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Biomedical subjects

P J Wallis

Publications and source records attributed to P J Wallis.

At least 19 recordsLinked to original sources
PubMed1994

Percutaneous endoscopic gastrostomy in a general hospital: prospective evaluation of indications, outcome, and randomised comparison of two tube designs.

The indications for percutaneous endoscopic gastrostomy (PEG) and patient outcome, were examined prospectively in the setting of a general hospital. In the course of 26 months, 76 patients underwent PEG (median age 62 years (range 18-99)) and were followed up for 6887 patient days. The median (range) duration of PEG feeding was 93 (3-785) days. The procedure was carried out for neurological indications in 76% of cases (stroke 51%) and 53% of patients were severely malnourished (body mass index < 17 kg/m2) at the time of referral. In 12 (16%) patients swallowing recovered and the PEG was removed after a median (range) of 55 days (20-150). Three (4%) deaths were related to PEG (one oesophageal perforation, one haemorrhage, and one aspiration pneumonia). One patient developed peritonism and ileus, which resolved with conservative treatment. Minor complications included local sepsis 3%, tube blockage 12%, and tube connector leak 5%. During seven days of observation, demands on nursing time for routine care of the PEG were the same as for nasogastric tube feeding, median (range) 21 (4-42) v 16 (4-40) min/day respectively, but in about half the latter cases the tube had to be replaced at least once. Over 15 months, 29 patients were randomised to receive a 1.9 mm inner, 2.9 mm (9F) outer diameter Fresenius and 27 a 3.0 mm inner, 4.0 mm (12F) outer diameter Bower polyurethane tube and were followed for 2920 and 2388 patient days respectively. There was no difference in the insertion time (median (range) 20 (10-45) v 24 (10-45) min respectively) or number of patients with complications (three v eight patients NS), although there were more minor mechanical problems (three v 12, p < 0.01) with the 12F tube. The internal anchoring device of the 12F tube allowed its non-endoscopic removal, a method applicable too 16% of cases. No tubes were removed because of blockage.

Adolescent↗
PubMed1989

Effect of naproxen on renal haemodynamics in elderly patients with arthritis.

The effects of naproxen on renal haemodynamics were observed in ten elderly arthritic patients who were otherwise healthy and without clinical evidence of renal disease. Glomerular filtration rate (GFR,51Cr-EDTA clearance) and effective renal plasma flow (ERPF, 125I-iodohippurate clearance) were measured after 2 weeks' treatment with naproxen 500 mg twice daily and again after 2 weeks off the drug, in random order. Baseline values for GFR and ERPF were within normal limits (mean 72 ml/min/1.73 m2, 110% predicted and 326 ml/min/1.73 m2, 111% predicted, respectively). On naproxen, ERPF and renal blood flow decreased by 10% and 9%, respectively (-32 ml/min/1.73 m2; p = 0.05 and -49 ml/min/1.73 m2; p less than 0.01). These events produced no untoward clinical effects. Nevertheless, this response might impair the kidney's ability to preserve GFR if a further stress were to supervene. Consequently, temporary withdrawal of non-steroidal anti-inflammatory drugs from elderly patients should be considered in response to intercurrent illness or drug therapy likely to compromise renal blood flow.

Age Factors↗
PubMed1988

Effect of diazepam on sleep in patients with chronic airflow obstruction.

The effect of a single dose of diazepam on sleep and respiration was studied in nine patients with chronic airflow obstruction with moderate arterial hypoxaemia but no hypercapnia. Diazepam improved sleep duration without exacerbating nocturnal hypoxaemia and there was no change in the number of apnoeic events after a single 5 mg dose at night.

Aged↗
PubMed1986

Effects of packed cell volume reduction on renal haemodynamics and the renin-angiotensin-aldosterone system in patients with secondary polycythaemia and hypoxic cor pulmonale.

