I saw this week that there was an important new paper on swimming induced pulmonary edema (SIPE). Richard Moon, MD, and his colleagues at Duke University published a report entitled, “Immersion Pulmonary Edema and Comorbidities: Case Series and Updated Review” in a recent edition of the sports medicine journal, Medicine & Science in Sports & Exercise (1).
SIPE is known to occur not only in recreational or competitive swimmers, but also in divers. In fact, the condition was first recognized because of breathing difficulties encountered by military divers. As triathlete and swimmer readers here will know, there are many reasons why an athlete might develop shortness of breath during an open water swim. Water conditions, water and air temperature, exertion, and anxiety all play a role. SIPE is something different, altogether, though. This is a condition that develops because of immersion in the water, in which fluid builds up in the lungs and makes breathing difficult. The condition is believed to be self-limiting; if a swimmer gets out of the water, the condition will resolve. The underlying mechanisms and risk factors are not completely understood.
I’ve written about this condition in 2 previous blog posts….SIPE and More on SIPE. These posts might be a good starting point.
The newly published report is important because it reviews the medical literature and gathers all of the pertinent information about pre-existing medical conditions, or so-called comorbidities, in victims of SIPE. Dr. Moon is probably the world’s foremost authority on the topic of SIPE, so this new report deserves our attention.
The Study
There are 2 parts to the study: 1) a look at the Duke University experience with recreational swimmers who’ve had a SIPE episode and 2) a review of the medical literature on SIPE cases, both in military and recreational divers and swimmers.
In the first part, the investigators collated information on 41 swimmers who, over the past several years, had been studied at Duke University after reporting a SIPE episode. The mean age was 50.1 +/- 10.8 years (range, 25-71 years). Complete medical history data was available for 36 of the 41 swimmers.
In the second part, the investigators collected 45 previously published articles in the medical literature that reported on 292 cases of SIPE. There were 156 recreational swimmers or divers (89 men and 67 women), with a mean age of approximately 47.8 +/- 11.3 years. There were also 136 military swimmers or divers (135 men and 1 woman), with a mean age of approximately 23.3 years (range, 18-47 years).
For each of these groups, the investigators gathered information about pre-existing medical conditions in order to determine potential risk factors for the development of SIPE, focusing on: hypertension (high blood pressure), lung disease, overweight/obesity, sleep apnea, hypothyroidism, and cardiac abnormalities).
The Results
Among the Duke University group, 9 (25%) of the 36 swimmers with available health history were completely healthy. The remaining 27 (75%) had 1 or more medical/health conditions, including:
- overweight/obesity in 12
- hypertension in 7
- cardiac arrhythmias in 4
- heart valve problem (mitral valve prolapse) in 1
- reduced heart function in 2
- repaired congenital heart conditions in 2
- asthma in 3
- COPD in 1
- reactive airways disease in 1
- hypothyroidism in 3
- diabetes in 2
- polycystic ovary syndrome in 1
- obstructive sleep apnea in 2
Twelve subjects had more than one of these conditions.
In the literature review, all of the 136 military swimmers and divers were healthy; they had none of the pre-existing medical/health conditions that were surveyed. In contrast, 70 (45%) of the 156 recreational swimmers or divers had one or more significant pre-existing risk factors:
- asthma in 4
- enlarged heart in 2
- arrhythmias in 2
- coronary artery disease in 3
- diabetes in 4
- exercise-induced cough in 1
- Elevated serum lipids in 22
- hypertension (high blood pressure) in 25
- thickening of the left ventricle in 9
- peripheral vascular disease in 1
- sleep apnea in 6
As a side note, approximately 17% of cases in the literature review reported similar previous episodes or follow-up episodes that were suggestive of SIPE, giving an important look at the potential recurrence rate. And in total, 6 fatal cases of SIPE were identified in the literature review.
My Thoughts
How can all of this collated information be useful to us?
First, it’s important to note that all of the military swimmers and divers included in the literature review were healthy. We shouldn’t overlook the possibility that even completely healthy swimmers may experience SIPE.
Second, the recurrence rate of ~17% in the literature review is probably an underestimate. No doubt, some swimmers who experienced a worrisome episode of SIPE might avoid future swimming altogether. It’s very important to remember that this condition may recur.
