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Biomedical subjects

D J Hendrick

Publications and source records attributed to D J Hendrick.

At least 19 recordsLinked to original sources
PubMed2005

Relation of expired carbon monoxide to smoking history, lapsed time, TLCO measurement and passive smoking.

We quantified the influence of lapsed time, measurement of gas-transfer factor (TLCO), and passive smoking on expired carbon monoxide (CO) levels, and then evaluated the accuracy of smoking histories against expired CO measurements in patients newly attending 'occupational' compared with 'general' chest clinics. Expired CO levels had an estimated average rate of decline of 3.4 ppm/h in the presumed absence of further smoking, though individual rates depended necessarily on the initial levels (2.1, 3.9, 5.7 and 7.5 ppm/h, respectively, when the initial levels were 10, 20, 30 and 40 ppm). TLCO measurement was associated with a median increase in expired CO of 4.0 ppm, but passive exposure to tobacco smoke in non-smokers had negligible effect. Expired CO levels indicative of current smoking (> 8 ppm) were noted much more commonly in the current cigarette smokers (88%) than those who claimed to be current non-smokers (6.0%), but without significant difference between the non-smokers attending the occupational and general clinics (6.6% vs 5.3%). We conclude that the lapse of 1 h and the measurement of TLCO exert mild but important influences on the expired CO level, but that passive smoking does not. 'Occupational' and 'general' patients give similarly false declarations of current non-smoking when presenting initially for clinical evaluation.

Adult↗
PubMed2002

Apparent but not real increase in asthma prevalence during the 1990s.

The authors investigated changes in asthma prevalence and perception of bronchoconstriction over 6 yrs in adults of Newcastle-upon-Tyne. Postal questionnaires were sent to 6,000 subjects aged 20-44 yrs in 1992-1993 and 1998-1999. Random samples of 600 responders had assessments of atopy, airway responsiveness, and their ability to perceive methacholine-induced bronchoconstriction. The prevalences of asthmatic symptoms, physician-diagnosis, and medication use increased by an average of 4.4%, particularly in subjects aged <30 yrs (8.7 versus 2.7). Atopy prevalence increased from 25% to 31% but atopics and nonatopics had similar mean changes in questionnaire data (5.2 versus 3.4). The probability of a positive methacholine test decreased as did the mean methacholine dose/response slope (0.00527 to 0.00379), indicating lower levels of airway responsiveness. This can be largely explained by an increase in use of inhaled corticosteroids (5.0-9.3%). The proportion of subjects perceiving bronchoconstriction during methacholine tests increased from 63 to 77%. The authors conclude that current changes in asthma epidemiology in adults may result from increased awareness of symptoms (and/or an increased willingness to report them), and from an increased willingness of physicians to make the diagnosis and prescribe treatment, not from increased disease prevalence.

Adolescent↗
PubMed2001

Asthmagenicity of coal mine roof-bolting resins: an assessment using inhalation provocation tests.

Inhalation provocation tests were used to assess whether the volatile products of an activated resin had caused occupational asthma in a non-random sample of six asthmatic coal miners. The resin system uses the polymerization of polyester and styrene under the influence of the cross-linking agent dibenzoyl peroxide to secure roof, wall and floor bolts in mine tunnels. The tests were conducted sequentially in a double-blind fashion over a 'dose' range which extended just beyond the maximum likely to have been experienced occupationally during a single day's work. The tests were monitored by symptoms, changes in the forced expiratory volume in 1 s (FEV1) and changes in airway responsiveness. All subjects completed the series of tests without any significant decrements in FEV1 or significant increases in airway responsiveness. We conclude that the use of this resin system is not likely to have been the cause of the asthma in the test subjects, nor in the larger group of miners of which they were a sample, but neither possibility is fully excluded and the participants may not have been adequately representative of other asthmatic coal miners.

Asthma↗
PubMed2000

Effect of inhaled fluticasone propionate on airway responsiveness in treatment-naive individuals--a lesser benefit in females.

A randomized double-blind placebo-controlled parallel group study with inhaled fluticasone propionate over 6 weeks, designed to quantify the beneficial effect on airway responsiveness, and so assess whether short pulses of intermittent prophylactic treatment might serve as an alternative means of managing mild asthma, is reported. The 20-50-yr-old participants, who were recruited from an epidemiological study of the general population, had never knowingly received any regular treatment for asthma. Fluticasone propionate at the maximum recommended dose level (2,000 microg daily) and placebo were administered via metered-dose inhalers, and airway responsiveness was quantified conventionally by the provocative dose of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1) (PD20) at 2-week intervals during the treatment phase and at various intervals subsequently. Compared with placebo fluticasone propionate was associated with a highly significant decrease in airway responsiveness (1.9 doublings of the geometric mean PD20), which was maximal at the end of the 6-week treatment period. No persisting benefit was detectable at the next measurement 2 weeks later, or thereafter. Multiple linear regression analysis showed that the magnitude of the fluticasone propionate effect was significantly greater in males than in females (3.2 versus 1.2 doublings respectively of the geometric mean PD20), but was uninfluenced by current smoking, age or FEV1. In conclusion, in the absence of any possibility of tachyphylaxis, inhaled fluticasone propionate at this dose causes a steadily increasing improvement in airway responsiveness over a 6-week period, which is modified by sex but lost almost immediately on treatment cessation. Short pulses of intermittent prophylactic treatment would not, therefore, be useful as a means of managing mild asthma.

