Swimming induced pulmonary edema (SIPE) may occur in healthy subjects during or immediately after swimming and exercise. It is characterized by an acute onset cough which may be accompanied by difficulty breathing, chest tightness and frothy red sputum. If not recognized, symptoms which are typically initially mild may quickly worsen and become life threatening. Due to its multifactorial nature and a lack of specific symptoms, the condition may frequently be misdiagnosed and treatment delayed.
In Diagnosis of Swimming Induced Pulmonary Edema — A Review Grunin and co-authors studied thirty-eight cases of SIPE published in seventeen papers to identify symptoms, signs, findings and history that help to establish diagnoses. (1)
They have found that an acute onset of cough and difficulty breathing were common to all cases. Tightness of chest was sometimes present. At onset the cough is usually nonproductive but occasionally it may produce sputum with traces of blood. Athletes or divers experiencing any of these symptoms should exit water and stop exercising immediately. Emergency oxygen typically lessens symptoms and helps recovery. Initial evaluation by auscultation usually finds crackles, rales and wheezing, signs of fluid in airways. These findings may affect only one lung. At admission most cases show hypoxemia and radiological signs of pulmonary edema. The majority of the cases (82%) resolve within 48 hours.
SIPE used to be associated with combat swimmers training with reported prevalence of 1.4% to 60%. Prevalence also seem high in triathletes (1.4%). Snorkelers and scuba divers are also at risk, especially those with cardiopulmonary disease and pulmonary hypertension. Other risk factors include cold water, exercise, elevated negative inspiratory pressure, and emotional stress. Some research indicates that women may be at a higher risk of SIPE than men. It is important to realize that both divers with some pre-existing conditions as well as healthy fit young athletes are at risk. With the increasing popularity of aquatic sports the prevalence of SIPE is expected to increase as well. Thus, participants in aquatic sports and health care providers should be familiar with manifestations and diagnosis of SIPE. This paper provides an excellent material for that purpose.
The Dive Lab 
This sounds in some ways as an extreme case of exercised induced asthma. Are the related? How do the risk factors, clinical presentation, prevention and treatment differ?
Thanks for the question Rich. SIPE and exercise induced asthma are not related. The former occurs due to increased pressure in pulmonary capillaries and leaking fluids flooding alveoli, while the later involves narrowing of small airways and increased resistance to air flow. Both conditions are provoked with exercise and cold. Symptoms are similar but in the case of SIPE it is the cough and gurgling in lungs that are dominant while in the case of EIA it is difficulty breathing and wheezing. At the beginning symptoms may not be distinguishable, but the medical history of asthma points in direction of EIA. However, nearly 50% of athletes exercising in cold with have some degree of bronchoconstriction without history of asthma. Divers and other athletes with acute onset of coughing, wheezing or difficulty breathing while exercising, should stop exercise and if symptoms do not start to resolve immediately, they should be urgently referred for medical evaluation and treatment. Physicians have at their hands diagnostic tools that help them to clearly distinguish two conditions and provide proper treatment.
Dr. Petar J. Denoble
Vice President Mission
Divers Alert Network