Response to external obstruction in preterm infants with apnea

Effect of prone and supine position on sleep, apneas, and arousal in preterm infants

OBJECTIVE

Prematurely born compared with term born infants are at increased risk of sudden infant death syndrome, particularly if slept prone. The purpose of this work was to test the hypothesis that preterm infants with or without bronchopulmonary dysplasia being prepared for neonatal unit discharge would sleep longer and have less arousals and more central apneas in the prone position.

METHODS

This was a prospective observational study in a tertiary NICU. Twenty-four infants (14 with bronchopulmonary dysplasia) with a median gestational age of 27 weeks were studied at a median postconceptional age of 37 weeks. Video polysomnographic recordings of 2-channel electroencephalogram, 2-channel electro-oculogram, nasal airflow, chest and abdominal wall movements, limb movements, electrocardiogram, and oxygen saturation were made in the supine and prone positions, each position maintained for 3 hours. The duration of sleep, sleep efficiency (total sleep time/total recording time), and number and type of apneas, arousals, and awakenings were recorded.

RESULTS

Overall, in the prone position, infants slept longer, had greater sleep efficiency (89.5% vs 72.5%), and had more central apneas (median: 5.6 vs 2.2), but fewer obstructive apneas (0.5 vs 0.9). The infants had more awakenings (9.7 vs 3.5) and arousals per hour (13.6 vs 9.0) when supine. There were similar findings in the bronchopulmonary dysplasia infants.

CONCLUSIONS

Very prematurely born infants studied before neonatal unit discharge sleep more efficiently with fewer arousals and more central apneas in the prone position, emphasizing the importance of recommending supine sleeping after neonatal unit discharge for prematurely born infants.

Does gastroesophageal reflux cause apnea in preterm infants?

Gastroesophageal reflux (GER) and apnea are both common occurrences in premature infants but their relationship is controversial. We present the evidence for and against an association between GER and apnea and discuss the merits and limitations of the various methodologies employed in characterizing such a relationship. Overall, GER and apnea do not appear temporally related in preterm infants, despite strong physiologic evidence that stimulation of laryngeal afferents elicits central apnea and laryngeal adduction. In a subpopulation of infants with neurodevelopmental compromise, there may be an increased incidence of both apnea and GER, although the direct association between GER and apnea in this population is unclear. Therefore, we believe there is no evidence to support widespread use of anti-reflux medications in the treatment of apnea in preterm infants. Further studies are needed to clarify the existence of a small subpopulation of infants who may have GER-induced apnea, to identify potential triggering mechanisms, and to document benefit from newer pharmacological approaches.

The role of the upper airway in neonatal apnoea

Up to 50% of apnoeic episodes are obstructive or mixed apnoeas in which, by definition, there is upper airway obstruction. The other 50% of apnoeas are central in origin, but in 40% of these there is evidence of upper airway obstruction, which also occurs in periodic breathing. The obstruction occurs in the upper pharynx. It is due to a failure of activation of the muscles, including the genioglossus, which support the compliant pharynx and normally prevent its collapse. Fibreoptic studies have demonstrated obstruction also at the entrance to the larynx by the arytenoid masses and the aryepiglottic folds. There is some evidence that inspiring against a closed airway can induce central apnoea, possibly via the intercostal-phrenic inhibitory reflex. Upper airway secretions can trigger obstruction. Continuous positive airway pressure distends both the pharynx and laryngeal aperture and so prevents mixed and obstructive apnoeas, but has no effect on central apnoea.

Airway obstruction in two extremely low birthweight infants treated with oxygen cannulas

Two extremely low birthweight (ELBW) infants developed airway obstruction while being treated with oxygen cannulas. We have previously shown that nasal mucosal injury from use of oxygen cannulas in ELBW infants increases nasal secretions and bleeding. Airway patency may be compromised when ELBW infants are treated with oxygen cannulas.

Apnea of prematurity: diagnosis, implications for care, and pharmacologic management

Apnea is a disorder of respiratory control commonly seen in premature infants. Several mechanisms have been proposed to explain apnea, and many clinical conditions have been associated with its development. Apnea of prematurity is seen in infants less than 37 weeks gestation, with the incidence increasing as gestational age decreases. Expert and consistent nursing care is essential for management of premature infants with apnea. This article reviews the differential diagnosis, pathogenesis, and implications for care of apnea of prematurity.