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Biomedical subjects

S B Pearson

Publications and source records attributed to S B Pearson.

At least 55 records · Page 3Linked to original sources
PubMed1981

The diagnosis and management of patients admitted to hospital with acute breathlessness.

The authors have studied 352 emergency medical admissions during a summer period and 355 during the winter months to identify 177 patients who had been treated for breathlessness. Multiple and rapidly changing treatments have been taken to indicate diagnostic uncertainty. Using this model, the authors have shown that there is much more uncertainty in winter than in summer and that the working diagnosis of chest infection or asthma is particularly likely to be associated with multiple treatment. It is questionable whether the stereotyped descriptions of diseases in standard text books provide an adequate basis for emergency treatment decisions and it is considered that the diagnostic value of investigations such as chest radiography needs further careful scrutiny.

Acute Disease↗
PubMed1979

The effect of beta-adrenoceptor blockade on factors affecting exercise tolerance in normal man.

1 We have studied the effects of single oral doses of 80 mg propranolol and 100 mg metoprolol on the cardiovascular and respiratory responses to progressive exercise in nine healthy men in double-blind, placebo-controlled experiment. As judged by their effects on exercise heart rate and cardiac output the doses of the two drugs used were equivalent. 2 Beta-adrenoceptor blockade reduced oxygen consumption by 3.5% over the whole work range with an increase in the respiratory exchange ratio of 0.056 units. Carbon dioxide production and exercise ventilation were unchanged. The two drugs had similar effects. Possible mechanisms for these observations are discussed. 3 Perceived exertion during exercise was increased by both the beta-adrenoceptor blocking drugs and this may be of relevance to the symptom of fatigue reported by patients on these drugs. Endurance, assessed as either total work done or maximal work achieved, was reduced by 15%.

Adrenergic beta-Antagonists↗
PubMed1979

Legionnaires' disease: a clinical description of thirteen cases.

We describe 13 patients with legionnaires' disease in Nottingham, all presenting with lobar pneumonia. Six patients required artificial ventilation and 2 died. No common source of infection has yet been identified, but the disease appears to be prevalent and possibly endemic in this city.

Adult↗
PubMed1978

The influence of low, normal and high Pa(O2) on the respiratory effects of Pa(CO2) oscillations in anaesthetised cats.

The present study examines the influence of oxygen tension on the recurrent tidal volume changes caused by oscillations in arterial P(CO2). The oscillations have a period equal to two respiratory cycles, and are produced by giving alternately CO2 -enriched and CO2 -free gas mixtures. The results show alternation of the tidal volume with the same incidence (is greater than 50%) at low, normal and high oxygen tensions. However, the magnitudes of the breath-by-breath changes are significantly greater at low oxygen tension than at normal oxygen tension. Under high oxygen tension breath-by-breath tidal volume changes are indistinguishable from those at normal oxygen tension.

Animals↗
PubMed1978

Propranolol and the ventilatory response to hypoxia and hypercapnia in normal man.

1. The effect on respiration of a single dose of propranolol has been studied in normal subjects. 2. The degree of beta-adrenoreceptor blockade was assessed in terms of the impaired heart-rate response to progressive exercise and the plasma propranolol concentration. 3. No effect of propranolol was demonstrated on either the ventilatory response to rebreathing CO2 in hyperoxia, or the response to progressive isocapnic hypoxia. Simple indices of maximal expiratory flow (FEV 1.0% and PEFR) were also unchanged. 4. The absence of any effect of propranolol on the chemical control of breathing in man is discussed in relation to the conflicting literature.

Adult↗
PubMed1973

The respiratory effects in man of altering the time profile of alveolar carbon dioxide and oxygen within each respiratory cycle.

1. Breathing hypoxic gas through an external dead space (ca. 1200 c.c.) stimulated ventilation disproportionately. A loop (ca. 250 c.c.) in the inspiratory pathway reduced the effect.2. The alveolar time patterns of P(CO) (2) and P(O) (2) characteristic of tube breathing with or without the loop have been simulated in moderate hypoxia by changing the composition of inspired gas at selected intervals after the beginning of inspiration.3. Supplying CO(2)-free gas in late inspiration usually stimulated ventilation, but less than did real tube breathing. Supplying CO(2)-free gas early in inspiration usually depressed ventilation. The difference between the ;CO(2)-free late' and ;CO(2)-free early' effects was 20% of the control ventilation (P < 0.001), i.e. was nearly the same as between the effects of real tube breathing without and with the loop.4. Tube-like P(A, O) (2) time patterns had no effects.5. A-a P(CO) (2) and P(O) (2) gradients remained constant throughout.6. The V(E), f and V(T) relations were unaltered in tube breathing.7. The respiratory system can discriminate between small differences in time patterns of P(A, CO) (2) but not of P(A, O) (2); the signal is amplified by steady hypoxia. The arterial chemoreceptors are probably responsible for these effects.

Adult↗
PubMed1973

The effects of various time patterns of alveolar CO 2 and O 2 on breathing in man.

We have studied the responses of human arterial chemoreceptors to various patterns of quick change of stimulation. (i) Transient abolition of hypercapnia lowers VE after 2 breaths (chemoreceptor latency) only if PAO2 is low, therefore hypoxia is necessary for an arterial chemoreceptor response to CO2. (ii) Alternate breaths of euoxia and hypoxia, and of eucapnia and hypercapnia, separately and combined, have no special effect on mean V. However, oscillating CO2 commonly causes breath-by-breath alternation of V, but only if hypoxia is present; oscillating only the low O2 seldom causes oscillation of V. Concluded (a) that chemoreceptor responses to delta-CO2 are quicker than to delta-O2; (b) that, above CO2 threshold, response to rising CO2 is equal and opposite to response to falling CO2. (iii) Three time patterns of PACO2 within single respiratory cycles have been compared in hypoxia. At a single mean arterial PCO2, a small sharp fall of PACO2 early in inspiration depresses mean V, while a smaller sharp fall of PACO2 late in inspiration increases mean V. Concluded that human respiratory system distinguishes between these rather similar patterns presumably through arterial chemoreceptor pathway since the phenomenon depends on the presence of hypoxia. The importance of exact timing is emphasised.

Carbon Dioxide↗