Contribution of hyperoxia to reduced pulmonary function after deep saturation dives

Area of Science:

• Physiology
• Diving Medicine
• Pulmonary Function Testing

Background:

• Saturation diving involves prolonged exposure to increased ambient pressure.
• Previous studies suggest deep saturation dives can impact pulmonary function.
• The role of elevated oxygen partial pressure (PO2) in these changes requires further investigation.

Purpose of the Study:

• To assess the effects of a 28-day saturation dive with controlled PO2 on pulmonary function.
• To determine if elevated PO2 contributes to observed pulmonary function changes in divers.

Main Methods:

• Eight subjects underwent a 28-day saturation dive to 0.25 MPa with varying PO2.
• Pulmonary function tests included lung volumes, flows, carbon monoxide transfer factor (TLCO), and exercise tests.
• A control group (six subjects) dived to 0.15 MPa with a constant PO2 of 21 kPa.

Main Results:

• A significant reduction in TLCO (9.8%) and peak oxygen uptake (10.1%) was observed post-dive.
• Forced midexpiratory flow rate also decreased significantly (9.8%).
• No significant changes in lung function were noted after the control dive.

Conclusions:

• Elevated PO2 during saturation diving significantly contributes to pulmonary function impairment.
• TLCO is a more sensitive indicator of oxygen toxicity than vital capacity.
• These findings have implications for understanding and mitigating risks in deep saturation diving.