Acute cardiovascular changes following heat exposure during simulated shipboard firefighting

Area of Science:

• Cardiovascular Physiology
• Occupational Health
• Emergency Medicine

Background:

• Shipboard firefighting presents unique cardiovascular stress due to extreme exertion and lack of experience.
• Sudden cardiac death is a concern in firefighters, but shipboard responses are undescribed.

Purpose of the Study:

• Investigate acute cardiac, macrovascular, and microvascular responses to simulated shipboard firefighting.
• Characterize cardiovascular strain and impairment following this demanding activity.

Main Methods:

• Nineteen participants completed a simulated shipboard firefighting protocol (SBFFP) with physical tasks.
• Measurements included echocardiography, blood pressure, subendocardial viability ratio (SEVR), and reactive hyperemia index (RHI) pre, post, and 1-hour post-protocol.

Main Results:

• Immediately post-SBFFP, decreases were observed in left ventricular dimensions, brachial systolic blood pressure, SEVR, and RHI.
• Ventricular fractional shortening increased significantly.
• Most metrics returned to baseline after 1 hour, except for a persistent decrease in SEVR.

Conclusions:

• Simulated shipboard firefighting induces acute cardiovascular strain and temporary impairment.
• Persistent reduction in SEVR suggests potential mechanisms for increased cardiac event risk post-firefighting.