The Diving Reflex and Sudden Cardiac Death

But first, why “drenched doc”?  Here’s the connection.  It is from an earlier chapter of my life--my life as an interesting case--an FUO.   We wrote it up. and it was published in the New England Journal of Medicine in 2007.

The Drenched Doctor 

Daniel R. Kaul, M.D., Mark B. Orringer, M.D., Sanjay Saint, M.D., M.P.H., and Stephen R. Jones, M.D.N Engl J Med 2007; 356:1871-1876 May 3, 2007 http://www.nejm.org/doi/full/10.1056/NEJMcps065377

I’ve lived happy and well since the discovery of that tracheal-bronchial fistula by Dr. Frank Baumeister and its surgical resolution by Dr. Larry Eidemiller and Ed Irish.  A important part of my recovery was the care I received in the hospital and at home from Beth.  That’s why at age 72 I was brave enough to go snorkeling.

Cardiac arrest and snorkeling, here’s the consensus of what happened to me.  There is a well-known physiological phenomenon known as the diving reflex.  It is activated when the face is placed in water that is less than 70 F.  This elicits a series of neurologic responses that cause apnea and a decrease in heart rate, sometimes as low as 20% of baseline in extreme responses.  Under normal circumstances, this causes a compensatory increase in blood pressure to insure sufficient circulation to the heart and brain.  However, rather than increase, my blood pressure decreased, likely due to my pre-existing pulmonary hypertension and the medications that I take.  As a result, there was no effective circulation of my blood.

It is likely that the diving reflex partially abated on the way to the pier while Beth supported my circulation with CPR.  My circulation was further normalized by the intravenous infusions that they gave me at the emergency clinic in Zihautanejo. 

The Mexican clinicians, and my cardiologist, Dr Jack McAnulty, made sure that the more usual causes of sudden cardiac arrest did not apply:  pulmonary embolus, or ventricular fibrillation from coronary occlusion.

Since writing my first piece I have talked with several people who have family members with symptomatic slowing of the heart rate when their face is in cool water. 

Background:

1.     http://en.wikipedia.org/wiki/Mammalian_diving_reflex

2.     JAMA. 1965;192(8):25-27. doi:10.1001/jama.1965.03080210089047.

3.     http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2279457

4.     http://www.scientificamerican.com/article.cfm?id=breath-holding-dive-reflex-extends