Effects of self-contained breathing apparatus on ventricular function during strenuous exercise

Area of Science:

• Cardiovascular Physiology
• Exercise Physiology
• Respiratory Physiology

Background:

• Firefighters and other professionals often use self-contained breathing apparatus (SCBA) during strenuous activity.
• Understanding the impact of SCBA on cardiovascular function is crucial for occupational safety.
• Previous research suggests increased intrathoracic pressure can affect cardiac function.

Purpose of the Study:

• To investigate left-ventricular (LV) function during strenuous exercise while using an SCBA.
• To compare LV function under SCBA conditions versus a low-resistance breathing valve.
• To determine the effects of SCBA use on cardiac output and related parameters during exercise.

Main Methods:

• Twenty healthy men performed sustained exercise (3 x 10 min) wearing fire protective equipment.
• Two breathing conditions were tested: SCBA and a low-resistance breathing valve.
• Two-dimensional echocardiography, esophageal pressure, and physiological variables were measured.

Main Results:

• SCBA use led to higher peak expiratory esophageal pressure.
• End-diastolic cavity area (EDCA) and stroke area (SA) were significantly lower with SCBA.
• Despite reduced preload (EDCA), LV end-systolic cavity area (ESCA) and contractility remained similar, but SA could not be maintained under SCBA conditions.

Conclusions:

• Increased intrathoracic pressure from SCBA reduces LV preload (EDCA).
• During strenuous exercise with heat stress, SCBA use compromises venous return, limiting the ability to maintain stroke area (SA).
• These findings highlight potential cardiovascular strain associated with SCBA use in demanding occupational settings.