UCSF

CARDIOVASCULAR RISK FACTORS IN CAREER FIREFIGHTERS

Background: Sudden cardiac death is the leading cause of on-duty death among career firefighters. Limited literature as to the etiology of on-duty sudden cardiac death in firefighters is available. Cardiovascular risk profiles of firefighters are similar to those of the general population. Firefighters seem not to be protected from the national obesity epidemic; and hypertension and/or hypercholesteremia are often not diagnosed, or are under treated.

Methods: Accurately assessing cardiopulmonary capacity in career firefighters is critical to duty assignment and prevention of sudden cardiac death. Eighty-three male career firefighters performed maximal exercise treadmills (per the revised 2008 Wellness-Fitness Initiative (WFI)) and direct VO2max assessments to determine the accuracy of WFI estimates of VO2max and maximal heart rate.VO2 and heart rate at ventilatory threshold and at maximal exercise were measured. They then wore Holter monitors and were asked to record their activities for 24 hours on duty. Subsequently, 63 career firefighters completed a sub-maximal exercise treadmill for comparison to the direct measure VO2max and historical estimates.

Results: The WFI maximal exercise treadmill test overestimated ~ 1.16 METs; the initial WFI sub-maximal estimation over-estimated ~ 2.23 METs; and the revised WFI sub-maximal estimation was found to accurately estimate VO2max when compared to directly measured VO2max. Maximum heart rates on duty were analyzed to determine if measured maximal heart rate, or heart rate at ventilatory threshold, were reached. About 18% exceeded their measured maximal heart rate, 51% exceeded their measured heart rate at ventilatory threshold, and 20.5% had an episode of tachycardia while on duty. The most common activity at peak 24-hour heart rate was exercising (32.5%), followed by performance drills (28.9%), pack tests (14.5%), fire suppression and overhaul (10.8%), responding to other calls (9.6%), and other (3.7%). About 90% of the participants experienced elevated heart rates while being monitored. The range of maximum METs demonstrated on duty was 4.8 to 17.0.

Implications: Excessive heart rates and work demands may contribute to cardiac compromise if there is underlying cardiovascular disease. Occupational health practitioners should advocate for accurate cardiopulmonary testing and treatment of underlying cardiovascular risk factors in career firefighters.