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Patient-swimmer testimonial unbalances PR release on Viagra study

DURHAM, N.C. — Swimmers and divers who are prone to a sudden and potentially life-threatening form of pulmonary edema in cold water could benefit from a simple and readily available dose of sildenafil, according to findings from a small study by Duke Health researchers.

The drug — best known as Viagra™ — is normally used for treatment of male impotence, but also for pulmonary arterial hypertension. It dilates blood vessels, giving it the potential to ease an abrupt cold water-induced constriction of blood vessels in the arms and legs that can lead to blood pooling in the heart and lungs.

Athletes and others with this condition — called swimming-induced pulmonary edema, or SIPE — cough up blood, labor to breathe and have low blood-oxygen typically brought on by swimming or scuba diving, usually in cold water. Often the symptoms dissipate over 24 hours, but the condition can be serious and even fatal and medical attention is recommended. Many don’t know they are prone to the problem until they are in the water and quickly develop symptoms.

“During immersion in water, particularly cold water, susceptible people have an exaggerated degree of the normal redistribution of blood from the extremities to the chest area, causing increased pressure in the blood vessels of the lungs and leakage of fluid into the lungs,” said Richard Moon, M.D., an anesthesiologist and medical director of the Duke Center for Hyperbaric Medicine & Environmental Physiology.

“Some cases of SIPE appear to have been the result of cardiac problems,” said Moon, who was lead author of the study published online February 16 in Circulation: Journal of the American Heart Association.

Moon and colleagues studied these responses in 10 athletes who had experienced the condition while exercising or competing in triathlons. During a carefully monitored test in Duke’s hyperbaric center, the researchers had the participants exercise under water in a dive pool that recreated the conditions of a swim that could trigger the SIPE response.

They compared those participants with 20 others who did not have a history of SIPE. None of the participants in either group had heart abnormalities, but the SIPE-susceptible athletes had higher pulmonary arterial pressure and pulmonary artery wedge pressure during the underwater exercise, confirming that SIPE is a form of pulmonary edema caused by high pressure in the blood vessels within the lungs.

When the SIPE participants were given sildenafil and then performed the same underwater exercise, the pressures were no longer as elevated.

“This is a small study, but also very intensive with direct, accurate pressure measurements,” Moon said. “It appears that the drug, which dilates the blood vessels, could be creating more capacity in the blood vessels in the arms and legs, reducing the tendency for blood to redistribute to the thorax, and therefore reducing the high pressure in the pulmonary vessels.”

One study participant, triathlete Katherine Calder-Becker, said her bouts with SIPE threatened to end her competitive career. She said she would have no problems during training in swimming pools, but then experienced debilitating shortness of breath and distress during the swim portions of competitions in colder open water. She coughed up blood and was once hospitalized.

Triathlete Calder-Becker, 51, was diagnosed with SIPE and enrolled in studies at Duke in 2011. Afterward, she consulted her cardiologist and was prescribed a low dose of sildenafil that she takes shortly before competitions.

“I have successfully raced in 20 triathlons since I started taking sildenafil, including five ultra events that require 10-kilometer swims,” Calder-Becker said. “I have not had an incident since then. I didn’t want to give up racing — this is something my husband and I do together, and we travel together to competitions — so it has meant everything to me to continue.”

Moon said larger studies are needed to replicate the results and learn more about possible adverse side effects of the drug. He also said research is ongoing to further illuminate the causes of SIPE and potential ways of diagnosing it early.

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In addition to Moon, study authors include 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.

This study received funding from the Divers Alert Network and U.S. Naval Sea Systems Command Contracts (N61331-03-C-0015, N0463A-07-C-0002).

Study suggests sildenafil may relieve severe form of edema in swimmers

Our Review Summary

swimmerThis news release describes a small study of individuals prone to swimming-induced pulmonary edema (SIPE, fluid in the lung) that found that giving them a dose of sildenafil (sold under the brand name Viagra) dilated blood vessels and prevented the cold water-induced constriction that may cause the problem. The study involved 10 individuals with a history of SIPE and 20 control subjects.

