoflurane anesthesia, a) ketamine reduced cerebrovascular response to CO₂, but cerebral blood flow (CBF) during hypercapnic conditions was comparable with controls, and b) although propofol decreases CBF, it maintains the cerebrovascular response to CO₂.     

A comparison: The efficacy of sevoflurane-nitrous oxide or propofol-nitrous oxide for the induction and maintenance of general anesthesia

Study Objective: To compare sevoflurane-nitrous oxide with propofol-nitrous oxide for the induction and maintenance of anesthesia, and to determine the rates of recovery following each anesthetic.Design: Randomized, controlled study.Setting: Teaching hospital.Patients: 50 ASA physical status I and II patients, ranging in age from 18 to 70 years.Interventions: General anesthesia was induced with either sevoflurane or propofol and maintained with 60 % to 70% nitrous oxide and either sevoflurane or a propofol infusion and supplemental fentanyl. At the conclusion of surgery, the oxygen flow was increased to 6 L/min and all anesthetics were discontinued simultaneously. Patients were monitored for the nature and speed of induction and emergency from anesthesia.Measurements and Main Results: Induction of anesthesia was significantly slower in the sevoflurane group than in the propofol group (2.0 ± 1.1 vs. 0.8 ± 0.5 min, respectively). The ease of induction and the time required for emergence from anesthesia were the same in both study groups (eye opening: 9.0 ± 4.4 min vs. 8.0 ± 5.0 min; following commands: 11.2 ± 5.0 min vs. 9.8 ± 6.9 min; extubation: 9.1 ± 4.5 min vs. 8.6 vs. 5.1 min in the sevoflurane and propofol groups, respectively). Patients in the sevoflurane group experienced nausea and vomiting more frequently than patients in the propofol group (13 and 5 patients vs. 3 and 0 patients in the sevoflurane and propofol groups, respectively), which were not related to the administration of neostigmine or intraoperative opioids.Conclusion: Sevoflurane allows for rapid inhalation induction of, and emergence from, general anesthesia.     

Patient-controlled drug administration during local anesthesia: A comparison of midazolam, propofol, and alfentanil

Study Objective: To evaluate the perioperative effects of alfentanil, midazolam, and propofol when administered using a patient-controlled analgesia (PCA) device during local anesthesia.

Design: Randomized, single-blind comparative study.

Setting: Outpatient surgery center at a university teaching hospital.

Patients: Ninety outpatients undergoing minor elective surgical procedures with local anesthetic infiltration were assigned to one of three treatment groups.

Interventions: After premedication with midazolam 1 mg intravenously (IV) and fentanyl 50 μg IV, patients were allowed to self-administer 2 ml bolus doses of either alfentanil 250 μg/ml, midazolam 0.4 mg/ml, or propofol 10 mg/ml at minimal intervals of 3 minutes to supplement a basal infusion rate of 5 ml/hr.

Measurements and Main Results: The total intraoperative dosages of alfentanil, midazolam, and propofol were 2.7 ± 1.1 mg, 4.7 ± 2.7 mg, and 114 ± 42 mg, respectively, for procedures lasting 48 ± 28 minutes to 51 ± 19 minutes (means ± SD). Propofol produced more pain on injection (39% vs. 4% and 6% in the alfentanil and midazolam groups, respectively). Episodes of arterial oxygen saturation less than 90% were more frequent with alfentanil (28%) than with midazolam (3%) or propofol (13%). Using the visual analog scale, patients reported comparable levels of discomfort, anxiety, and sedation during the operation in all three treatment groups. Postoperative picture recall was significantly decreased with midazolam versus alfentanil and propofol. Finally, postoperative nausea was reported more frequently in the alfentanil group (29%) than in the midazolam (10%) or propofol (18%) groups, contributing to a significant prolongation of the discharge time in the alfentanil-treated patients.

