What Researchers Did
Researchers studied how the heart performed in six individuals simulating breath-hold dives to 20 meters in a hyperbaric chamber, both while submerged and not submerged.
What They Found
Breath holding at a large lung volume decreased the heart's pumping ability (cardiac index). However, during simulated dives, the cardiac index increased by 35.1% in nonsubmerged conditions and 29.5% when submerged, compared to breath holding at the surface. Overall, the heart's performance during these dives remained similar to surface levels. Submerged diving showed a smaller drop in chest pressure but more blood pooling in the chest, potentially reducing the risk of thoracic squeeze but increasing the risk of overloading the central circulation.
Canadian Relevance
No direct Canadian connection identified. This study is not by Canadian authors, nor does it cover a Health Canada-recognised indication for therapeutic hyperbaric oxygen treatment.
Study Limitations
The study involved a very small group of only six subjects, which limits how broadly the findings can be applied.