Besides helping infants' lungs mature, sighs may "reset" breathing regulation mechanism

BETHESDA, MD (August 12, 2004) As if new parents don't have enough to worry about getting in synch with their infants, many of them wonder "what's with these sighs?"

Of course adults sigh; not as often as infants, though sometimes often enough to annoy others. But with an adult, you can ask if there's a problem. With newborns, it's hard to know if it's good or bad, partly because how often they occur can vary from once every 50 breaths to every 100 or more. The good news is, sighs are good. The issue is, how good, and exactly what purpose do they serve?

Role in mechanical lung development

It's been pretty well documented by researchers that deep inspirations, the technical phrase for sighs, play a significant role in helping the mechanical function of healthy lungs. Infants actively regulate their lung function, elevating lung volume above what would be expected by their relatively stiff lung tissue and floppy chest wall compared to adults.

These seemingly "spontaneous" deep breaths often help re-open parts of the lung, especially very small airways, or alveoli, which are prone to collapse. Thus sighs help keep the lungs inflated making them more efficient and possibly also improving the exchange of gases.

On the clinical side, abnormalities of breathing control are occasionally seen in adults and infants, especially during illness. Premature babies often have transient pauses in their breathing pattern, called "periodic breathing." When these pauses last for an abnormally long period, they are known as "apneas." It is these excessively long pauses that may reflect some degree of abnormal function in the system that controls breathing. In its most severe form, this may be seen in conditions such as sudden
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Contact: Mayer Resnick
mresnick@the-aps.org
301-634-7209
American Physiological Society
12-Aug-2004