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Biomedical subjects

M R Hetzel

Publications and source records attributed to M R Hetzel.

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

Regular versus symptomatic aerosol bronchodilator treatment of asthma.

Regular treatment with salbutamol or placebo aerosols was compared in a double-blind study in 18 asthma patients. Although symptom scores and respiratory function tests were not significantly different, wheezing attacks requiring additional puffs of a standard salbutamol aerosol were significantly more frequent during the period on placebo when patients were receiving symptomatic treatment only. Thus regular treatment with bronchodilator aerosols provides better control of asthma than symptomatic use alone.

Adult↗
PubMed1980

Comparison of normal and asthmatic circadian rhythms in peak expiratory flow rate.

A computer technique (cosinor analysis) has been used to evaluate circadian rhythms in airway calibre in normals and asthmatics. Two hundred and twenty-one normal subjects recorded peak expiratory flow rate (PEFR) at home four times a day for seven days. Rhythm detection was statistically significant in 145 of them (65.6%) who showed a mean amplitude of 8.3% of individual mean PEFR (+/- SD 5.2%). Amplitude was independent of age, sex, atopy, family history of asthma, and smoking habit. Fifteen of them were also studied three times a day for five days in the laboratory with flow-volume loops. Eleven showed significant PEFR rhythms at home. No single measurement from the flow-volume loop showed periodicity in as many of them but rhythms were now also detected in the other four normal subjects in some components of the loop. Fifty-six asthma patients were studied with a similar protocol of PEFR measurement and compared with the 145 rhythmic normal subjects. Mean phases of the normal and asthmatic rhythms were not significantly different with acrophases (peak of rhythm cycle) at 1557 and 1526 respectively. The mean asthmatic amplitude was, however, significantly greater at 50.9%. Nocturnal asthma, therefore, probably represents an exaggeration of a normal circadian rhythm in airway calibre. The amplitude of the PEFR rhythm is an index of bronchial lability and is thus valuable in monitoring asthma patients. An amplitude of greater than 20% should be a useful screening test for asthma.

Adolescent↗
PubMed1979

Can patients keep their own peak-flow records reliably?

Fifty patients recorded their peak expiratory-flow rate (P.E.F.R.) in hospital, unaided by nursing staff, five times a day for 5 days. Each patient's readings were randomly and independently checked on two occasions during this period. 69% of checked readings were accurate. Most patients kept satisfactory records as a table, but were less efficient in recording their results on a P.E.F.R. chart. Recording of P.E.F.R. by patients with respiratory disease saves nursing time and provides valuable clinical information.

Adolescent↗
PubMed1979

Does sleep cause nocturnal asthma?

The effects of sleep interruption and deprivation were studied in 21 patients with nocturnal asthma. Seven patients were awakened at 0200 on three consecutive night and exercised for 15 minutes. This produced no significant improvement in the overnight fall in peak expiratory flow rate (PEFR) compared with a control night of uninterrupted sleep. In a second study in five patients PEFR was measured at two-hourly intervals to estimate the time of onset of the nocturnal fall in PEFR. On three subsequent nights they were awakened and exercised one hour before this time. This also failed to prevent a fall in PEFR by 0600. Eleven patients, who had followed a similar protocol to the second study, were kept awake until after 0300 or later, and PEFR was observed hourly. Six of them (group A) sustained their usual fall in PEFR while awake, proving that sleep was not responsible for their nocturnal asthma. Five patients (group B) showed little fall in PEFR until they were allowed to sleep, when an appreciable fall was noted on waking at 0600. When sleep deprivation was repeated in two patients in group B, however, they sustained falls in PEFR while still awake. We conclude that the circadian rhythm in PEFR is often in phase with the timing of sleep but sleep does not cause nocturnal asthma. Disruption of sleep therefore has no apparent value in the treatment of nocturnal asthma.

Adolescent↗
PubMed1978

Value of pacing in cardiac failure associated with chronic atrioventricular block.

The effect of permanent pacing on chronic complete atrioventricular block complicated by cardiac failure was studied in 6 patients by measurement of indirect left atrial pressure 15 minutes after institution of pacing and again 3 to 12 months later. In addition, 21 patients with complete heart block and clinical plus radiological evidence of cardiac failure at the time of pacing 3 to 6 years earlier were also reviewed. Only 1 of 6 patients studied haemodynamically improved and 1 died in cardiac failure. Of 21 patients assessed clinically, 10 had improved and 8 had died after a mean follow-up of 53 months. In the absence of syncope, pacing was of little symptomatic benefit but still may be justified to prolong survival. Both studies indicated a particularly poor prognosis for patients known to have coronary artery disease. No reliable means were found of determining the prognosis in the individual patient with cardiac failure before pacing.

Adult↗
PubMed1977

Asthma: analysis of sudden deaths and ventilatory arrests in hospital.

