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Comparison of recovery tests after intravenous sedation with diazepam-methohexital and diazepam-methohexital and fentanyl.

A model for the assessment of recovery to street fitness from two commonly used techniques for intravenous sedation is described. Well-known psychometric research methods and simple paper-and-pencil tests that could be given by interested clinicians were used. The speed of recovery from diazepam-methohexital, and diazepam-methohexital and fentanyl (with naloxine reversal), did not differ significantly. Psychomotor skills were recovered before both perceptual and cognitive functions. Two simple paper-and-pencil tests easily identified perceptual and cognitive deficits at least three hours postoperatively.

Adult

Dissolving methohexital in a lipid emulsion reduces pain associated with intravenous injection.

Pain often accompanies intravenous injection of 1% methohexital. The aim of the present study was to test whether pain on injection could be reduced by dissolving methohexital in a lipid emulsion (study A) and whether this would affect anesthetic potency (study B). In study A, 24 healthy volunteers, 36 +/- 1 yr (mean +/- SE), were given 1 ml 1% methohexital in saline, 1 ml 1% methohexital in lipid emulsion, and 5 ml 0.1% methohexital in saline in random order. The injections were given in a small vein in the forearm at 5-min intervals. One minute after each injection, the subject was asked to assess the injection pain on a visual analog scale (0-100 mm). The pain score (median [range]) was 44.5 (0-77) after 1% methohexital in saline, 0.5 (0-26) after 1% methohexital in a lipid emulsion, and 1.0 (0-26) after 0.1% methohexital in saline. The pain score for 1% methohexital in saline was significantly greater than those for the other two solutions (P less than 0.001 for each comparison). In study B, 42 patients, 41 +/- 3 yr, were given 1% methohexital in lipid emulsion (n = 22) or 1% methohexital in saline (n = 20). A bolus of either solution was administered over 10 s, and the patient was considered asleep if there was no gross movement or response to verbal command 40-70 s after injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

Induction of anesthesia in children following administration of methohexital into the sigmoid colon.

The authors evaluated the sigmoidal administration of methohexital, the effect of methohexital concentration (1% versus 2%), the effect of dosage (25 mg/kg versus 15 mg/kg) on sleep-success rate, administration - sleep time, recovery time and the effect of aspirating the residual methohexital on recovery time. The study demonstrated that both 1% solution and 25 mg/kg of sigmoidal methohexital were independently associated with significantly higher sleep success rate and faster onset of sleep compared with 2% and 15 mg/kg of sigmoidal methohexital solution respectively. The recovery time was significantly affected by the dose of methohexital and was not significantly affected by the concentration of methohexital solution. Aspiration of the residual methohexital did not significantly affect the recovery time.

Catheterization

Cardiovascular effects of rectal methohexital in children.

STUDY OBJECTIVE: To define the cardiovascular effects of rectal methohexital in children with normal cardiac function. DESIGN: Cardiovascular evaluation of each patient was performed before and after medication. Each patient's predrug results were used as control measurements for comparison with measurements made after methohexital administration. SETTING: Inpatient operating room induction area in a privately endowed philanthropic children's hospital. PATIENTS: Forty-seven children age 35 +/- 22 months (mean +/- SD) scheduled for elective orthopedic or plastic surgery, free of cardiac or pulmonary disease, and receiving no medication with central nervous system activity. INTERVENTIONS: Control measurements of heart rate (HR), blood pressure (BP), and echocardiographic evaluations were obtained on the day before scheduled surgery. Repeat measurements were performed after the onset of methohexital-induced sleep. The time span of the measurements was designed to include the period of peak plasma methohexital concentration. In the preoperative holding area, 30 mg/kg of a 10% methohexital solution was administered rectally. If sleep did not occur in 15 minutes, an additional 15 mg/kg was given. MEASUREMENTS AND MAIN RESULTS: HR increased markedly after rectal methohexital [126 +/- 23 beats per minute (bpm) to 144 +/- 21 bpm, p less than 0.001], and stroke volume (SV) decreased (24 +/- 9 ml to 21 +/- 8 ml, p less than 0.01). There were no significant changes in BP or cardiac index. The shortening fraction and ejection fraction remained within the normal range for this age-group. CONCLUSIONS: Rectal methohexital induces sleep in healthy pediatric patients with minimal cardiovascular side effects. The primary effects are increased HR and decreased SV.

