Thread by @RichardEMoon

Why do most deaths during triathlons occur during the swimming portion, despite it being the first and shortest of all three legs?

The answer might surprise you.

#tweetorial #triathlete #triathlon

Evidence supports the notion that a significant portion of triathlon deaths are due to swimming-induced pulmonary edema (SIPE).

bmjopensem.bmj.com/content/bmjose…

SIPE is relatively common occurring in up to 2% of triathletes!!!

What is SIPE?

SIPE = Cough productive of blood-tinged secretions associated with hypoxemia and radiographic evidence of pulmonary edema.

What do you think underlies the pathophysiology of SIPE?

Yes, the pathophysiology is related to heart failure. Immersion (esp in cold water during exertion) induces redistribution of blood from the extremities and splanchnic veins into the thorax, which raises pulmonary artery pressure and pulmonary artery wedge pressure (PAP and PAWP)

Studies in individuals who have experienced SIPE reveal that during exercise in cold water, PAP and PAWP are higher than in normal volunteers.

ncbi.nlm.nih.gov/pubmed/26882910

Some SIPE-susceptible people have cardiac pathology that predisposes to systolic or diastolic failure during the volume overload during immersed exercise.

Other possible causes are under investigation.

What medication might be helpful in reducing the risk of SIPE?

Yes, sildenafil seems to work.

Sildenafil is a venodilator that may work by increasing venous capacitance, thus reducing blood volume in pulmonary vessels.

This is currently under study as part of a clinical trial. Click here to learn more: researchoutreach.org/articles/silde…

So to recap:
(1) SIPE is relatively common (~2% in triathletes)
(2) SIPE is due to increases in PA pressure after patients become submerged in (particularly cold) water
(3) Sildenafil may⬇️risk of SIPE. RCT ongoing.

Thanks for joining in on my inaugural Tweetorial!