Third, it’s very apparent that, among recreational swimmers who experience SIPE, the prevalence of important pre-existing medical conditions is rather high, at 75% in the Duke group and 45% in the recreational swimmers in the literature review. I suspect that the Duke investigators were more thorough in their history-taking and the 75% is probably more reflective of the reality.
The investigators’ aim was to identify risk factors for SIPE. Sadly, there’s obviously no single, unifying thread here. Hypertension (high blood pressure) was the most commonly identified condition among the cases, but this accounted for only ~15% of the cases. As I mentioned at the top, the physiologic underpinnings of SIPE are not completely understood and indeed there may be more than one responsible mechanism leading to some common final pathway by which fluid accumulates in the lungs. All of the various cardiovascular abnormalities identified in the cases might conceivably play a role. There’s more to learn.
It’s worth noting that the long list of medical conditions that were identified deserve careful medical attention before participating in recreational swimming events.
Advice
I’ll reprint here my best advice to athletes and event organizers regarding SIPE. I originally included this in another blog post, but this is still my best advice!
- Triathletes and open water swimmers should be aware of SIPE and the possibility that this condition can be lethal.
- Symptoms of SIPE can manifest for the first time even in experienced swimmers. Symptoms may develop rapidly, be unexpected, and confuse the athlete about the cause.
- The development of SIPE does not appear to be confined to cold water swims or only to victims who are wearing a wetsuit at the time.
- SIPE appears to be self-limiting–that is, the symptoms will subside if the victim stops exercising and gets out of the water.
- Because of #2, #3, and #4, athletes who experience breathing difficulties in the open water should treat the problem like a medical emergency and STOP swimming and SEEK immediate assistance. Because of the challenges of rescue in the open water, your life could depend on recognizing a problem early and getting out of the water. I would encourage affected athletes to get complete medical evaluation as soon as possible after an episode.
- There appear to be no effects on lung function after an episode of SIPE, but repeat episodes of SIPE may occur.
- Affected athletes have described a variety of strategies for preventing repeat episodes of SIPE. From athlete accounts, no single strategy appears to be universally successful.
- Affected athletes should use EXTREME CAUTION in subsequent open water training and races, being hypervigilant for warning signs.
- Event organizers and on-water rescue personnel should be familiar with SIPE. The safety plan should allow for athletes with breathing difficulties to be removed from the water as quickly as possible.
Reference
1. Peacher DF, Martina S, Otteni C, et al. Immersion pulmonary edema and comorbidities: Case series and updated review. Med Sci Sports Exerc 2015;47(6):1128-1134.
Related Posts:
1. Swimming Induced Pulmonary Edema (SIPE)
2. More on Swimming Induced Pulmonary Edema (SIPE)
i just requested friendship on Facebook.
Not too many know my situation at this time.
Hi Doc. Creswell,
My name is Fran Fidler, i’m 59, white male. Grew up in Boston, moved to Naples, FL IN 1986.
I see a heart surgeon on Tuesday (June 9), here in Naples, and currently have a 2nd opinion scheduled for July 14 in Boston (I am trying to make that sooner).
I have been recently diagnosed with Aortic root and Left Atrium mildly dilated. Mild is the word throughout. Then, there is a bicuspid aortic valve with moderate to severe aortic stenosis. Peak gradient 67, mean gradient 39. Everything else appears normal. I’m a (little/lots) lost! Triathlon race season begins tomorrow a.m. I have a 70.3 set for Aug. 9 and a full IM Nov 7, various events between now and then. I know this is last minute. I’ve been googling info for a few days now. I just found found your blog, then looked at Anthony’s. I just got my 2 appt.s yesterday and thursday. Would you share your thoughts to me. Thanks so much, Fran Fidler
I’ve always been athletic, swimming etc, and did my 1st tri in 1982. I have a heart murmur.
Since my last episode of very serious SIPE (which took me 72 hours to recover from) in the St Pölten half Ironman I have experimented a great deal:
– swimming with a tight wetsuit vs a thinner/more loose version and just using neoprene shorts
– swimming with and without snorkel
– different levels of hydration and warmup (jogging) before swimming
– swimming under different conditions (large waves vs calm water, fresh vs salt water) etc.
My personal conclusion was that I have fewer problems when using a wetsuit (or neo shorts) with less compression and when using a snorkel.
