Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Two case reports have cited the recreational use of cocaine as possible trigger of a malignant hyperthermia (MH) crisis. We evaluated whether toxic concentrations of cocaine altered the in vitro muscle response to halothane during contracture tests for MH. Twenty-two patients were studied. ⋯ In contrast, in the presence of 1% halothane, MH-susceptible muscle showed either no change in contracture (six patients), an increase (two patients), or a decrease (two patients) when exposed to cocaine. However, the overall effect of cocaine on muscle contracture in the presence of 1% halothane was insignificant in both groups. We conclude that cocaine, even at toxic levels, does not have a direct effect on skeletal muscle contractility and thus is safe for MH-susceptible patients.
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Randomized Controlled Trial Clinical Trial
Enhancement of pressor response to intravenous phenylephrine following oral clonidine medication in awake and anaesthetized patients.
Clonidine, an alpha 2-adrenergic agonist, augments the pressor response to intravenous ephedrine. If this effect is partly due to clonidine-induced potentiation of alpha 1-adrenoceptor-mediated vasoconstriction, it is also assumed that clonidine would enhance the pressor effect of phenylephrine as an alpha 1-adrenergic agonist. The authors studied haemodynamic responses to intravenous phenylephrine in 80 patients who received either preanaesthetic medication with clonidine approximately 5 micrograms.kg-1 po (clonidine group, n = 40), or no medication (control group, n = 40). ⋯ Oral clonidine preanaesthetic medication, 5 micrograms.kg-1, augments the pressor responses to phenylephrine 2 micrograms.kg-1 iv in awake and anaesthetized patients. These results suggest that the enhancement of the pressor responses to phenylephrine following oral clonidine may be due to clonidine-induced potentiation of alpha 1-adrenoceptor-mediated vasoconstriction. This implies that restoration of blood pressure can be achieved effectively by phenylephrine in hypotensive patients with clonidine premedication.
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Randomized Controlled Trial Clinical Trial
Quantifying the effect of enflurane on atracurium infusion requirements.
The present study was designed to evaluate the interaction between atracurium and enflurane in 40 adult surgical patients using closed-loop feedback control of infusions of atracurium. Anaesthesia was induced with thiopentone and fentanyl and intubation was facilitated with atracurium 0.5 mg.kg-1 lean body mass. During the first 90 min, anaesthesia was maintained with nitrous oxide in oxygen (2:1) and fentanyl. ⋯ Patient characteristics and controller performance, i.e., the ability of the controller to maintain the neuromuscular blockade constant at the setpoint, did not differ among groups. In Group II ISS decreased from 0.33 +/- 0.12 to 0.26 +/- 0.08 mg.kg-1.hr-1 (P < 0.01), in Group III from 0.32 +/- to 0.12 to 0.24 +/- 0.08 mg.kg-1.hr-1 (P < 0.001) and in Group IV from 0.29 +/- 0.09 to 0.21 +/- 0.09 mg.kg-1.hr-1 (P < 0.001). In the control group atracurium requirements remained unchanged throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)
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An emulsion of isoflurane in Intralipid for intravenous (iv) injection was formulated and its anaesthetic properties determined in mice. The major advantage of iv delivery of volatile agents is to accelerate the induction of anaesthesia by circumventing the anesthetic circuitry and the lung's functional residual capacity. Isoflurane was added to Intralipid in varying concentrations. ⋯ The only negative effect was local skin ulceration with an inadvertent interstitial injection. We conclude that iv induction and maintenance with emulsified isoflurane in Intralipid can be carried out with safety and reproducibility in the mouse. Further larger animal studies are warranted assessing the haemodynamic, toxicological, physiochemical and pharmacokinetic characteristics of these and other similar preparations.
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The laryngeal mask airway (LMA) has been used extensively to provide a safe airway in spontaneously breathing patients who are not at risk from aspiration of gastric contents. The role of the LMA in the event of a failed intubation in an obstetrical patient, and its place in a failed intubation drill remains unclear. Two hundred and fifty consultant obstetric anaesthetists in the United Kingdom were asked to complete an anonymous questionnaire regarding their views about using the laryngeal mask airway (LMA) in obstetrical anaesthesia. ⋯ Seventy-two per cent of anaesthetists were in favour of using the LMA to maintain oxygenation when tracheal intubation had failed and ventilation using a face mask was inadequate. Twenty-four respondents had had personal experience with the LMA in obstetrical anaesthesia, eight of whom stated that the LMA had proved to be a lifesaver. We believe that the LMA has a role in obstetrical anaesthesia when tracheal intubation has failed and ventilation using a face mask proves to be impossible, and it should be inserted before attempting cricothyroidectomy.