Death by Reflex?

The hyaline membrane disease that kills at least 25,000 infants every year (among them: Patrick Bouvier Kennedy) and the heart attacks that are fatal to 500,000 adult Americans seem poles apart as subjects for medical research. But doctors half the world away from each other have just implicated the same reflex as a possible cause of both killers: a primitive response apparently built into the human body to protect it against asphyxiation.

Concentrates the Blood. University of Oklahoma's Professor of Medicine Stewart Wolf, who was working on heart disease, and seven physicians (six Americans, one Malaysian) working on hyaline membrane disease at Singapore's Kandang Kerbau Hospital, all found themselves reaching back to studies of ducks and seals--experiments that were in some cases nearly a century old. When those aquatic creatures swim below the surface, a "dive" reflex slows their heartbeats and contracts their peripheral arteries, thus concentrating the available oxygenated blood in the heart and brain. Most of the body's tissues then switch from an oxygen-burning system to one in which nutrients are "burned" without oxygen.

Dr. Wolf wondered how strong this reflex was in man, and whether it might sometimes go too far. Instead of the heart simply slowing down, Dr. Wolf asked himself, might it not actually stop? To check his reasoning, he talked his wife and three children into joining other volunteers in repeatedly dunking their faces in a wash basin while he took their electrocardiograms. Their heart rates promptly slowed down. One of Wolfs most important findings was that fear intensified the reflex. If a man feels severe pain and suspects he is having a heart attack, Wolf concluded, he may panic, thus causing a reflex so marked that his heart will quit. Or chemical changes caused by the too-strong reflex action may throw the heart into equally fatal fibrillation (a useless twitching).

In Pediatrics, the seven medical researchers suggest that this same reflex may be what causes many premature and some full-term infants to shut down the flow of blood through their lungs. Some unborn infants may have had the reflex activated to compensate for an oxygen shortage caused by low blood pressure in the mother, or a constriction or partial separation of the umbilical cord. As a result, the babies are born with thousands of constricted arterioles that do not carry sufficient blood to the lung's air spaces where oxygen is picked up--a condition that leads to the formation of a glassy (hyaline) membrane covering the inside walls of the lungs.

Struggling for Breath. The doctors in Singapore sought to counteract the arterial constriction with a powerful agent released by some nerve endings, acetylcholine, which causes sweating, flushing and, most important, dilation of the blood vessels in the lung. They used the chemical on twelve infants, all of whom had the classical signs of HMD: labored breathing, grunting, and an excess of body fluids. Four infants who may have received too little of the chemical or had the injection too late, did not survive. One died from an infection, but seven others lived. And one of the first babies in the U.S. to be treated with acetylcholine, a "blue infant struggling for breath" born one month prematurely at Stanford Medical Center, was breathing normally after ten hours. He left the hospital nine days later and is now a healthy 20-pounder. For all its dramatic help, though, acetylcholine is a powerful and dangerous drug, and the doctors hope to find safer blood-vessel dilators that will be even more effective.

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