Anesthesia, Rectal

Electroconvulsive therapy-induced cardiac arrhythmias during anesthesia with methohexital, thiamylal, or thiopental sodium.

STUDY OBJECTIVE: To determine the frequency of electroconvulsive therapy (ECT)-induced arrhythmias under methohexital, thiamylal, or thiopental sodium anesthesia with and without atropine premedication. DESIGN: A randomized, double-blind study, placebo-controlled for atropine. SETTING: The inpatient psychiatric unit at a university medical center. PATIENTS: Forty-nine patients scheduled for ECT. INTERVENTIONS: Atropine 0.6 mg intravenously (IV) or an equal volume of normal saline IV was given before IV induction of anesthesia with methohexital 0.5 to 1.0 mg/kg, thiamylal 1.5 to 2.5 mg/kg, or thiopental sodium 1.5 to 2.5 mg/kg. MEASUREMENTS AND MAIN RESULTS: Single-lead electrocardiogram (ECG) recordings were made for 1 minute before induction, during induction of anesthesia, and for 5 minutes after the ECT stimulus. Each ECG was evaluated for arrhythmias and evidence of ischemia in a blinded fashion. Blood pressure and ECG evidence of ischemia did not differ among the groups. Seizure duration was significantly (p less than 0.05) prolonged by a mean of 5 seconds during methohexital anesthesia compared with thiopental sodium and thiamylal (47.6 +/- 18.6 seconds, 42.7 +/- 13.2 seconds, and 42.7 +/- 15.2 seconds, respectively). The frequency of sinus bradycardia was decreased (p less than 0.05) with methohexital (8%) compared with thiopental sodium (20%) and thiamylal (20%). The frequency of premature atrial contractions was decreased (p less than 0.05) with methohexital (43%) compared with thiamylal (61%) but not with thiopental sodium (57%). The frequency of premature ventricular contractions was decreased (p less than 0.05) with methohexital (27%) compared with thiopental sodium (44%) but not with thiamylal (40%). Atropine decreased the frequency of bradycardia (9% vs. 24%) and premature atrial contractions (47% vs. 61%) and increased the frequency of sinus tachycardia (88% vs. 75%). CONCLUSIONS: These data suggest that anesthesia for ECT therapy should be induced with methohexital to minimize the possibility of potentially life-threatening cardiac arrhythmias. Atropine premedication may further decrease the frequency of premature atrial contractions and bradycardia, while increasing the frequency of tachycardia.

Adult

Left ventricular performance during propofol or methohexital anesthesia: isotopic and invasive cardiac monitoring.

Using gated radionuclide ventriculography and invasive cardiac monitoring, the effects of propofol and methohexital on left ventricular volumes and function were investigated in 22 unpremedicated patients (ASA physical status III, 50-78 yr) with chronic coronary artery disease (NYHA class II-III). Anesthesia was induced with either propofol or methohexital (2 mg/kg), followed by a maintenance infusion of 100 micrograms.kg-1.min-1. Vecuronium (0.05 mg/kg) was administered and ventilation (FIO2, 1.0) was manually controlled (FECO2, 0.04-0.05). Data acquisitions were serially obtained over 15 min. Propofol and methohexital anesthesia caused an average 15% decrease in mean arterial pressure, associated with a 20% decrease in cardiac index without a decrease in systemic vascular resistance index. It is interesting that the determinants of these hemodynamic effects were different. Heart rate did not change during propofol infusion despite the decrease in mean arterial pressure, whereas heart rate increased during methohexital infusion. In the propofol group, the decrease in cardiac index was associated with decreases in indicators of preload (end-diastolic volume and pulmonary capillary wedge pressure), whereas end-systolic volume and global ejection fraction did not change statistically. In the methohexital group, the decrease in cardiac index was associated with a decrease in global ejection fraction and an increase in end-systolic volume, whereas indicators of preload remained unchanged. It is concluded that methohexital reduces left ventricular performance. In contrast, propofol preserves left ventricular performance despite a likely negative inotropic effect.

