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 TrialTramadol added to mepivacaine prolongs the duration of an axillary brachial plexus blockade.
Tramadol is an analgesic drug that is antagonized by alpha2-adrenoceptor antagonists, as well as opioid antagonists. We hypothesized that tramadol might produce effects on an axillary brachial plexus blockade similar to those of clonidine. We designed a prospective, controlled, double-blinded study to assess the impact of tramadol added to mepivacaine on the duration of an axillary brachial plexus blockade. After institutional approval and informed consent, 60 patients (ASA physical status I or II) scheduled for forearm and hand surgery after trauma under brachial plexus anesthesia were included in the study. Patients were randomly assigned to receive either 40 mL of mepivacaine 1% with 2 mL of isotonic sodium chloride solution (Group A, n = 20); 40 mL of mepivacaine 1% with 100 mg of tramadol (Group B, n = 20); or 40 mL of mepivacaine 1% with 2 mL of isotonic sodium chloride solution and 100 mg of tramadol i.v. (Group C, n = 20). Sensory block, motor block, and hemodynamics were recorded before and 5, 10, 30, 60, 120, 180, and 360 min after local anesthetic injection. Duration of sensory and motor block was significantly longer (P < 0.01; P < 0.05) in Group B (299 +/- 84 and 259 +/- 76 min) than in Group A (194 +/- 35 and 181 +/- 24 min) and Group C (187 +/- 35 and 179 +/- 16 min). There was no difference in onset of sensory and motor blockade among groups. Hemodynamics remained unchanged in all patients throughout the study period. We conclude that the addition of tramadol prolongs the duration of brachial plexus block without side effects. Tramadol may be an alternative to epinephrine or clonidine as an adjuvant to local anesthesia for an axillary block. ⋯ This study demonstrates that the admixture of 100 mg of tramadol with mepivacaine 1% for brachial plexus block provides a pronounced prolongation of blockade without side effects. Our data support a specific analgesic effect of tramadol on peripheral nerves.
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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
Randomized Controlled Trial Clinical TrialEvaluating T-wave amplitude as a guide for detecting intravascular injection of a test dose in anesthetized children.
Previous reports have suggested that accidental intravascular injection of an epinephrine-containing test dose increases T-wave amplitude in anesthetized children. We designed this study to prospectively determine whether changes in T-wave amplitude could be a reliable indicator for detecting intravascular injection. We studied 32 ASA physical status I infants and children (3.4 +/- 1.7 yr) undergoing elective minor surgeries during 1.0 minimum alveolar anesthetic concentration of sevoflurane and 67% nitrous oxide in oxygen. After the i.v. administration of atropine 0.01 mg/kg, the patients were randomly assigned to receive either saline (n = 16) or a test dose consisting of 1% lidocaine (0.1 mL/kg) with 1:200,000 epinephrine (0.5 microg/kg, n = 16) via a peripheral vein to simulate the intravascular injection of the test dose. Heart rate (HR) and systolic blood pressure (SBP) were recorded every 20 and 30 s, respectively, and the T-wave amplitude of lead II was continuously recorded for subsequent analysis. Of the 16 children receiving the test dose, 16, 13, and 16 developed increases in HR, SBP, and T-wave amplitude > or = 10 bpm, > or = 15 mm Hg, and > or = 25%, occurring at 30 +/- 7, 70 +/- 31, and 20 +/- 5 s, respectively. Because no patient receiving saline met these criteria, sensitivity, specificity, and positive and negative predictive values were all 100% based on the criteria using the T-wave amplitude and the peak HR. Our results suggest that changes in T-wave amplitude are as effective as HR for detecting the intravascular injection of an epinephrine-containing test dose in sevoflurane-anesthetized children. ⋯ To determine whether an epidurally administered local anesthetic is unintentionally injected into a blood vessel, a small dose of epinephrine is often added to a local anesthetic. We found that increases in T-wave amplitude by > or = 25% in lead II monitor electrocardiography are as effective as a heart rate increase > or = 10 bpm for detecting intravascular injection in sevoflurane-anesthetized children.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of epidural ropivacaine infusion alone and in combination with 1, 2, and 4 microg/mL fentanyl for seventy-two hours of postoperative analgesia after major abdominal surgery.
Our aim in this prospective, randomized, double-blinded study was to compare the analgesic effectiveness and side effects of epidural infusions with ropivacaine 2 mg/mL alone (Group R; n = 60) and in combination with fentanyl 1 microg/mL (R1F; n = 59), 2 microg/mL (R2F; n = 62), and 4 microg/mL (R4F; n = 63) for up to 72 h after major abdominal surgery. Effective epidural neural blockade was established before surgery; postoperatively, the infusion rate was titrated to a maximum of 14 mL/h for analgesia. No additional analgesics other than acetaminophen were permitted during the infusion. The median of individual visual analog scale score with coughing were <20 mm for all groups (0 = no pain, 100 = worst pain) and was significantly lower (P < 0.01) for Group R4F at rest and with coughing (compared with Group R). Infusions were discontinued due to inability to control pain in significantly fewer patients in Group R4F (16%) than the other groups (34% to 39%; P < 0.01). For all groups, >90% of patients had no detectable motor block after 24 h. Hypotension, nausea, and pruritus were more common with the larger dose of fentanyl. We conclude that, after major abdominal surgery, an epidural infusion of ropivacaine 2 mg/mL with fentanyl 4 microg/mL provided significantly more effective pain relief over a 3-day period than ropivacaine alone or ropivacaine with lower concentrations of fentanyl. ⋯ Postoperative epidural analgesic infusions are widely used, but there is little information regarding optimal strengths of opioid with local anesthetic. In this blinded, prospective study, we compared four different epidural infusion solutions for efficacy and side effects over a clinically useful postoperative period and conclude that an epidural infusion of ropivacaine 2 mg/mL with fentanyl 4 microg/mL was most effective.