The physiology and pathophysiology of human breath-hold diving

[trux]

Dr. Lindholm, leading freediving physiologist, published a new study (on 30th October). I guess it may interest some of you.

The physiology and pathophysiology of human breath...[J Appl Physiol. 2008] - PubMed Result

Abstract from PubMed:

This is a brief overview of physiological reactions, limitations and pathophysiological mechanisms associated with human breath-hold diving. Breath-hold duration and ability to withstand compression at depth are the two main challenges which have been overcome to an amazing degree as evidenced by the current world records in breath-hold duration at 10:12 min and depth of 214 m. The quest for even further performance enhancements continues among competitive breath-hold divers, even if absolute physiological limits are being approached as indicated by findings of pulmonary edema and alveolar haemorrhage post-dive. However, a remarkable, and so far poorly understood, variation in individual disposition for such problems exists. Mortality, connected with breath-hold diving is primarily concentrated to less well trained recreational divers and competitive spear fishermen who fall victim to hypoxia. Particularly vulnerable are probably also individuals with pre existing cardiac problems and possibly, essentially healthy divers who may have suffered severe alternobaric vertigo as a complication to inadequate pressure equilibration of the middle ears. The specific topics discussed include the diving response and its expression by the cardiovascular system which exhibits hypertension, bradycardia, oxygen conservation, arrhythmias and contraction of the spleen. The respiratory system is challenged by compression of the lungs with barotrauma of descent, intrapulmonary hemorrhage, edema and the effects of glossopharyngeal insufflation and exsufflation. Various mechanisms associated with hypoxia and loss of consciousness are discussed, including hyperventilation, ascent blackout, fasting and excessive post exercise oxygen consumption. The potential for high nitrogen pressure in the lungs to cause decompression sickness and nitrogen narcosis is also illuminated.

[trux]

And when I am at it, there are some other new studies that the APNEA.cz news feed bot added recently to the database:

Metabolic costs of foraging and the management of ...[J Exp Biol. 2008] - PubMed Result
Estimating the effect of lung collapse and pulmona...[Respir Physiol Neurobiol. 2008] - PubMed Result
IngentaConnect Cheetahs of the deep sea: deep foraging sprints in short-finned p...
IngentaConnect Heart rate and blood pressure time courses during prolonged dry a...
IngentaConnect Characteristics of the respiratory mechanical and muscle function...
SpringerLink - Journal Article
Barotraumatic orbital emphysema of rhinogenic orig...[Undersea Hyperb Med. 2008 May-Jun] - PubMed Result
SpringerLink - Journal Article
...

[hteas]

The paper "Characteristics on the Respiritory Mechanical and Muscle Function... " is really quite important. Mullins, and quite a few other divers who pack before dives, should sleep easier now. The lung expansion really doesn't have any lasting effect they were able to find.

Thanks Trux.