Infant,Premature
Conditions
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).
Interventions
OTHERAssessment of oxygenation instability
Recordings of SpO2 and heart rate will be analyzed by dedicated software to obtain frequency, duration and severity of episodes of hypoxemia and hyperoxemia.
OTHERDetermination of mechanisms of hypoxemia episodes
Recordings of SpO2, heart rate, esophageal pressure, tidal volume, minute volume, respiratory rate and transcutaneous PCO2 will be analyzed to determine the prevalence, severity and duration of hypoxemia episodes produced by the different mechanisms.
OTHERAssessment of respiratory instability
Recordings of tidal volume, minute volume and respiratory rate will be analyzed to determine frequency of apnea, periodic breathing, distribution of inter-breath intervals.
OTHERapneic threshold of CO2
In mechanically ventilated infants the apneic threshold of CO2 will be measured by transcutaneous PCO2 following a step wise increase in ventilator rate until spontaneous breathing ceases transiently. In spontaneously breathing infants the apnea threshold of CO2 will be measured during episodes central apnea.
OTHERAssessment of peripheral chemoreceptor function
The Dejours test will be used to assess peripheral chemoreceptor function by measuring the immediate ventilatory response to high-inspired oxygen.
OTHERAssessment of central chemo-receptor function
Central chemo-receptor function will be assessed by measuring the ventilatory response to inspired CO2.
Sponsors
National Heart, Lung, and Blood Institute (NHLBI)
University of Miami
Study design
Observational model
OTHER
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Peripheral chemoreceptor control of breathing function | at 32 weeks corrected postmenstrual age | Ventilatory response to oxygen (Dejours test) |
| Central chemoreceptor control of breathing function | at 32 weeks corrected postmenstrual age | Ventilatory response to carbon dioxide |
| 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
| Measure | Time frame | Description |
|---|---|---|
| Apneic CO2 threshold in central apnea | at 32 and 36 weeks corrected postmenstrual age | Carbon dioxide level change at onset of central apnea |
| Ventilatory stability - Apnea frequency | at 32 and 36 weeks corrected postmenstrual age | Frequency of apnea episodes per hour |
| 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 |
| Ventilatory stability - Periodic breathing density | at 32 and 36 weeks corrected postmenstrual age | Percent of time with periodic breathing |
| 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 |
| 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 |
Countries
United States
Outcome results
None listed