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Biomedical subjects

R J Leggett

Publications and source records attributed to R J Leggett.

16 recordsLinked to original sources
PubMed2000

Small cell lung carcinoma presenting as acute cardiovascular collapse due to tumour cell embolisation.

We present a case of small cell lung carcinoma causing acute cardiovascular collapse due to pulmonary tumour emboli. Although pulmonary tumour emboli may complicate a number of malignancies, this is rarely seen in cases of carcinoma of the bronchus. Patients suffering with pulmonary tumour emboli often have previous symptoms, and show progressive dyspnoea. To our knowledge there have been no reports of tumour emboli presenting acutely without any previous history of symptoms.

Angiography↗
PubMed1984

A trial of intravenous and oral mexiletine in acute myocardial infarction.

Intravenous and oral mexiletine prophylaxis was compared with lignocaine supplemented placebo in a single blind trial in 240 high-risk patients with acute myocardial infarction. Although atrial fibrillation, supraventricular tachycardia and ventricular extrasystoles occurred less frequently in the mexiletine treated patients, ventricular tachycardia and primary ventricular fibrillation were not prevented. Mortality at 6 weeks was less in the mexiletine group (19%) than placebo (27%) but not significantly so (0.2 greater than p greater than 0.1). An 80% chance of showing a significant difference would require 860 high-risk patients. Low plasma mexiletine levels after 3 h treatment were due to diamorphine and may explain failure to prevent major arrhythmias. Pretreatment with intravenous metoclopramide tended to reverse this effect of diamorphine.

Administration, Oral↗
PubMed1982

Cigarette smoking and secondary polycythemia in hypoxic cor pulmonale.

We have related the red cell mass (RCM) in 47 hypoxic patients with COPD (mean PO2, 52.5 +/- 5.2 SD mmHg; mean PCO2, 51.7 +/- 6.7 mmHg; mean/FEV1, 0.6 +/- 0.2 L; mean FVC, 1.7 +/- 0.6 L) to their smoking habits and outpatient carboxyhemoglobin concentrations. The mean RCM was 42.5 +/- 8.0 ml/kg in the 31 patients who still smoked, significantly (p less than 0.01) higher than in the 16 who were currently nonsmokers (RCM, 29.7 +/- 4.4 ml/kg). Measurements of arterial PO2, pH, P50, and COHb showed that the saturation of available hemoglobin (SO2A) was less well correlated (r = -0.36, p less than 0.05) with RCM in the smokers, than was SO2T (r = -0.58, p less than 0.001), SO2T including a corrective term for COHb. The RCM correlated well with the mean outpatient COHb measured repeatedly over 6 to 36 months in 40 of the patients but poorly with thier average arterial oxygen saturation (r = 0.15, p less than 0.1). In 15 patients given long-term oxygen therapy (15 hours/24-hour period) for 12 months RCM decreased significantly only in those who stopped smoking, as shown by a decrease in COHb. We conclude that cigarette smoking may determine the severity of secondary polycythemia in patients with hypoxic COPD, and prevent its correction by long-term oxygen therapy.

Carboxyhemoglobin↗
PubMed1981

Carbon monoxide and exercise tolerance in chronic bronchitis and emphysema.

The effects of carbon monoxide on exercise tolerance as assessed by the distance walked in 12 minutes were studied in 15 patients with severe chronic bronchitis and emphysema (mean forced expiratory volume in one second 0.56 1, mean forced vital capacity 1.54 1). Each subject walked breathing air and oxygen before and after exposure to sufficient carbon monoxide to raise their venous carboxyhaemoglobin concentration by 9%. There was a significant reduction in the walking distance when the patients breathed air after exposure to carbon monoxide (p less than 0.01), and the significant increase in walking distance seen after exercise when breathing oxygen at 2 1/minute via nasal cannulae was abolished if carbon monoxide has previously been administered. Thus concentrations of carboxyhaemoglobin frequently found in bronchitic patients who smoke may reduce their tolerance of everyday exercise, possibly by interfering with the transport of oxygen to exercising muscles.

Bronchitis↗
PubMed1979

Transient hypoxaemia during sleep in chronic bronchitis and emphysema.

Arterial oxygenation, breathing pattern, and electroencephalogram were studied during sleep in patients with chronic bronchitis and emphysema and in healthy subjects. All of the 10 "blue and bloated" patients had episodes of transient hypoxaemia lasting 1--100 min, when their oxygen saturation fell by more than 10%, whereas such desaturation did not occur in 2 "pink and puffing" patients or in 4 healthy subjects. Hypoxaemic episodes usually occurred during the rapid-eye-movement stage of sleep. It is suggested that these hypoxaemic episodes result from a combination of hypoventilation and impaired ventilation/perfusion relationships and that these episodes may contribute to the development of the pulmonary hypertension and secondary polycythaemia which characterises "blue and bloated" patients.

Adult↗
PubMed1979

Accuracy sensitivity to carboxyhemoglobin, and speed of response of the Hewlett-Packard 47201A ear oximeter.

