Characteristics of occupational medicine practitioners and practice in Canada.

To obtain baseline information with respect to occupational medicine practice in Canada, a questionnaire survey of members of the Occupational and Environmental Medical Association of Canada was carried out by mail in 1993. One hundred eighty-six responses were received (56% of the membership). The average age of the respondents was 49.5, 12% were female, and 55% worked full-time in occupational medicine. Practice types included corporate settings (58%), clinics (23%), government agencies (14%), worker's compensation boards (7%) and academic settings (5%). Sixty percent had some formal training in occupational medicine, and 46% had occupational medicine certification by either the Royal College of Physicians and Surgeons of Canada, the Canadian Board of Occupational Medicine, or the American Board of Preventive Medicine. Younger physicians were more likely to be female and have gone directly into occupational medicine. Women were more likely to be working full-time in occupational medicine but worked fewer hours per week. Those physicians with specialty qualifications were older and more likely to be working full-time in occupational medicine and be active in professional activities. The Association intends to continue surveying its members on a triennial basis, identifying trends in the practice profiles and continuing education needs.

Workers' compensation claims: hidden agendas.

Successful management of compensable occupational disorders requires an understanding of both the medical and social models of illness. In addition to the usual roles of medical diagnosis and treatment, the physician must assume a number of hidden roles, including assessing job hazards, arriving at an opinion of work-relatedness, identifying unrealistic expectations and factors that may delay recovery, and identifying as early as possible when vocational rehabilitation is necessary. As a central member of the claims management team, the practising physician can contribute meaningfully to the employee's successful return to the work-force.

Respiratory neuromuscular output during breath holding.

The involuntary respiratory muscle contractions that occur during breath holding were found in almost all of 52 subjects and were regular in a majority. In detailed studies, subjects rebreathed a mixture of 8% CO2 in O2 and then held their breath on an occluded mouthpiece, with glottis open, at functional residual capacity. Contractions monitored as waves of negative pressure were reproducible and increased in amplitude and frequency through the breath hold, but the breakpoint did not always correspond to the same pressure or frequency. Frequency and the time derivative of pressure (dP/dt) of contractions were much higher during breath holding than frequency of breathing and dP/dt of occluded breaths at the same gas tensions during rebreathing. Contractions were reduced in amplitude after the subject took three breaths without altering gas tensions. The results are consistent with the hypothesis that contractions contribute to dyspnea in breath breath holding, but there is not a simple correlation between their magnitude and the degree of dyspnea.