Canadian Anaesthetists' Society journal最新文献

Plasma cholinesterase activity was estimated following administration of edrophonium 0.5 or 1.0 mg X kg-1 given for antagonism of atracurium-induced neuromuscular block. There was no inhibition of enzyme activity for up to three hours following edrophonium administration. This is in contrast to profound and prolonged inhibition of enzyme activity seen following neostigmine and pyridostigmine.

Anaesthesia for Caesarean sections performed during 1982-83 at the Women's Hospital in Kathmandu, Nepal is reviewed. In a twelve-month period 535 Caesarean sections were performed, representing 7.36 per cent of 7,263 deliveries. Many pregnant women in Nepal do not have antenatal care and the mean haemoglobin of these mothers was 86 g X L-1. In the absence of an on-call anaesthetist for obstetrics, more than 90 per cent of the anaesthetics were given by junior obstetric residents, using open drop diethyl ether without endotracheal intubation. Eleven patients developed postoperative chest infection; in none of these was there any suggestion of inhalation of gastric contents and all recovered uneventfully. Of the 18 maternal deaths in the 7,263 deliveries during this period, one occurred during Caesarean section. This was due to uncontrollable haemorrhage and was not attributable to the anaesthetic. For poor risk patients, and in unskilled hands, diethyl ether remains a remarkably safe anaesthetic.

To define the role of muscle relaxants in haemodynamic responses to high-dose (75 micrograms X kg-1) fentanyl anaesthesia and to noxius stimuli associated with intubation and sternal spread during coronary artery bypass surgery, we compared haemodynamics between three groups of patients given either pancuronium (0.1 mg X kg-1, n = 11), vecuronium (0.086 mg X kg-1, n = 11) or atracurium (0.43 mg X kg-1, n = 12). Additional doses of the relaxants were given to maintain a 90 per cent neuromuscular block. Patients given pancuronium showed no increases in mean values of heart rate, arterial pressure or cardiac output during the induction of anaesthesia or after intubation, whereas a decrease in these variables was observed in the vecuronium group. The haemodynamics in the atracurium group were intermediate compared with the other two study groups. In spite of a decrease in coronary perfusion pressure, no patient given vecuronium developed myocardial ischaemia. An advantage of vecuronium over pancuronium and atracurium was an attenuation of the blood pressure response to sternotomy. Patients given atracurium had a small increase in pulmonary vascular resistance during sternotomy. Our patients continued their beta-adrenergic antagonist medication until the morning of the day of operation and they were pretreated with a small intravenous dose of diazepam (0.1 mg X kg-1) before induction of anaesthesia. These drugs may have prevented the deleterious haemodynamic effects observed by some investigators after the administration of pancuronium during high-dose fentanyl anaesthesia.

Thirteen post-thoracotomy patients were entered into a double-blind, randomized clinical trial comparing the effects of epidural morphine (Group E) and intravenous morphine (Group I) on postoperative respiratory depression. Postoperative respiratory depression was assessed for 24 hours by (a) PaCO2 at 2, 6, 12 and 24 hours (b) hourly assessment of respiratory rate (RR) (c) presence of respiratory rate of less than ten breaths per min for greater than 5 min (SRR) (d) hypopnoea/apnoea (H/A). RR, SRR, and H/A were measured using respiratory inductive plethysmography. PaCO2 was significantly elevated at 2, 6 and 12 hours in Group E and only at two hours in Group I. One of five patients in Group I had a single episode of SRR whereas five of eight patients in Group E had multiple episodes of SRR. None of the patients in Group I had H/A episodes, in contrast to six of eight in Group E who had numerous H/A episodes post-operatively. This difference was statistically significant. Multiple doses of epidural morphine produce an insidious and unpredictable change in respiratory pattern. Electronic monitoring is useful to assess those at risk of overdose and possible respiratory arrest.

Techniques for sensing, acquiring, processing and displaying physiological variables used to assist the process of monitoring in anaesthesia and intensive care have been reviewed. The role of instrumental monitoring in clinical practice and the comparative effectiveness of Man versus Machine has been outlined. Future developments in monitoring in clinical practice have been identified. It is important that physicians stay abreast of developments in the technology of measurement and monitoring instrumentation so that they not only assist in the development of standards but also have a complete understanding of the precision and real usefulness of any given item of equipment. To this end, guidelines have been tabulated which may permit those who have the responsibility for acquiring updating or using monitoring equipment, to more completely examine the features of any apparatus which is being considered for purchase.

Hydropneumothorax is an uncommon but potentially fatal complication for a patient undergoing positive pressure ventilation. The case of a 23-year-old woman with severe asthma requiring lung lavage is described. Twenty minutes after an uneventful left lung lavage, the patient experienced increased peak airway pressure, decreased oxygen saturation and hypercarbia, despite ventilation with 90 per cent oxygen. A chest x-ray revealed mediastinal shift and a left sided pneumothorax. Drainage was carried out, revealing air and clear fluid in the pleural space. The importance of technical problems such as patient and endotracheal tube positioning, elimination of cross-spilling and cardiopulmonary effects of lavage are discussed.