British journal of anaesthesia
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A questionnaire was sent to all centres of cardiac surgery in the United Kingdom, enquiring into their current use of hypothermia. Moderate hypothermia without cardiopulmonary bypass and the Drew technique of profound hypothermia are becoming less popular, each technique being used in only two of the 30 centres which replied. ⋯ Although some centres use moderate hypothermia out of habit, the main benefits from its use are considered to be the protection afforded to the myocardium and a greater safety margin in the event of technical difficulties. Profound hypothermia, usually induced by means of the pump oxygenator, followed by circulatory arrest is becoming increasingly popular for the correction of complex congenital anomalies in infants.
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In 10 patients receiving prolonged respirator treatment, respiratory deadspace was measured at 12, 18 and 24 b.p.m. and with two different minute volumes. The physiological deadspace (the sum of apparatus, anatomical and alveolar deadspaces) was derived using the Bohr equation, and the anatomical and alveolar deadspaces were measured by carbon dioxide analysis. Tracheal pressure was measured concurrently. ⋯ The VD/VT ratio did not vary with frequency or minute volume. A relationship between tracheal end inspiratory pressure and anatomical deadspace was found, with a correlation coefficient of 0.80. The slope of the regression line indicated a high airway compliance of approximately 10 ml/cm H2O.
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Ketamine, currently being evaluated as an obstetric anaesthetic agent, is said to provide analgesia without depression of the protective airway reflexes or depression of the respiratory or cardiovascular systems. We have studied the effects of ketamine on the uterine blood flow, the foetus and the newborn in five monkeys (Macaca nemistrina). Uterine blood flow, (UBF) was measured by the steady-state infusion technique using tritiated water as the indicator. ⋯ This was not seen in the two infants delivered from mothers receiving 1 mg/kg. Others have shown that neonatal depression is dose- and time-related. We conclude that ketamine should be administered to obstetric patients in small single doses or by continuous infusion in very low concentrations.
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Comparative Study
Surface anaesthetic properties of the new local anaesthetic amid etidocaine (Duranest): A laboratory evaluation.
The surface local anaesthetic properties of the new local anaesthetic amid etidocaine (Duranest) were studied in experimental animals. Etidocaine produced topical local anaesthesia of high intensity, rapid onset and with a comparatively long duration of action following corneal, intranasal and intratracheal application. ⋯ When applied to the mucous surfaces of the nose and the respiratory tract, etidocaine was less toxic than amethocaine and bupivacaine but more toxic than lignocaine. The data justify a clinical evaluation of etidocaine as a surface anaesthetic.
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Seven patients with intracranial disorders were studied during recovery from anaesthesia with nitrous oxide and halothane. Arterial, intracranial, and central venous pressure, and arterial carbon dioxide tension were measured and compared with the patient's clinical state. No patient had evidence of increased brain volume when the dura was closed. ⋯ In the following minutes, until the patients were awake, the intracranial pressure decreased to normal or near normal values, with minimal change in PaCO2. In these seven patients in whom there were no signs of brain swelling, the skull was closed, the patients were allowed to resume spontaneous respiration, and anaesthesia was terminated without major changes in intracranial pressure or cerebral perfusion pressure. However, hyperventilation is advocated after operation in patients with marked brain swelling.