Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1997
Randomized Controlled Trial Comparative Study Clinical TrialIntracranial pressure, middle cerebral artery flow velocity, and plasma inorganic fluoride concentrations in neurosurgical patients receiving sevoflurane or isoflurane.
This study examined the concentration-related effects of sevoflurane and isoflurane on cerebral physiology and plasma inorganic fluoride concentrations. Middle cerebral artery flow velocity (Vmca), intracranial pressure (ICP), electroencephalogram (EEG) activity, and jugular bulb venous oxygen saturation were measured, and cerebral perfusion pressure (CPP) and estimated cerebral vascular resistance (CVRe) were calculated at baseline and at 0.5, 1.0, and 1.5 minimum alveolar anesthetic concentration (MAC) sevoflurane (n = 8) or isoflurane (n = 6). Mannitol 0.5-0.75 g/kg was given before dural incision, and blood was sampled for plasma inorganic fluoride during surgery and for up to 72 h postoperatively. Both sevoflurane and isoflurane decreased Vmca (to 31 +/- 12 - 36 +/- 14 cm/s, mean +/- SD), did not significantly alter ICP (13 +/- 9 - 15 +/- 11 mm Hg), and did not cause epileptiform EEG activity. With sevoflurane, decreased Vmca was accompanied by decreased CPP and unchanged CVRe at 0.5 MAC, and unchanged CPP and increased CVRe at 1.0 and 1.5 MAC. Plasma inorganic fluoride was 39.0 +/- 12.9 microM at the end of anesthesia (3.2 +/- 2.0 MAC hours) with sevoflurane, similar to the value (36.2 +/- 3.9 microM) for 3.7 +/- 0.1 MAC hours sevoflurane in patients not receiving mannitol. Decreased Vmca during sevoflurane presumably results from decreased cerebral metabolic rate, with CVRe changing secondarily in accord with CPP. Plasma inorganic fluoride does not seem to be altered by mannitol-induced diuresis. ⋯ In neurosurgical patients, sevoflurane decreased middle cerebral artery flow velocity and caused no epileptiform electroencephalogram activity and no increase of intracranial pressure or plasma inorganic fluoride. These effects are suitable for neurosurgery. Two other possible effects of sevoflurane, i.e., increased cerebrospinal fluid volume and/or intracranial elastance, may not be suitable for neurosurgery and warrant further study.
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Anesthesia and analgesia · Sep 1997
Randomized Controlled Trial Clinical TrialIntrathecal fentanyl with small-dose dilute bupivacaine: better anesthesia without prolonging recovery.
Recent concern regarding lidocaine neurotoxicity has prompted efforts to find alternatives to lidocaine spinal anesthesia. Small-dose dilute bupivacaine spinal anesthesia yields a comparably rapid recovery profile but may provide insufficient anesthesia. By exploiting the synergism between intrathecal opioids and local anesthetics, it may be possible to augment the spinal anesthesia without prolonging recovery. Fifty patients undergoing ambulatory surgical arthroscopy were randomized into two groups receiving spinal anesthesia with 3 ml 0.17% bupivacaine in 2.66% dextrose without (Group I) or with (Group II) the addition of 10 microg fentanyl. Median block levels reached T7 and T8, respectively (P = not significant [NS]). Mean times to two-segment regression, S2 regression, time out of bed, time to urination, and time to discharge were 53 vs 67 min (P < 0.01), 120 vs 146 min (P < 0.05), 146 vs 163 min (P = NS), 169 vs 177 min (P = NS), and 187 vs 195 min (P = NS) respectively. Motor blockade was similar between groups, but sensory blockade was significantly more intense in Group II (P < 0.01). Six of 25 blocks failed in Group I, whereas none failed in Group II. The addition of 10 microg fentanyl to spinal anesthesia with dilute small-dose bupivacaine intensifies and increases the duration of sensory blockade without increasing the intensity of motor blockade or prolonging recovery to micturition or street fitness. ⋯ Concerns about the neurotoxicity of lidocaine have prompted efforts to find alternatives to lidocaine spinal anesthesia. We studied 50 patients undergoing ambulatory surgical arthroscopy and found that although small-dose bupivacaine alone is inadequate for this procedure, the addition of fentanyl makes it reliable.
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Anesthesia and analgesia · Sep 1997
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of light wand and suspension laryngoscopic intubation techniques in outpatients.