Conclusions: When self-administered as adjuvants during local anesthesia using a PCA delivery system, alfentanil, midazolam, and propofol were equally acceptable to patients. However, propofol and midazolam were associated with fewer perioperative complications than was alfentanil.     

The effects of preanesthetic oral clonidine on total requirement of propofol for general anesthesia

Study Objective: To investigate the effects of preanesthetic oral clonidine on total propofol requirement for uniform minor surgery (breast conservative surgery: breast cancer removal with axillary lymph node dissection), and to compare the action of clonidine with that of preanesthetic oral diazepam, a commonly used benzodiazepine.

Design: Randomized double-blinded study.

Setting: Operating room ASA physical status I and II room and recovery room of the cancer center.

Patients: 80 breast cancer patients scheduled for surgery.

Interventions: Patients were randomized to one of four treatment groups (placebo, clonidine 75 μg, or 150 μg of clonidine, or 10 mg of diazepam were orally administered 60 min before induction of anesthesia); n = 20 per group. After evaluating the sedation and anxiety levels of patients using a visual analog scale, anesthesia was induced with propofol (1.5 mg/kg), and maintained with oxygen (O₂): nitrous oxide (N₂O) (30:70) with a continuous infusion of propofol. The propofol infusion was started at 10 mg/kg/h for 10 minutes, then decreased to 8 mg/kg/h, and 6 mg/kg/h thereafter, and the rate of infusion was adjusted to obtain adequate anesthesia (maintaining hemodynamic parameters within 20% of that prior to premedication). Fentanyl 0.2 mg (each 0.1 mg was given for intubation and axillary lymph node dissection, respectively) was administered.

Measurements and Main Results: Preanesthetic oral clonidine (150 μg) and diazepam (10 mg) induced anxiolysis without sedation. The total requirement (the mean infusion rates) of propofol in placebo, clonidine 75 μg, clonidine 150 μg, and 10 mg of diazepam groups were 841 ± 70 (9.0 ± 0.3), 720 ± 63 (7.1 ± 0.4), 491 ± 39 (5.6 ± 0.2), and 829 ± 77 mg (7.9 ± 0.4 mg/kg/h), respectively. The cost of propofol in these groups was $51.0 ± 3.8, $45.5 ± 3.2, $33.5 ± 2.3, and $50.5 ± 4.4, respectively.

Conclusions: Preanesthetic oral clonidine (150 μg) but not diazepam (10 mg) reduced the total requirement of propofol while stabilizing hemodynamic parameters. In addition, 150 μg of oral clonidine attenuates the hemodynamic responses associated with tracheal intubation.     

Desflurane potentiates atracurium in humans: A comparative study with isoflurane

Study Objective: (1) To evaluate the neuromuscular effects of desflurane and its interactions with atracurium and (2) to compare desflurane and isoflurane in these effects.

Design: Sequential entry of informed and consenting patients randomly assigned to receive desfurane (n = 25) or isofurane (n = 25).

Setting: Operating suite of a county-university medical center.

Patients: Fifty adults, ASA physical status I, undergoing elective orthopedic surgery.

Interventions: Following establishment of steady desfurane or isofurane anesthesia, at 1.25 minimum alveolar concentration (MAC) exhaled for 15 minutes, a randomly predetermined dose of atracurium (0.05, 0.1, or 0.15 mg/kg) was injected intravenously (IV). At the end of surgery, neostigmine 0.04 mglkg IV was given to reverse the residual block. The neuromuscular effects of desfurane or isofurane alone, and the dose-response relationship, time course, and reversibility of the neuromuscular effects of atracurium with either anesthetic, were examined in detail and compared using electromyographic quantification of the response of the first dorsal interosseous muscle to train-of-four (TOF) stimulation of the ulnar nerve.

