Anesthesia and analgesia
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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 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 TrialThe cost-effectiveness of methohexital versus propofol for sedation during monitored anesthesia care.
We designed this study to test the hypothesis that methohexital is a cost-effective alternative to propofol for sedation during local anesthesia. Sixty consenting women undergoing breast biopsy procedures under local anesthesia were randomly assigned to receive an infusion of either propofol (50 microg x kg(-1) x min(-1)) or methohexital (40 microg x kg(-1) x min(-1)). The sedative infusion rate was titrated to maintain an observer's assessment of alertness/sedation (OAA/S) score of 3 (with 1 = awake/alert to 5 = asleep). Fentanyl 25 microg i.v. was administered as a "rescue" analgesic during the operation. We assessed the level of sedation (OAA/S score), vital signs, time to achieve an OAA/S score of 3 at the onset and a score of 1 after discontinuing the infusion, discharge times, perioperative side effects, and patient satisfaction. The direct cost of methohexital was lower than that of propofol, based on the milligram dosage infused during the operation. The sedative onset (to achieve an OAA/S score of 3) and the recovery (to return to an OAA/S score of 1) times, as well as discharge times, did not differ between the two groups. Patients receiving methohexital had a significantly lower incidence of pain on initial injection compared with those receiving propofol (10% vs 23%). Because the use of methohexital (29.4 +/- 2.7 microg x kg(-1) x min(-1)) for sedation during breast biopsy procedures has a similar efficacy and recovery profile to that of propofol (36.8 +/- 15.9 microg x kg(-1) x min(-1)) and is less costly based on the amount infused, it seems to be a cost-effective alternative to propofol for sedation during local anesthesia. However, when the cost of the drug infused and drug wasted was calculated, there was no difference in the overall drug cost. ⋯ When administered to maintain a stable level of sedation during local anesthesia, methohexital is an acceptable alternative to propofol. However, the overall drug costs were similar with the two drugs.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialUse of remifentanil during anesthetic induction: a comparison with fentanyl in the ambulatory setting.
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Anesthesia and analgesia · Apr 1999
Perioperative plasma endothelin-1 and Big endothelin-1 concentrations in elderly patients undergoing major surgical procedures.
Plasma concentrations of the vasoconstrictor endothelin-1 (ET-1) increase during acute physiologic stress, but the role of ET-1 in the pathophysiology of stress remains largely undefined. Whether ET-1 mediates thermoregulatory changes in vasomotor tone is unknown. ET-1 and its more stable precursor, Big ET-1, were measured in plasma obtained at several perioperative time points from 95 consecutive elderly patients (mean age 70 +/- 1 yr) randomized to receive either normothermic or hypothermic perioperative care while undergoing major surgical procedures. In the postoperative period, there were no significant changes in plasma ET-1 concentrations, but Big ET-1 concentrations increased considerably (P < 0.0001). There were no significant differences in mean ET-1 or Big ET-1 levels in normothermic and hypothermic patients. Preoperative and postoperative ET-1 concentrations were significantly higher in patients with a history of hypertension (P < 0.002) and in those requiring treatment for postoperative hypertension (P < 0.003). Patients with cancer and those undergoing abdominal surgery had significantly higher Big ET-1 concentrations (P < 0.0001 and P < 0.003, respectively). These data support the hypothesis that Big ET-1 is a more sensitive measure of endothelin system activation after major surgery. Premorbid conditions and location and type of surgery influence perioperative ET-1/Big ET-1 concentrations. ⋯ The endothelin response seems to be significantly associated with perioperative hemodynamic aberrations. The endothelin-1 (ET-1) precursor Big ET-1 is a more sensitive measure of the endothelin system activation in response to surgical stress than ET-1 alone. Thermoregulatory vasoconstriction in response to mild perioperative hypothermia occurs independently of the endothelin system.