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Published on: October 25, 2015
High-CPAP Does Not Impede Cardiovascular Changes at Birth in Preterm Sheep
Tessa Martherus1, Kelly J Crossley2, Karyn A Rodgers2
1Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, Netherlands.
Insights
High continuous positive airway pressure (CPAP) effectively supports preterm lambs after birth, improving pulmonary blood flow without negatively impacting cerebral blood flow or jugular vein pressure.
Area of Science:
- Neonatal Physiology
- Cardiovascular Research
- Respiratory Support
Background:
- Current use of continuous positive airway pressure (CPAP) in preterm infants is limited to 4-8 cmH2O.
- Concerns exist regarding potential adverse effects of high-CPAP on pulmonary overexpansion and the cardiovascular system.
Purpose of the Study:
- To investigate the effects of high-CPAP on pulmonary blood flow (PBF), cerebral blood flow (CBF), and jugular vein pressure (JVP) in preterm lambs post-birth.
- To compare the outcomes of low-CPAP, high-CPAP, and dynamic high-CPAP.
Main Methods:
- Preterm lambs were delivered at 133/146 days gestation and instrumented with flow probes and catheters.
- Lambs received either low-CPAP (5 cmH2O), high-CPAP (15 cmH2O), or dynamic high-CPAP (15 decreasing to 8 cmH2O).
- Measurements of PBF, CBF, and JVP were taken for up to 30 minutes post-birth.
Main Results:
- Mean PBF was significantly higher in high-CPAP and dynamic high-CPAP groups compared to the low-CPAP group.
- Cerebral blood flow (CBF) and jugular vein pressure (JVP) remained similar across all CPAP groups.
- High-CPAP groups required less ventilation support and intubation, with no increased incidence of pneumothorax compared to low-CPAP.
Conclusions:
- High-CPAP (15 cmH2O) did not impede the necessary increase in pulmonary blood flow at birth in preterm lambs.
- High-CPAP effectively supported preterm lambs without adverse effects on cerebral blood flow or jugular vein pressure.
- These findings suggest that higher CPAP levels may be safely utilized in neonatal respiratory support.
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.