We have shown that the Hewlett-Packard 47201A ear oximeter measures arterial O2 saturation within 95 per cent confidence limits of +/- 4 per cent when arterial blood saturation is more than 65 per cent, but at lower saturations the oximeter consistently provides a reading that is too low. The oximeter is sensitive to carboxyhemoglobin, progressively overestimating arterial saturation as carboxyhemoglobin concentration increases from 0 to 18 per cent. The time response is exponential, with a normal time constant of 3 sec, but this is halved in the fast mode or operation.

Carboxyhemoglobin↗
PubMed1977

Portable oxygen and exercise tolerance in patients with chronic hypoxic cor pulmonale.

Breathing 30% oxygen during exercise alleviated arterial hypoxaemia and reduced minute ventilation in patients with severe chronic bronchitis. A similar level of oxygen (2 or 4 litres of oxygen/minute) from nasal prongs also increased their exercise tolerance, as assessed by the distance that they could walk on the level in 12 minutes. Nevertheless, a single-blind controlled study showed that the effort of carrying their portable supply of liquid oxygen, in the Union Carbide Oxygen Walker, abolished this gain in exercise tolerance. The improvement in walking distance was restored when oxygen on exercise was provided by wheeling the oxygen walker on a light-weight shopping trolley.

Arteries↗
PubMed1977

Oxygen affinity in vivo and in vitro in chronic ventilatory failure.

1. The oxygen affinity in vitro, haematological indices, erythrocyte 2,3-diphosphoglycerate and plasma inorganic phosphate were determined in 20 patients with chronic ventilatory failure and in 20 healthy non-smokers of similar age. 2. No significant difference was observed between the mean oxygen affinity or phosphate concentrations of the patients and healthy subjects but the mean haemoglobin and packed cell volume were significantly higher in the patients. 3. There was a positive correlation between plasma and intraerythrocytic pH which was similar in both patients and healthy subjects. 4. The arteriovenous difference in oxygen saturation in vivo (directly measured at cardiac catheterization) correlated closely with that calculated from the individual patient's oxygen affinity determined in vitro and arterial and mixed venous oxygen and carbon dioxide tensions, suggesting that oxygen affinity in vitro accurately reflects the curve in vivo.

Adult↗
PubMed1976

Effect of age on oxygen-binding in normal human subjects.

1. Oxygen-binding, plasma and intra-erythrocytic pH, and haemoglobin, 2,3-diphosphoglycerate and inorganic phosphate concentrations were measured in sixty-two healthy non-smokers aged between 18 and 89 years. 2. P50 (oxygen tension at 50% oxygen saturation) expressed at plasma pH 7-40 and PCO2 5-33 kPa showed a positive correlation with age. 3. This correlation of P50 with age was closer when P50 was expressed at a constant intra-erythrocytic pH 7-20. On average P50 at intra-erythrocytic pH 7-20 increased from 3-59 kPa at 20 years to 3-96 kPa at 90 years of age. 4. 2,3-Diphosphoglycerate, inorganic phosphate, haemoglobin and mean corpuscular haemoglobin concentrations did not correlate with P50 or with age.

Adolescent↗
PubMed1976

Long-term domiciliary oxygen therapy in cor pulmonale complicating chronic bronchitis and emphysema.

Ten patients with cor pulmonale complicating severe chronic bronchitis and emphysema have been treated with 2 litres/min of oxygen for prolonged periods in the day, at home, over 12 to 62 months. Two patients died after 12 and 36 months of treatment. Pulmonary arterial pressure was reduced in seven patients, and red cell mass in eight, when the oxygen was given for over 15 hours in the day. Hospital inpatient treatment was greatly reduced following the start of long-term oxygen treatment in all patients. This treatment is expensive, and a controlled trial is necessary to establish its definitive place and cost-effectiveness, but the results of such a current Medical Research Council trial will not be available for a further two years.

Aged↗
PubMed1976

Arterial blood gas tensions, hydrogen ion, and electroencephalogram during sleep in patients with chronic ventilatory failure.

We have studied arterial PO2, PCO2, and hydrogen ion and electroencephalogram during sleep in 10 patients with stable severe chronic respiratory failure. As a group the patients slept badly. Sleep was associated with a worsening of hypoxia and no significant change in PCO2 and H+. Two patients were restudied, receiving oxygen therapy overnight. Both had improved sleep but one, who had an intact hypoxic drive to breathing, developed marked hypercapnia and acidosis when his PO2 was restored to normal during sleep; the other, who had no hypoxic drive to breathing, developed no more hypercapnia or acidosis during sleep when breathing oxygen than when breathing air. Oxygen therapy may improve sleep disturbance in these patients, but its effect on the drive to breathing during sleep should be considered if severe hypercapnia and acidosis are to be avoided.

Carbon Dioxide↗
PubMed1975

Hyperuricaemic acute renal failure after epileptic seizures.

Seven patients admitted to hospital during or immediately after status epilepticus or recurrent episodes of grand-mal seizures had very high concentrations of uric acid in their blood at a time when the blood-urea was normal in five of them. The blood-lactic-acid was high in the five patients in whom it was measured. All of the patients developed reversible renal failure, and two required haemodialysis. The blood-uric-acid should be measured in patients who have had prolonged seizures, and the measures which might be taken in hyperuricaemic patients to prevent the development of acute renal failure include rehydration, alkalinisation of urine, and, where alkalinisation is impossible, haemodialysis.

Acute Kidney Injury↗