Relationship Between Functional Residual Capacity and Oxygen Desaturation During Short Central Apneic Events During Sleep in “Late Preterm” Infants

Abstract

Apneic episodes are frequent in the preterm neonate and particularly in active sleep (AS), when functional residual capacity (FRC) can be decreased. Furthermore, FRC may be inversely correlated with the speed of blood-O 2 -desaturation. We evaluated the potential involvement of FRC in the mechanisms responsible for blood-O 2 -desaturation during short central apneic events (Ͼ3 s) in "late-preterm" infants and analyzed the specific influence of sleep state. Apneic events were scored in 29 neonates (postmenstrual age: 36.1 Ϯ 1.2 wk) during AS and quiet sleep (QS). FRC was measured during well-established periods of regular breathing. Apneas with blood-O 2 -desaturation (drop in SpO 2 Ͼ5% from the baseline, lowest SpO 2 during apnea: 91.4 Ϯ 1.8%) were more frequent in AS than in QS, whereas no difference was seen for apneas without desaturation. The magnitude of the FRC did not depend on the sleep state. In AS only, there was a negative relationship between FRC and the proportion of apneas with desaturation. Even in late preterm infants who do not experience long-lasting apnea, blood-O 2 -desaturation during short apneic events is related (in AS but not QS) to a low baseline FRC. Sleep stage differences argue for a major role of AS-related mechanisms in the occurrence of these apneas.

Ventilatory control and supplemental oxygen in premature infants with apparent chronic lung disease

“…Within PROP, which is designed to identify clinical risk factors and candidate biomarkers for CLD among infants born between 24 and 28 weeks PMA, we suspect that the current clinical definition of CLD will complicate our studies because the need for supplemental oxygen support at 36 weeks PMA may be multifactorial and reflect an interaction between parenchymal dysfunction due to lung disease and immature respiratory control. Infants with significant CLD may also be particularly susceptible to developing PB when they become hypoxaemic with even brief central apnoeas 24 25. Some of the infants studied had marked chest wall dyssynchrony (table 1) in addition to requiring supplemental O 2 , suggesting that significant respiratory system compromise contributed to their propensity for desaturation during PB.…”

A Model Analysis of Arterial Oxygen Desaturation during Apnea in Preterm Infants

“…Two reports offer support for this view. First, rapid desaturation occurs in infants with low functional residual capacity [15], a finding that may help to explain the more frequent O 2 desaturation events during active sleep [33] when functional residual capacity is reduced. Second, frequent desaturation is characteristic of preterm infants with bronchopulmonary dysplasia (BPD) [34] whose O 2 consumption is 25% greater [35], and functional residual capacity is 25% less [36], than in preterm infants without BPD; Equations 11 and 12 predict that such differences increase both immediate and peak by ∼70%.…”

“…In the current study it was assumed that lung volume did not fall during apnea, as in active sleep [24], when apneic desaturation events are most common [33]. With lung volume constant, conservation of mass requires that passive airflow into the unobstructed airway must occur in response to a net pulmonary gas uptake into the pulmonary blood [11].…”

NAVA—synchronized compared to nonsynchronized noninvasive ventilation for apnea, bradycardia, and desaturation events in VLBW infants

“…The most frequent type of apneic event is termed mixed, where short, sometimes undetectable, breathing cessation of central origin is quickly followed by bradycardia and/or desaturations . These desaturations, detected or subthreshold, may be due to airway collapse or they may be related to a low functional residual lung capacity (FRC) . Bradycardias can result from the hypoxemia, or they may occur in isolation due to immature vagus nerve reflexes that fire during inspiration and resolve with the resumption of airflow .…”