Measurements and Main Results: TOF fade and depression of the first response (T₁) of the TOF were measured in response to desfurane or isofurane, atracurium, and neostigmine. Desf urane caused more TOF fade than isofurane prior to atracurium administration. The TOF ratios were 0.91 ± 0.02 and 0.98 ± 0.01, respectively (p < 0.05). For other measured neuromuscular parameters, atracurium-induced depression tended to be greater in the presence of desfurane than in the presence of isofurane, but none of the measured differences reached the statistical significance level of p < 0.05. The ED₅₀, ED₉₅, and 25–75% recovery index of atracurium were 0.038 mg/kg (95% confidence level; range 0.030 to 0.047 mg/kg), 0.11 mg/kg (0.095 to 0.14 mg/kg), and 31 ± 4 minutes (means ± SEM) with desfurane anesthesia, versus 0.043 mg/kg (0.035 to 0.052 mg/kg), 0.13 mg/kg (0.11 to 0.16 mg/kg), and 23 ± 4 minutes with isofurane anesthesia (p = 0.1-0.2). Continuation of either anesthetic at 1.25 MAC prevented complete recovery of neuromuscular functions spontaneously or following neostigmine 0.04 mg/kg.

Conclusion: In ASA physical status I adults, 9% desfurane has neuromuscular effects equal to or slightly in excess of those of 1.6% isofurane.     

Desflurane versus propofol maintenance for outpatient laparoscopic cholecystectomy

Background : The aims of the study were to evaluate costs and clinical characteristics of desflurane-based anaesthetic maintenance versus propofol for outpatient cholecystectomy.
Methods : All 60 patients received ketamine 0.2 mg kg^-1, fentanyl 2 μg kg^-1 and propofol 2 mg kg^-1 for induction. Ketorolac 0.4 mg kg^-1 and ondansetron 0.05 mg kg^-1 +droperidol 20 μg Kg^-1 was given as prophylaxis for postoperative pain and emesis, respectively. The patients were randomly assigned into Group P with propofol maintenance and opioid supplements, or Group D with desflurane in a low-flow circuit system.
Results : All the patients were successfully discharged within 8 h without any serious complications. Emergence from anaesthesia was more rapid after desflurane; they opened their eyes and stated date of birth at mean 6.4 and 8.4 min respectively, compared with 9.6 and 12 min in the propofol group (P<0.05). Nausea and pain were more frequent in Group D, 40% and 80% respectively; versus 17% and 50% in Group P (P<0.05). By telephone interview at 24 h and 7 d after the procedure, there was no major difference between the groups. With desflurane, drug costs per case were 10 $ lower than with propofol.
Conclusion : We conclude that desflurane is cheaper and has a more rapid emergence than propofol for outpatient cholecystectomy. However, propofol results in less pain and nausea in the recovery unit. Despite ondansetron and droperidol prophylaxis, there was still a substantial amount of nausea and vomiting after desflurane.     

Use of desflurane for outpatient anesthesia. A comparison with propofol and nitrous oxide.

Desflurane's induction and recovery characteristics were compared to those of propofol-nitrous oxide in outpatients undergoing laparoscopic procedures. Ninety-two healthy patients were randomized to receive either: 1) propofol induction and propofol-nitrous oxide maintenance (control), 2) propofol induction and desflurane-nitrous oxide maintenance, 3) desflurane-nitrous oxide, or 4) desflurane alone for induction and maintenance of anesthesia. Inhalation induction with desflurane-nitrous oxide was faster than with desflurane alone (100 +/- 35 vs. 124 +/- 43 s). Inhalation inductions were associated with a high incidence of apnea (17 and 26%), breath-holding (26 and 39%), and coughing (30 and 22%) in groups 3 and 4, respectively. The emergence time after discontinuation of desflurane in oxygen (4.5 +/- 2.1 min.) was significantly less than that after propofol-nitrous oxide (7.3 +/- 3.9 min.). However, times from arrival in the recovery room until the patients were judged fit for discharge were similar for all four treatment groups. Digit-symbol substitution test results and sedation visual analogue scores also were similar during the first 2 h in the recovery room. A lower incidence of moderate-to-severe nausea was reported in group 1 (15% vs. 52, 52, and 59% in groups 2, 3, and 4, respectively). In conclusion, induction of anesthesia with desflurane was rapid but is associated with a high incidence of airway irritation. Emergence and recovery profiles after maintenance of anesthesia with desflurane compared favorably to a propofol-nitrous oxide combination. However, propofol was associated with a lower incidence of nausea than was desflurane after outpatient anesthesia for laparoscopic surgery.     

