British journal of anaesthesia
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Comparative Study
Comparison of the adductor pollicis and the first dorsal interosseous muscles during atracurium and vecuronium blockade: an electromyographic study.
The pattern of neuromuscular blockade in the first dorsal interosseous muscle (1st DI) and the adductor pollicis muscle was compared electromyographically following atracurium or vecuronium. There were no clinically significant differences between the muscles in respect of onset time, maximum blockade, train-of-four ratio, or recovery index. There were no problems in recording a consistent electromyogram from the 1st DI, which appears to be well suited to clinical monitoring.
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Fetal aortic and umbilical blood flows were studied in 15 mothers before and during spinal (intrathecal) anaesthesia for elective Caesarean section, using a method combining real-time ultrasonography and a pulsed Doppler technique. Spinal anaesthesia with 0.5% bupivacaine hydrochloride 2.5 ml in 8% glucose monohydrate solution was administered after preloading with 2 litre of lactated Ringer's solution. Simultaneously with the subarachnoid injection, an infusion i.v. of ephedrine 50 mg in 500 ml normal saline was initiated. ⋯ Fetal heart rate increased (P less than 0.05) 30 min after the introduction of the spinal anaesthesia, but blood flows in the fetal descending aorta and umbilical vein were unaffected. The pulsatility index of the fetal blood velocity decreased (P less than 0.05) both in the fetal aorta and in the umbilical artery 30 min after induction of the spinal anaesthesia, indicating a possible decrease in the placental vascular resistance. We conclude that, when normotension is maintained in the mother with a preload infusion and an infusion of ephedrine, spinal anaesthesia for Caesarean section has no harmful effect on the fetal circulation.
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Anaesthesia was induced with propofol 2.5 mg kg-1 followed by suxamethonium 1.5 mg kg-1 in six young healthy females undergoing laparoscopy. ECG was monitored continuously. ⋯ The bradycardia may be prevented by premedication with atropine. In contrast to thiopentone, propofol apparently lacks central vagolytic activity and may exert a central vagotonic effect which can exaggerate the muscarinic effects of suxamethonium.
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The effects of methohexitone, ketamine, Althesin and droperidol on the peripheral vagal transmission to the heart were studied in decerebrate cats by evaluating the influences of the drugs on the heart rate responses to vagal electrostimulation and the injection of acetylcholine i.v. The sites of the peripheral vagal transmission (vagal ganglia and sino-atrial pacemaker cells) were reached by the application of the drugs to the pericardial space. The bradycardia in response to vagal electrostimulation was attenuated by Althesin (2.1 x 10(-4)-3.3 x 10(-3) mol litre-1; expressed as the concentration of alphaxalone), ketamine (2.9 x 10(-4)-4.6 x 10(-3) mol litre-1) and droperidol (2.6 x 10(-5)-6.6 x 10(-4) mol litre-1) in a concentration-dependent manner, but not influenced by methohexitone (2.8 x 10(-4)-4.4 x 10(-3) mol litre-1). The bradycardia-attenuating effects were probably caused by an atropine-like action since the heart rate responses to the injection of acetylcholine i.v. were also attenuated by the same three drugs.