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Pulmonary protective mechanisms in human infants
Insights
Infants frequently swallow secretions during sleep, a key mechanism for airway protection and preventing aspiration pneumonia. This study explores the reflexes and coordination of these swallows, especially during apnea.
Area of Science:
- Pediatrics
- Pulmonology
- Gastroenterology
Background:
- Pulmonary aspiration of oral and nasal secretions during sleep is a recognized cause of bacterial pneumonia in infants and adults.
- Infants exhibit a higher frequency of swallowing during sleep compared to adults, facilitating the transport of secretions to the digestive tract.
- Nonfeeding swallows, characterized by brief airway closure, are observed during apneic spells in preterm infants, with underlying reflex mechanisms remaining unclear.
Purpose of the Study:
- To investigate the mechanisms of airway protection during sleep in infants, focusing on swallowing reflexes and their coordination with respiration.
- To explore the association between regurgitation and apnea in infants and the potential role of laryngeal chemoreceptors.
- To elucidate the unclear reflex mechanisms responsible for nonfeeding swallows during apnea in preterm infants.
Main Methods:
- Observational study analyzing swallowing patterns and respiratory coordination during sleep in infants.
- Documentation of "swallow-breaths" and their temporal relationship with the respiratory cycle.
- Investigation of airway closure events during nonfeeding swallows and postfeeding regurgitation.
Main Results:
- Swallowing during sleep is a primary mechanism for clearing oral and nasal secretions in infants, with a higher rate than in adults.
- Nonfeeding swallows, involving airway closure, are frequently observed during mixed and obstructive apneic spells in preterm infants.
- Postfeeding regurgitation and upper airway closure occur in close sequence, suggesting a protective airway mechanism, though the simultaneous occurrence with prolonged apnea in some infants is unexplained.
Conclusions:
- Swallowing during sleep plays a crucial role in airway protection and preventing aspiration in infants.
- The reflex mechanisms governing nonfeeding swallows during apnea require further investigation.
- The association between regurgitation and apnea in infants may involve laryngeal chemoreceptors, warranting further study.
Abstract:
The flow of oral and nasal secretions into the pharynx is a recognized source of pulmonary aspiration during sleep in infants and adults alike. Such aspiration probably accounts for many cases of bacterial pneumonia. In infants, swallowing occurs frequently in sleep, and the rate of swallowing appears to be far greater than that of the sleeping adult. Such swallowing during sleep appears to be the major mechanism whereby oral and nasal secretions are transported to the digestive tract. Certain aspects of those swallows, such as "swallow-breaths" and their coordination with the respiratory cycle, have been documented. A brief period of airway closure is always seen during such nonfeeding swallows. Nonfeeding swallows are usually seen during mixed and obstructive apneic spells in preterm infants. The underlying reflex mechanisms responsible for such swallows during apnea are unclear. During ordinary postfeeding regurgitation, upper airway closure and swallowing occur in close temporal sequence. These events appear to be major mechanisms of airway protection during regurgitation. In certain infants, regurgitation and prolonged apnea often occur simultaneously. The mechanism underlying their association is unclear but may involve laryngeal chemoreceptors.