Administration, Inhalation↗
PubMed1999

A confidential enquiry into certified asthma deaths in the North of England, 1994-96: influence of co-morbidity and diagnostic inaccuracy.

To understand more fully the nature of events leading to asthmatic death, we conducted a confidential enquiry prospectively throughout 1994-96 among the surviving relatives and respective general practitioners of subjects whose deaths could be attributed to asthma, whether wholly or partly. We also reviewed relevant hospital records and autopsy reports, and we submitted all the gathered information to an enquiry panel for evaluation. The subjects were identified from death certificates issued in five districts of the Northern Health Region of England (population 1 million) on which asthma was recorded as the primary cause of death. The enquiry panel agreed that asthma had been a critical factor in causing death in only 33 of the 79 certified cases for which there were sufficient data. The level of concordance was substantially greater for subjects aged < 65 years (76%) than for those who were older (17%). In 16 of the 33 cases asthma alone appeared to be responsible for death, but in 17 cases a wide variety of additional, co-morbid, disorders appeared to have contributed. They included, during the 24 h preceding death, gastric aspiration, septicaemia, a single dose of a beta-blocker, the abuse of organic solvents or illicit drugs and possibly, an inadvertent exposure to horse allergen. More chronic causes of co-morbidity included ischaemic heart disease, chronic obstructive pulmonary disease (COPD), thoracic cage deformity and alcohol abuse. There were possible errors of judgement in two cases by the supervising physician (6%) and in three cases by the patient (9%). Poor compliance and psychosocial disruption probably exerted an additional adverse influence in nine cases (27%). We conclude: (1) that asthma death certification in subjects aged 65 years or more is very unreliable, (2) that for approximately half of the deaths in which asthma exerted a critical role there were critical co-morbid disorders and (3) that errors of judgement, poor compliance, or psychosocial disruption are likely to have exerted an additional adverse influence in an important minority of cases.

Adolescent↗
PubMed1999

Asthma precipitated by cessation of lithium treatment.

We report symptomatic asthma, associated with objective and highly significant increases in both airway responsiveness and airflow limitation, presenting de novo in a male patient 6 weeks after suddenly discontinuing lithium carbonate therapy.

Adult↗
PubMed1998

Adverse effects of a single dose of (+)-sotalol in patients with mild stable asthma.

AIMS: To investigate the effect of (+)-sotalol, which is not thought to possess clinically significant beta-adrenoceptor blocking activity, on airway responsiveness in subjects with mild asthma. METHODS: A placebo controlled, double-blind, single dose, cross over study, evaluating the effects of oral (+)-sotalol 300 mg and oral (+/-)-sotalol 240 mg, on airway responsiveness, FEV1, and heart rate in 18 asthmatic volunteers with quantifiable levels of airway responsiveness. RESULTS: Compared with placebo, (+)-sotalol induced a significant increase in airway responsiveness, and a significant decrease in FEV1, but there was no significant change in heart rate. Following (+/-)-sotalol there was no significant effect on airway responsiveness, but there were significant decreases in FEV1 and heart rate. In one subject both (+)-sotalol and (+/-)-sotalol provoked a 49% decrement in FEV1, and in another there were decrements of 20% and 18%, respectively. CONCLUSIONS: Despite theoretical considerations, it cannot be assumed that (+)-sotalol is safe in patients with asthma.

Adolescent↗
PubMed1998

Age-dependent inaccuracy of asthma death certification in Northern England, 1991-1992.

Asthma mortality appeared to increase two-fold in the UK from the mid- 1970s to the early 1990s, but there is evidence of inaccuracy in asthma death certification and so a region-wide investigation was undertaken to assess whether this recorded statistical trend might have been partly or wholly artefactual. A total of 35 respiratory physicians, distributed in panels of three, systemically reviewed the hospital and general practice records of 210 subjects with physician-diagnosed asthma who died in 1991 and 1992. The death certificates indicated that asthma was considered to be the primary cause of death in 103 (group 1), a contributory cause in 70 (group 2) and not relevant in 37 (group 3). There was agreement within the panels that 43% of the subjects had probably never suffered from asthma. Discordance between the panels and the certifying physicians over the correct death certification category was high for group 1 (45% for those aged <65 yrs, 75% for those aged > or =65 yrs and 64% overall) and group 2 (67%), but much less for group 3 (22%). This study concludes that asthma death certification provides a markedly inaccurate picture of asthma mortality, particularly in elderly subjects. Thus, it is speculated that if the magnitude of this source of inaccuracy has increased over the last two decades, the apparent recent increase in asthma mortality may be largely artefactual.

