Swimming induced pulmonary edema (SIPE)


SIPE, which is also known as Immersion Pulmonary Edema, has been occasionally reported during the last two decades. It may affect scuba divers, breath-hold divers and swimmers. The incidence of SIPE is probably underestimated, because mild cases may resolve on their own and the most severe cases may be mistaken for drowning or cardiac-related death. Two recent papers present three documented and unusual cases of SIPE.

Case 1

A 33-year-old healthy military diver was immersed for 10 minutes in 50 F (10 C) while wearing a 5 mm neoprene wetsuit. After two breath-hold dives to 18 ft (6 m) for 0.5-1 min duration with a surface interval of 1 min, he noted wheezing and coughed pink, frothy sputum. At admission to a hospital, he had already improved but imaging of his lungs showed obvious signs of SIPE. This was an unusually short exposure, shallow dive and quick onset of symptoms.1

Case 2

A 46-year-old man was spearfishing in 5 m of water in a 5 mm neoprene wetsuit. He did not report feeling cold, although the water was 57.2 F (14 C).While swimming back to shore against strong current for only two minutes, he suddenly felt such respiratory distress that he could not call for help or swim. His wife brought him back to shore; he was unconscious. He recovered in a few hours and was discharged from the hospital after three days.2

Case 3

A 48-year-old man was performing an 800-m swim test. The day before, during the same exercise he reported becoming severely breathless, but recovered within a short period of time. On his next attempt, he had to swim 500 m with a snorkel while wearing his complete scuba equipment. After 250 m his buddy discovered he was unconscious and sinking. An emergency medical team responded quickly and properly, but he was in a coma when admitted to a hospital where he was kept in artificially induced protective hypothermia (the initial diagnosis was cardio-circulatory arrest and drowning).2

In all three cases, the victims recover – some sooner, others later. Medical causes, except hypertension in the first case, could not be identified; all victims appeared to be in normal health, except for the findings of lung edema.

The lesson learned is that SIPE may occur suddenly and be very severe. It can be life threatening while in water and it may require intensive care to recover. The apparently low incidence of SIPE may be due to misidentification of some fatalities as a cardiac-related death instead of SIPE.

Authors suggest two major points to prevent SIPE and fatal outcome in case of it:

  •  Do not struggle against a strong current; maintaining a good respiration is better than increasing the swimming effort.
  • Always have diving or swimming buddy.

To learn more, read “Immersion Pulmonary Edema.”

Studies referenced in this post:

  1.  Gempp E. et al. Pulmonary oedema in breath-hold diving: an unusual presentation and computed tomography findings. Diving Hyperb Med 2013; 43:162-163.
  2. Cochard G. et al. Swimming-induced immersion pulmonary edema while snorkeling can be rapidly life-threatening: Case reports. UHM 2013; 40(5): 411-415

Post written by: Petar Denoble, MD, D.Sc.

When to refer a diver for PFO screening?


Postdive occurrence of bubbles in divers venous blood (venous gas emboli or VGE) is quite common. VGE are usually filtered out of circulation by the pulmonary capillary filter. However, in the case of PFO, transpulmonary passage of venous blood or other rare causes of right-to-left shunt (RLS), VGE may pass to the arterial circulation and cause damage of vital tissues manifesting decompression illness (DCI). Note that DCI includes both decompression sickness and cerebral arterial gas embolism. Because of high prevalence of RLS, mainly as a result of PFO, and low incidence of DCI, there is a general agreement that screening for RLS should not be done routinely on all divers. While in some cases screening may be useful, there is no consensus about when the screening is justified. In a recent paper by Oliver Sykes and James E. Clark titled, “Patent foramen ovale and scuba diving: a practical guide for physicians on when to refer for screening,” the authors detail clear guidelines for physicians as well as their definitions of safe diving practices, provocative dive profiles and factors suggestive of PFO. Their recommendations are very useful. Do not miss this paper. It is available for free from the above link.

Their recommendations are summarized in Figure 8 of Sykes and Clark’s paper:


Figure 1. Flow chart on when to refer for screening by a cardiologist with an interest in diving. Courtesy of London Hyperbaric Medicine.

The findings in DAN’s PFO study coincide with most of the recommendations above. Retrospectively established incidence of various DCI manifestations in divers with PFO participating in our study is shown in following table:


Multiorgan DCI manifestations were a frequent finding and we suggest adding it to the indications for RLS screening. In this context, multiorgan means coincidental occurrence of symptoms from two or more of the following symptom groups: skin, neurological (brain, spinal cord, ocular or inner ear), pulmonary and constitutional.

Learn more: Read about the dive and DCS history in divers who tested positive for PFO and pursue closure.

Post written by: Petar Denoble, MD, D.Sc.

Deep capability or deep trouble?


Dr. Simon Mitchell gave an outstanding plenary presentation at the UHMS Annual Scientific Meeting. As a current rebreather diver, he recognizes how much he can do using rebreather, as well as the risks associated with such complex, high-maintenance machine. Divers must be knowledgeable, skilled and disciplined. With new models of rebreathers that target average diver (“recreational rebreathers”) we must do more to prevent injuries, some of which are caused by unsafe human behavior, errors and omissions and other by lack of recognizing predictable machine failure (oxygen cell failure, for example). Simon stressed the conclusions of Rebreather Forum 3.0 (RF3) and the need to use checklists. Checklists should be cleverly designed and printed out, not just mnemonics. It is essential for proper dive leadership to foster a culture of safety in the diving community. I hope you will have opportunity to attend Simon’s presentation at some of dive shows scheduled in the future. In the meantime, here are a few of his lectures from RF3.

CCR Physiology

Anatomy of a CCR Dive

Discussion and Consensus

Post written by: Petar Denoble, MD, D.Sc.

DAN at UHMS: A Recap


At the Undersea Hyperbaric Medical Society (UHMS) Annual Scientific Meeting, DAN produced six papers, two collaborative papers and funded two more. With additional five papers from International DAN organizations – DAN contributed approximately one-third of the diving medicine presented at the meeting.

I gave an oral presentation about effectiveness of predive checklists, with Shabbar Ranapurwala, doctoral student in epidemiology at UNC as a first author. The paper is coming, but let me tell you in confidentiality, checklists work, even in diving. It was confirmed in a randomized trial conducted in three dive resorts. Volunteers received either a predive checklist and a postdive report (the intervention group) or the postdive report only (the control group). Divers who received the predive checklist experienced fewer mishaps during the dive than divers who did not receive it. Divers in control group were not prohibited from using their own checklists nor were they reminded to do so. The reduced number of mishaps in the intervention group indicates the effectiveness of predive checklists in prevention of accidents and a value of reminding divers to use it.

To learn more, read “Checklists: Keys to safer diving?”

Post written by:

Petar Denoble, MD, D.Sc.

Dr. Petar Denoble is the Vice President of DAN Medical Research. After graduating from medical school, Dr. Denoble joined the Navy in the former Yugoslavia and specialized in naval and diving medicine. For 13 years he was involved with training, supervision and treatment of divers in open circuit, closed circuit, deep bounce and saturation diving. His doctoral thesis focused on studying oxygen consumption in underwater swimming. He has been at DAN for 20 years where he has been involved in the development of the largest database of exposure and outcomes in recreational diving, the monitoring of diving injuries and the study, treatment and prevention of fatal outcomes and long-term consequences of diving accidents.