Polycythaemia was corrected by erythrapheresis in ten patients with hypoxic cor pulmonale who were stable on regular diuretic therapy. Renal haemodynamics, renal function and the renin-angiotensin-aldosterone system were assessed before and afterwards. Before erythrapheresis effective renal plasma flow (ERPF) was reduced (63% predicted) but glomerular filtration rate (GFR) was preserved (88% predicted) by a rise in filtration fraction (FF) (138% predicted). A negative correlation existed between ERPF and packed cell volume (r = -0.723; P less than 0.02) and also between ERPF and PaCO2 (r = -0.710; P less than 0.05). Polycythaemia was sufficient to maintain renal oxygen delivery (97% predicted). After erythrapheresis systemic blood pressure, blood volume and blood viscosity all decreased. ERPF increased by 18% (P less than 0.02). FF fell by 11% (P less than 0.05) and GFR was unchanged. Renal oxygen delivery diminished by 25% (P less than 0.001). Plasma renin activity was increased in five patients and plasma aldosterone increased in two patients before erythrapheresis. No sustained fall occurred in plasma renin activity or plasma aldosterone, possibly because the haemodynamic consequences of the procedure had opposing actions on renin secretion. Although the reduction in FF would per se tend to enhance renal sodium and water excretion, a diuresis or natriuresis did not occur consistently.

Aged↗
PubMed1986

Effects of erythrapheresis on pulmonary haemodynamics and oxygen transport in patients with secondary polycythaemia and cor pulmonale.

Reducing packed cell volume has been advocated as a therapeutic procedure in patients with polycythaemia secondary to hypoxic cor pulmonale. The aim of this investigation was to evaluate the effects of this manoeuvre on resting pulmonary haemodynamics and tissue oxygenation in 12 such patients. The subjects were studied whilst they were breathing air (n = 12), after breathing 35% oxygen for 30 min (n = 11) and breathing air 30 min after isovolaemic reduction in packed cell volume, from 0.61 +/- 0.02 to 0.50 +/- 0.02 (mean +/- SEM), by erythrapheresis (n = 12). Initial values for the group were: PaO2 6.5 +/- 0.3 kPa; red cell mass 152 +/- 12% predicted; mean pulmonary artery pressure (PAP) 41 +/- 3 mmHg; cardiac index 3.1 +/- 0.31 min-1 m-2. Breathing 35% oxygen reduced PAP by 3.1 +/- 1.0 mmHg (P less than 0.02), cardiac index by 0.28 +/- 0.121 min-1 m-2 (P less than 0.05) and right ventricular stroke work by 0.05 +/- 0.01 J (P less than 0.01). Systemic vascular resistance was unchanged. Systemic oxygen transport increased and peripheral oxygen consumption was unaltered. Erythrapheresis reduced blood viscosity at shear rates 23 S-1 and 230 S-1. PAP fell by 2.4 +/- 1.1 mmHg (P less than 0.05) and cardiac index increased by 0.32 +/- 0.091 min-1 m-2 (P less than 0.01), but right ventricular stroke work was unchanged. Systemic vascular resistance was reduced by 25 +/- 7 kPa S l-1 (P less than 0.01). Systemic oxygen transport decreased but peripheral oxygen consumption was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

The relationship between salivary aldosterone and plasma free aldosterone concentrations.

The proportion of aldosterone in plasma not bound to proteins (% plasma free aldosterone, %PFA) was measured using an equilibrium dialysis technique and was found to lie predominantly in the range 25-40% although extremes of 20% and 60% were encountered. From this value and the total concentration of aldosterone in plasma (plasma aldosterone, PA) the concentration of free aldosterone in plasma (PFA) was calculated. Percentage PFA was not affected by the in-vitro addition of aldosterone (up to the equivalent of 2000 pmol/l) but the incremental addition of cortisol (up to the equivalent of 550 nmol/l) resulted in a linear increase in % PFA from 26% to 34%. Percentage PFA was found to be significantly, negatively correlated with serum albumin concentration (r = -0.87; P less than 0.001) but it was only when this was less than 15 milligrams that % PFA was abnormally high. Salivary aldosterone concentration (SA) was more highly correlated with PFA (r = 0.84) than with PA (r = 0.75), which indicates that even modest variance in %PFA has a discernible effect upon the overall SA-PA relationship. We conclude that measurement of salivary aldosterone concentrations gives a useful estimate of plasma free aldosterone level. Variations in the latter are determined more by changes in the total concentration of aldosterone in plasma than by variations in the degree of binding by plasma proteins.

