Pulmonary artery changes in response to recurrent episodes of anoxia.

Newborn rats exposed to anoxia for 30 seconds twice daily for 4 weeks developed thickening of the media of small muscular pulmonary arteries as measured by point-counting morphometric techniques. These findings are similar to those described in postmortem studies on the lungs of victims of sudden infant death syndrome and support the hypothesis that repeated episodes of apnea alone are a sufficient respiratory abnormality to produce some of the morphometric changes described in victims of sudden infant death syndrome.