The news release, based on the study published in the journal Circulation, describes the condition and the study parameters nicely but then overwhelms the cautionary comments appropriate for such a modest design with an enthusiastic testimonial from a participant who felt the medicine was a life-changer. The release would be stronger if it had added some quantification of the benefits and relied less on a patient testimonial to make its case.

 

Why This Matters

A treatment for swimming-induced pulmonary edema likely won’t matter to most of us recreational swimmers since the incidence of the condition seems low and confined to serious, competitive swimmers and divers. However, the subset of individuals diagnosed with the problem may find the availability of a medication attractive — if it stands up to the rigor of larger studies.

Criteria

Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

Cost is not mentioned in the release.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

Although the press release indicates that measures of pulmonary arterial pressure “were no longer as elevated” in individuals who received sildenafil, the document got no more specific than that. The author described the benefit very vaguely in this statement:

“It appears that the drug, which dilates the blood vessels, could be creating more capacity in the blood vessels in the arms and legs, reducing the tendency for blood to redistribute to the thorax, and therefore reducing the high pressure in the pulmonary vessels.”

We’re also concerned with the glowing anecdote that the release uses to illustrate the drug’s benefits. The study itself looked at pulmonary arterial pressure and had nothing to say about sildenafil’s ability to prevent bouts of SIPE during competition. Nevertheless, this study participant gushes,

“I have successfully raced in 20 triathlons since I started taking sildenafil, including five ultra events that require 10-kilometer swims,” Calder-Becker said. “I have not had an incident since then. I didn’t want to give up racing — this is something my husband and I do together, and we travel together to competitions — so it has meant everything to me to continue.”

The anecdote goes well beyond the limited parameters of the study and overwhelms any cautions regarding the limitations of current evidence.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

Although the study itself is silent on the potential harms seen in the subjects treated with sildenafil, we think that the story should have noted that explicitly. Are four-hour erections an issue that swimmers need to be concerned about? Harmful side effects of ingesting sildenafil certainly exist but are not broached here.

Does the news release seem to grasp the quality of the evidence?

Satisfactory

The news release describes the published study in some detail, and the first author goes on record calling for larger studies “to replicate the results and learn more about possible adverse side effects of the drug.”

Does the news release commit disease-mongering?

Not Satisfactory

The release offers no information about the incidence of this condition among swimmers and divers and, because this condition is rare, it could unnecessarily raise some alarms. And while it makes clear that the symptoms of swimming-induced pulmonary edema “often” disappear over the course of 24 hours in the subset of swimmers and divers who have the condition, it also notes that the problem can be fatal, again without providing any incidence data. The reader will likely be more concerned than she or he should be.

Does the news release identify funding sources & disclose conflicts of interest?

Satisfactory

The funders are mentioned, although the release makes no effort to clarify possible conflicts of interest. The study on which this news release is based states that the principle investigators have no conflicts of interest.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

Information about possible treatment alternatives (for example, diuretics or oxygen) is not provided.

Does the news release establish the availability of the treatment/test/product/procedure?

Satisfactory

The very first sentence of the release characterizes sildenafil as “readily available.” Indeed it is. It is Viagra ™.

Does the news release establish the true novelty of the approach?

Satisfactory

The release notes that the drug is already used as a treatment for another lung condition — pulmonary arterial hypertension — so this application would be an extension of sildenafil to another lung condition. Health professionals have speculated in the past on the ability of drugs such as sildenafil to help individuals cope with swimming-induced pulmonary edema. The published research notes that this study tested that hypothesis.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Satisfactory

We found no language in the release that was clearly out of bounds. As noted above, however, we’re concerned that cautionary language is overwhelmed by an enthusiastic testimonial from a swimmer who believes she has benefited from using the drug.

Total Score: 5 of 10 Satisfactory

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