Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2002
Comparative StudyBispectral index monitoring: a comparison between normal children and children with quadriplegic cerebral palsy.
We performed this study to compare the correlation of bispectral index (BIS) values with different sevoflurane concentrations between normal children and those with quadriplegic cerebral palsy with mental retardation (CPMR). Twenty children with CPMR (Group I) and 21 normal children (Group II) between 2 and 14 yr of age were studied. Anesthesia was induced and maintained with sevoflurane and 66% N(2)O/O(2). Bispectral values were recorded on an Aspect Medical Systems (Natick, MA) monitor, and sevoflurane concentrations were measured with an Ohmeda (Hanover, MA) inhaled anesthetic monitor. The BIS values were recorded after midazolam premedication; after the induction of anesthesia; at end-tidal sevoflurane concentrations of 1%, 3%, and again at 1%; and after emergence from the anesthetic. Both groups were similar in age and sex distribution, but children in Group I weighed less than those in Group II (P < 0.05). The BIS values were significantly lower in Group I compared with Group II after sedation, at 1% sevoflurane concentrations, and after emergence. No difference was observed between the two groups at anesthesia induction (8%) and at 3% sevoflurane concentration. We conclude that, in children with CPMR, BIS values exhibit a pattern of change similar to that observed in normal children. However, absolute BIS values obtained in such children are lower than those in normal children while awake and at different sevoflurane concentrations. ⋯ We compared bispectral (BIS) values with different sevoflurane concentrations between normal children and children with cerebral palsy. We observed that, in children with cerebral palsy, BIS values exhibited a similar pattern of change as is observed in normal children. However, absolute BIS values obtained in such children are lower than those in normal children while awake and at different sevoflurane concentrations.
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Anesthesia and analgesia · Dec 2002
Acetylcholine receptors and thresholds for convulsions from flurothyl and 1,2-dichlorohexafluorocyclobutane.
There are acetylcholine receptors throughout the central nervous system, and they may mediate some forms and aspects of convulsive activity. Most high-affinity binding sites on nicotinic acetylcholine receptors for nicotine, cytisine, and epibatidine in the brain contain the beta2 subunit of the receptor. Transitional inhaled compounds (compounds less potent than predicted from their lipophilicity and the Meyer-Overton hypothesis) and nonimmobilizers (compounds that do not produce immobility despite a lipophilicity that suggests anesthetic qualities as predicted from the Meyer-Overton hypothesis) can produce convulsions. The nonimmobilizer flurothyl [di-(2,2,2,-trifluoroethyl)ether] blocks the action of gamma-aminobutyric acid on gamma-aminobutyric acid(A) receptors, whereas the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (2N, also called F6) does not. 2N can block the action of acetylcholine on nicotinic acetylcholine receptors. We examined the relative capacities of these compounds to cause convulsions in mice having and lacking the beta2 subunit of the acetylcholine receptor. The partial pressure causing convulsions in half the mice (the 50% effective concentration [EC(50)]) was the same as in control mice. For the knockout mice, the EC(50) for flurothyl was 0.00170 +/- 0.00030 atm (mean +/- SD), and for 2N, it was 0.0345 +/- 0.0041 atm. For the control mice, the respective values were 0.00172 +/- 0.00057 atm and 0.0341 +/- 0.0048 atm. The ratio of the 2N to flurothyl EC(50) values was 20.8 +/- 3.5 for the knockout mice and 21.7 +/- 7.0 for the control mice. These results do not support the notion that acetylcholine receptors are important mediators of the capacity of 2N or flurothyl to cause convulsions. However, we also found that both nonimmobilizers inhibit rat alpha4beta2 neuronal nicotinic acetylcholine receptors at EC(50) partial pressures (0.00091 atm and 0.062 atm for flurothyl and 2N, respectively) that approximate those that produce convulsions (0.0015 atm and 0.04 atm). ⋯ The results from the present study provide conflicting data concerning the notion that acetylcholine receptors mediate the capacity of nonimmobilizers to produce convulsions.
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Anesthesia and analgesia · Dec 2002
The use of neuromuscular blocking drugs in adult cardiac surgery: results of a national postal survey.
Available data suggest that the choice of neuromuscular blocking drugs (NMBDs) can influence early clinical recovery of the fast-track cardiac surgical patient. The aim of this study was to use a survey tool to determine practice patterns of anesthesiologists for the use of NMBDs in the cardiac surgical setting. We mailed a survey to one third of the 3295 active members of the Society of Cardiovascular Anesthesiologists. A follow-up letter and survey were sent to each individual who did not respond to the initial mailing. After the second mailing, 459 surveys were returned, yielding a response rate of 43%. Pancuronium was listed as the primary NMBD used in the majority of patients undergoing cardiopulmonary bypass (69%) and off-pump (41%) procedures. Only 28% of respondents routinely used a peripheral nerve stimulator to monitor neuromuscular blockade in the operating room. Residual neuromuscular blockade was routinely reversed before tracheal extubation by only 9% of cardiac anesthesiologists. This survey demonstrates that long-acting NMBDs are often administered to fast-track cardiac patients. Peripheral nerve stimulator monitoring is rarely used in the operating room or intensive care unit, and reversal drugs (anticholinesterases) are infrequently administered in the postoperative period. ⋯ This postal survey of cardiac anesthesiologists demonstrates that long-acting muscle relaxants are frequently administered to fast-track cardiac surgical patients. Neuromuscular blockade is rarely monitored or reversed in this patient population.