SIDS trigger? It’s too darn hot

From Washington, D.C., at the Experimental Biology 2004 meeting

Infants occasionally stop breathing for short periods during sleep, a phenomenon called apnea. Working with newborn pigs, researchers from Dartmouth Medical School in Hanover, N.H., have found that overheating—even to a degree that could occur in a swaddled baby in a warm room—dramatically prolongs apnea.

The result suggests one explanation for some instances of sudden infant death syndrome (SIDS), says team leader Aidan Curran, a respiratory physiologist at Ross University School of Medicine in Roseau, Dominica, an island in the West Indies. SIDS occurs most commonly during winter months when parents are most likely to fuss over keeping their babies warm.

The study was spurred by epidemiological data indicating that the core body temperature of some SIDS babies is higher than normal “even several hours after death,” Curran notes.

His team anesthetized infant pigs and then removed parts of their brains, leaving the animals comatose and unable to feel pain. The researchers then occasionally deposited a tiny drop of water onto each animal’s larynx—to simulate what happens when a baby regurgitates a little milk, a common occurrence that is known to trigger apnea and then a cough.

Normally, the water triggered a session of apnea lasting 10 to 40 seconds. However, when the scientists wrapped an animal in heating blankets to slowly raise its core body temperature 4° to 5°F, the induced apnea lasted some 200 seconds. “In one case, it continued for 5 minutes,” Curran recalled. “I thought I’d killed the animal.”

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.