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Sleep, respiratory rate, and growth hormone in chronic neonatal lung disease
D Fitzgerald1, P Van Asperen, P O'Leary
1Royal Alexandra Hospital for Children, Sydney, Australia.
Insights
Infants with chronic neonatal lung disease (CNLD) and high respiratory rates (RR) showed slower growth and elevated urinary growth hormone (U-GH) in early infancy. These issues resolved as tachypnea improved, indicating U-GH may reflect stress or impact lung repair.
Area of Science:
- Neonatology
- Pediatric Pulmonology
- Endocrinology
Background:
- Chronic neonatal lung disease (CNLD) affects preterm infants, potentially impacting growth and hormone regulation.
- Respiratory rate (RR) is a key indicator of respiratory distress in neonates.
- Urinary growth hormone (U-GH) excretion can reflect growth status and physiological stress.
Purpose of the Study:
- To investigate the correlation between respiratory rates (RRs), urinary growth hormone (U-GH) excretion, and sleep architecture in infants with CNLD.
- To compare these parameters in infants with high versus normal RRs and control infants across early, middle, and late infancy.
Main Methods:
- Twenty-three preterm infants (16 CNLD, 7 controls) were studied on 51 occasions.
- CNLD infants were stratified into "High RR CNLD" and "Normal RR CNLD" groups based on early infancy non-REM sleep respiratory rate (NREM RR).
- Measurements included respiratory rates, U-GH excretion, sleep architecture (REM%, SWS%), and growth parameters (birthweight, length, growth velocity).
Main Results:
- "High RR CNLD" infants exhibited lower birthweight, current weight, length, and growth velocity in early infancy compared to controls and "Normal RR CNLD" infants.
- Mean U-GH excretion was significantly higher in "High RR CNLD" infants (1,932 ng/g) versus "Normal RR CNLD" (394 ng/g) and controls (320 ng/g).
- With tachypnea resolution by mid-infancy, growth parameters and U-GH excretion normalized, and CNLD infants showed increased sleep efficiency.
Conclusions:
- Tachypneic infants with CNLD experience impaired growth and elevated U-GH in early infancy.
- Resolution of tachypnea leads to improved growth, decreased U-GH excretion, and enhanced sleep consolidation.
- Elevated U-GH in tachypneic CNLD infants may indicate physiological stress, GH resistance, or a feedback mechanism for lung repair.
Abstract:
This study assessed whether respiratory rates (RRs) correlate with urinary growth hormone (U-GH) excretion and sleep architecture in infants with chronic neonatal lung disease (CNLD) in early (1 month), middle (6 months), and late (10 months) infancy. Twenty-three preterm infants (CNLD=16, controls=7) were studied on 51 occasions. CNLD infants were stratified according to mean non-REM sleep respiratory rate (NREM RR) in early infancy into "High RR CNLD" infants (mean NREM RR >2 SD higher than controls) and "Normal RR CNLD" infants (mean NREM RR within 2 SD of controls' mean). "High RR CNLD" infants (RR >45) had a lower mean birthweight (P=0.015), current weight (P=0.042), current length (P=0.02), and growth velocity in early infancy (grams/week gained: P=0.042) than "Normal RR CNLD" and control infants. Mean (95% CI) U-GH excretion (ng U-GH/g urinary creatinine) was higher in "High RR CNLD" infants in air or their usual O2 (1,932 [459, 3,406]) than "Normal RR CNLD" (394 [147, 642]) and controls (320 [147, 492]) (P=0.024). With resolution of tachypnea by mid-infancy, hemoglobin oxygen saturation (SaO2) >93%, mean growth parameters and U-GH excretion for the "High RR CNLD" group were not significantly different from "Normal RR CNLD" and control groups. CNLD infants demonstrated increased sleep efficiency (P=0.016), whereas controls had similar sleep efficiency between early and middle infancy (P=0.452). Mean percent time in REM sleep (REM%) and slow wave sleep (SWS%) were not significantly different between early and middle infancy and did not vary in relation to respiratory rate. We conclude that tachypneic infants with CNLD have slower growth and elevated U-GH excretion in early infancy. With resolution of tachypnea, growth improved, U-GH excretion decreased, and sleep consolidation occurred. An elevated U-GH in tachypneic CNLD infants may reflect stress, compromised nutrition (GH resistance), or a feedback loop involving a direct effect of GH on lung growth and repair.