Respiratory function in the upright, working diver at 6.8 ATA (190 fsw)

Area of Science:

• Physiology
• Diving Medicine
• Respiratory Mechanics

Background:

• Static lung loading can affect respiratory function during exercise.
• Diving environments present unique challenges to respiratory control.
• Understanding these effects is crucial for diver safety and performance.

Purpose of the Study:

• To investigate the influence of static lung loading on respiratory parameters during graded leg exercise in divers.
• To compare the effects of static lung loading in upright versus prone postures.
• To determine optimal breathing system settings for diver comfort and safety.

Main Methods:

• Subjects performed graded leg exercise in an upright posture while submerged and breathing air at pressures up to 6.76 ATA.
• Static lung loads (neutral, positive, negative) were applied.
• Respiratory parameters and dyspnea were monitored.
• Data were compared to previous studies in the prone posture.

Main Results:

• Less dyspnea was observed in the upright posture compared to the prone posture.
• Neutral and moderately positive static lung loads reduced dyspnea compared to negative loads.
• Respiratory function indices remained largely normal, but hypoventilation and CO2 accumulation occurred during heavy exercise at 190 fsw.
• Dyspnea and static lung load did not strictly correlate with hypoventilation.

Conclusions:

• Breathing gear for divers using a full face mask should provide a static lung load of approximately 0 to +10 cmH2O.
• An upright posture is recommended for divers during strenuous activity to minimize dyspnea.
• Divers may experience hypoventilation at depth regardless of static lung load or dyspnea, necessitating careful monitoring.