Endotracheal intubation can produce postoperative sore throat and hoarseness, as well as changes in cardiovascular variables. A major goal of ambulatory surgery is the prompt return of patients to their daily activities. Postoperative sore throat may impede this and may decrease patient satisfaction with their anesthetic and surgical experience. We conducted a prospective, randomized study in 40 outpatients having lower extremity arthroscopies to compare the effects of direct laryngoscopy and light wand intubation on cardiovascular changes, sore throat, hoarseness, and dysphagia. Subjects were randomly assigned to either Group A (endotracheal intubation by rigid laryngoscopy) or Group B (endotracheal intubation with a light wand). A standardized anesthetic technique was used. Heart rate and blood pressure were recorded before induction, after induction but before endotracheal intubation, and at 1-min intervals for the first 5 min after intubation. Sixteen to twenty-four hours postoperatively, the incidence and severity of sore throat, hoarseness, and dysphagia was assessed by a follow-up phone call. This study demonstrated no clinically significant difference in cardiovascular variables between the two techniques. Patients had a significantly lower incidence and severity of sore throat, hoarseness, and dysphagia when a light wand was used for intubation. In conclusion, this study suggests that light wand intubation may decrease the incidence and severity of postoperative sore throat, hoarseness, and dysphagia, thereby potentially increasing satisfaction in ambulatory surgical patients. ⋯ This prospective, randomized study found that the incidence and severity of postoperative sore throat, hoarseness, and difficulty in swallowing among ambulatory surgical patients is more frequent when they are endotracheally intubated with a rigid laryngoscope than with a light wand. The authors, therefore, recommend more frequent use of the light wand for endotracheal intubation.
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Anesthesia and analgesia · Sep 1997
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialUse of the laryngeal mask airway as an alternative to the tracheal tube during ambulatory anesthesia.
We designed a prospective, randomized, multicenter study to compare anesthetic requirements, recovery times, and postoperative side effects when a laryngeal mask airway (LMA) was used as an alternative to the tracheal tube (TT) during ambulatory anesthesia. After induction of anesthesia with midazolam 2 mg, fentanyl 1 microg/kg, and propofol 2 mg/kg, 381 patients were randomly assigned to receive either an LMA (n = 207) or TT (n = 174) for airway management. In patients assigned to the TT group, succinylcholine 1 mg/kg or a nondepolarizing muscle relaxant was administered to facilitate tracheal intubation. Anesthesia was maintained with volatile anesthetics in combination with nitrous oxide 60% and oxygen. The average time to placement of the two airway devices (5 min) and the failure rates (1%) were similar in the two groups. Although there was a significant decrease in the intraoperative fentanyl requirement in the LMA group, the difference was of little clinical significance. Furthermore, there were no differences in the volatile anesthetic requirements. The time from end of surgery to removal of the airway device (5 min) was also similar in the two study groups. Although duration of the postanesthesia care unit stay and time to ambulation were significantly shorter in the LMA group, there were no differences in the times to "home readiness." The incidence of nausea and vomiting and the need for rescue antiemetic treatments in the postoperative period were similar in the two airway management groups. However, the incidence of postoperative sore throat was significantly greater in patients receiving the TT (versus the LMA). In conclusion, this study suggests that the LMA is a useful alternative to the TT for airway management during ambulatory anesthesia. ⋯ Use of the laryngeal mask airway can obviate the need for insertion of a tracheal tube for many ambulatory surgery procedures, and thereby decrease the incidence of postoperative sore throats.
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Anesthesia and analgesia · Sep 1997
Randomized Controlled Trial Multicenter Study Clinical TrialTreatment of postoperative nausea and vomiting with single intravenous doses of dolasetron mesylate: a multicenter trial. Dolasetron Mesylate PONV Treatment Study Group.
This study was conducted to determine the efficacy and safety of four intravenous (I.V.) doses of dolasetron, an investigational 5-HT3 receptor antagonist, for the treatment of postoperative nausea and/or vomiting (PONV) after outpatient surgery under general anesthesia. This multicenter, randomized, double-blind trial compared the antiemetic efficacy of 12.5, 25, 50, or 100 mg I.V. dolasetron with placebo over 24 h using complete response (no emetic episodes and no rescue medication), time to first emetic episode or rescue medication, and patient nausea and satisfaction with antiemetic therapy as rated by visual analog scale (VAS). Of 1557 patients enrolled, 620 patients were eligible for treatment. Complete response rates for all dolasetron doses--12.5 mg (35%), 25 mg (28%), 50 mg (29%), and 100 mg (29%)--were significantly more effective than placebo (11%, P < 0.05). There was a significant gender interaction for complete response (P < 0.01). Of the patients in the 25-mg and 100-mg dose groups, 12% and 13%, respectively, experienced no nausea (VAS score < 5 mm) versus 5% in the placebo group (P < 0.05). There were no clinically relevant changes in vital signs or laboratory values and no trends with dose for adverse events. Dolasetron is effective for treating PONV and has an adverse event profile similar to that of placebo. The 12.5-mg dose was as effective as larger doses for complete response. ⋯ Nausea and vomiting are common problems for postsurgical patients. In this study of 620 patients undergoing surgery, a 12.5-mg dose of intravenous dolasetron, a new serotonin-receptor blocker, was significantly more effective than placebo in treating established postoperative nausea and vomiting. Dolasetron 12.5 mg was as safe as placebo.