Are multiple dives more risky for DCS than just 1 dive?

[boulderjohn]

It took a while, but I got this reply from Emmanuel Dugrenot, senior researcher for DAN.

Thank you very much for your questions! You are probably mentioning a presentation about a study from our team (A study of decompression sickness using recorded depth-time profiles - PubMed (nih.gov)). Indeed, from that study, it seems that DCS is more likely to happen at the beginning of the trip… but we must consider these data with caution, as they are only considering declared DCS which can be more severe and far from the real number (A survey of scuba diving-related injuries and outcomes among French recreational divers - PubMed). If you also look at DCS associated with high multi day repetitive dive counts, the dive guides are more at risk as they are diving the most.

One of the hypothesis to explain that, is the micro bubble seeds from which bubbles are growing, are eliminated after the first dives, so we indeed observe a decrease in high bubble grades after the first days (Influence of repeated daily diving on decompression stress - PubMed (nih.gov)). Nevertheless, bubbles are not the only risk factor of decompression sickness, which is also highly correlated to inter and intra individual parameters like dehydration, stress and fatigue or inflammatory responses. From that, we can also easily imagine that diving really often can promote dehydration and a basal inflammatory state which on the contrary is not good.

Hoping my answer was clear, otherwise don’t hesitate to come back to me.

Best regards,

Emmanuel

 

[Kendall Raine]

Also found this study suggesting 2 minutes of mini trampoline jumping pre-dive reduced VGE. n=8 so who knows. Not as whacky as using dark chocolate as a pre-conditioning regime and certainly more effective.

Mini Trampoline, a New and Promising Way of SCUBA Diving Preconditioning to Reduce Vascular Gas Emboli? - PubMed

<span><b>Background:</b> Despite evolution in decompression algorithms, decompression illness is still an issue nowadays. Reducing vascular gas emboli (VGE) production or preserving endothelial function by other means such as diving preconditioning is of great interest. Several methods have been...

pubmed.ncbi.nlm.nih.gov

Preconditioning to Reduce Decompression Stress in Scuba Divers - PubMed

This experiment, which had the same subjects perform all control and preconditioning dives in wet but completely standardized diving conditions, demonstrates that endothelial dysfunction appears to not be solely related to VGE.Germonpré P, Balestra C. Preconditioning to reduce decompression...

pubmed.ncbi.nlm.nih.gov

 

[dmaziuk]

Also found this study suggesting 2 minutes of mini trampoline jumping pre-dive reduced VGE. n=8 so who knows. Not as whacky as using dark chocolate as a pre-conditioning regime and certainly more effective.

Oi! I resemble that remark! Google "endothelial protection dark chocolate" and be enlightened: there is at least one article in PubMed specific to diving, but plenty other studies of effect of cocoa flavonoids on endothelial function -- including inflammatory response which is what presumably nitrogen bubbles cause. I my chocolate and I'll take if over 99 Surfing GrapeFruits any day.

 

[Kendall Raine]

Oi! I resemble that remark! Google "endothelial protection dark chocolate" and be enlightened: there is at least one article in PubMed specific to diving, but plenty other studies of effect of cocoa flavonoids on endothelial function -- including inflammatory response which is what presumably nitrogen bubbles cause. I my chocolate and I'll take if over 99 Surfing GrapeFruits any day.

Excellent! Go for it. Note, however, that dark chocolate did not seem to reduce reduce VGE. But anything that reduces inflammation is good.

 

[Johnoly]

Excellent! Go for it.

Agree with @Kendall Raine . The US Navy has tried every whacked crazy idea to reduce DCS/injury/etc in diving over the past century. They are not giving navy seals dark chocolate. But do your own independent testing and maybe you'll find something.

 

[kissonerga.ccr]

Also found this study suggesting 2 minutes of mini trampoline jumping pre-dive reduced VGE. n=8 so who knows. Not as whacky as using dark chocolate as a pre-conditioning regime and certainly more effective.

Mini Trampoline, a New and Promising Way of SCUBA Diving Preconditioning to Reduce Vascular Gas Emboli? - PubMed

<span><b>Background:</b> Despite evolution in decompression algorithms, decompression illness is still an issue nowadays. Reducing vascular gas emboli (VGE) production or preserving endothelial function by other means such as diving preconditioning is of great interest. Several methods have been...

pubmed.ncbi.nlm.nih.gov

Preconditioning to Reduce Decompression Stress in Scuba Divers - PubMed

This experiment, which had the same subjects perform all control and preconditioning dives in wet but completely standardized diving conditions, demonstrates that endothelial dysfunction appears to not be solely related to VGE.Germonpré P, Balestra C. Preconditioning to reduce decompression...

pubmed.ncbi.nlm.nih.gov

Wow. Mini-trampoline, eh? Got to love science. From now on, I‘ll have strong bias in favor of dive shops that make these available as standard equipment. That, and dark chocolate!

One thing not quite clear from the study is whether jumps must be performed fully geared up. If so, then how to best secure stage tanks to the jumping diver, and whether BM is better than SM. Also, would synchronous jumping by a dive team produce better results. So much more to investigate