Page 92 - Physiological based CPAP for preterm infants at birth Tessa Martherus

Chapter 4
Abstract Objective
Continuous positive airway pressures (CPAP) used to assist preterm infants at birth are limited to 4-8 cmH2O due to concerns that high-CPAP may cause pulmonary overexpansion and adversely affect the cardiovascular system. We investigated the effects of high-CPAP on pulmonary (PBF) and cerebral (CBF) blood flows and jugular vein pressure (JVP) after birth in preterm lambs.
Methods
Preterm lambs instrumented with flow probes and catheters were delivered at 133/146 days gestation. Lambs received low-CPAP (LCPAP: 5 cmH2O), high-CPAP (HCPAP: 15 cmH2O) or dynamic HCPAP (15 decreasing to 8 cmH2O at ~2 cmH2O/min) for up to 30 min after birth.
Results
Mean PBF was lower in the LCPAP (median (Q1-Q3); 202 (48-277) mL/min, p=0.002) compared to HCPAP (315 (221-365) mL/min) and dynamic HCPAP (327 (269-376) mL/min) lambs. CBF was similar in LCPAP (65 (37-78) mL/min), HCPAP (73 (41-106) mL/min), and dynamic HCPAP (66 (52-81) mL/min, p=0.174) lambs. JVP was similar at CPAPs of 5 (8.0 (5.1-12.4) mmHg), 8 (9.4 (5.3-13.4) mmHg), and 15 cmH2O (8.6 (6.9-10.5) mmHg, p=0.909). Heart rate was lower in the LCPAP (134 (101-174) bpm; p=0.028) compared to the HCPAP (173 (139-205)) and dynamic HCPAP (188 (161-207) bpm) groups. Ventilation or additional caffeine was required in 5/6 LCPAP, 1/6 HCPAP, and 5/7 dynamic HCPAP lambs (p=0.082), whereas 3/6 LCPAP, but no HCPAP lambs required intubation (p=0.041), and 1/6 LCPAP, but no HCPAP lambs developed a pneumothorax (p=0.632).
Conclusion
High-CPAP did not impede the increase in PBF at birth and supported preterm lambs without affecting CBF and JVP.
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