According to my doctor (Dr. Wille Bergöö, retired doctor in charge for the Swedish army forces’ diving and air forces), the snorkel might just add enough of pressure through the air tube to keep my body’s blood pressure in check. Also, I do not have to turn my body out of the water to take breaths so the pressure on my body from external forces is kept more constant.
Just weeks before the Ironman Austria (June 28) I found out that one is allowed to wear a snorkel at the race with a doctor’s certificate. The only drawback: one may not qualify for Hawaii if using a snorkel.
I chose to swim in my tight wetsuit since in combination with the snorkel I had not had any problems and it makes for a faster swim.
So how did it go… I had no problems up till the first turn buoy at 1250 meters. During this first third of the swim I kept a slow but steady pace and had very few bumps with other swimmers. (Stupidly) I chose to take a narrow turn around that first buoy which led to involuntary close encounters (incl a unintentional kick in the face) with several fellow athletes. The stress that followed made my blood pressure race and at 1300 meters I was right back where I had found myself in St Pölten. I realised that I must get out of the water and waved at the life guards who saw me but could not get to me through the many swimmers. Midst panic I managed to get hold of a buoy and hung there for a minute. This helped me calm down and I actually continued the swim for another 400 meters without much problem when the same thing happened again. To make a long story short, I got through the entire swim and Ironman race by stopping and hanging on to another buoy and also a medical team’s boat for a couple of minutes.
I am thrilled to have finished the race even though my inability to take deep breaths or race at a usual heart rate made for a slow finish (11:45). As in St Pölten, it was the run that was most impacted by this since cycling does not require as high heart rate or heavy breathing as running does.
I am now convinced that even though I can comfortably swim almost any distance in training (when using a snorkel) I will run into problems when racing along hundreds/thousands of other athletes. It is the stress that comes from bumping into others, getting kicks and elbows in the face that makes my blood pressure race and that leads to SIPE.
My intention is to test my theory by booking another half or full Ironman and this time really stay out of everyone’s way and rather swim 10% longer than everyone else than having any physical contact whatsoever with another athlete. I will let you know how that turns out.
Keep us posted, Theo!
I have SIPE and flew to Duke to have the entire work up by Dr Moon and his team. Before meeting Dr Moon, I struggled with the condition without understanding what was actually happening to me, resulting in some terrifying experiences. After going through a series of exercise tests immersed in 68 degree water, (pre and post treatment), it was recommended that I take Viagra. I take it before every open water swim and before every race. I haven’t had one incident since I started. My heartfelt gratitude goes out to Dr. Moon and his team for the diagnosis and treatment plan.
Very informative post on SIPE here. Hopefully increased awareness of it will lead to a better understanding and thus, better treatment. Thanks for sharing!
hi molly hayes here, bozeman mt. i have completed 336 triathlons, last 3 yrs about 15 of those 336 were sprints, rest olympic, couple in 1986-7 were near 1/2 iron.
all but about 20 of 336 were cold water. i am 87 end year, sister madonna always in my age group, done many tris with her. started getting sipe2003, cold new zealan worlds, stupid me no wet suit. soo had sipe 13 times always worse, budapest worlds 2010, paramedics drug me out swim into raft, drug me to first aid, bloody toes worse than sipe. so 13 pull outs swim.
recent 7/14/19 cold deep small lake helena mt, got sipe 400 meters, had own water safety, triathlete, saw it start 400 meters, i neede to finish so ended up verticle dog paddle cough up frothy pink, so weak crawled out slow like turtle.
dr. visit this week and echo, aortic valve is still moderate placque/brie cheese i think, soo what good cardio doc said is, due to stenosis ph of blood would change, and give me alethal vfib, could have been gone in 30sec. only thing saved me this time, had to get to finish thru shallow stream warmer and into shallow murky warmer pond to finish, i was weak barely had any lung volume felt like, took 20 min to transition and onto wobbly bike, but i finished in under 3hr, which is sick. they call me unsinkable molly, we ahve a bar in bozeman, called that, but i will not let that happen. i am ok in warm salt water like st. petersburg, so will only do that area for 3 a seson , sister madonna had said prayers for me that july day too, probably saved my bacon.
thanks cheers molly hayes age group 85-89