Randomized Comparison of Isoflurane and Sevoflurane for Laparoscopic Gastric Banding in Morbidly Obese Patients

Study Objective: To compare the efficacy and recovery profile of sevoflurane and isoflurane as the main anesthetics for morbidly obese patients.

Design: Randomized, blinded study.

Setting: Inpatients.

Patients: 30 ASA physical status II and III obese patients [body mass index (BMI) > 35 kg/m²] undergoing laparoscopic gastric banding for morbid obesity.

Interventions: After standard intravenous induction of general anesthesia and tracheal intubation, anesthesia was maintained with either sevoflurane or isoflurane as the main anesthetics. The end-tidal concentrations of the volatile drugs were adjusted to maintain systolic arterial blood pressure within ±20% from baseline values. When the surgeon started the skin suture, the end-tidal concentration of the inhalational drug was reduced to 0.5 minimum alveolar concentration in both groups. At the last skin suture, the inhalational drug was discontinued and the vaporizator was removed to allow blinded evaluation of the emergence times.

Measurements and Main Results: No differences in anesthetic exposure, hemodynamic parameters, incidence of untoward events, or postoperative pain relief were reported between the two groups. Extubation, emergence, and response times were shorter after sevoflurane [6 min (3–15 min), 8 min (5–18 min), and 12 (6–25 min)] than isoflurane [10 min (6–26 min), 14 min (6–21 min), and 21 min (14–41 min)] (p = 0.001, p = 0.03, and p = 0.0005, respectively). The median time for postanesthesia care unit discharge was 15 minutes (25th—75th percentiles: 10–18 min) after sevoflurane and 27 minutes (25th—75th percentiles: 20–30 min) after isoflurane (p = 0.0005).

Conclusions: Sevoflurane provides a safe and effective intraoperative control of cardiovascular homeostasis in morbidly obese patients undergoing laparoscopic gastric banding, with the advantage of a faster recovery and earlier discharge from the postanesthesia care unit than isoflurane.     

Effect of low fresh gas flow rates on inspired gas composition in a circle absorber system

Study Objective: To determine the effects of fresh gas f ow on inspired gas composition during low flow anesthesia.

Design: Randomized trial with 2-hour observation periods in patients assigned to one of three groups.

Setting: Inpatient surgery clinic at a medical center.

Patients: Thirty-six patients undergoing abdominal surgery with low flow anesthesia. Interventions: Fresh gas flow was given at a starting rate of 5 L/min for 6 minutes. Thereafter, the fresh gas flow setting was nitrous oxide (N₂O) 1 L/min and oxygen (O₂) 0.6 L/min (Group 1), N₂O 0.5 L/min and O₂ 0.5 L/min (Group 2), and with a moderate surplus of N₂O and O₂ with respect to the patient's O₂ consumption (Group 3).

Measurements and Main Results: The inspired O₂ concentration (FIO₂) was measured using a paramagnetic technique, and N₂O levels were measured with infrared sensors; the inspired nitrogen concentration (FIN₂) was calculated by the following formula: (FIN₂) = 1 - FIO₂ - FIN₂O, where FIN₂O is the inspired N₂O concentration. After 1 hour of anesthesia, FIO₂ was significantly lower in Group 1 than in Groups 2 and 3 (p < 0.01), and FIN₂ was significantly higher in Groups 2 and 3 than in Group 1 (p < 0.01). After 2 hours of anesthesia, (FIN₂) returned to normal in Group 2 but continued to increase in Group 3. FIN₂O was close to 0.7% only in Group 1.

