Human lung mechanics during water immersion

Area of Science:

• Physiology
• Pulmonary Medicine
• Environmental Health

Background:

• Understanding the physiological effects of immersion on respiratory mechanics is crucial for safety in diving and aquatic activities.
• Previous studies have indicated potential alterations in lung function due to hydrostatic pressure and body positioning during immersion.

Purpose of the Study:

• To investigate the impact of neck-deep water immersion on static and dynamic lung volumes and mechanics in healthy men.
• To assess changes in lung elastic recoil, maximum expiratory flow, and closing volumes under immersion conditions.

Main Methods:

• Measurements included lung volumes, static deflation pressure-volume curves, maximum expiratory flow-volume curves, and closing capacities.
• Five healthy men were tested standing immersed to the neck in water.
• Data were analyzed to compare lung function parameters before and during immersion.

Main Results:

• Functional residual capacity (FRC) decreased by 27% during immersion.
• Lung elastic recoil increased at high lung volumes and decreased at low lung volumes, suggesting vascular congestion.
• Maximum expiratory flow increased at high lung volumes but decreased at low lung volumes, consistent with altered recoil.
• Closing capacities remained unchanged, though some individuals showed decreased alveolar plateau slope and cardiogenic oscillations.

Conclusions:

• Neck-deep water immersion significantly alters lung volumes, particularly FRC, and affects lung mechanics.
• Hydrostatic pressure influences lung elastic recoil and expiratory flow in a volume-dependent manner.
• Despite causing volume restriction similar to chest strapping, immersion did not induce comparable changes in overall lung mechanics.