Breath hold diving (BHD) cannot lead to decompression illness. Is this paradigm still true today?
Another article in the DHMJ deals with the occurrence of decompression illness (DCI) in BHD. For a long time it was assumed that this only occurs in scuba diving due to the supersaturation of inert gases, but not in BHD. In recent years, however, there is increasing evidence that BHD can also lead to DCI. (N.B. The authors understand DCI to include both classic decompression syndrome (DCS) with direct exposure of tissues to gas bubbles, but also the clinical manifestation of arterial gas embolism (AGE)). A compilation of 14 relevant publications yielded a total of 44 published cases of DCI after BHD.
What is remarkable about this compilation is, first, that it supports the impression that BHD can also trigger DCI, although it has long been assumed that this is impossible because of the relatively short dive time, and second, with one exception, it did not involve extreme dives but repetitive dives to shallow to moderate depths (e.g., spearfishing). In these cases, the shallowest dive depth was just 18 m. However, all cases, except for the mentioned exception, had many repetitive dives in common, which were performed with very variable surface breaks from a few seconds up to 5-6 minutes, partly over hours. In 8 of the 14 publications a classical DCS and in 4 an AGE was suspected or diagnosed. The remaining 2 publications were more obscure in this respect.
Breath hold diving can lead to decompression illness.
This must dispel the widespread opinion that BHD does not lead to DCI. It seems that many repeated free dives can very well lead to a relevant supersaturation of the tissues with gas bubble formation, which finally manifests itself as DCS or AGE. The relatively rapid ascents to the water surface during BHD, which are performed much more rapidly than during scuba diving and without safety stops for desaturation, could also contribute to this.
Rules of conduct for practice
The mentioned articles underline the importance of the way repeated free dives are performed. Certainly, series with excessive repetitions should be avoided. Furthermore, sufficiently long surface intervals must be strongly recommended for the settlement of an "oxygen debt" and, if necessary, also for the desaturation of the tissues.
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