August 1999 newsletter

Inner and middle ear barotrauma

A description of three cases of aural barotrauma and subsequent literature review. The authors conclude that it may be safe for divers to resume careful diving in contradiction to previously published advice. They describe the three mechanisms of damage which include haemorrhage, tear of the labyrinth or lymphatic fistula. Only the fistula requires surgical repair.

Sheridan MF, Hetherington HH, Hull JJ. Ear Nose Throat J 1999;78(3):181-7

Arterial gas embolism

This is the first published confirmation of paradoxical gas embolism through a patent foramen ovale and the detection of gas embolism within the cerebral circulation detected by transcranial Doppler ultrasound. This confirms what many have suspected but as yet have not proved. It is also consistent with other recent studies showing hyperintense white matter lesions in the brain on MRI scanning in divers with neurological decompression sickness although this also requires confirmation. The MRI findings have yet to be correlated with clinically significant abnormalities and so far have not been associated with changes in EEG, neurological or psychological function.

Ries S, Knauth M, Kern R, Klingmann C, Daffertshofer M, Sartor K, Hennerici M. Neurology 1999;52(2):401-4 and
Sipinen SA, Ahovuo J, Halonen JP. Undersea Hyperbaric Med 1999;26(2):61-5

Long term safety of diving

This study examined neuropsychological function in experienced commerical divers who had not performed saturation diving and compared their performance to much less experienced divers and also to construction workers. The 20 experienced divers had performed on average 4000 dives each (range 450 to 13,200) and had been diving for 18 years (range 5 to 33). There was no significant difference between the two groups in terms of neuropsychological function but a slightly prolonged reaction time was shown.

Bast-Pettersen R. Aviat Spac Envir Med 1999;70:52-7

Review of diving accidents at Leicester

A summary of the 25 cases seen in five years in Leicester with descriptions of those requiring recompression. The factors commonly associated with presentation included uncontrolled or fast ascents, cold water, poor visibility and inexperience. There were 7 deaths in this group.

Hart A, White S, Conboy P, Bodiwala G, Quinton D. J Accid Emerg Med 1999;16(3):198-200

Outcome after neurological DCI

The authors apply a previously published scoring system retrospectively to 217 cases of neurological decompression illness from the British Hyperbaric Association database of incidents. Factors predicting poor outcome after recompression included repetitive dives, clinical status before recompression, objective sensory or motor deficits and loss of voluntary bladder control. While this is not the prospective study required for full validation there was good correlation of predictive score and outcome in this separate population.

Boussuges A, Thirion X, Blanc P, Molenat F, Sainty JM. Undersea Hyperbaric Med 1996;23(3):151-5
Pitkin AD, Benton PJ, Broome JR. Aviat Space Environ Med 1999;70(5):517-21