Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Comparative Study
Assessment of double-burst monitoring at 10 mA above threshold current.
We compared fade measurements in response to double-burst stimulation (DBS) at 10 mA above the threshold for the second response (D2) to that for DBS at 60 mA in order to determine the utility of low-current DBS testing. In 20 healthy adults undergoing general endotracheal anesthesia with isoflurane 0.5-1% end-tidal, a vecuronium infusion (0.25-1.5 micrograms.kg-1 x min-1) was delivered until a stable train-of-four (TOF) response to ulnar nerve stimulation was documented with an adductor pollicis force transducer. Then DBS responses were recorded, and the D2/D1 ratios were determined at 60 mA and at 10 mA above the D2 threshold current (TS + 10 mA). ⋯ A strong correlation was noted between the degrees of fade determined at the low and high currents (r = 0.95). We conclude that, although stimulation at 10 mA above the D2 threshold is associated with a slight negative bias, it is virtually interchangeable with testing at higher current in the clinical setting. This technique thus may be used effectively to monitor neuromuscular fade in settings where neurostimulation with low current is deemed desirable.
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Randomized Controlled Trial Comparative Study Clinical Trial
A clinical assessment of desflurane anaesthesia and comparison with isoflurane.
In 48 randomly assigned ASA I adult patients undergoing elective orthopaedic procedures, we compared the pharmacodynamics of desflurane (DF) and isoflurane (IF), and their pharmacokinetics during rapid induction of deep anaesthesia (via face mask, to 1.5-2 MAC, after thiopentone), maintenance of anaesthesia at 1.25 MAC, and emergence therefrom. During induction, laryngeal reactions ranging from mild crowing to laryngospasm occurred more frequently with DF than with IF (15/24 DF, 5/24 IF; P < 0.05) and was more severe (9/24 DF, 1/24 IF, excluding the mildest form, P < 0.05). As a result, induction of anaesthesia was not accomplished faster with DF, in spite of a faster equilibration between exhaled and inhaled concentrations. ⋯ Premature ventricular contractions did not occur in any patient even during periods of difficulty with the airway and oxygen desaturation. It is concluded that DF is a safe anaesthetic, pharmacokinetically superior to IF but clinically inferior for induction of anaesthesia via a face mask. Because of the fast equilibration, the exhaled concentration of DF can be controlled more precisely by the dial setting of the vaporiser.
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Comparative Study Clinical Trial Controlled Clinical Trial
Epidural morphine reduces the risk of postoperative myocardial ischaemia in patients with cardiac risk factors.
Perioperative myocardial ischaemia is a predictor of postoperative cardiac morbidity (PCM). Epidural anaesthesia and adequate perioperative analgesia have been shown to improve myocardial oxygen dynamics due to interruption of pain and sympathetic pathways. The aim of the present study was to compare the incidence of ischaemia after either general anaesthesia followed by parenteral analgesia with morphine or combined epidural/general anaesthesia followed by analgesia with epidural morphine. ⋯ Forty-two percent of ischaemic episodes were associated with a heart rate > 100 bpm, or an increase of 20% over the baseline heart rate. We conclude that epidural anaesthesia/analgesia reduces but does not eliminate the risk of myocardial ischaemia and tachyarrhythmia. We were unable to determine any associated reduction in the risk of PCM.
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Clinical Trial
Amrinone, in combination with norepinephrine, is an effective first-line drug for difficult separation from cardiopulmonary bypass.
A crucial element for weaning patients from cardiopulmonary bypass (CPB) rests on the selection of an appropriate therapeutic regimen. Amrinone, a phosphodiesterase III inhibitor, combines inotropic support with pulmonary and systemic vasodilatation, without increasing heart rate (HR) or myocardial oxygen consumption. These characteristics should be useful in the failing heart during weaning from CPB. ⋯ Successful weaning from CPB was possible 12 +/- 8 min after the amrinone bolus. Weaning resulted in a cardiac index similar to that measured pre-bypass. Amrinone is rapidly effective during weaning from CPB and, in combination with norepinephrine, provides the necessary inotropic support during this unstable period.
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To remedy the lack of information about the continuing medical education (CME) practices of anaesthetists, we designed a survey to define and compare the CME activities of specialist anaesthetists in community-based and university-affiliated practices: 463 members of the Canadian Anaesthetists' Society in the Province of Ontario (263 community-based and 200 university-affiliated (University of Toronto) anaesthetists). Data from 304 (65.6%) respondents (172 community-based and 132 university-affiliated anaesthetists) were analyzed by non-parametric analysis (statistical significance P < 0.05). Most respondents spent between two to four hours per week on CME activities. ⋯ Formal teaching, including seminars, workshops, and annual society meetings, although the second most commonly used technique to obtain CME, was considered as effective as journal reading. Instructional media techniques were the least commonly used and considered the least effective (P < 0.05). Most community-based and university-affiliated anaesthetists obtained CME by a variety of techniques; of all respondents, 77% have no formal method of assessing their learning needs and 88% would consider participation in a formalized learning needs assessment programme.