Resting β-Adrenergic Blockade Does Not Alter Exercise Thermoregulation in Children With Burn Injury: A Randomized
Eric Rivas1,2,3, Serina J McEntire, David N Herndon1,2
1Shriners Hospitals for Children, Galveston, TX.
Summary
Propranolol, a beta-blocker, did not increase heat illness risk in burned children during exercise. However, severe burn injuries independently suppressed cardiac function, leading to exercise intolerance in these children.
Area of Science:
- Pediatric Medicine
- Exercise Physiology
- Burn Rehabilitation
Background:
- Propranolol is frequently prescribed to burned children.
- The combined effects of propranolol and exercise-heat stress on burned children's thermoregulation and exercise capacity are not well understood.
- Burn injuries can impact cardiovascular function and exercise tolerance.
Purpose of the Study:
- To investigate if propranolol combined with exercise-heat stress increases the risk of heat illness and exercise intolerance in burned children.
- To compare the physiological responses of burned children receiving propranolol, burned children receiving placebo, and nonburned children during exercise in hot conditions.
Main Methods:
- A randomized, double-blind study involving 20 burned children (10 receiving propranolol, 10 receiving placebo) and a control group of nonburned children.
- Participants exercised in hot conditions (34.3°C, 26% RH) at 75% of their peak aerobic capacity.
- Measurements included core and skin temperatures, heat loss, thermal conductance, physiological strain index, exercise duration, and cardiac function metrics.
Main Results:
- No significant differences were observed in core or skin temperatures, heat loss, thermal conductance, or physiological strain index among the groups.
- Burned children, regardless of propranolol treatment, exercised for shorter durations and had lower calculated exercise tolerance indices compared to nonburned children.
- Burned children exhibited lower peak heart rates and higher relative cardiac work rates during exercise, indicating suppressed cardiac function independent of propranolol.
Conclusions:
- Resting beta-adrenergic blockade with propranolol does not appear to affect the thermoregulation of burned children exercising at similar relative intensities in the heat.
- Independent of propranolol, suppressed cardiac function in children with severe burn injuries may contribute to exercise intolerance.
- Further research is needed to understand the long-term implications of altered cardiac function on the physical rehabilitation of burned children.
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