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Biomedical subjects

A P Hothersall

Publications and source records attributed to A P Hothersall.

8 recordsLinked to original sources
PubMed1983

Protamine titration after cardiopulmonary bypass.

A method of protamine titration, with the use of the 'Haemochron 400' system for reversal of heparinisation after cardiopulmonary bypass is described. Twenty-three patients, average age 47 years, undergoing this procedure for either valve replacement or coronary artery bypass grafting were studied. Accurate reversal of heparinisation was achieved using comparatively small doses of protamine. A linear relationship between the dose ratio of protamine and heparin and the time interval between their respective administrations was defined where only a single dose of heparin had been administered.

Adult↗
PubMed1980

The effect of hypovolaemia on colonic blood flow in the dog.

The effects of a minor degree of hypovolaemia on colonic blood flow and on systemic haemodynamics have been studied in nine greyhound dogs. A loss in blood volume of 10 per cent over 20 min produced no change in blood pressure and only a 7 per cent rise in heart rate. Cardiac output, however, fell by 26 per cent and central venous pressure also fell significantly. Colonic blood flow fell by 28 per cent and oxygen availability by 29 per cent. All these changes were statistically highly significant. Retransfusion of shed blood resulted in a slow and incomplete return to pre-bleed status. Since colonic blood flow and oxygen availability during and after surgery may be important for colonic healing, it is suggested that even the slightest degree of hypovolaemia should be avoided in cases involving colonic anastomosis. Systemic blood pressure may be an inadequate index of the need for transfusion in these cases.

Animals↗
PubMed1980

Colon blood flow in the dog: effects of changes in arterial carbon dioxide tension.

A new method for measuring blood flow in the colon using a 133Xenon clearance technique has been developed in the greyhound. Values for 133Xe tissue blood partition coefficient for colon have been established. The mean basal colon blood flow in 35 animals was 39.8 cm3.min-1.100g-1 with a coefficient of variation for repeat measurements of 8.7%. Hypercapnia produced a significant rise in colon blood flow to a mean maximum level of 62.2 cm3.min-1.100g-1 and hypocapnia a significant fall to a mean level of 27.9 cm3.min-1.100g-1. For arterial carbon dioxide tension (PCO2) values between 2 and 12 kPa (15 and 90 mmHg) there was a straight line relationship between colon blood flow and arterial PCO2. When hypercapnia was prolonged for 75 min, the initial rise in colon blood flow was only partially sustained, while prolonged hypocapnia for a similar period resulted in sustained reduction in flow. Mean resting colon oxygen consumption in 35 animals was 1.17 cm3.min-1.100g-1 and this was not significantly affected by hypocapnia. Hypercapnia to arterial PCO2 levels between 8 and 14 kPa (60 and 105 mmHg), however, produced a significant rise in colon oxygen consumption. Since changes in colon blood flow during and after surgery may affect healing of colonic anastomoses, these results may be relevant when considering anaesthetic techniques for patients undergoing colon resection.

Animals↗
PubMed1979

Dural dimpling in the dog.

Indentation of the dura has been proposed as the cause of subatmospheric pressure in the extradural space, but has never been demonstrated directly in humans. In this study, radiographs have been produced showing dimpling of the dura by a needle tip lying in the extradural space in the dog. Pressure tracings demonstrate that advancement of the needle tip produces a progressive decrease in extradural pressure, and observations made using an image intensifier have confirmed that the pressure changes are proportional to the degree of dural indentation.

Anesthesia, Epidural↗