Articles: anesthetics.
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The effects of halothane, isoflurane and enflurane were compared on three CNS excitatory synaptic pathways in vitro, to determine whether selective actions described in vivo result from differential effects on anatomically distinct cortical pathways and neurone populations. Halothane (0.25-1.25 vol%) depressed postsynaptic excitability of CA1 pyramidal neurones in response to activation of stratum radiatum synaptic inputs, and concentration-dependent excitatory (0.25-1.25 vol%) and depressant (1.5-2.0 vol%) actions were observed on dentate granule neurone excitability and perforant path evoked synaptic responses. In contrast, isoflurane increased CA1 neurone excitability (0.25-0.75 vol%) and produced postsynaptic depression of dentate neurones (0.5-4.0 vol%). ⋯ Differential actions were also observed for the three anaesthetics on stratum oriens excitatory inputs to CA1 neurones, and on antidromic responses. A good correlation (r = 0.992) exists between the membrane/buffer partition coefficients of these anaesthetics and their half-maximal concentrations for depression of synaptic responses; however, this correlation does not reflect the different, anaesthetic-specific actions observed. The results indicate that inhalation anaesthetics act at multiple and selective hydrophobic recognition sites which are heterogenously distributed on different synaptic pathways.
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Propofol like thiopental and etomidate, suppresses cortical electrical activity in a dose-related manner, which leads to a 36% decrease in cerebral oxygen uptake and a 51% decrease in cerebral blood flow after an induction dose of 2 mg/kg followed by a maintenance dose of 0.2 mg/kg per min. In this study, the effects of propofol and varying paCO2 values on cerebral energy and amino acid metabolism were examined. METHODS. ⋯ Lactate/glucose index was calculated from the equation. Formula: see text. where a-vD lactate and a-vD glucose represent the arterial-cerebral venous substrate differences in mmol/l. Cerebral electrical activity was recorded by Fourier analysis of the EEG.(ABSTRACT TRUNCATED AT 250 WORDS)
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J Cardiothorac Anesth · Apr 1988
Randomized Controlled TrialHormonal effects of an induction dose of etomidate for patients undergoing urgent myocardial revascularization.
The use of etomidate for induction of anesthesia in patients requiring urgent coronary artery surgery provides good cardiovascular stability. However, long-term etomidate infusions may cause transient signs of adrenocortical suppression. The purpose of this study was to determine whether an induction bolus dose of etomidate would cause clinically relevant endocrine dysfunction in urgent coronary artery bypass patients. ⋯ Cortisol also increased from the time of cross-clamp removal to 12 and 24 hours post-bypass. During anesthesia and surgery in the pre-bypass period, there was a decrease in cortisol over time in the etomidate group, and there was an increase with diazepam. Thus, etomidate provided stable hemodynamics, possible mild intraoperative adrenocortical suppression, a depressed hormonal stress response to intubation, and a normal hormonal reaction to the later part of surgery and the postoperative period.
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Southern medical journal · Apr 1988
Case ReportsVentricular tachyarrhythmias during cesarean section after ritodrine therapy: interaction with anesthetics.
This case illustrates that patients receiving ritodrine for preterm labor may risk interactions between the residual betamimetic effects of ritodrine and the effects of anesthetics during cesarean section. Such interactions may result in serious cardiovascular complications even after cessation of an infusion of ritodrine. ⋯ Careful fluid administration and cautious use of titrated doses of ephedrine are advised. After delivery of the infant, there should be no contraindication to the use of an alpha-adrenergic vasopressor such as phenylephrine to treat hypotensive patients with tachycardia.
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J Cardiothorac Anesth · Apr 1988
Randomized Controlled Trial Comparative StudyComparison of the hemodynamic and echocardiographic effects of sufentanil, fentanyl, isoflurane, and halothane for pediatric cardiovascular surgery.
Sufentanil, fentanyl, halothane, and isoflurane were compared as sole anesthetic agents in 48 infants and children aged 6 months to 9 years, undergoing repair of congenital heart defects. Patients were randomly assigned to receive sufentanil, 20 microg/kg, fentanyl, 100 microg/kg, isoflurane, 1.6%, or halothane, 0.9%, along with pancuronium, 0.08 mg/kg, for induction and maintenance of anesthesia. Cardiovascular function was measured by echocardiography prior to induction, postinduction, and postintubation. ⋯ Arterial pressure immediately prior to bypass was significantly less than baseline in each group; however, arterial pressure was higher in the narcotic groups during isolation and cannulation of the great vessels. It is concluded that halothane, 0.9%, used as an induction agent in infants and children undergoing cardiac surgery causes a clinically significant decrease in LVEF. Based on the echocardiographic data, sufentanil, fentanyl, and isoflurane as used in the present study do not have a clinically significant effect on cardiac function and may offer an advantage to infants and children with marginal cardiovascular reserve.