Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1993
Randomized Controlled Trial Comparative Study Clinical TrialExcitatory effects and electroencephalographic correlation of etomidate, thiopental, methohexital, and propofol.
Excitatory movements have been observed during induction of anesthesia with etomidate, thiopental, methohexital, and propofol. We studied the frequency of these excitatory effects and correlated movements with electroencephalographic (EEG) findings in 67 unpremedicated patients (mean age 66.1 yr, range 45-82 yr). Excitatory effects, including myoclonus, tremor, and dystonic posturing, occurred in 86.6% of patients receiving etomidate; 69.2% of the patient responses were myoclonic. ⋯ In most patients, the excitatory movements were coincident with the early slow phase of the EEG which corresponds to the beginning of deep anesthesia. We conclude that perhaps caution should be exercised when administering etomidate to patients with a history of seizures as the myoclonic activity is associated with seizure activity. The incidence of excitatory movements after administration of propofol is very low.
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Anesthesia and analgesia · Nov 1993
N omega-nitro-L-arginine methyl ester prevents cerebral hyperemia by inhaled anesthetics in dogs.
The mechanism by which halothane, isoflurane, and nitrous oxide increase cerebral blood flow (CBF) is unknown. We assessed the cerebrovascular effects of nitrous oxide (70%; n = 6), isoflurane (1 minimum alveolar anesthetic concentration: 1.4%; n = 6) or halothane (1 minimum alveolar anesthetic concentration: 0.8%; n = 6) before and after blockade of nitric oxide (NO) synthase with 40 mg/kg N omega-nitro-L-arginine methyl ester (L-NAME) intravenously in dogs with baseline pentobarbital anesthesia. Baseline CBF (microspheres) was determined after 1 h of pentobarbital anesthesia. ⋯ On the contrary, nitrous oxide increased CBF similarly (40 +/- 6 to 57 +/- 8 mL.min-1 x 100 g-1), but increased cerebral oxygen consumption (2.2 +/- 0.3 to 3.0 +/- 0.3 mL.min-1 x 100 g-1). L-NAME decreased blood flow in the neurohypophysis by 80% with no change in blood flow in other brain regions. After L-NAME, reexposure to nitrous oxide, halothane, or isoflurane resulted in no change in CBF.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Nov 1993
Randomized Controlled Trial Comparative Study Clinical TrialEpidural anesthesia for labor in an ambulatory patient.
The effectiveness of two epidural analgesic regimens on the ability to ambulate was compared in women in labor by a prospective, randomized, double-blind design. One group of patients received epidural fentanyl, a 75-micrograms bolus and an infusion of fentanyl 2.5 micrograms/mL at 15 mL/h (FENT, n = 53). A second group received ultra low-dose bupivacaine (0.04%), epinephrine (1.7 micrograms/mL), and fentanyl (1.7 micrograms/mL) (BEF, n = 77), a 15-mL bolus followed by an infusion at 15 mL/h. ⋯ Neither problem occurred in FENT patients. Neonatal outcome was similar in both groups. Approximately 70% of women receiving epidural analgesia with fentanyl or ultra low-dose bupivacaine, epinephrine, and fentanyl may ambulate safely during labor.
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Anesthesia and analgesia · Nov 1993
Randomized Controlled Trial Comparative Study Clinical TrialPreliminary pharmacokinetics and pharmacodynamics of an ultra-short-acting opioid: remifentanil (GI87084B).
Remifentanil is a newly synthesized 4-anilido-piperidine with an ester side chain susceptible to esterase metabolism. We evaluated the safety, analgesic efficacy, and pharmacokinetics of remifentanil in 48 male volunteers. Volunteers were randomized to receive increasing doses of remifentanil, alfentanil, or placebo. ⋯ Remifentanil had a small volume of distribution of 0.39 (SD, +/- 0.25) L/kg (alfentanil, 0.52 +/- 2 L/kg), with a rapid distribution phase of 0.94 (SD, +/- 0.57) min and an extremely short elimination half-life of 9.5 (SD, +/- 4) min compared with an elimination half-life of alfentanil of 58 (SD, +/- 7.6) min. The t1/2 ke0 (half-time for equilibration between plasma and the effect compartment) of remifentanil for analgesia was calculated as 1.3 min. Thus, remifentanil appears to have a pharmacologic profile similar to other potent mu agonists, but with exceptionally short-lasting pharmacokinetics, which is likely to make it a very useful opioid for clinical practice.