Anesthesia and analgesia
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialComparison of sevoflurane with propofol for laryngeal mask airway insertion in adults.
We performed a prospective, randomized, controlled trial to compare the quality and ease of laryngeal mask airway (LMA) insertion after either rapid inhaled sevoflurane or i.v. propofol induction of anesthesia. Seventy-six unpremedicated ASA physical status I or II patients were anesthetized with either a single vital capacity breath of sevoflurane 8% or i.v. propofol 3 mg/kg, which produced equally rapid loss of consciousness (40.5 +/- 13.9 vs 37.7 +/- 9.9 s; P > 0.05). The LMA was inserted more rapidly in patients in the propofol group (74 +/- 29 vs 127 +/- 35 s; P < 0.01) and required fewer attempts (1.2 vs 1.6; P < 0.05) than the sevoflurane group. There was a greater incidence of initially impossible mouth opening in the sevoflurane group (45% vs 21%; P < 0.05). Once mouth opening was possible, the degree of attenuation of laryngeal reflexes was similar. The overall incidence of complications related to LMA insertion, especially apnea (32% vs 0%; P < 0.01), was more frequent in the propofol group (82% vs 26%; P < 0.01). There were four failures of LMA insertion in the propofol group and none in the sevoflurane group. Both groups had stable hemodynamic profiles and good patient satisfaction. We conclude that sevoflurane vital capacity breath induction compares favorably with i.v. propofol induction for LMA insertion in adults. However, prolonged jaw tightness after the sevoflurane induction of anesthesia may delay LMA insertion. ⋯ In this randomized, controlled trial, we compared the ease of insertion of the laryngeal mask airway in adults after induction of anesthesia with either a sevoflurane vital capacity breath technique or propofol i.v.. We conclude that sevoflurane compares favorably with propofol, although prolonged jaw tightness may delay laryngeal mask airway insertion.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Clinical TrialThe effects of three graded doses of meperidine for spinal anesthesia in African men.
The intrathecal injection of 0.7-1 mg/kg meperidine provides spinal anesthesia of only short duration. In this study, we investigated the effects of three different doses of meperidine for spinal anesthesia on the duration and level of sensory block and the incidence of side effects. Forty-five African men were randomly allocated to receive one of three doses of intrathecal meperidine: Group A = 1.2 mg/kg, Group B = 1.5 mg/kg, and Group C = 1.8 mg/kg. The duration of sensory block was significantly longer after 1.5 mg/kg compared with 1.2 mg/kg meperidine (112 +/- 19 vs 79 +/- 27 min; P = 0.001). Increasing the dose to 1.8 mg/kg did not further increase the duration of block. The level and the onset of the block were not affected by the dose. Common side effects were fatigue (27%), pruritus (20%), and nausea (7%). Seven patients had respiratory depression and seven had a decrease of systolic arterial blood pressure (SAP) >30% from baseline. There was no difference in the incidence of any side effect among groups. Respiratory depression and decreases in SAP were observed 5-50 min after meperidine injection. Twenty-two patients had no pain after the sensory block had terminated. We conclude that increasing the dose of meperidine from 1.2 to 1.5 mg/kg increased the duration, but not the level, of sensory block without an increase in side effects. ⋯ Intrathecal meperidine 1 mg/kg provides surgical anesthesia for only 40-90 min. We investigated the effects of three larger doses of meperidine in 45 African men. The 1.5 and 1.8 mg/kg doses provide a longer duration of anesthesia compared with 1.2 mg/kg. Nausea, pruritus, and respiratory depression were common in all dose groups. We conclude that increasing the dose of meperidine from 1.2 to 1.5 mg/kg increased the duration, but not the level, of sensory block without an increase in side effects.
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Anesthesia and analgesia · Apr 1999
Comparative StudyExposure to sevoflurane and nitrous oxide during four different methods of anesthetic induction.
The National Institute for Occupational Safety and Health-recommended exposure levels for nitrous oxide exposure are 25 ppm as a time-weighted average over the time of exposure. The exposure limit for halogenated anesthetics (without concomitant nitrous oxide exposure) is 2 ppm. Inhaled sevoflurane provides an alternative to i.v. induction of anesthesia. However, the inadvertent release of anesthetic gases into the room is likely to be greater than that with induction involving i.v. anesthetics. We therefore evaluated anesthesiologist exposure during four different induction techniques. Eighty patients were assigned to one of the induction groups to receive: 1) sevoflurane and nitrous oxide from a rebreathing bag, 2) sevoflurane and nitrous oxide from a circle circuit, 3) propofol 3 mg/kg, and 4) thiopental sodium 5 mg/kg. Anesthesia was maintained with sevoflurane and nitrous oxide via a laryngeal mask. Trace concentrations were measured directly from the breathing zone of the anesthesiologist. During induction, peak concentrations of sevoflurane and nitrous oxide with the two i.v. methods rarely exceeded 2 ppm sevoflurane and 50 ppm nitrous oxide. Concentrations during the two inhalation methods were generally <20 ppm sevoflurane and 100 ppm nitrous oxide. During maintenance, median values were near 2 ppm sevoflurane and 50 ppm nitrous oxide in all groups. Sevoflurane concentrations during inhaled induction frequently exceeded the National Institute for Occupational Safety and Health-recommended exposure ceiling of 2 ppm but mostly remained <20 ppm. Exposure during the maintenance phase of anesthesia also frequently exceeded the 2-ppm ceiling. We conclude that operating room anesthetic vapor concentrations are increased during inhaled inductions and remain increased with laryngeal mask ventilation. ⋯ We compared waste gas concentrations to sevoflurane and nitrous oxide during four different induction methods. During inhaled induction with a rebreathing bag or a circle circuit system, waste gas concentrations frequently exceed National Institute for Occupational Safety and Health limits of 2 ppm sevoflurane and 50 ppm nitrous oxide. Therefore, we recommend that people at risk (e.g., women of child-bearing age) should pay great attention when using this technique.
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Anesthesia and analgesia · Apr 1999
Tracheal intubation of healthy pediatric patients without muscle relaxant: a survey of technique utilization and perceptions of safety.
We conducted a survey of Society for Pediatric Anesthesia anesthesiologists practicing within the United States to determine the frequency of tracheal intubation of healthy infants and children using an inhaled anesthetic without muscle relaxation (IAWMR). We also examined reasons for the use of this technique. Of all responders who listed their most often used technique for tracheal intubation of healthy infants and children, IAWMR was chosen over intubation with a muscle relaxant by 38.1% and 43.6%, respectively. Anesthesiologists who most often used IAWMR for tracheal intubation of healthy infants and children had over twice the odds (odds ratio [OR] 2.30 for infants, 95% confidence interval [CI] 1.18-4.50; P = 0.015) of classifying their own practice as nonacademic, and one-third the odds (OR 0.34 for infants, 95% CI 0.17-0.68; P = 0.002) of conducting more than half of their cases in a supervisory role. Anesthesiologists who use IAWMR to tracheally intubate healthy pediatric patients most commonly selected as their reasons the lack of need for a muscle relaxant and the desire to avoid both succinylcholine and the excessive duration of nondepolarizing muscle relaxants. ⋯ Inhaled anesthetic without muscle relaxation is the most often used method of intubation for more than one third of Society for Pediatric Anesthesia anesthesiologists when tracheally intubating healthy, fasted pediatric patients undergoing elective procedures. The frequency of this practice seems to be highest in nonacademic practices.