Elsevier

Early Human Development

Volume 66, Issue 2, February 2002, Pages 107-121
Early Human Development

A review of the anatomy of the upper airway in early infancy and its possible relevance to SIDS

https://doi.org/10.1016/S0378-3782(01)00242-0Get rights and content

Abstract

Background: Since the danger of prone sleeping in the first 6 months of life has been publicised, there has been a dramatic and consistent reduction in the incidence of sudden infant death syndrome (SIDS). However, unexpected infant deaths and apparent life-threatening events (ALTEs) continue to occur that are clearly not associated with known epidemiological risk factors. Aims: To review the unique features of the anatomy and function of the upper airway of the young infant which contribute to increased vulnerability to hypoxia in this age group. We discuss the clinical identification of those infants at risk of obstruction or restriction of the upper airway and the management of the ‘at risk’ infant. Conclusions: In the era after the “back to sleep” campaigns, it is likely that an increasing proportion of cases of ALTEs and SIDS will be related to obstruction or limitation of upper airway size leading to sleep hypoxia/asphyxia. This type of problem may be anticipated by evaluation and investigation of infants with signs or a clinical history consistent with possible upper respiratory tract compromise, including micrognathia.

Section snippets

Shape of the upper airway in infancy

The upper airway, between the external nares and the trachea, is obviously crucial to the delivery of air to the lungs, and thus of oxygen to the whole body. The shape of the upper airway and the forces acting upon it in infancy are not the same as in adult life. At birth the head is approximately one quarter of the total length of the infant. The brain is nearing adult size, as are the eyes, whilst the face, the maxilla and especially the mandible are small and undeveloped (Fig. 1a). The

General principles

The epidemiological identification of a number of risk factors for sudden infant death syndrome (SIDS) such as prone sleeping, and their subsequent reduction in the general population has been associated with a dramatic fall in the incidence of SIDS [9], [10]. Nevertheless, unexpected infant deaths still occur that are not associated with these known epidemiological risk factors. Obstruction or restriction of the upper airway is one likely cause of such cases. In practice virtually all

Examination and investigation for possible upper airway inadequacy

The most obvious facial clue to an upper airway problem is often that the infant has a very small jaw (is micrognathic) [11], [49]. Babies with inadequate upper airways often have an anxious expression and have a ‘fat chops’ look, because the posteriorly positioned tongue bulges the infant's submental region as there is no sufficient room for it between the mandible and the soft palate. These facial characteristics have been noted in families who have experienced SIDS or ALTEs in subsequent

Summary

In conclusion, unexpected infant deaths and ALTEs continue to occur. Although many other potential causes will contribute to these problems, there is increasing evidence that a significant proportion may be related to obstruction or restriction of the upper airway during sleep. This review has highlighted features of the development and anatomy of the young infant that predispose to functional/positional and structural restriction or obstruction of the upper airway. These data help guide the

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