Diagnosing Decompression Illness


There are many possible causes for symptoms that are also attributable to decompression illness; a physician should rule those out before prescribing hyperbaric treatment.


A 49-year-old female certified recreational scuba diver called the DAN® Emergency Hotline from George Town, Grand Cayman, around noon on a February day. She was experiencing a sudden, intense and sharp abdominal and back pain that had started 12 hours after her last dive, which had been on the previous day. That dive had been the third of a single-day series of mild, recreational repetitive scuba dives on air with no mandatory decompression stops. She had proper safety stops with the first two dives and maintained adequate surface intervals between all three dives.

Her dives had been uneventful until the last one, when she ran out of air after being at 32 feet for approximately 30 minutes. She had not been paying close attention to her air gauge and had to perform an emergency controlled ascent to the surface. Her buddy was too far away, so she ascended without any assistance. The diver likely started the dive with a half-empty cylinder by mistake.

She denied having any other symptoms, including skin discoloration, limb or joint pain, or any perceivable neurological deficit. She had no relevant past medical history, specifically of genitourinary disease, hypertension or other cardiological or vascular diseases.

Regarding the sudden onset of a severe pain 12 hours postdive and a relatively long stay at a shallow depth before the last ascent, the diagnosis of decompression illness (DCI) was not the first choice, although it couldn't be excluded. With limited information available, the acute abdomen and possible acute cardiac condition (heart attack) had to be excluded. The acute pain in the abdomen could be caused by the following:
  • an abdominal aortic aneurism, which is an abnormal and dangerous dilatation of the main artery that takes blood to the entire lower half of the body and puts the person at risk of fatal internal bleeding if this artery ruptures
  • a gynecological or urinary event such as a miscarriage or a severe urinary infection

The DAN medic who took the call explained the possibility of DCI as well as the other conditions.

The general recommendations for this diver were to seek further care at the closest hospital emergency room (ER) and to hydrate and get oxygen in the meantime. At the local ER she received an initial assessment, laboratory tests and a physical examination, with particular attention to neurological function. We do not know the extent of her abdominal examination. She had no positive findings except for the nonspecific abdominal pain. While not producing any new conclusive information, the examination and test results led the medical team to a clinical diagnosis of possible DCI. The hospital staff quickly moved her to the hospital's hyperbaric chamber to start immediate treatment with a U.S. Navy Treatment Table 6 recompression protocol.

Her pain lessened during the chamber treatment but worsened immediately afterward. The hospital team reassessed the diver and found an abdominal rigidity upon palpation; imaging showed an intestinal obstruction. The diver had surgery to remove the small damaged part of her intestine. She recovered well and returned home to the U.S. a few days later. She had no significant repercussions that interfered with her general health or her return to scuba diving after an extended recovery period.

In most cases, DCI has no specific and exclusive symptom and can be a diagnosis of exclusion. We first have to rule out all other possible causes, especially serious conditions that need other immediate intervention, before deciding to treat the diver with recompression in a hyperbaric chamber. The findings of a serious medical condition will change from its initial presentation, and symptoms and clinical conditions can change in a matter of hours, demanding a reassessment of the possible diagnoses and recommended treatments.

That's why in the event of a suspected dive accident divers should always go to the nearest medical facility and not directly to a hyperbaric chamber. Divers and ER staff should keep in mind that divers can have other health problems not directly related to diving, as this case illustrates. The examination should be directed with usual clinical leads like symptoms, signs and previous medical history. In the case of abdominal pain, an acute abdomen should always be excluded. This diver could have experienced this same obstruction and pain while hiking in the woods or working in an office. Fixating only on a dive-related diagnosis has resulted in delays in obtaining a correct diagnosis and proper treatment.

It is difficult to diagnose a patient over the phone, especially in cases of something that requires an evaluation to exclude a life-threatening possibility. If you call the DAN Emergency Hotline, our medics can help you understand what is happening and assist you in getting the help that you need, wherever you are.

© Alert Diver — Q2 2020