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Biomedical subjects

D W Empey

Publications and source records attributed to D W Empey.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1985

Serum immunoreactive erythropoietin in hypoxic lung disease with and without polycythaemia.

We studied 20 patients with chronic airflow obstruction, 10 patients without polycythaemia and 10 patients with compensatory polycythaemia having respectively mean red cell mass 24.7 (SD 4.2) and 47.8 (SD 7.5) ml/kg, mean daytime PaO2 7.6 and 6.9 kPa, mean FEV1 0.85 and 0.821. Groups were matched for severity of daytime arterial hypoxaemia but nocturnal arterial oxygen desaturation was more severe in the patients with polycythaemia than in those without. We also studied six additional patients with chronic airflow obstruction and polycythaemia and 19 normal controls. Estimates of serum immunoreactive erythropoietin (siEp) in those without polycythaemia were 19 m-i.u./ml (geometric mean) with 95% confidence range 11-35 m-i.u./ml and stable during 3 months. In those with polycythaemia they were similar and consistent in five and, in the other five, higher on at least one occasion. There was no significant difference between siEp in daytime (12.00 hours to 16.00 hours) and morning (07.00 hours) samples but geometric mean estimates of erythropoietin in paired daytime and morning samples were higher and more variable in patients with polycythaemia than in those without. The geometric mean estimate of siEp in all patients with chronic airflow obstruction and polycythaemia was greater than in normal subjects but, despite secondary polycythaemia, siEp could be in the range for normal subjects. In the patients with polycythaemia we were unable to predict the finding of normal or elevated siEp. Changes in siEp after erythrapheresis (10-26% reduction in packed cell volume) were observed in the 10 patients with polycythaemia and in one without. One month after erythrapheresis, packed cell volume remained below and siEp was above initial pretreatment levels, implying an erythropoietin secretory response and that the development of secondary polycythaemia had induced a fall in siEp.

Aged↗
PubMed1985

Respiration and sleep in Parkinson's disease.

Sleep and respiration during sleep were studied in patients with idiopathic Parkinson's disease, patients with Parkinsonism with autonomic disturbance, and normal age and sex matched controls. Patients with idiopathic Parkinson's disease showed significantly reduced REM sleep, and more frequent and prolonged waking throughout the night. Hypoventilation and sleep apnoea did not occur in the idiopathic Parkinson's disease or normal groups, but respiration was disorganised with frequent central and obstructive apnoeas in the autonomic disturbance group. Respiratory rate during non rapid eye movement sleep was similar in the idiopathic Parkinson's disease and normal groups, but patients with idiopathic Parkinson's disease showed tachypnoea awake and during REM sleep.

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↗
PubMed1984

Comparison of pseudoephedrine and triprolidine, alone and in combination in preventing nasal congestion in subjects with allergic rhinitis using nasal histamine challenge.

The abilities of triprolidine 2.5 mg and pseudoephedrine 60 mg, alone and in combination, to protect against an increase in nasal airway resistance (NAR) after histamine challenge were determined in eighteen individuals with grass pollen allergy. The study was conducted outside the pollen season using a double-blind, placebo controlled crossover design. The prior administration of pseudoephedrine 60 mg and triprolidine 2.5 mg alone or in combination was superior to placebo in reducing the increase in NAR after challenge with 1.0% histamine. However, such NAR measurements did not differentiate between pseudoephedrine 60 mg and triprolidine 2.5 mg administered alone or in combination. Challenge with 0.1% histamine failed to discriminate between any of the test medications.

Adult↗
PubMed1984

Erythrapheresis compared with placebo apheresis in patients with polycythaemia secondary to hypoxic lung disease.

We have assessed the effects of erythrapheresis, a method of isovolaemic haemodilution, and placebo apheresis in 10 patients with polycythaemia secondary to chronic hypoxic lung disease (Mean PaO2 7.2kPa (54 mm Hg]. The mean packed cell volume decreased from 0.60 to 0.48, with significant decreases in blood viscosity at both high and low shear rates (p less than 0.001). The 6-min walking distance improved after erythrapheresis with no significant placebo effect of the procedure compared to control subjects (p less than 0.01). Erythrapheresis is a safe procedure for packed cell volume reduction. It is associated with clinical improvement and there is no demonstrable placebo effect on exercise tolerance.

Blood Viscosity↗
PubMed1983

Nocturnal hypoxia and prolactin secretion in obese women.

