Monday, July 17, 2006

Assessing Fitness to Return to Diving after Decompression Illness

The DMAC in the UK, (The Diving Medical Advisory Committee) has the following 'Guidance' concerning the return to diving of commercial divers who have had decompression illness. These have not been updated since 1994, but appear valid for divers now. The main difference between commercial divers and sport divers is the multiday, multidive aspect of recreational diving and the ability of commercial diving to recompress immediately on the dive boat. These recommended times away from diving differ somewhat for the diving instructor, who comes under commercial regulation by the HSE directive at
http://hse.gov.uk/diving/ma1.pdf. [Thanks to Dr. John Ross for this information].
* See below for times away.

"The following minimum periods are recommended before returning to diving after decompression illness. The period begins after completion of successful treatment (there are no residual manifestations). It is stressed that these recommendations represent minima and longer lay-offs may be necessary in individual cases.

A. Limb pain, cutaneous (skin rash with severe itching), lymphatic (swelling of tissues) or non-specific (persistent headache, excessive fatigue, loss of appetite, nausea) manifestations only
i) With uncomplicated recovery: 24 hour lay-off
ii) Where there has been a recurrence or relapse requiring further recompression: 7 day layoff

B. Neurological or pulmonary manifestations:
i) Altered sensation involving the limbs only: 7 day layoff
Return to diving only after review by a diving medicine specialist
ii) Other neurological (including audiovestibular) or pulmonary manifestations: 28 day lay-off
Return to diving only after review by a diving medicine specialist

C. After an incident of pulmonary barotrauma resulting in a pneumothorax or mediastinal/subcutaneous emphysema, the diver should be assessed by a diving medicine specialist. Return to diving may be permitted, but not normally until at least 28 days following complete recovery.
In cases where there are significant residual neurological manifestations, even after repeated treatment, the diver should normally be considered unfit to dive. Return to diving should only be permitted if sanctioned by a diving medicine specialist.

Divers Alert Network has a question and answer FAQ about returning to diving after decompression illness. This link also reproduces the recommendations of the US Navy.

Lippmann and Mitchell, in the latest edition of their book, "Deeper into Diving", state that most resolved cases of decompression illness should wait at least one month before returning to diving. They feel that divers who have had CAGE (cerebral arterial gas embolism) from pulmonary barotrauma should not return to diving due to the probability of lung scarring and elevated risk of subsequent recurrence of DCI.

Others feel that return to diving depends upon the cause of the barotrauma and allow resumption of diving after three months and no evidence of air trapping upon spiral CT scan study of the lungs.

For example, if a diver has a cause for the pulmonary barotrauma, such as an emergency ascent or other breath holding rise from depth - then a resumption of diving in three months can be entertained after ascertaining that there is no air trapping as shown by functional tests (helium loop), chest x-ray or a CT scan.
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*Times away from diving

13. The recommended minimum times away from diving after successful treatment with no sequelae are:
SIMPLE DECOMPRESSION ILLNESS, LIMB PAIN, SKIN "BEND” LYMPHATIC SWELLING, FATIGUE etc
---Uncomplicated recovery 24 hours
---Recurrence/relapse requiring further recompression 7 days

NEUROLOGICAL DECOMPRESSION ILLNESS
---Altered sensation in limbs only--- 7 days
---Audiovestibular, motor---- 28 days
Other
Pulmonary decompression Illness--- 28 days
14. Because of the nature of their diving patterns and profiles and the lack of supervision, it is recommended that the time away from diving for those diving at work in the recreational sector should be longer. The Diver’s Alert Network (DAN) Website recommendations on diving layoff times for recreational divers are found at:
http://diversalertnetwork.org/medical/faq/faq.asp?faqid=137