Albumins↗
PubMed1986

Calf blood flow and oxygen carriage after reversal of polycythaemia secondary to hypoxic lung disease.

Reduction of packed cell volume has been recommended as a therapeutic procedure in patients with polycythaemia secondary to hypoxic lung disease. We have investigated the effects of this policy on blood flow and oxygen carriage to the calf in 12 such patients. Packed cell volume was decreased from 0.61 to 0.51 (mean) by isovolaemic haemodilution on a cell separator, with significant reductions in blood viscosity at high and low shear rates. Resting calf blood flow was unchanged but peak flow during reactive hyperaemia increased by 17% and 21% one and seven days after the procedure. Oxygen carriage to the calf at rest was initially unchanged but had fallen by 20% at seven days. During reactive hyperaemia oxygen carriage was not impaired by the reduction in packed cell volume since the rise in blood flow offset any reduction in arterial oxygen content. This study has shown that when blood flow is stressed during reactive hyperaemia oxygen carriage is not compromised by a therapeutic reduction in packed cell volume.

Aged↗
PubMed1986

Effects of haematocrit reduction on the haemoglobin-oxygen saturation curve in polycythaemia secondary to hypoxic lung disease.

20 patients were studied with chronic airflow obstruction and arterial hypoxaemia, 10 with and the other 10 without secondary polycythaemia. There were no differences in the value of the P50 for the two patient groups (Polycythaemics 3.31 +/- 0.17 kPa; non-polycythaemics 3.47 +/- 0.25 kPa). Isovolaemic haemodilution was performed by erythrapheresis on a cell separator in the 10 polycythaemic patients. Following removal of a mean 558 ml of packed red cells, there was a fall in the mean PCV from 0.57 +/- 0.02 to 0.46 +/- 0.04. There was no change in the value of the P50 when estimated 24 hrs after treatment. Reduction of an elevated haematocrit in hypoxic polycythaemic patients had no effect on the haemoglobin-oxygen saturation curve.

Female↗
PubMed1985

Gas transfer for carbon monoxide in polycythaemia secondary to hypoxic lung disease.

The transfer factor for carbon monoxide and its subdivisions, the membrane diffusing capacity (Dm) and the pulmonary capillary blood volume (Vc), were measured in 16 patients with polycythaemia secondary to chronic hypoxic lung disease and in ten hypoxic non-polycythaemic control subjects. The mean pulmonary capillary blood volume was significantly lower in the polycythaemic patients (31.6 ml, SD 11.2) compared with the control group (65.2 ml, SD 22.5) (P less than 0.001). Erythrapheresis, as a method of isovolaemic haemodilution, was performed in 15 of the polycythaemic patients. The mean packed cell volume fell from 58 (SD 5)% to 47 (SD 5)% after treatment, with significant reductions in blood viscosity at both high and lower shear rates (P less than 0.001). The mean pulmonary capillary blood volume increased from 32.3 ml (SD 11.3) before treatment to 48.7 ml (SD 18.7) after erythrapheresis (P less than 0.01), with no significant change in membrane diffusing capacity. The rise in pulmonary capillary blood volume is another potential physiological advantage of the reduction of packed cell volume in patients with polycythaemia secondary to hypoxic lung disease.

Adult↗
PubMed1984

An electromyographic method of objectively assessing cough intensity and use of the method to assess effects of codeine on the dose-response curve to citric acid.

The integrated surface abdominal electromyogram (EMG) has been used as a simple measurement of cough intensity which correlates well with the volume, air flow and noise produced in different coughs. Using the integrated abdominal EMG as a measure of cough intensity, dose response curves to inhaled citric acid can be drawn which are highly reproducible. We have studied the effects of codeine (60 mg) on these curves, and have demonstrated a reduction in cough intensity. It is suggested that this method of testing the effects of an antitussive on such a dose-response curve may be a useful one.

Action Potentials↗