DSMB Issues

diving safety

A case study of a patient who developed decompression illness following a dive in which a rapid ascent was made, missing. all decompression stops. The rapid ascent was a result of having dsmb issues: difficulties deploying a Delayed Surface Marker Buoy at depth.

The following anonymised case history is based upon a real case seen at our hyperbaric facility.  By summarising real case histories we aim to highlight some of the causes of decompression illness we see and give an idea of how dci can present and evolve following a dive.

Dive History

A diver in his 50’s had carried out a single dive to a depth of 30 metres using air. Total bottom time around 31 minutes. The dive was pleasant and uneventful up to the point of starting his ascent. To prepare for his ascent he started to deploy his delayed surface marker buoy but became entangled in it.

He then made a rapid, uncontrolled ascent to the surface, missing all required decompression stops on the way. His dive computer showed a rapid ascent and missed decompression alarm, locking out as a result. On surfacing he initially reported symptom free and was placed on oxygen and then transferred for assessment.

Examination & Treatment

On examination he was found to have brisk lower limb reflexes and reported feeling constitutionally unwell and tired. He was recompressed and on post-treatment examination a few hours later all reflexes had returned to normal, the tiredness had resolved and he reported feeling much improved.


Whilst the right thing to do, breathing oxygen as a first aid measure can mask symptoms. We have come across many cases where a diver suddenly becomes unwell after they come off oxygen and later in the evening, often when they have returned home and are some distance from recompression facilities.

Following this dive profile he was clearly at greater risk from the rapid ascent and omitted decompression and so recompression can quickly resolve any symptoms present and also prevent more serious ones developing.

The Diver Clinic

Written by  The Diver Clinic