A CASE OF SUDDEN DEATH POSSIBLY DUE TO VAGUS INHIBITION
Authors: E. D. Telford
Journal: BMJ (1906)

<h3>OBJECTIVES</h3> To find the nature and incidence of symptoms experienced by a large sample of hospital endoscopy nurses. To find whether nurses in endoscopy units develop asthma under current working conditions in endoscopy units. To obtain analytically reliable data on exposure concentrations of glutaraldehyde (GA) vapour in endoscopy units, and to relate them to individual hygiene and work practices. To characterise any exposure-response relations between airborne GA and the occurrence of work related symptoms (WRSs). Due to the growing concern about the perceived increase in WRSs among workers regularly exposed to biocides, all of whom work within a complex multiexposure environment, a cross sectional study was designed. <h3>METHODS</h3> Current endoscopy nurses (n=348) from 59 endoscopy units within the United Kingdom and ex-employees (who had left their job for health reasons (n=18) were surveyed. Symptom questionnaires, end of session spirometry, peak flow diaries, skin prick tests (SPTs) to latex and common aeroallergens, and measurements of total immunoglobulin E (IgE) and IgE specific to GA and latex were performed. Exposure measurements included personal airborne biocide sampling for peak (during biocide changeover) and background (endoscopy room, excluding biocide changeover) concentrations. <h3>RESULTS</h3> All 18 ex-employees and 91.4% of the current nurses were primarily exposed to GA, the rest were exposed to a succinaldehyde-formaldehyde (SF) composite. Work related contact dermatitis was reported by 44% of current workers exposed to GA, 56.7% of those exposed to SF composite, and 44.4% of ex-employees. The prevalence of WRSs of the eyes, nose, and lower respiratory tract in current workers exposed to GA was 13.5%, 19.8%, and 8.5% respectively and 50%, 61.1%, and 66.6% in the ex-employees. The mean percentage predicted forced expired volume in 1 second (ppFEV<sub>1</sub>) for ex-employees (93.82, 95% confidence interval (95% CI) 88.53 to 99.11) was significantly lower (p&lt;0.01) than that of current workers exposed to GA (104.08, 95% CI 102.35 to 105.73). Occupational peak flow diaries completed by current workers with WRSs of the lower respiratory tract showed no evidence of bronchial asthma (&lt;15% variation). Six per cent of the population had positive latex SPTs. Positive indications of one GA specific IgE and 4.1% latex specific IgE occurred. There was no conformity between the latex specific IgE and positive SPTs. Positive SPTs to latex were associated with WRSs of dermatitis and ocular WRSs, but no other WRSs. Exposures were above the current maximum exposure limit (MEL) of 0.2 mg/m<sup>3</sup> (0.05 ppm) in eight of the units investigated. A significant relation existed between peak GA concentrations and work related chronic bronchitis and nasal symptoms (after adjustment for types of local ventilation) but not to other WRSs. Peak GA concentrations were significantly higher in units that used both negative pressure room and decontaminating unit ventilation. <h3>CONCLUSION</h3> This study documents a significant level of symptoms reported in the absence of objective evidence of the physiological changes associated with asthma. Ex-employees and current workers with WRSs warrant further study to elucidate the cause and mechanisms for their symptoms. Ventilation systems used for the extraction of aldehydes from the work area may be less effective than expected and due to poor design may even contribute to high peak exposures.