664 - Optimising Continuous Positive Airway Pressures and Oxygen levels to support Spontaneous Breathing in Preterm Rabbits at Birth.

Monday, May 1, 2023

9:30 AM – 11:30 AM ET

Poster Number: 664
Publication Number: 664.442

kelly J. Crossley, Hudson Institute of Medical Research, Clayton, Victoria, Australia; Ebony R. Cannata, The Hudson Institute of Medical Research, Melbourne, Victoria, Australia; Erin V. McGillick, Hudson Institute of Medical Research/Monash University, Clayton, Victoria, Australia; Megan J. Wallace, Monash University, Clayton, Victoria, Australia; Marcus J.. Kitchen, Monash University, Clayton, Victoria, Australia; Michelle K. Croughan, Monash University, murrumbeena, Victoria, Australia; Dylan W. O'Connell, Monash University, Melbourne, Victoria, Australia; Sophie Cramer, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands; Arjan te pas, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands; stuart Hooper, Monash University, Melbourne, Victoria, Australia; Dominic Jurkschat, Monash University, Clayton, Victoria, Australia

Presenting Author(s)

kelly J. Crossley, PhD (she/her/hers)

Senior Research Fellow
Hudson Institute of Medical Research
Clayton, Victoria, Australia

Background:

Preterm birth, before 37 weeks’ gestation, is associated with over 50% of worldwide neonatal mortality rates making it the biggest cause for concern in the delivery room. Preterm infants commonly receive 4-8cmH₂O continuous positive airway pressure (CPAP) and 21-30% fraction of inspired oxygen (FiO₂) immediately after birth. However, the optimal level of support to promote lung aeration and spontaneous breathing in preterm infants is unknown.

Objective: To investigate the independent effects of CPAP level and FiO₂on supporting spontaneous breathing and lung aeration in preterm rabbits.

Design/Methods: Two groups of preterm rabbit kittens (29/32 days gestation) were supported with 5cmH₂O (n=12) or 15cmH₂O (n=15) CPAP. These groups were sub-divided to receive either 30% (5cmH₂O CPAP n=6 or 15cmH₂O CPAP n=8) or 60% (5cmH₂O CPAP n=6 or 15cmH₂O CPAP n=7) FiO₂ for up to 15 minutes after delivery. Phase-contrast x-ray imaging was used to measure breathing rate and change in lung aeration (functional residual capacity; FRC), as well as the severity of CPAP belly i.e. gas in the stomach (absent, significant or non-significant). Statistical analysis for breathing rate and FRC over imaging time was analysed using a mixed-effect model analysis and post-hoc Holm-Sidak test. CPAP belly incidence was analysed using a Chi-square test. Statistical significance was accepted as p< 0.05.

Results: Kittens that received 15cmH₂O CPAP and 60% FiO₂had the highest breathing rate (47±3 breaths/min), whereas kittens that received 5cmH₂O CPAP and 30% FiO₂ had the lowest breathing rate (23±3 breaths/min); p< 0.05. Kittens that received 15cmH₂O CPAP and 60% FiO₂ had an increase in FRC volume (3.7±1 mL/kg) whereas kittens that received 5cmH₂O CPAP and 30% FiO₂ had lost FRC volume (-1.3± 3mL/kg) during imaging; p=0.2051. There was no difference in the severity of CPAP belly between groups (seen as significant severity in 4/27 kittens). However, the incidence of significant severity CPAP belly was higher with 15cmH₂O CPAP (3/4, 75%) compared to 5cmH₂O CPAP (1/4, 25%); p=0.6532.

Conclusion(s): In preterm rabbits, higher CPAP (15cmH₂O) and FiO₂ (60%) improved spontaneous breathing rates and lung aeration after birth with no increased risk for CPAP belly.