Document Detail

Maturation and transformation of reflexes that protect the laryngeal airway from liquid aspiration from fetal to adult life.
MedLine Citation:
PMID:  11749929     Owner:  NLM     Status:  MEDLINE    
Several reflexes are initiated in the fetus and newborn when hypochloremic or strongly acidic solutions contact the epithelium that surrounds the entrance to the laryngeal airway. These reflexes, known collectively as the laryngeal chemoreflex (LCR), include startle, rapid swallowing, apnea, laryngeal constriction, hypertension, and bradycardia. Many studies have shown that prolonged apnea associated with the LCR may be life threatening and might conceivably be a cause of sudden infant death syndrome. This certainly may be true, but the concept of a lethal LCR paradoxically contrasts with the view that these several reflexes have an important airway-protective role. As the infant matures, rapid swallowing and apnea become much less pronounced, whereas cough and possibly laryngeal constriction become more prominent. This transformation is primarily related to central neural processing rather than to changes in the airway mucosal "water receptors" that initiate the reflex. The LCR develops in the fetus, in an all-aqueous environment, during a period in which aspiration of amniotic fluid poses a serious threat to life. This and other considerations suggest that the transformation in LCR responses from fetal to adult life can be viewed as functionally appropriate to their primary role in defending the airway from aspiration. The laryngeal "water receptors" that initiate the LCR in infants and adults alike appear to be the primary sensory mechanism for defending the airway from aspiration of liquids.
B T Thach
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  The American journal of medicine     Volume:  111 Suppl 8A     ISSN:  0002-9343     ISO Abbreviation:  Am. J. Med.     Publication Date:  2001 Dec 
Date Detail:
Created Date:  2001-12-25     Completed Date:  2002-01-14     Revised Date:  2005-11-16    
Medline Journal Info:
Nlm Unique ID:  0267200     Medline TA:  Am J Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  69S-77S     Citation Subset:  AIM; IM    
Department of Pediatrics, Washington University School of Medicine, Division of Newborn Medicine, St Louis Children's Hospital, One Children's Place, St Louis, Missouri 63110, USA.
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MeSH Terms
Adaptation, Physiological
Age Factors
Airway Resistance
Apnea / etiology,  prevention & control*
Child Development / physiology
Child, Preschool
Deglutition / physiology*
Embryonic and Fetal Development / physiology
Infant, Newborn
Larynx / embryology*,  physiology
Pharynx / embryology*,  physiology
Pneumonia, Aspiration / prevention & control*
Reflex / physiology*

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