Anesthesiology
-
Although it does not suppress movement in response to noxious stimuli, the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6, also known as 2N) does cause amnesia and seizures. These occur at 0.48 and 1.3 times, respectively, the concentrations that are predicted from its lipid solubility to cause immobility. The molecular and cellular basis of these effects is not known. The ionotropic gamma-aminobutyric acid type A (GABAA) receptor is modulated strongly by anesthetics, and it plays an important role in many seizure models. Also, the hippocampus is a structure central to the formation of memory and is susceptible to seizure generation. The authors therefore investigated the effect of F6 on GABAA receptor- mediated inhibition in hippocampal neurons. ⋯ At concentrations that bracket the in vivo amnestic and seizure-inducing range, F6 has no discernible effect on fast synaptic GABAA receptors in hippocampal CA1 pyramidal neurons. Synaptic GABAA receptors sharply discriminate between volatile anesthetics and a prototype nonimmobilizer. Similar in vivo effects of anesthetics and nonimmobilizers may be mediated by different cellular mechanisms.
-
Randomized Controlled Trial Clinical Trial
Preventive analgesia is associated with reduced pain disability 3 weeks but not 6 months after major gynecologic surgery by laparotomy.
Most studies of preemptive or preventive analgesia restrict outcomes to pain and analgesic consumption in the acute postoperative period. The potential longer-term effects on these and other domains of functioning have received little empirical attention. The purpose of this study was to follow up patients who had received general anesthesia plus epidural fentanyl and lidocaine before (group 1) or after (group 2) incision or general anesthesia plus a sham epidural (group 3). ⋯ The short-term beneficial effects of preventive epidural analgesia translated into less pain disability 3 weeks after surgery. Progress in understanding the processes involved in postsurgical recovery and the risk factors for chronic postsurgical pain would be aided by baseline and postsurgical measures of relevant psychological, emotional, and physical variables.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Spectral entropy as an electroencephalographic measure of anesthetic drug effect: a comparison with bispectral index and processed midlatency auditory evoked response.
The authors compared the behavior of two calculations of electroencephalographic spectral entropy, state entropy (SE) and response entropy (RE), with the A-Line ARX Index (AAI) and the Bispectral Index (BIS) and as measures of anesthetic drug effect. They compared the measures for baseline variability, burst suppression, and prediction probability. They also developed pharmacodynamic models relating SE, RE, AAI, and BIS to the calculated propofol effect-site concentration (Ceprop). ⋯ Compared with BIS and AAI, both SE and RE seem to be useful electroencephalographic measures of anesthetic drug effect, with low baseline variability and accurate burst suppression prediction. The ability of the measures to predict Ceprop was best for BIS.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Sciatic nerve block via posterior Labat approach is more efficient than lateral popliteal approach using a double-injection technique: a prospective, randomized comparison.
For peripheral nerve blockade, the double-injection technique proved to be superior to a single injection in previous investigations. The current study was designed to compare onset time and efficacy of two different double-injection approaches for sciatic nerve block with 0.75% ropivacaine. ⋯ A double injection with a relatively low volume of 0.75% ropivacaine generated a higher success rate and a shorter onset time of sensory and motor blockade after the classic Labat approach than after a lateral popliteal approach.
-
Randomized Controlled Trial Clinical Trial
Evidence that intravenous vasopressors can affect rostral spread of spinal anesthesia in pregnancy.
The authors have previously observed an apparent association between rostral spread of spinal anesthesia and choice of intravenous vasopressor given to maintain maternal systolic arterial pressure during cesarean delivery. This study tested the hypothesis that an intravenous infusion of phenylephrine can reduce rostral spread of spinal anesthesia in pregnancy, compared with ephedrine. ⋯ This study provides evidence that intravenous phenylephrine can decrease rostral spread of spinal anesthesia in pregnancy, compared with intravenous ephedrine. Further work is required to investigate possible mechanisms and to assess its clinical significance.