A New Taxonomy Using the Dejours Test to Describe Carotid Body Maturation in Extremely Preterm Infants
Year: 2021
Type: conference-abstract
Abstract: Rationale: The carotid body (CB) quickly responds to hyperoxia and hypoxemia.At birth infants slowly adapt to much higher PaO 2 than in utero ("resetting" of the CB).In term infants resetting takes several weeks, with increasing contribution from the CB to ventilatory drive.Less is known about CB maturation in preterm infants.Preterm infants are often exposed to intermittent hypoxia and hyperoxia, both which can alter maturation of the CB ("developmental plasticity").If short (30 second) exposure to FiO 2 = 1.00 -Dejours test -reduces minute ventilation (V E ), this represents the relative contribution of the CB to ventilatory drive.Aberrant CB function, with excessive periodic breathing, has been implicated in the need for O 2 at 36 weeks PMA, complicating the diagnosis of bronchopulmonary dysplasia (BPD).We used the Dejours test to more completely characterize maturation of CB function and to broaden understanding of ventilatory control instability as part of the BPD "phenotype."Methods: 34 infants born 24 0/7 to 28 6/7 weeks postmenstrual age (PMA) underwent Dejours tests during quiet sleep at 32, 36, 40, and 52 weeks PMA.Testing was performed if infants were not intubated, deemed clinically stable, and receiving ≤3 liters per minute of flow by nasal cannula. 1 to 3 hyperoxia tests were performed per infant at each PMA (Table 1).Respiratory inductance bands were used to measure respiratory rate and estimate changes in tidal volume.V E was calculated and averaged over a four-breath moving window.Qualitative and quantitative responses to FiO2 = 1.00 were described.Responses were excluded if infant aroused or was not in quiet sleep.Results:There were 4 categories of responses to FiO 2 = 1.00: initial decrease in V E +/-subsequent sigh; initial apnea +/-subsequent sigh; initial sigh followed by either apnea or V E fall; no response.At earlier PMA, apnea was a more common response.At later PMA, decrease in V E was more frequent (Chi-squared, p < 0.01).Average percent initial V E decrease was not significantly different across PMA (p = 0.051).Conclusions:Infants at lower PMA more frequently had apnea in response to FiO 2 = 1.00; infants at later PMA were more likely to have V E decrease.Both qualitative and quantitative approaches should improve the usefulness of brief hyperoxia exposure in characterizing the maturation of CB function, its potential contribution to ventilatory pattern instability, and refine our understanding of supplemental O 2 needs and the definition of BPD.
Authors: D.M. Mammel, J.L. Carroll, B.B. Warner, B.A. Edwards, D. Mann, J. Egan, J. Hoover, M. McLeland, J. Hoffmann, J.S. Kemp
Language: English
Subfield: Endocrine and Autonomic Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: gold
OpenAlex ID: W4247098826