What does grunting in infants during exhalation help maintain?

Grunting during exhalation in infants serves a crucial physiological purpose—it helps maintain positive pressure in the alveoli. When an infant grunts, they are essentially creating a sound through their vocal cords while partially closing the glottis at the end of an exhalation. This action results in a slight increase in pressure within the airways and lungs.

Maintaining positive pressure in the alveoli is essential for keeping the alveoli open, especially in cases where the infant may be experiencing respiratory distress or conditions that lead to atelectasis (collapse of lung units). By increasing the pressure in the lungs during exhalation, grunting helps to stabilize the alveoli and facilitate gas exchange, allowing the infant to retain adequate oxygen levels and reduce the workload of breathing.

This mechanism reflects the body's natural response to optimize lung function, particularly in a vulnerable population like infants who may have weaker respiratory systems.