Anaesthesia and intensive care
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Anaesth Intensive Care · Nov 1989
The influence of CO2 production and physiological deadspace on end-tidal CO2 during controlled ventilation: a study using a mechanical model.
A mechanical lung model was used to investigate the effect of varying carbon dioxide production and deadspace on the end-tidal carbon dioxide levels achieved during mechanical ventilation when using the Bain, Humphrey ADE, and circle systems. Both factors had significant influence on end-tidal carbon dioxide concentration and could result in values in excess of those considered acceptable in clinical practice. The implications of the results are discussed.
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Perioperative pulse oximetry was performed on one hundred consecutive abdominal surgical patients to audit our management of perioperative oxygenation. Oximetry was performed preoperatively, in the recovery room, and daily in the ward until discharge or the sixth postoperative day, with prescribed oxygen therapy continuing during measurement. ⋯ In this group of patients, clinical assessment of oxygenation and the need for oxygen therapy was inadequate. Intermittent oximetry is rapidly and simply performed, and by detecting patients with arterial haemoglobin desaturation, could improve oxygen prescribing in the perioperative period.
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Anaesth Intensive Care · Nov 1989
A method for implementing programmed infusion of thiopentone and methohexitone with a simple infusion pump.
We have tabulated the series of steps in infusion rate required to maintain constant arterial levels of thiopentone and methohexitone. The tables are based on multiexponential equations for infusion rate, derived from plasma drug efflux studies. ⋯ The tables provide rates suitable for delivery by a standard syringe pump to achieve and maintain an arterial concentration of 10 mg/l of thiopentone and 5 mg/l of methohexitone. Other desired drug concentrations can be derived from the table by simple multiplication.
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Anaesth Intensive Care · Aug 1989
Comparative StudyA comparison of brachial, femoral, and aortic intra-arterial pressures before and after cardiopulmonary bypass.
Following recent evidence that brachial and femoral artery pressures are more reliable than radial artery pressures after cardiopulmonary bypass, thirty-one adults had simultaneous pre- and post-bypass measurements of brachial, femoral, and ascending aortic pressures. Two minutes after cardiopulmonary bypass, brachial artery systolic pressure and mean arterial pressure fell significantly below corresponding pressures in the femoral artery and aorta. Five minutes after cardiopulmonary bypass, only brachial artery systolic pressure was still less than femoral and aortic systolic pressures. ⋯ Equivalent aortic-to-femoral mean pressure diminution occurred in two (6%) patients at two minutes and one (3%) patient at five and ten minutes after bypass. Neither systemic vascular resistance nor body temperatures contributed significantly to post-bypass central-to-peripheral pressure reductions. Immediately following bypass, femoral artery pressures reproduce central aortic pressures more reliably than do radial or brachial artery pressures.