Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Randomized Controlled Trial Clinical Trial
Preoperative plateletpheresis does not reduce blood loss during cardiac surgery.
Acute preoperative plateletpheresis has been reported to be effective in reducing blood loss and blood component transfusion while improving haematological profiles in patients undergoing open-heart surgery. However, in these studies, the concomitant use of cell saver techniques may have been responsible for the beneficial effects because they remove free haemoglobin and activated procoagulants and, therefore, could mask the deleterious effects of combined plateletpheresis and cardiopulmonary bypass (CPB). In the present study, 40 patients undergoing primary myocardial revascularization were randomly divided into two groups: a control group without plateletpheresis performed, and a second group in which preoperative platelet-rich plasma 10 ml.kg-1 (PRP group) was collected and later reinfused after reversal of heparin. ⋯ Reinfusion of autologous PRP did not improve platelet count and function, nor tests of coagulation. Fibrinogen concentrations were lower in the PRP group on the operative day (P < 0.05), suggesting increased fibrinogen consumption; and more patients in the PRP group had low haptoglobin levels during CPB (8/19 vs 0/20 patients, P < 0.005), which indicated greater haemolysis in this group. We conclude that acute preoperative plateletpheresis offers no advantage in haemostasis during elective primary myocardial revascularization surgery.
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Randomized Controlled Trial Comparative Study Clinical Trial
Patient response to laryngeal mask insertion after induction of anaesthesia with propofol or thiopentone.
The response to insertion of the laryngeal mask airway (LMA) following either propofol 2.5 mg.kg-1 or thiopentone 5 mg.kg-1 was assessed in two groups of patients. The purpose of the study was to ascertain which of these two induction agents provided the better conditions for insertion of the LMA. Anaesthesia was induced by propofol in 35 patients and by thiopentone in 37. ⋯ Thiopentone was associated with an adverse response in 76% of patients, compared with propofol in 26% (P < 0.01). Gagging, laryngospasm and head movement were more common using thiopentone (P < 0.01, P < 0.05 and P < 0.05 respectively) and in 11% (P < 0.05) of the thiopentone group insertion of the LMA was impossible due to inadequate relaxation. We conclude that, using these doses, propofol is superior to thiopentone as an induction agent for insertion of the laryngeal mask airway.
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Randomized Controlled Trial Clinical Trial
Improved peribulbar anaesthesia with alkalinization and hyaluronidase.
A prospective double-blind randomized study was carried out to determine the effect of pH and the addition of hyaluronidase to a mixture of lidocaine and bupivacaine on the efficacy of peribulbar anaesthesia. One hundred patients were assigned to one of five groups. All groups received a solution of two parts bupivacaine (0.75%) and one part lidocaine (2%) (with 1:100,000 adrenaline) as the base components of their anaesthesia. ⋯ The solution containing hyaluronidase and pH adjusted to 6.7 was found to be the most effective (P < 0.025). The presence of hyaluronidase without alkalinization did not improve the efficacy of the mixture; and similarly, alkalinization in the absence of hyaluronidase was ineffective. These results reflected the pH- and temperature-dependent thermodynamic properties of local anaesthetics, and the pH-dependent activity of hyaluronidase.
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Intermittent jet ventilation was used during anaesthesia in a 66-yr-old woman who had severe tracheal narrowing secondary to compression by a retrosternal goitre. The trachea was intubated by a small-bore tube, which was placed above the site of narrowing. ⋯ Arterial blood gas analysis during jet ventilation showed PaO2 150 mmHg, PaCO2 35 mmHg and pH 7.4. It is concluded that low-frequency jet ventilation may provide adequate oxygenation and carbon dioxide elimination in the presence of tracheal narrowing.
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Most surgical patients are first seen by an anaesthetist after admission to hospital, either the evening before or on the day of surgery. Some medical ethicists believe that an approach by an anaesthesia researcher made after admission is unethical because the hospital itself is a coercive environment, and patients have insufficient time for reflection or consultation. Others believe that an approach prior to admission may be an invasion of the patient's privacy and confidentiality. ⋯ In one centre, the REB always requested informed consent to be obtained before the patient's admission to the hospital. Surgeons had no involvement with consent for anaesthesia research in 14 centres while in the other two they gave permission for their patients to be studied and informed patients of the potential approach by anaesthesia researchers. We conclude that it is ethically acceptable to obtain informed consent for most low-risk clinical anaesthesia research after the patient's admission to hospital.