18 Feb Risk/Benefits of Sildenafil For Swimming-Induced Pulmonary Edema

MedicalResearch.com Interview with:

Dr. Richard Moon

Richard Moon, MD, CM, MSc,
FRCP(C), FACP, FCCP
Medical Director, Hyperbaric Center
Professor of Anesthesiology
Department / Division
Anesthesiology / GVTU Division
Medicine / Pulmonary
Duke University School of Medicine

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

Dr. Moon: This study was performed to investigate the reason why young, fit individuals develop a condition usually associated with severe heart disease: pulmonary edema. Immersion pulmonary edema (also known as swimming-induced pulmonary edema, SIPE) develops in certain susceptible individuals while swimming or scuba diving, usually in cold water. Some SIPE-susceptible people include highly conditioned triathletes and Navy SEAL trainees. The prevalence of SIPE in triathletes is around 1.5%, and in open sea swimming trials in naval special forces trainees has been reported to be 1.8-60%. SIPE often requires hospitalization and has caused death.

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

Dr. Moon: We directly measured arterial pressure, pulmonary artery pressure (PAP) and PA wedge pressure (PAWP) during submersed exercise in cold water. We found that both PAP and PAWP were higher in swimming-induced pulmonary edema-susceptible individuals compared with a group of volunteers of similar age who had never experienced SIPE. This confirmed that SIPE is a form of hemodynamic pulmonary edema, which is curious since all of the people we studied had normal hearts. We hypothesized that the cause could be differences between the groups in venous tone or LV diastolic compliance. When we retested the SIPE-susceptibles under the same conditions after a dose of sildenafil, pulmonary artery pressures were decreased, with no adverse effects on hemodynamics. We concluded that by dilating pulmonary vessels and systemic venous sildenafil could be an effective prophylaxis against SIPE. 

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

Dr. Moon: A clinical trial or even case series of  swimming-induced pulmonary edema-susceptible triathletes pre-treated with sildenafil prior to a race would add further evidence for its efficacy in this condition. 

Medical Research: Is there anything else you would like to add?

Dr. Moon: While some  Swimming-Induced Pulmonary Edema-susceptible triathletes or swimmers may be inclined to try sildenafil as a preventive measure, the drug could be dangerous for scuba divers. Sildenafil increases the risk of central nervous system oxygen toxicity, including seizures. A seizure underwater is likely to be lethal. Thus, diving could be dangerous after taking sildenafil when breathing a gas mixture with a partial pressure of oxygen greater than 1 atmosphere (e.g. air deeper than 125 feet, or 32% oxygen deeper than 70 feet).

Citation:

Richard E. Moon, Stefanie D. Martina, Dionne F. Peacher, Jennifer F. Potter, Tracy E. Wester, Anne D. Cherry, Michael J. Natoli, Claire E. Otteni, Dawn N. Kernagis, William D. White, and John J. Freiberger.Swimming-Induced Pulmonary Edema: Pathophysiology and Risk Reduction With Sildenafil. Circulation: Journal of the American Heart Association, February 2016 DOI: 10.1161/CIRCULATIONAHA.115.019464

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Richard Moon, MD, CM, MSc,, & FRCP(C), FACP, FCC (2016). Risk/Benefits of Sildenafil For Swimming-Induced Pulmonary Edema 

Last Updated on February 18, 2016 by Marie Benz MD FAAD