The incidence of episodes of unexpected ventilatory arrest, some of which led to sudden death, was studied in 1169 consecutive hospital admissions for asthma. Of the most acute cases, 458 were initially managed in a special care unit where only one ventilatory arrest occurred. A further nine cases of arrest, three of which proved fatal, happened on general wards. Accepted clinical criteria of a severe attack were not present in those episodes occurring outside the unit, which were apparently mild attacks. The risk of sudden death could not be related to the severity of the attack but it did correlate with the presence of excessive diurnal variation in peak expiratory flow rate (PEFR). Special treatment of patients with this sign might reduce mortality.

Asthma↗
PubMed1977

Diurnal variation of asthma.

We have studied possible aetiological factors in the large diurnal variation in peak expiratory flow rate seen in some asthmatics. This phenomenon occurred in both atopic and non-atopic patients. It could not be attributed to recumbency in bed at night or to allergy to the house dust mite in bedding. Circadian variation in asthmatic shift workers was intimately related to sleep and virtually independent of solar time. Treatment tends to lose its effect as it is discontinued during sleep and this increases the apparent diurnal variation in many patients. Excessive circadian variation may be an important factor in sudden asthma deaths. The importance of effective nocturnal medication is stressed.

Asthma↗
PubMed1977

Do sympathomimetic amines prevent exercise-induced asthma by bronchodilatation alone?

Seventeen patients with exercise-induced asthma were studied. Eleven patients (cases 7-17), of whom seven were atopic subjects, were given isoetharine or isoprenaline and were subsequently tested for exercise-induced asthma after bronchodilatation had ceased. In two atopic and one non-atopic patients protection was observed which could not be attributed to chance. Two of these three patients were studied again and this phenomenon was repeatable. Prevention of exercise-induced asthma 30 min after inhalation of isoetherine and sodium cromoglycate was compared in 10 patients (cases 1-10), of whom six were atopic subjects. There was no significant difference in the results and protection from isoetharine was not related to the magnitude of its bronchodilator effect. These results suggest that beta-adrenergic agonists may have both bronchodilator and other actions in exercise-iduced asthma. Whether these other actions are anti-alergic is unknown.

Adolescent↗
PubMed1977

Comparison of salbutamol Rotahaler with conventional pressurized aerosol.

Salbutamol in a powder aerosol from the Rotahaler insufflator was compared, with equal doses of the conventional pressurized aerosol by dose-response curves and in a 1 month open trial, in the treatment of asthma patients with good inhalation technique. Results were not significantly different in either study. A further group of asthma patients, who were known to be incapable of using pressurized aerosols effectively, were shown to benefit from treatment with the Rotahaler. This device should increase the value of the sympathomimetic drugs to the minority of asthma patients who cannot use conventional aerosols correctly.

Administration, Intranasal↗
PubMed1977

Physiological patterns in early morning asthma.

Sixteen asthmatic patients who regularly showed early morning falls in peak expiratory flow rate of more than 25% were studied at 06.00 hours and 14.00 hours. At 06.00 hours considerable deterioration in static lung volumes and airways resistance occurred which was typical of an attack of acute asthma. Blood gas analysis showed less variation, with mild hypoxia and a wide alveolar-arterial oxygen tension gradient throughout the study. Diurnal variation was also seen in the response of maximal mid expiratory flow rates to the inhalation of helium/oxygen mixture in seven patients, but another seven were consistently non-responders. The overall pattern of results suggests that the calibre of both large and small airways decreased at night but improvement was more complete in large airways during the day. Despite these findings patients had few symptoms at 06.00 hours when most of them showed marked reversibility after inhaling aerosol salbutamol. This phenomenon might account for the sudden nature of some asthma deaths as these often occur in the early morning. If this is the case, the minority of patients whose early morning decline in lung function was not immediately reversible would appear to be at greatest risk.

Adult↗
PubMedDate not supplied

Metabolic oxidation phenotypes as markers for susceptibility to lung cancer.

That bronchial carcinoma is not an inevitable consequence of cigarette smoking has stimulated the search for host factors that might influence the susceptibility of the individual smoker. One plausible host factor would be a polymorphic gene controlling the metabolic oxidative activation of chemical carcinogens, giving rise to wide inter-subject variation in the generation of cancer-inducing and/or promoting species. Recently, three genetic polymorphisms of human metabolic oxidation have been demonstrated (as characterized by debrisoquine, mephenytoin and carbocysteine), with the metabolism of several substrates exhibiting the phenomenon. Debrisoquine 4-hydroxylation segregates into two human phenotypes, each comprising characteristic metabolic capability. We report here the frequency of debrisoquine 4-hydroxylation phenotypes in age-, sex- and smoking history-matched bronchial carcinoma and control patients. Cancer patients showed a preponderance of probable homozygous dominant extensive metabolizers (78.8%) with few recessive poor metabolizers (1.6%) compared with smoking controls (27.8% and 9.0% respectively). We conclude that the gene controlling debrisoquine 4-hydroxylation may be a host genetic determinant of susceptibility to lung cancer in smokers and that it represents a marker to assist in assessing individual risk.

Carcinoma, Bronchogenic↗