Conclusions: The same initial period of denitrogenation is not adequate to denitrogenate the circle system in all cases. The lower the fresh gas flow, the longer the initial period of denitrogenation should be. Various levels of fresh gas flow for low-flow anesthesia have been suggested, but none guarantees adequate control of inspired gas composition unless f owmeters are continuously adjusted.     

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.     

Onset and recovery of neuromuscular blockade after two doses of rocuronium in children

Study Objective: To determine if 450 μg/kg (1.5 times the ED₉₅) of rocuronium would result in a comparable onset with a shorter duration of action when compared with 600 μg/kg (2 times the ED₉₅).

Design: Randomized, single-blind study.

Setting: Teaching hospital.

Patients: 85 ASA physical status I and II children ages 2 through 12, undergoing elective surgery with an inhalation induction using halothane.

Interventions: Group 1 received 600 μg/kg rocuronium, and Group 2 received 450 μg/kg rocuronium.

Measurements and Main Results: The two groups were compared using a Student’s t-test, with p < 0.05 significant. The time of onset, or time to 95% suppression of neuromuscular twitch with standard errors, was 140 ± 13 seconds (range 46 to 365 sec) in Group 1 and 148 ± 13 seconds (range 82 to 345 sec) in Group 2 (NS = not significant). The times to 25% return of twitch from baseline (T₂₅) in Groups 1 and 2 were 28 ± 1.5 minutes (range 14 to 45 min) and 26 ± 1.6 minutes (range 10 to 55 min), respectively (NS). The differences between these two doses in onset of, and recovery from, block were not found to be statistically significant. The results, however, excluded 5% of the higher dose group and 31% of the lower dose group who did not achieve 95% suppression of twitch. Time to maximal suppression of neuromuscular blockade, however, was not statistically significant for the 85 patients with a time of 270 ± 28 seconds (range 91 to 605 sec) with a mean maximal suppression of 98.7% in Group 1 and 313 ± 25 seconds (range 91 to 899 sec) with a mean maximal suppression of 93.1% in Group 2.

Conclusion: The two doses of rocuronium did not differ statistically in onset or duration. Rocuronium at 600 μg/kg offers more reliability than 450 μg/kg in achieving adequate muscle relaxation, and the lower dose may result in a significantly large number of patients who may have inadequate intubating conditions.     

The effects of adding ischemic preconditioning during desflurane inhalation anesthesia or propofol total intravenous anesthesia on pneumoperitoneum-induced oxidative stress

Background: The aim of the study was to explore the differences in oxidative stress during anesthesia with desflurane/N₂O or propofol/remifentanil in patients undergoing laparoscopic cholecystectomy and additionally to evaluate the differential effects of desflurane and propofol on ischemic preconditioning (IP).

Materials and methods: One hundred patients were randomly allocated to four groups. For anesthesia maintenance, the inhalation group (Group I) and the inhalation plus IP group (Group IIP) received desflurane at an end-tidal concentration of 4–6 vol% in oxygen/N₂O, and the TIVA group (Group T) and TIVA plus IP group (Group TIP) received infusions of propofol and remifentanil. In Groups IIP and TIP, IP was carried out by 10?min of pneumoperitoneum followed by 10?min of deflation. Preoperative and postoperative plasma total antioxidant status (TAS), total oxidant status (TOS), paraoxonase, stimulated paraoxonase, arylesterase, ceruloplasmin, and myeloperoxidase levels were analyzed; oxidative stress index (OSI) was calculated.

Results: When oxidative stress parameters were compared between groups, myeloperoxidase values in Group I were statistically significantly lower compared to Group TIP (p?=?.004 with Bonferroni’s correction). There were no differences between preoperative and postoperative TAS, paraoxonase, stimulated paraoxonase, arylesterase, or ceruloplasmin levels (p?>?.05). In intragroup evaluations, postoperative paraoxonase and stimulated paraoxonase levels were found to be lower than preoperative values in Group TIP (p?=?.021 and .012, respectively).

