Canadian Anaesthetists' Society journal
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To examine a possible mechanism which could cause arterial hypoxaemia following pulmonary embolism, we collapsed and did not ventilate one lung in each of eleven dogs, to produce hypoxic pulmonary vasoconstriction. In five dogs (Starch Group), PaO2 fell from 10 to 7.7 kPa (76.6 to 58.4 torr) as shunt fraction (Qs/Qt) rose from 19 to 31 per cent. Mean pulmonary artery pressure (ppa), paCO2 and VD/VT remained constant. ⋯ We conclude from these results that emboli are preferentially distributed to ventilated lung. After embolization PPA increases. At least in this pulmonary embolism model the increased PPA may overcome hypoxic pulmonary vasoconstriction, redistribute blood to non-ventilated lung and create arterial hypoxaemia.
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Sensory profiles of lumbar epidural anaesthesia were studied in 57 patients, during active labour. The local anaesthetics used were chloroprocaine three per cent with and without epinephrine, chloroprocaine two per cent, bupivacaine 0.25 per cent and a mixture of chloroprocaine three per cent and bupivacaine 0.5 per cent. ⋯ Inguinal and suprapubic discomfort ("missing segment") occurred when S1 was not blocked. Under the conditions of this experiment, the addition of bupivacaine to chloroprocaine did not increase the duration of the blockade significantly.
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The effects on the haemodynamic and biochemical parameters of three different anaesthetic induction regimes, namely fentanyl (4.1 micrograms.kg-1 or 15 micrograms.kg-1) plus 60 per cent nitrous oxide with oxygen and fentanyl 15 micrograms.kg-1 plus 60 per cent nitrogen with oxygen, were studied in patients undergoing coronary artery surgery. Fentanyl 15 micrograms.kg-1 with nitrous oxide and oxygen produced simultaneous reductions in oxygen uptake, cardiac index and left ventricular stroke work with an unaltered oxygen extraction. Diastolic blood pressure (an index of coronary artery perfusion) was only slightly reduced, and there were no changes in arterial lactate, glucose and free fatty acids. ⋯ The patients receiving fentanyl 15 micrograms.kg-1 with nitrogen and oxygen showed increases in heart rate, blood pressure, cardiac index and left ventricular stroke work, together with a significant fall in oxygen extraction. Moreover, in the patients who received fentanyl 4.1 micrograms.kg-1 with nitrous oxide and oxygen and fentanyl 15 micrograms.kg-1 with nitrogen and oxygen there were significant increases in blood lactate, glucose and free fatty acids, indicating increased sympathetic activity. We conclude that fentanyl 15 micrograms.kg-1, together with 60 per cent nitrous oxide with oxygen provides a satisfactory haemodynamic and biochemical state during induction of anaesthesia in patients with myocardial function prejudiced by coronary artery insufficiency.
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The authors reviewed the records of seventy preterm infants suffering from respiratory distress syndrome and, in most cases, refractory congestive heart failure, who underwent ligation of patent ductus arteriosus. The peri-operative management of these patients is described. The anaesthetic technique consisted of nitrous oxide and oxygen supplemented with a relaxant. ⋯ The infants were protected from significant temperature fluctuations by various methods which are described. The overall survival rate of all preterm infants with respiratory distress syndrome. The management presented is considered acceptable to the infants, to the surgeons and to the anaesthetists.