Aged

An electroencephalographic comparison of effects of propofol and methohexital.

Thirty-eight patients were randomly allocated to receive propofol 1 mg/kg (group A, N = 10), methohexital 0.7 mg/kg (group B, N = 9), propofol 2 mg/kg (group C, N = 10), methohexital 1.5 mg/kg (group D, N = 9). They were all male with a mean age of 65.8 years (range, 46-85) and a mean weight of 76.2 kg (range, 50-109). Patients received no premedication. All drugs were administered as a single i.v. bolus. After baseline EEG recordings were obtained, i.v. bolus doses were given and the recording continued until the patients became fully responsive to verbal commands. The EEGs were visually analyzed and classified into 4 phases: phase 0, the wake physiologic pattern; phase 1, initial changes after i.v. bolus doses; phase 2, state of deep anesthesia; and phase 3, stage of recovery. The main change during phase 1 was increase in the amplitude of the background rhythms. Phase 2 was characterized by theta and delta activity and burst suppression in some patients. During phase 3 beta activity was seen following methohexital. Propofol produced a much deeper level of anesthesia compared to methohexital. The stage of deep anesthesia was prolonged following propofol. The clinical and EEG recoveries were prolonged after induction doses of propofol. The quality of recovery, however, was far superior with propofol. Methohexital produces a "hang over" effect which delays full recovery.

Aged

Electroencephalographic study of the short-acting hypnotics etomidate and methohexital in dogs.

Beagles, implanted with cortical and subcortical electrodes, were given etomidate i.v. (1 mg/kg) over a period of 10 sec. The effects on the EEG were compared with those obtained with 7 mg/kg of methohexital. Both compounds induced hypnosis for a duration of approximately 8 min. The EEGs showed a remarkable similarity. Visual inspection of the records as well as power spectrum analysis revealed a sustained theta-activity with underlying fast activity. The configuration of the waves was rather sharp. The power obtained after etomidate was, however, 2 to 3 times that obtained after methohexital. When the animals awoke from etomidate-induced hypnosis slow waves appeared and were followed by alpha-activity, whereas after methohexital-hypnosis beta-activity predominated. Etomidate slightly increased heart rate, but respiratory depression was not observed. Methohexital caused pronounced tachycardia and apnoea. In 3 out of 6 dogs methohexital caused myoclonus of the hind legs upon awakening from anaesthesia. Etomidate induced myoclonus in one dog during hypnosis.

Animals

Methohexital: a practical review for outpatient dental anesthesia.

Methohexital is an ultrashort-acting barbiturate widely used in dentistry because of its rapid onset, predictable effects, and short duration of action. Like other barbiturates, methohexital exerts its effects through the gamma-aminobutyric acid (GABA) receptor complex. By binding to its own receptor on the complex, methohexital augments the inhibitory effect of GABA on neurons and additionally can exert a similar effect independent of GABA. After intravenous injection, maximal brain concentrations are achieved within 30 sec and then quickly fall as the drug is redistributed to other tissues, yielding a duration of action after a single dose of 4 to 7 min. Hepatic metabolism accounts for elimination of the drug. Methohexital at conventional doses in healthy individuals is a mild respiratory depressant with modest cardiovascular effects. Adverse effects, however, can include apnea, cardiovascular depression, laryngospasm, hiccough, and allergic-like reactions. Although more recently introduced drugs, such as midazolam, etomidate, and propofol, have specific advantages, methohexital remains a drug of choice for dental outpatient anesthesia because of its low cost, rapid onset, short duration, lack of secretory or emetic properties, and proven history.

Anesthesia, Dental

[Methohexital clearance in patients with acute hepatitis (author's transl)].

Pharmacokinetics of methohexital were studied in patients with acute hepatitis and after a treatment period either with "essential phospholipids" or phenobarbital. During the acute phase the distribution of methohexital was significantly altered. No change had been observed in the methohexital clearance. During remission the distribution of methohexital was in a normal range. After treatment with phenobarbital the methohexital clearance increased significantly whereas no change was observed after treatment with "essential phospholipids".

Acute Disease

Identification of speech lateralization by intracarotid injection of methohexital.