Conclusion: In laparoscopic cholecystectomy lasting less than 60?min, there were no differences in the measured oxidative stress parameters between maintenance of anesthesia by desflurane/N₂O and propofol/remifentanil/N₂O. The addition of 10?min IP administration during both anesthesia techniques did not result in additional changes in the analyzed oxidative stress.     

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.     

The use of a remifentanil infusion for hemodynamic control during intracranial surgery.

Remifentanil is an extremely rapid and short-acting opioid analgesic which is effective in controlling acute stress responses during surgery. During neurosurgical anesthesia, laryngoscopy and intubation, application of the head holder, scalp incision, and the craniectomy can produce significant increases in mean arterial pressure (MAP). In this dose-response study, we evaluated the efficacy of a remifentanil infusion in maintaining hemodynamic stability during intracranial surgery under desflurane anesthesia. Forty-five patients were assigned randomly to one of the three remifentanil infusion groups. All patients received a standardized anesthetic induction consisting of midazolam, 2 mg IV, lidocaine 0.75 mg/kg IV, propofol 1.0 mg/kg IV, and remifentanil 0.5 microg/kg IV. Immediately after induction of anesthesia, a remifentanil infusion was started at 0.0625 microg x kg(-1) x min(-1) (Group 1), 0.125 microg x kg(-1) x min(-1) (Group 2), or 0.250 microg x kg (-1) x min(-1)(Group 3) according to a double-blinded study protocol. Maintenance of anesthesia consisted of desflurane 3% (end-tidal) in air/oxygen. If the MAP exceeded 80 mm Hg, a supplemental bolus of remifentanil, 0.5 microg/kg IV was administered, and when the MAP decreased below 65 mm Hg, the remifentanil infusion was discontinued temporarily. "Rescue" cardiovascular medications consisted of nitroprusside (100 microg IV) or phenylephrine (100 microg IV). Heart rate, systolic, diastolic, and MAP values, were recorded every minute for 20 min after each specific stimulus. The overall quality of the intraoperative hemodynamic control was evaluated by the attending anesthesiologist on a scale from 1 = poor to 5 = excellent. The overall quality of the hemodynamic control was superior in Group 2 compared with Group 1 (P < 0.05). Although the total dose of remifentanil administered during the study period did not differ among the three groups, Group 1 required significantly more supplemental boluses of remifentanil (66%-80%) than Groups 2 (13%-33%) and 3 (70% 13%), and the remifentanil infusion was discontinued more often in Group 3 (80%-93%) than in Groups 1 (0%-13%) and 2 (21%-40%). In conclusion, the recommended remifentanil infusion rate for controlling acute autonomic responses during neurosurgical anesthesia is 0.125 microg x kg(-1) x min(-1) when administered during a desflurane-based anesthetic. IMPLICATIONS: Compared with remifentanil 0.0625 microg x kg(-1) x min(-1) and 0.250 microg x kg(-1) x min(-1), a remifentanil infusion rate of 0.125 microg x kg(-1) x min(-1) provided more stable hemodynamic conditions during intracranial surgery under desflurane anesthesia.     

Inhaling nitrous oxide reduces the induction dose requirements of propofol

Inhaling nitrous oxide (N(2)O) before propofol induction appears to decrease propofol usage. To investigate the efficacy of N(2)O as a component of the drugs used to induce anesthesia, the effect of inhaling a N(2)O:oxygen (O(2)) mixture on the dose of propofol required to induce anesthesia was determined in a double-blinded manner. We randomized 117 unpremedicated patients scheduled for elective surgery into three groups. Group FN received 1 microg/kg fentanyl and breathed 4 L/min N(2)O + 2 L/min O(2). Group PN received placebo and breathed 4 L/min N(2)O + 2 L/min O(2). Group FO received 1 microg/kg fentanyl and breathed 6 L/min O(2). Propofol was infused at 20 mg/min after 1 min of gas mixture inhalation, and the infusion stopped when there was loss of response to verbal command. The mean (SD) propofol dose was 0.75 (0.30), 0.84 (0.26), and 1.33 (0.51) mg/kg, and the induction time 133 (57), 142 (47), and 226 (78) s for Groups FN, PN, and FO, respectively. We conclude that inhalation of 66% N(2)O in O(2) 1 min before the IV induction of anesthesia with propofol at 20 mg/min, reduces the induction dose of propofol by 44% and decreases the time required for the induction of anesthesia (P < 0.001).     

