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Biomedical subjects

P Wilmshurst

Publications and source records attributed to P Wilmshurst.

69 records · Page 4Linked to original sources
PubMed1984

Arterial plasma potassium measured continuously during exercise in man.

Five continuous records of arterial plasma potassium were obtained from three normal subjects during brief periods (5-7 min) of exercise (100 W). In two of these subjects hepatic venous blood samples were withdrawn at 0.5-1.0 min intervals and analysed in vitro for plasma potassium. Arterial plasma potassium rose rapidly at the start of exercise from 3.8 +/- 0.3 mmol/l (mean +/- SD) to plateau levels of 5.4 +/- 0.1 mmol/l. One of the above subjects and a further subject were studied after beta-blockade with propranolol. This resulted in an exaggerated rise in arterial plasma potassium during exercise. Hepatic venous potassium measurements indicated that the liver probably had little effect on potassium changes during exercise. The changes in arterial plasma potassium during exercise are rapid and substantial. If transmitted to the extracellular fluid these changes would alter cell transmembrane potential and might as a result alter receptor sensitivity.

Adult↗
PubMed1983

Pressure-derived indices of left ventricular isovolumic relaxation in patients with hypertrophic cardiomyopathy.

High fidelity measurements of left ventricular pressure were made at increasing pacing rates in 21 patients with hypertrophic cardiomyopathy and a control group of 11 patients investigated for chest pain who proved to have normal hearts. In both groups the fall in pressure during isovolumic relaxation from the point of min dp/dt approximated closely to a monoexponential, and could be described by a time constant and asymptote. The time constant shortened and the asymptote increased as heart rate rose in both groups. The time constant was longer and min dp/dt less in the cardiomyopathy group than controls at all heart rates. In the cardiomyopathy patients min dp/dt, but not the time constant, was related to systolic pressure. During pacing, eight cardiomyopathy patients developed metabolic evidence of myocardial ischaemia, but indices of relaxation did not differ between these eight and the other 13 either at basal heart rate or the highest pacing rate. In 10 cardiomyopathy patients measurements were repeated at comparable pacing rates after propranolol (0.2 mg/kg). Left ventricular end-diastolic pressure and indices of contractility decreased after the drug, but the time constant did not change. Eight patients received verapamil (20 mg) after which there were substantial reductions in systolic pressure and contractility. Min dp/dt decreased in proportion to systolic pressure, but the time constant was unchanged. At the highest pacing rate before drug administration three patients had abnormal lactate extraction which was corrected by either propranolol (one patient) or verapamil (two patients). Despite abolition of metabolic evidence of ischaemia, relaxation did not improve. It is concluded that abnormal isovolumic relaxation is common in patients with hypertrophic cardiomyopathy, but its severity correlates poorly with other features of the disease. Abnormal relaxation is not the result of ischaemia, and pressure derived indices of relaxation do not improve after the administration of propranolol or verapamil.

Adult↗
PubMed1980

The measurement of gastric transit time in obese subjects using 24Na and the effects of energy content and guar gum on gastric emptying and satiety.

1. A new method has been used to measure mean gastric transit time. 2. This method, based on the absorption of 24Na from the proximal small bowel, is simple, non-invasive and can be used at the bedside. 3. The mean transit time was increased by adding guar gum to a test meal. 4. There was a significant correlation between mean gastric emptying time and a subjective measure of satiety.

Adult↗
PubMedDate not supplied

Incidence of decompression illness in amateur scuba divers.

This paper reports changes in the incidence and manifestations of decompression illness in amateur scuba divers in the United Kingdom (UK) between 1981 and 1993, a period during which the popularity of the sport increased. Since 1981, there has been a trend to increased annual incidence of decompression illness, but the large yearly fluctuations reflect a considerable annual variation in the numbers of dives. The need for recompression facilities to treat decompression illness in amateur scuba divers in the UK should take account of this greater public participation in the sport, and should also allow for large annual fluctuations related to meteorological and financial factors.

Data Collection↗