Aged↗
PubMed1998

Perception of respiratory symptoms after methacholine-induced bronchoconstriction in a general population.

In an epidemiological study, methacholine-induced bronchoconstriction was used as a physical illustration of the sensations associated with asthma. The objective of this study was to assess whether familiarity with these sensations could be used as a measure of asthma prevalence. Eight hundred and seventy six subjects aged 20-44 yrs completed a respiratory questionnaire and a measurement of airway responsiveness (the provocative dose of methacholine causing a 20% fall in forced expiratory volume in one second (PD20)). Subjects were asked about their perception of, familiarity with and description of the respiratory sensations experienced at the time of maximal bronchoconstriction. The questionnaire-derived lifetime prevalences of wheeze, chest tightness and undue breathlessness were 43, 35 and 22% respectively. Asthma medication was used by 8% and the lifetime prevalence of diagnosed asthma was 12%. Quantifiable levels of airway responsiveness were measured in 34%, and airway responsiveness in the range considered to be consistent with untreated active asthma was present in 21%. Bronchoconstriction was perceived by 59%. Perception of bronchoconstriction was associated with the magnitude of bronchoconstriction, younger age, female sex and questionnaire-reported symptoms. Of subjects able to perceive bronchoconstriction, 58% reported previous experience of (familiarity with) the associated respiratory sensations. Familiarity with the sensations of bronchoconstriction was associated with questionnaire-reported symptoms, diagnosed asthma and increasing levels of airway responsiveness. There was poor agreement between the respiratory symptoms reported by questionnaire before the methacholine test and the words used to describe respiratory sensations induced by the test. Familiarity with the sensations of methacholine-induced bronchoconstriction has all the appropriate associations of a measure of asthma prevalence and may be a useful adjunct to symptom questionnaires and airway responsiveness measurements in epidemiological studies. A sizeable number of subjects can be identified with intermediate levels of airway responsiveness, who are able to perceive bronchoconstriction and are familiar with the sensations associated with it, yet who are not recognized to suffer from asthma.

Adult↗
PubMed1997

Occupational asthma due to porcine pancreatic amylase.

A case of occupational asthma in a 41 year old histopathology laboratory technician attributable to a powder preparation of the porcine pancreatic enzyme amylase is reported. The diagnosis was confirmed by a double blind, placebo controlled, inhalation challenge study which showed immediate and late asthmatic reactions associated with a significant increase in airway responsiveness to methacholine.

Adult↗
PubMed1997

Occupational asthma in an isothiazolinone manufacturing plant.

A chemical plant operator developed asthma five months after starting work in an isothiazolinone manufacturing plant. He described symptoms of late asthmatic reactions after work with isothiazolinone. Airway responsiveness to methacholine improved tenfold when he was removed from the plant for 18 days. A workplace challenge study then resulted in a deterioration in airway responsiveness to its earlier level and in progressive falls in forced expiratory volume in one second (FEV1) over three days at work compared with control days, indicating statistically significant late asthmatic reactions of increasing severity.

Anti-Infective Agents↗
PubMed1997

Occupational asthma due to a widely used soft solder flux not containing colophony.

A 19 year old woman presented with symptoms suggestive of occupational asthma. The causative agent was thought to be a soft solder flux, which did not contain colophony. The diagnosis was established by specific inhalation challenge tests, which demonstrated both late asthmatic reactions and short-lived increases in airway responsiveness.

Adult↗
PubMed1996

Speeds of action of single doses of formoterol and salbutamol compared with placebo in reversing methacholine-induced bronchoconstriction.

We compared the speeds of action of two doses of the long acting beta-agonist formoterol (12 micrograms and 24 micrograms) with those of salbutamol (400 micrograms) and placebo using a double-blind, randomized, cross-over study design in 16 asthmatic subjects. A methacholine test was used on four separate study days to produce a standardized degree of bronchoconstriction (a decrement in FEV1 > or = 20%) and one of the study medications as dry powder was administered immediately afterwards via an Aerolizer inhaler device. The speeds of recovery were estimated from measurements of FEV1 over the following 2-90 min. All active treatments produced significantly greater bronchodilation than placebo as early as 2 min after administration, and their peak effects within 10 min; and no significant differences were noted between them. Mean recovery times by 50% of the FEV1 decrement provoked by methacholine were significantly shorter for the active medications: 5.7 min (formoterol 24 micrograms), 6.4 min (salbutamol 400 micrograms), 10.2 min (formoterol 12 micrograms), and 53.1 min (placebo); the respective times for recovery by 80% being 18.0, 17.4, 22.1, and 83.3 min. We conclude that single doses of the dry powder formulations of all three active treatments produce rapid and effective bronchodilation. This conclusion should not, however, be extrapolated to the regular use of these medications, since differential down-regulation and tachyphylaxis may then exert an influence.

Adolescent↗