Biomedical subjects
H H Rea
Publications and source records attributed to H H Rea.
Death from asthma in Auckland: circumstances and validation of causes.
New Zealand has experienced an epidemic of asthma deaths since 1977 with mortality rates of over 3.0/100 000 for people aged 5-34 years, more than three times the rate of comparable countries. To examine the reasons for this high mortality rate all deaths from asthma in people under 70 years in the Auckland region in 1981-82 were investigated. A total of 84 possible cases were studied and the validity of death certificates was found to be excellent for people under the age of 50 years. Fifty-three cases had usefully reversible asthma at the time of death and the mortality rate was almost four times higher in Pacific Islanders than in caucasians, with the Maori rate being intermediate. Sixty-seven percent (35) of the deaths in people with usefully reversible asthma occurred at home. In only 40% of cases had the patient reached some form of medical care. No deaths occurred in the patients admitted to hospital with the diagnosis of asthma during this period.
Human pulmonary dirofilariasis.
Dirofilaria immitis, the canine heartworm, is a relatively rare, but well-documented cause of human lung disease. The disease presents in man as a solitary, peripheral parenchymal lung nodule which may simulate a peripheral lung neoplasm. This case is the first report of the disease in New Zealand, a country where the parasite has not become established in the dog population. A brief review of the life cycle, epidemiology and clinical data relating to human dirofilariasis is included.
Hospital admissions for asthma.
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Computed tomographic assessment of the mediastinum in patients with lung cancer.
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Mortality from asthma: a new epidemic in New Zealand.
Trends in mortality attributed to asthma in the 5-34-year age group were examined in New Zealand, Australia, England and Wales, the United States, Canada, and West Germany for the years 1959-79. An epidemic of deaths from asthma occurred in the mid-1960s in New Zealand, Australia, and England and Wales but not in the other countries. In Australia and England and Wales the death rate quickly returned to pre-epidemic levels, but in New Zealand the decline in mortality was slow, and by 1974 the death rate was still almost double the pre-epidemic level. Of great concern was an abrupt increase in reported deaths from asthma in New Zealand after 1976 with the mortality rate during 1977-9 being greater than during the previous epidemic. In contrast, asthma mortality had remained relatively stable in the other populations.The new epidemic in New Zealand was investigated and appeared to be real. It could not be explained by changes in the classification of deaths from asthma, inaccuracies in death certification, or changes in diagnostic fashions. The most likely explanation appeared to be related to the management of asthma in New Zealand, and this is being investigated.
Drug interactions and asthma deaths.
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Accuracy of computed tomographic scanning in assessment of the mediastinum in bronchial carcinoma.
We believe that malignant involvement of mediastinum is a contraindication to attempted resection of bronchial carcinoma. It was hoped that computed tomographic (CT) scanning might improve our ability to assess the mediastinum prior to thoracotomy. The accuracy of CT scanning, performed with modern techniques, in assessment of the mediastinum of 22 patients with bronchial carcinoma has therefore been determined. In all the patients CT scan impressions have been correlated with the histologic findings at thoracotomy or mediastinoscopy. In detection of malignant involvement of the mediastinum, the CT scan had a sensitivity of 80% and a specificity of 76%. There was only one false negative CT scan report, and in this case the mediastinum was involved at a site which could not have been inspected at anterior cervical mediastinoscopy. We conclude that a negative CT scan makes mediastinoscopy an unnecessary screening procedure in determining resectability. Since there was a significant number of false positive CT scans, we feel that such a report necessitates tissue confirmation before the decision to withhold thoracotomy is made. The CT scan may help to determine the best test to achieve this tissue confirmation.
The effects of cardiopulmonary bypass upon pulmonary gas exchange.
Cardiac output, venous admixture, physiological dead space, blood gas tensions, inspired gas distribution, and other respiratory variables were measured in 10 patients breathing both air and oxygen before and on five occasions up to 10 days after coronary artery vein-graft operations under cardiopulmonary bypass with moderate hypothermia. Cardiac output was unchanged at 8 hours but fell 8 percent by 22 hours. Thereafter it progressively increased and at 10 days was higher than before the operation. Venous admixture rose to a maximum at 28 to 48 hours, postoperatively, but the increase was inversely related to the magnitude of preoperative admixture. The part played by airway and alveolar closure in determining venous admixture is discussed. While admixture increased, the nitrogen-clearance curve improved, presumably due to progressive "dropout" of the worst-ventilated regions. Physiological dead space fell to a minimum at 28 hours after operation; this was attributed to a fall in the end-inspiratory position consequent upon a reduction in both functional residual capacity and tidal volume. There was an increase in ventilation after operation, and this persisted at 10 days; it appeared to be due to reflex stimulation from the lungs and chest wall.
The effects of posture on venous admixture and respiratory dead space in health.
Alveolar-arterial PO2 difference ([A-a]PO2), venous admixture, and physiologic dead space were measured in 24 healthy men and women 23 to 72 years of age in the sitting and supine positions, breathing air, breathing O2, and breathing O2 in deep breaths. In the supine (but not the sitting) position, (A-a)PO2 and venous admixture, breathing both air and O2, were more highly correlated with the difference between closing volume and expiratory reserve volume than with age. The change in (A-a)PO2 and venous admixture from sitting to lying was related to the change in closing volume minus expiratory reserve volume, during both air and O2 breathing. These results confirm previous work on the contribution of gravity-dependent airway closure to the air-breathing venous admixture. They further indicate that the same mechanism is important when O2 is breathed, and it may account for most of the alveoli that close during O2 breathing because of critically low ventilation perfusion ratios. Physiologic dead space in the supine position may be predicted by subtracting 12.5% from the normal sitting value for the same tidal volume and respiratory frequency.
Thoracic society of Australia and New Zealand. Asthma management plan, 1989.
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