Respiration during sleep was studied in six obese women who had impaired prolactin response to insulin induced hypoglycaemia (non-responders), six obese women with a normal prolactin response to hypoglycaemia (responders), and six lean women. Sleep apnoea did not occur in any subject. All the obese women showed a decrease in haemoglobin oxygen saturation when asleep, which occurred predominantly during periods of rapid eye movement sleep. That the fall in oxygen saturation was significantly greater (p less than 0.05) in the obese non-responders suggests that central as well as mechanical factors may be important for the genesis of nocturnal hypoxia and is evidence for a disturbance of central nervous function in some obese women.

Adolescent↗
PubMed1983

Erythrapheresis in patients with polycythaemia secondary to hypoxic lung disease.

Erythrapheresis was performed in 10 patients with polycythaemia secondary to hypoxic lung disease (mean PaO2, 6.8 kPa (51 mm Hg)). The mean packed cell volume decreased from 0.64 to 0.48 in men and from 0.56 to 0.42 in women, with significant decreases in blood viscosity at both high and low shear rates (p less than 0.001). Patients showed significant improvement in six-minute walking distances (p less than 0.001) and in tests of mental alertness (p less than 0.01) compared to control subjects. Visual analogue scales confirmed symptomatic improvement after erythrapheresis. Erythrapheresis significantly improved symptoms, mental function, and work performance in patients with polycythaemia secondary to hypoxic lung disease. The procedure was well tolerated by all patients and no complications occurred.

Aged↗
PubMed1983

Effect of airway infections on bronchial reactivity.

The pathological changes in the airway epithelium of patients with asthma and viral upper respiratory tract infection is similar. We have shown that such infections temporarily increase the airway reactivity to histamine and lower the threshold for citric acid-induced cough in normal subjects. We have postulated that sensitisation of airway irritant receptors played a part in this phenomena. Other workers have confirmed these results and in dogs with airway infections an exaggerated discharge of irritant receptors has been shown in response to histamine challenge.

Asthma↗
PubMed1982

A comparison of the bronchodilator action of pseudoephedrine and ephedrine in patients with reversible airway obstruction.

A double-blind randomised cross-over study was performed on 12 subjects suffering from reversible airway obstruction (asthma) to determine the relative bronchodilator effects of oral pseudoephedrine 60 mg, pseudoephedrine 180 mg, ephedrine 25 mg and matched placebo. Spirometry was used to measure vital capacity and forced expired volume in 1 s, and whole body plethysmography was used to measure specific airway conductance. Measurements were recorded before each drug was given, and 1 h and 2 h after each drug. Reversibility of the airway obstruction on each day of the study was demonstrated by significant improvements in all parameters of lung function in response to 400 micrograms of isoprenaline inhaled after the 2-h measurement. No significant bronchodilator effect could be shown following the ingestion of pseudoephedrine 60 mg or 180 mg. Only a week bronchodilator effect was demonstrated after ephedrine 25 mg in that the percentage change in vital capacity at 2 h after ephedrine was greater than that following either dose of pseudoephedrine or the placebo. It is concluded that oral pseudoephedrine in single doses of 60 mg or 180 mg has no significant bronchodilator action in man, and that a single dose of up to 180 mg pseudoephedrine does not cause tachycardia or hypertension.

Asthma↗
PubMed1981

Analysis of simple pulmonary function screening tests in preoperative assessment before lung resection for bronchogenic carcinoma.

Simple pulmonary function screening tests were performed prospectively in a group of patients with carcinoma of the bronchus being evaluated for lung resection. Of the 22 who subsequently had a resection performed, 7 suffered post-operative ventilatory difficulties unrelated to technical surgical complications. By analysis of combinations of variables, it was possible to separate significantly the complication group from the non-complication group. This was not possible using one variable alone. The method of empiric determination of values which produce maximum separation is described and contrasted with the more statistically acceptable technique of discriminant analysis. With the latter it is possible to incorporate information from any number of variables and to achieve greater definition of the two groups. It is proposed that such an analysis might provide the means for more valid scientific assessment of simple pre-operative screening tests than is usually employed.

Carcinoma, Bronchogenic↗
PubMed1981

Nasal decongestants.

When a patient presents with nasal obstruction a correct diagnosis must be made. Treatment may not always be required, and the need for intervention should be balanced against the risks of therapy. If the patient has an acute problem, such as the common cold or sinusitis, a topical decongestant may be the most immediately effective remedy, but this should never be continued for more than a few days and the patient should be warned against buying similar proprietary products. In more chronic cases, such as allergic or vasomotor rhinitis, or when decongestion of mucosa away from the nose (Eustachian tube) is required, oral treatment is best. A sympathomimetic administered orally (pseudoephedrine or phenylephrine) may be sufficient, or an antihistamine alone may be helpful in allergic rhinitis. Combination products are frequently effective, possibly more so than the individual ingredients, but when using such products the prescriber must remember the contraindications and precautions for each ingredient.

Administration, Oral↗