Speech lateralization was assessed in 25 patients with epilepsy by direct carotid injection of carotid catheterization from a femoral approach. Hemispheric anesthesia was induced by intracarotid injection of the rapidly acting barbiturate methohexital. This technique allowed same-day study of both hemispheres, permitted repeated injection of either carotid artery without accumulation of methohexital sufficient to cause systemic effects, and added little to the total time required for three-vessel cerebral angiography. Unilateral seizures were induced by methohexital injection in 4 patients. No other complication secondary to the methohexital study was observed.

Adolescent

Reversible focal ischemia in the rat: effects of halothane, isoflurane, and methohexital anesthesia.

Barbiturates and the volatile anesthetic isoflurane reduce CMR to similar values. If the mechanism of barbiturate protection against focal ischemic injury is due to a reduction in cellular energy requirements, then isoflurane should similarly reduce ischemic injury. To evaluate this, spontaneously hypertensive rats underwent 2 h of reversible middle cerebral artery occlusion (MCAO) while receiving deep methohexital, isoflurane, or halothane anesthesia. Ninety-six hours postischemia, neurologic deficits were present but without a difference between groups. Mean +/- SD infarct volume, as assessed by triphenyl tetrazolium chloride staining and computerized planimetry, was significantly less in the methohexital group (n = 8; 166 +/- 74 mm3) than in either the halothane (n = 9; 249 +/- 71 mm3; p less than 0.04) or the isoflurane (n = 9; 243 +/- 62 mm3; p less than 0.03) groups. One possible explanation for the lack of protective effect for isoflurane might be related to its vasodilative properties, which could result in a cerebral vascular steal. To examine this possibility, rats anesthetized with methohexital or isoflurane underwent autoradiographic determination of CBF with or without MCAO. In isoflurane-anesthetized sham rats (n = 5; no ischemia), CBF was approximately three times greater than in methohexital-treated (n = 5) sham rats. During ischemia, although a regional reduction in flow was noted in both anesthetic groups, mean flow remained greater in the isoflurane group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

Recovery and simulated driving after intravenous anesthesia with thiopental, methohexital, propanidid, or alphadione.

Recovery from anesthesia was assessed in a double-bind manner in 40 healthy volunteer students after intravenous anesthesia with thiopental (6.0 mg/kg), methohexital (2.0 mg/kg), propanidid (6.6 mg/kg), or alphadione (Althesin), 85 mul/kg using a driving simulator 2,4, 6, and 8 hours after injection of the drugs. Clinical recovery was faster after propanidid and methohexital than after thiopental or alphadione. Driving performances remained significantly (P less than 0.05) worse than in a control group for 6 hours after thiopental and for 8 hours after methohexital, and reaction times 8 hours after thiopental remained worse than in the control subjects. After alphadione driving skills were impaired at 6 hours only. Propanidid produced no impairment in driving skills at any time during the experiment. It is concluded that after the doses used in this study patients should not drive or operate machinery for at least 2 hours after propanidid and for at least 8 hours after alphadione. After methohexital and thiopental patients should probably not drive for 24 hours because of the severity of the disturbances at 8 hours.

Adult

Effect of upper abdominal surgery and cirrhosis upon the pharmacokinetics of methohexital.

The pharmacokinetic profile of methohexital was studied in cirrhotic patients (n = 8), patients undergoing upper abdominal surgery (n = 8) and orthopaedic patients under general anaesthesia (n = 8). The total plasma clearance of methohexital was unchanged in cirrhotics: 54 +/- 22 l.h-1 (mean +/- s.d.) as well as in patients undergoing upper abdominal surgery: 60 +/- 14 l.h-1 in comparison to orthopaedic surgery: 70 +/- 24 l.h-1. The central volume and total volume of distribution and the distribution and elimination half-lives were similar between the three groups. Despite its hepatic dependent elimination, methohexital elimination kinetics were unchanged in patients undergoing upper abdominal surgery and in cirrhosis. Owing to the high hepatic extraction ratio of methohexital, its elimination should be influenced by the hepatic blood flow. The unchanged elimination kinetics presently observed in patients with cirrhosis or those undergoing upper abdominal surgery suggest that the hepatic blood flow is less diminished than expected in these patients.

