Why Do Some Fit Triathletes Get Pulmonary Edema?

MedicalResearch.com Interview with:
Dr. David MacIver
Department of Cardiology
Musgrove Park Hospital, Taunton

Medical Research: What is the background for this study? What are the main findings?

Dr. MacIver: The study was prompted by 2 triathletes who presented to our hospital with similar symptoms suggesting they both had had fluid on the lungs whilst swimming. Both athletes were fit and active and had excellent heart function.

They were diagnosed with a condition is known as swimming-induced pulmonary oedema or edema (SIPO in the UK and SIPE in the USA). A condition that has been well-documented in Navy seals during training swims in open water. A similar condition has been described in divers sometimes with fatal consequences. Fluid on the lungs or pulmonary oedema more commonly occurs in patients as a complication of severe heart disease such as heart attacks and is called acute heart failure. Pulmonary oedema has also been documented healthy race-horses during competitions.

We had recently suggested that acute pulmonary edema in patients with heart disease could be explained by a transient mismatch in the right and left ventricular stroke volumes. We thought it would be interesting to see if a similar mechanism could explain swimming-induced pulmonary edema. We found that factors that might contribute included cold water and high blood pressure. We speculated that cross-training with land based activities (running, cycling) might be relevant.

In this study we proposed a possible mechanism for swimming-induced pulmonary edema – fluid from the blood is force into the lung air sacs by the strong right ventricle. In effect, the individual begins drowning in their own lung fluid.

Medical Research: What should clinicians and patients take away from your report?

Dr. MacIver: We think that swimming induced pulmonary oedema is much more common than is generally realised. For example, neither of our patients were diagnoses correctly during their initial assessment. We are aware of other cases in the medical literature that have been missed at post-mortem or not considered by the coroner; not surprising since the condition mimics drowning closely. We suggested that swimming-induced pulmonary edema is underdiagnosed both in survivors and as a cause of death.

Firstly, we would like the condition to be more widely recognized by clinicians, athletes and those organising or responsible for events involving swimming and diving. For example, there needs to be appropriately trained staff with the right equipment (such as rescue boats) rapidly available for individuals in distress.

Secondly, athletes should be screened for conditions that might predispose to swimming-induced pulmonary edema such as hypertension prior to participation and their risks assessed.

Thirdly, we would like athletes who have already suffered from symptoms that might be attributable to SIPE to be aware that it might recur and could be fatal. Assessment by an expert in the field is recommended.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. MacIver: Future research should involve trials of therapy to help prevent the condition such as vasodilators to reduce blood pressure. Investigation into the effect of changes in training regimes to lessen the impact of the imbalance in right and left heart function are required. Further studies into exacerbating factors such as tight wetsuits and cold environment that might impede left heart function are necessary. We would like to see the development of a database of all potential cases so the risk factors and preventative measures may be better understood.


Swimming-induced pulmonary oedema in two triathletes: a novel pathophysiological explanation

Helen Casey, Amardeep Ghosh Dastidar, and David MacIver

J R Soc Med 0141076814543214, first published on October 23, 2014 doi:10.1177/0141076814543214

Last Updated on October 27, 2014 by Marie Benz MD FAAD