IPE – Immersion Pulmonary Edema

Posted on

“It is a beautiful sunny day. The ocean is calm and there is no current. In short: a perfect day to plunge into the sea and dive the Spiegel Grove. The water is comfortable at 81 degrees and the visibility is over 100 ft. We are a team of four divers on rebreathers and it is going to be an easy dive.

About 35 minutes into the dive, I start coughing. First it only happens intermittently but over time, the coughing increases. I am beginning to notice mild wheezing when I breathe out. Because it feels harder to exhale, I reassess my loop volume, but everything checks out fine. I am less interested in the dive now and am becoming more interested in what is happening to me.

With my next cough, I get a slight metallic taste in my mouth. My chest feels tighter and the wheezing is worse. Not wanting to alarm my buddies, I am signaling that I am going up but that I am okay. I make it out of the wreck and swim toward the up-line. Breathing is more and more laborious. I bail to open-circuit just in case there is something wrong with my unit. Breathing from the regulator, however, is not relieving my symptoms. I am constantly coughing and with it, bring up metallic tasting liquid. Putting all of my signs and symptoms together, I conclude that I am in pulmonary edema.

I am air hungry! No, I am starving for air! When I finally make it to the up-line, my heart is hammering in my chest. All I want to do is get out of the water. I don’t want to breathe off a regulator anymore. My instincts are screaming for me to get up and out and take a mouthful of fresh air! Unfortunately, I have about 23 minutes of decompression. Do I stay and feel like I am drowning or do I go up and risk getting bend? Overcoming my impulse, I decide to stay! “Calm, calm yourself, slow down that heart, you are breathing, you are going to be OK”, is what I am telling myself as I make it through my deco stops. Knowing what is happening to me helps. I finally clear deco and pull myself slowly, so very slowly to the boat. The boat captain hears my distress calls and promptly assists me. He pulls me on the boat. Even with his help, the little exertion has me breathing like a “Thoroughbred after a race”! My lips are blue, my breathing ragged and I am coughing up rusty sputum. After a few minutes while resting, my heart finally starts to slow down again as is my breathing rate. I continue to cough up rusty colored-sputum, but that too, starts to slow down. When my dive buddies return back to the boat, we head to shore. I am no longer wheezing and my coughing fits have subsided considerably. I had left my stethoscope in my car and I found to have crackles on both sides about 2/3rds up. I was debating to go to an Emergency Room. They would confirm what I already knew: I am another case of Immersion Pulmonary Edema. “


Alveoli are like tiny balloons filled with air and surrounded by blood vessels. Increases in hydrostatic pressure within the pulmonary capillaries leads to extravasation of fluid, thus causing edema.

Immersion Pulmonary Edema (IPE) is just that: developing fluid in your lungs from the effects of immersion in water. It can happen to anybody venturing into water and immersing him or herself – even as low as your bathtub! No seriously, it has been reported in military combat swimmers, triathletes, snorkelers, open circuit divers and CCR-divers. Just because you have been diving for a long time and never had it, does not mean you will never get it. No one is immune to it. Just because you had it once, does not mean that you will never get it again. Some even believe that once exposed to IPE you will have an increased risk for a repeat event.

IPE does not occur because you swallowed or inhaled some water. The edema in the lungs happens from fluid that is usually contained in the pulmonary capillaries but is leaking into the little air sacks/alveoli of your lungs (see below). The exact triggering mechanism is still incompletely understood. However, it is postulated that increased pressure in your vessels that supply the lungs (pulmonary vessels) is exceeded and it is this pressure that drives tissue fluid into the alveoli.

Why would there be excessive pressure in the pulmonary capillaries/vessels?



A possible explanation might be from over-hydration. When we immerse in water up to our necks, we shunt about 700 ml of blood from the periphery to the central core, i.e. the central vasculature. When blood gets shunted suddenly to the core, the heart and great vessels have to accommodate this additional volume. Usually, vessels will attempt to dilate. Increasing the diameter of a vessel will result in a decrease in pressure. Without this dilation, the pressure remains high.

Prior to an immersion, our vasculature might alreadybe “full” when well hydrated. Although adequately hydrated on the surface, with immersion we might suddenly become over-hydrated. Typically our hearts are sensing this excessive volume and will signal the kidneys to get rid of water and salt to decrease the volume. The signaling mechanism is via hormones of increased Atrionatiuretic Peptide (ANP) and decreased Vasopressin. The results are not immediate, as our kidneys need a little time to complete the task.

By the way, the effect of immersion is independent of depth. Going deeper does not increase the effect of immersion. Thus when experiencing IPE, going shallower will not alleviate the symptoms.

Cold water has also been thought to predispose to IPE. Cold water typically shunts blood from the periphery to the core thereby exacerbating the effect of immersion. Similarly, a wet suit or vest that is too tight may “squeeze” the blood from the periphery to the central core.

The scientific community is not absolutely certain what the true cause of IPE is. It is quite possible that it is not an isolatable cause but rather a combination of factors.

What to do?

When we have fluid in our lungs, it is difficult for oxygen to get from our lungs into our blood stream to supply our organs. In other words, gas exchange is impeded because the fluid in our lungs is acting as a barrier. When our organs do not get the oxygen they need, our heart rate increases in an attempt to circulate blood faster through the system. This will bring partially oxygenated blood to the tissues more quickly and carries waste products away faster. The most effective thing we can do (other than getting out of the water) is to decrease our workload. The more we work by finning, pulling ourselves up etc. the more oxygen our body needs. Therefore decreasing our workload decreases our need for oxygen.

Attempting to stay calm will help avoid panic and decreases the release of “fear hormones” that increase our heart rates even further.

To summarize the symptoms experienced during IPE:
It happens while in the water
It can happen after a few minutes or later (20, 30 or more minutes) into the dive
Unexplained coughing

Coughing up metallic tasting fluid


Difficulty breathing

Tight chest

Feeling panicky

Feeling like you are drowning

What to do when it occurs:

Try to stay calm

Signal your buddies for assistance

Begin your ascent but try to stay within safe limits

Decrease your workload! –

Try to get neutrally buoyant to avoid excessive finning on your stops (if you have them)

Let your buddies assist your with excessive gear (stage/bail-out bottles)

Let the crew help you get on the boat and avoid helping them too much

Breathing oxygen on the boat will help slowing your breathing rate and heart rate faster

Consider going to an Emergency Room – there have been fatalities

You might have to deal with ER wait times

They will give you a chest x-ray

They might give you a breathing treatment

They might give you a diuretic that makes you pee more

In severe cases, they might put you on CPAP (continuous positive airway pressure)

In most cases, symptoms improve by themselves by simply being out of the water.

What to do BEFORE it occurs:

Agree with your buddies on a signal for IPE

Review what to do in the event of IPE

You might take the initiative and discuss this with the crew

If you have been a victim of IPE and might consider helping out the researchers that are studying this phenomenon, contact:

Richard Moon, MD

Professor of Anesthesiology and Medicine

Medical Director, Center for Hyperbaric Medicine &

Environmental Physiology

Chief, Div. of General, Vascular and Transplant Anesthesia

Duke University Medical Center

Durham, NC 27710, USA

Tel: (919) 668-0001, 684-8762

Fax: (919) 681-4698

Stefanie Martina

Research Assistant

Duke Center for Environmental and Hyperbaric Medicine


 Safe Diving!

Claudia L. Roussos MD

Diplomat Board of Anesthesiology

Member ADDHelium Dive Team

Last Update: 10 June 2013