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Biomedical subjects

P J Sloan

Publications and source records attributed to P J Sloan.

15 recordsLinked to original sources
PubMed1985

Clinical evaluation of the Infrasonde D4000 blood pressure monitor.

Choosing a blood pressure machine from their ever increasing number is often difficult due to lack of performance data. We have evaluated a new automated non-invasive blood pressure recorder, the Infrasonde D4000. In comparison with the Hawksley random zero mercury sphygmomanometer the Infrasonde showed less variability for both systolic and diastolic readings. However, it was found to record significantly lower mean systolic and diastolic pressures.

Blood Pressure Determination↗
PubMed1985

Comparison of blood pressure machines.

After examining published papers and our own experiences we suggest some simple guidelines for future studies which compare sphygmomanometers. The sample should be stratified to cover a wide range of blood pressures. Observers should measure pressures using a balanced cross-over design under standard conditions. Data should be shown on a scatterplot to allow visual estimation of bias, variability of readings and non-linear relationships. Statistical analyses if universally applied would allow comparison of studies. We suggest the use of the following common methods; the mean of the differences between paired readings with standard deviation, linear regression with both zero and non-zero intercepts and analysis of variance.

Blood Pressure↗
PubMed1984

Standardized methods for comparison of sphygmomanometers.

Medical research in general and equipment comparisons in particular suffer from a deficiency and disparity of statistical analysis. We studied four semi-automatic sphygmomanometers in comparison with the Hawksley random zero mercury manometer. The Astropulse 80 showed marked deviation from the standard machine in average blood pressure recorded and greater variation of readings. The Infrasonde M3010, Bosomat II and Infrasonde D4000 were similar to the standard machine. To help comparability in future studies we suggest the following guidelines; blood pressures to be taken under standard conditions, data to be shown as scatterplots, analysis of variance to be performed and regression analysis to be used only to give an approximate overall view. Finally, we urge the manufacturing companies to conduct such studies and include the results in their brochures.

Blood Pressure Determination↗
PubMed1984

The Quantab strip in the measurement of urinary chloride and sodium concentrations.

The "Quantab" strip (Ames) measures chloride in fluids. For sodium chloride solutions and urine we found very good correlations between the Quantab reading and the chloride concentration as measured by chemical assay (r = 0.95 for chloride and r = 0.85 for sodium in urine). The strip gave reproducible results over the temperature range 4 to 37 degrees C. There was very little inter- and intra-observer variation in reading the strip. Although 10 to 23 min is required to complete the reaction, the strip reading is stable thereafter. We suggest that the strip could be useful in epidemiological studies of urinary sodium concentration and clinically in helping patients adhere to a low-salt diet.

Chlorides↗
PubMed1983

Multisystem sarcoid presenting with gingival hyperplasia.

A case is reported in which granulomatous gingival hyperplasia was the presenting feature of generalised sarcoidosis. Treatment with oral prednisolone resulted in resolution of both the granulomatous lesion of the gums, and of proteinuria. It is pointed out that although on histological examination sarcoidosis in this site cannot be distinguished from Crohn's disease, the clinical appearance in this patient (and the only similar case in the literature) was quite different from that seen in oral Crohn's disease.

Adolescent↗
PubMed1983

Nifedipine in combination therapy for resistant hypertension.

Twenty patients with hypertension uncontrolled by existing therapy with two or three antihypertensive agents (a beta-blocker plus a thiazide diuretic in 10 and with the addition of hydralazine or prazosin in the other 10) were studied to assess the effects of additional long-term administration of nifedipine. Eighteen patients received 10 mg nifedipine 3-times daily and 2 received 20 mg twice daily. Patients were followed-up at monthly intervals. The results showed that mean blood pressure levels were reduced at 1 month and adequate control was achieved and maintained in 12 (60%) of the patients. Five of those who continued with the combined treatment remained non-responders and 3 patients had to stop nifedipine because of side-effects (flushing and headaches). Four other patients reported similar side-effects. No changes were evident in weight, pulse rate or the haematological and biochemical parameters studied.

Adult↗
PubMed1978

The effect of acute and chronic hypoxia on thoracic gas volume in anaesthetized rats.

1. Thoracic gas volume at end expiration (functional residual capacity, FRC) was measured in chronically and acutely hypoxic anaesthetized rats by a plethysmograph method. 2. FRC, measured during air breathing, was 34-62% larger in rats which had been kept in an environmental chamber in 8, 10 or 12% O2 for 3 weeks than in littermate controls. FRC returned to normal after the rats had returned to air for 9 days. There was no constant difference in the pattern of breathing between control and chronically hypoxic rats. 3. Pressure-volume curves measured post mortem showed no difference in the volume of the lung at 25 cm H2O pressure or in the compliance of the lung between chronically hypoxic and control rats. Thus there was no gross mechanical change in the lung to account for the increase in FRC. 4. Acute hypoxia caused by breathing 12% O2 increased FRC in control but not in chronically hypoxic rats. The increase in FRC in control rats was abolished by combined blockade of the vagus nerves and carotid bodies (with procaine) but not by vagal blockade alone. 5. The combined vagal and carotid body blockade reduced FRC significantly in rats which had been in 10% O2 for 3 days but not in those which had been in 10% O2 for 21 days. 6. Lung area measured from radiographs was not reduced by a muscle relaxant in chronically hypoxic rats. Electromyograms from anterior intercostal muscles and the diaphragm showed no electrical activity in expiration in chronically hypoxic rats which might indicate an active muscular basis for their increased FRC. However when FRC was raised by acute hypoxia in control animals there was also no increase in electrical activity in expiration which could have explained their increase in lung volume. 7. We concluded that the increase in FRC during acute hypoxia in control rats was probably due to a reflex from the carotid body. The increase in FRC in chronically hypoxic rats, which was present while they breathed air, may have had an active muscular component in the early stages but later on there was possibly a structural factor in the chest wall.

Acute Disease↗
PubMedDate not supplied

The action of hypercapnia during hypoxia on pulmonary vessels.

Two opposing actions of CO2 on pulmonary vessels, vasoconstriction and vasodilatation, were studied in dogs, cats, ferrets and rats using isolated lungs or a lobe of lung in vivo. Both preparations were perfused at a constant flow rate so that changes in inflow pressure at constant outflow pressure represented changes in vascular resistance. Lungs were ventilated with 5-15 percent CO2 during hypoxic vasoconstriction in order to permit demonstration of dilatation and because the two stimuli frequently concur. During hypoxia CO2 caused further constriction, dilatation or a biphasic response. Only constriction occurred in dogs and only dilatation in rats. Constriction predominated in cats but dilatation sometimes occurred in later tests in isolated lungs and after a carbonic anhydrase inhibitor. All three responses were seen in ferrets. The type of response did not depend on CO2 concentration. In rats dilatation turned to constriction after beta-adrenoreceptor blocking drugs. The vessels affected by dilatation could not be determined. Thus CO2 can enhance or diminish the action of hypoxia but the circumstances determining one or other action are not resolved.

Acetazolamide↗