Biomedical subjects
Publications and source records attributed to J M Gibbs.
Buprenorphine is a potent synthetic opioid-partial antagonist analgesic drug currently under clinical trial. When administered intravenously to human volunteers buprenorphine produced a significant depression of the ventilatory response to carbon dioxide stimulus for a period in excess of six hours.
A survey of New Zealand public hospitals undertaken at the end of 1974 shows that the country is training half the number of anaesthetists to maintain the public hospital-based anaesthetic services. There is a need to develop and expand training programmes for anaesthetists. New graduates can be assured that there are career prospects in the specialty.
Constant flow perfusion of the pulmonary circulation was established in isolated cat lungs. These were ventilated with 5% carbon dioxide in oxygen in order to maintain a near-normal carbon dioxide tension and acid-base status in the perfusing blood. The alteration of pulmonary vascular resistance in response to a change in inspired carbon dioxide concentration from 5% to 10% was investigated before, during and after the administration of 1% halothane (in 16 perfusions) or 5% diethyl ether (in 8 perfusions). An increase of inspired carbon dioxide concentration caused a significant increase in pulmonary vascular resistance, but the magnitude of the increase was diminished during the administration of both anaesthetic agents. The response increased again after the anaesthetics were withdrawn. The administration of halothane during ventilation with 5% carbon dioxide caused a significant reduction of pulmonary vascular resistance whilst diethyl ether resulted in a significant increase in this measurement. It is suggested that inhalation anaesthetic agents may increase ventilation/perfusion mismatching by altering the normal vasoconstrictor response to increased alveolar PCO2;
The effect of pancuronium on the cardiovascular system of the dog was studied in 12 greyhounds who were anaesthetized with pentobarbitone 30--40 mg/kg body weight. During the study, the animals were artificially ventilated to give an end-tidal carbon dioxide in the range 4-0--4-5 per cent. Duplicate cardiac output measurements were made before and ten minutes after the intravenous administration of pancuronium (0-18 mg/kg). There was a slight (but statistically insignificant) fall in cardiac output. Heart rate, aortic and pulmonary arterial pressures remained substantially unaltered. It is suggested that pancuronium should be used in the dog when muscle relaxation is required during pentobarbitone anaesthesia. In this way cardiovascular changes related to the drugs themselves will be minimized.
The cardiorespiratory effects of thrombin-induced disseminated intravascular coagulation (DIC) were studied in two groups of dogs. The main changes were a reduction in cardiac output and arterial pressure, an increase in pulmonary artery pressure and, an increase in pulmonary artery pressure and an increase in venous admixture. In one group of dogs the reduction in cardiac output was diminished by the infusion of dextran 35 ml/kg body weight. This resulted in an increased pulmonary artery pressure but no significant differences in the indices of the efficiency of gas exchange. However, the haemodilution resulted in a lower mixed venous and arterial PO2 in this group of dogs.
A double-lumen tube was inserted into the trachea of dogs anesthetized with intravenous pentobarbital (30-40 mg/kg). Blood flow/unit lung volume in each lung was measured with 133Xe. Both lungs were initially ventilated with oxygen and measurements of pulmonary blood flow, CO2 output, cardiac output, and blood gases were made. When nitrogen was administered to one lung blood flow was diverted to the opposite lung. The diversion of flow was reduced by the inhalation of 1% trichloroethylene but returned after withdrawal of the anesthetic. There were no significant changes in cardiac output. Changes in CO2 output and arterial Po2 were compatible with the xenon results. It is concluded that trichloroethylene may increase arterial hypoxemia by reducing vasoconstriction in hypoxic areas of lung.
The performance of two heated water-bath humidifiers was examined in terms of airway temperatures and humidities. These were the simple heated tank (Marshall and Spalding, 1953) and the Fisher and Paykel No. 328 (Spence and Melville, 1972), both of which had the potential to deliver gases at temperatures above 40 degrees C, and with a moisture content in excess of 50 mg/litre. The major advantage of the No. 328 was its heating wire in the delivery tube. This lessened or prevented condensation within the tube, and allowed the water bath to be maintained at lower temperatures. Independent heat controls for the water bath and the delivery tubing allow precision of humidities in the gases provided for inspiration through an artificial airway. When condensation is prevented, the temperature of the saturated gases leaving the humidifier limits the absolute humidity supplied. Monitoring and adjustment of airway temperature of the patient then allows selection of temperature and relative humidity in the inspired gas.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.