Combined popliteal and posterior cutaneous nerve of the thigh blocks for short saphenous vein stripping in outpatients: An alternative to spinal anesthesia

Study Objective: To compare a combination of peripheral nerve blocks with spinal anesthesia in ambulatory patients undergoing short saphenous vein stripping.

Design: Prospective, randomized study.

Setting: University hospital.

Patients: 28 ASA physical status I and II ambulatory surgery patients undergoing short saphenous vein stripping.

Interventions: 14 patients received a popliteal block (sciatic nerve block at the popliteal fossa) using 30 ml of alkalinized 3 % chloroprocaine and a posterior cutaneous nerve of the thigh block with 10 ml of 1% lidocaine. The 14 patients who were randomized to the spinal anesthesia group received 65 mg of 5% hyperbaric lidocaine.

Measurements and Main Results: There were no significant differences in age and gender between the two groups (mean age 53 ± 13 years, 8 men and 20 women). Patients in the peripheral nerve block group recovered significantly faster in phase 1 of the postanesthesia care unit (PACU) (67 ± 10 min vs. 122 ± 50 min, p < 0.01) and were discharged home sooner (222 ± 53 min vs. 294 ± 69 min, p < 0.01) than the patients in the spinal anesthesia group.

Conclusions: The combination of popliteal and posterior cutaneous nerve of the thigh blocks provided adequate anesthesia and a faster recovery profile with a similar subjective acceptance of both anesthetic techniques in ambulatory patients undergoing short saphenous vein stripping in the prone position.     

Different benefit of bispectal index (BIS) in desflurane and propofol anesthesia

BACKGROUND: Bispectal index (BIS) monitoring may reduce drug usage and hasten recovery in propofol and inhalation anesthesia. The faster emergence profile of desflurane may reduce the effect of BIS monitoring on recovery from desflurane compared with propofol. This study compared hypnotic drug usage, recovery, patient satisfaction and incidence of inadequate sedation in BIS monitored and nonmonitored women anesthetized with desflurane or propofol. METHODS: One hundred and sixty patients scheduled for elective gynecological surgery were randomly assigned to desflurane or propofol anesthesia with and without BIS monitoring. Fentanyl, vecuronium and remifentanil were administered according to clinical criteria. The BIS monitor was used in all patients, but the monitor screen was covered in the controls. A BIS level between 45 and 55 was targeted in the BIS monitored patients whereas depth of anesthesia was assessed by clinical criteria in the controls. RESULTS: The mean (SD) desflurane MAC-hours administered with and without BIS were 0.70 (0.15) and 0.76 (0.12), respectively, resulting in extubation times of 6.5 (4.1) and 8.3 (6.1) min. (NS). Bispectal index monitoring was associated with improved patient satisfaction, reduced postoperative nausea and antiemetic drug requirement, and fewer episodes with sustained BIS levels > 60. The mean (SD) propofol infusion rates were 6.0 (1.4) and 6.6 (0.9) mg kg(-1)h(-1) with and without the BIS monitor (P = 0.023), resulting in mean (SD) extubation times of 6.8 (4.6) and 10.5 min (5.9), respectively (P < 0.05). CONCLUSION: Bispectal index monitoring reduced propofol usage and hastened recovery after propofol anesthesia, whereas in desflurane anesthesia it was associated with improved patient satisfaction, probably because of decreased postoperative nausea and fewer episodes of inadequate hypnosis.