Abdomen

Pharmacokinetics of methohexital during cardiovascular surgery with cardiopulmonary bypass.

The pharmacokinetics of methohexital after intravenous bolus administration was studied during cardiovascular surgery with cardiopulmonary bypass. The effect of body temperature (normothermia and hypothermia) during cardiopulmonary bypass on methohexital pharmacokinetics was investigated. The pharmacokinetic data obtained were compared with those from vascular surgery without cardiopulmonary bypass. A marked decrease in plasma methohexital concentrations and therefore in area under curve and a significant increase in clearance and in volume of distribution were observed in the cardiopulmonary bypass groups compared to the vascular surgery group without cardiopulmonary bypass. However, the elimination half-life and the mean residence time were similar in the 2 groups. Furthermore, the study shows that body temperature during cardiopulmonary bypass does not influence methohexital pharmacokinetics.

Adult

[Interocular pressure after injection of etomidate and methohexital-na (author's transl)].

Studies of i.o. pressure, blood pressure and pulse frequence after injection of Etomidate and Methohexital-Na are carried out. I.o. pressure decreases after both, Etomidate and Methohexital. Blood pressure decreases more after injection of Methohexital-Na. After than intubation, with Etomidate, i.o. pressure was higher than normal, but it was normal with Methohexital-Na. Blood pressure increases in all the three groups. Before operation starts, i.o. pressure, blood pressure and pulse was lower as at the beginning.

Adolescent

A double-blind comparison of low-dose intravenous ketamine and methohexital in adults.

Two ultralight general anesthetic techniques, one using low-dose ketamine and the other using methohexital as the primary anesthetic agent, were compared for efficacy, safety, and psychomotor recovery in a double-blind fashion for use during third molar surgery. Low-dose intravenous ketamine as the primary anesthetic following premedication with fentanyl and midazolam, and in conjunction with nitrous oxide, appeared to produce less hypoxia, hypercarbia, and apnea than when methohexital was used. No significant differences were noted in heart rate or blood pressure between the techniques. The ketamine technique was universally preferred by the surgeons and anesthesiologists because of superior patient cooperation and airway management. No unpleasant psychomimetic side effects of significance were noted with the use of ketamine. Postoperative recovery took slightly longer in the ketamine group, with patients being judged fit for discharge approximately 10 to 15 minutes later than the patients who received methohexital.

Adolescent

A comparison of propofol, midazolam, and methohexital for sedation during retrobulbar and peribulbar block.

STUDY OBJECTIVE: To compare the efficacy of propofol, methohexital, and midazalom in providing adequate sedation during administration of retrobulbar block and satisfactory postoperative amnesia. DESIGN: Retrospective chart review over a 4-month period. SETTING: Ambulatory patients in the main operating room of a university-affiliated hospital. PATIENTS: One hundred forty-seven ambulatory patients undergoing ophthalmologic surgery of less than 2 hours' duration under regional anesthesia consisting of retrobulbar or peribulbar block and intravenous (IV) sedation. INTERVENTIONS: One of three drugs--propofol 0.47 +/- 0.06 mg/kg, midazolam 0.02 +/- 0.005 mg/kg, or methohexital 0.45 +/- 0.16 mg/kg--was administered IV. Patients were observed for a minimum of 60 seconds or until adequate sedation was achieved, after which a retrobulbar or peribulbar block was performed. MEASUREMENTS AND MAIN RESULTS: Blood pressure, electrocardiogram, and oxygen saturation were monitored and recorded. Patients were observed for apnea, hiccups, pain on injection, excitement, tremor, grimacing, or verbal response during the block. The requirement for additional sedation intraoperatively was noted. Patients were questioned postoperatively in the ambulatory recovery room for recall of needle insertion or discomfort during the block, as well as about their satisfaction with the overall experience. CONCLUSIONS: Grimacing or verbal response during the retrobulbar or peribulbar block did not predict or correlate with patient recall. Propofol was equal to both midazolam and methohexital in providing adequate sedation and postoperative amnesia but possesses the added advantages of reduced postoperative vomiting, lower intraocular pressure, and earlier return-to-home readiness.

Ambulatory Surgical Procedures