Oxygenation Instability and Maturation of Control of Breathing in Premature Infants

Completed

Brief Summary: Premature infants present with significant oxygenation instability in the form of frequent spontaneous episodes of hypoxemia during the first weeks after birth. These infants are also exposed to hyperoxemia.

The objective of this study is to determine the extent to which exposure to frequent episodes of hypoxemia and hyperoxemia in extreme premature infants during the early stages of their evolving lung disease is associated with altered maturation and function of their respiratory control system.

This study is part of the Prematurity-Related Ventilatory Control (Pre-Vent): Role in Respiratory Outcomes Clinical Research Centers (CRC) (U01) cooperative program of the National Heart Lung and Blood Institute (NHLBI) of the National Institutes of Health (NIH).

Detailed Description: Most extreme premature infants present with respiratory failure due to altered lung function compounded by breathing instability due to an immature respiratory control function.

Premature infants present with significant oxygenation instability in the form of frequent spontaneous episodes of hypoxemia during the first weeks after birth. As a result, these infants receive oxygen supplementation but this is often excessive and these infants are also exposed to hyperoxemia. The extent to which these episodes of hypoxemia or the exposure to hyperoxemia impact on the maturation and function of the control of breathing system in extreme premature infants during the evolving stages of their respiratory disease is unknown. This is a prospective study that will systematically evaluate such association in extreme premature infants.

The main objective of this study is to determine the extent to which exposure to frequent episodes of hypoxemia and hyperoxemia in extreme premature infants during the early stages of their evolving lung disease is associated with altered maturation and function of their respiratory control system.

This study is part of the Prematurity-Related Ventilatory Control (Pre-Vent): Role in Respiratory Outcomes Clinical Research Centers (CRC) (U01) cooperative program of the National Heart Lung and Blood Institute (NHLBI) of the National Institutes of Health (NIH).

Recruitment & Eligibility

Inclusion Criteria

Premature infants born at 23 0/7- 28 6/7 weeks gestational age
Postnatal age up to equivalent to 36 weeks postmenstrual age
Requiring supplemental oxygen and/or receiving mechanical ventilation, CPAP, nasal ventilation or nasal cannula

Exclusion Criteria

Severe congenital anomalies that may affect life expectancy or pulmonary or neurosensory development
Severe CNS pathology that may alter respiratory control function

Primary Outcome Measures

Name	Time	Method
Central chemoreceptor control of breathing function	at 36 weeks corrected postmenstrual age	Ventilatory response to carbon dioxide
Peripheral chemoreceptor control of breathing function	at 36 weeks corrected postmenstrual age	Ventilatory response to oxygen (Dejours test)
Change in peripheral chemoreceptor control of breathing function	Change from 32 to 36 weeks postmenstrual age	Ventilatory response to oxygen (Dejours test)
Change in central chemoreceptor control of breathing function	Change from 32 to 36 weeks postmenstrual age	Ventilatory response to carbon dioxide

Secondary Outcome Measures

Name	Time	Method
Ventilatory stability - Periodic breathing density	at 32 and 36 weeks corrected postmenstrual age	Percent of time with periodic breathing
Ventilatory stability - Apnea frequency	at 32 and 36 weeks corrected postmenstrual age	Frequency of apnea episodes per hour
Ventilatory stability - Time series analysis of inter-breath interval	at 32 and 36 weeks corrected postmenstrual age	Tail slope of the log-scaled probability density function of the inter-breath time series
Apneic CO2 threshold during mechanical ventilation	at 32 and 36 weeks corrected postmenstrual age	Carbon dioxide level change at onset of central apnea with stepwise increase in ventilator rate
Mechanisms of episodic hypoxemia	at 32 and 36 weeks corrected postmenstrual age	Classify etiology of episodes of hypoxemia as central, obstructive, or mixed apnea or active exhalation based on measurements of respiratory inductance plethysmography, esophageal pressure
Apneic CO2 threshold in central apnea	at 32 and 36 weeks corrected postmenstrual age	Carbon dioxide level change at onset of central apnea

Locations (1): NICU at Holtz Children's Hospital
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Miami, Florida, United States