Higher CPAP levels improve functional residual capacity at birth in preterm rabbits

Martherus, T.; Croughan, M.K.; Crossley, K.J.; Wallace, M.J.; McGillick, E.V.; Thio, M.; Roehr, C.C.; Pearson, J.T.; Lee, K.T.; Ruben, G.; Kitchen, M.J.; Pas, A.B. te; Hooper, S.B.

doi:doi:10.1038/s41390-021-01647-8

BACKGROUND: Preterm infants are commonly supported with 4-8 cm H2O continuous positive airway pressures (CPAP), although higher CPAP levels may improve functional residual capacity (FRC).METHODS: Preterm rabbits delivered at 29/32 days (similar to 26-28 weeks human) gestation received 0, 5, 8, 12, 15 cm H2O of CPAP or variable CPAP of 15 to 5 or 15 to 8 cm H2O (decreasing similar to 2 cm H2O/min) for up to 10 min after birth.RESULTS: FRC was lower in the 0 (6.8 (1.0-11.2) mL/kg) and 5 (10.1 (1.1-16.8) mL/kg) compared to the 15 (18.8 (10.9-22.4) mL/kg) cm H2O groups (p = 0.003). Fewer kittens achieved FRC > 15 mL/kg in the 0 (20%), compared to 8 (36%), 12 (60%) and 15 (73%) cm H2O groups (p = 0.008). While breathing rates were not different (p = 0.096), apnoea tended to occur more often with CPAP < 8 cm H2O (p = 0.185). CPAP belly and lung bulging rates were similar whereas pneumothoraces were rare. Lowering CPAP from 15 to 5, but not 15 to 8 cm H2O, decreased FRC and breathing rates...Show moreBACKGROUND: Preterm infants are commonly supported with 4-8 cm H2O continuous positive airway pressures (CPAP), although higher CPAP levels may improve functional residual capacity (FRC).METHODS: Preterm rabbits delivered at 29/32 days (similar to 26-28 weeks human) gestation received 0, 5, 8, 12, 15 cm H2O of CPAP or variable CPAP of 15 to 5 or 15 to 8 cm H2O (decreasing similar to 2 cm H2O/min) for up to 10 min after birth.RESULTS: FRC was lower in the 0 (6.8 (1.0-11.2) mL/kg) and 5 (10.1 (1.1-16.8) mL/kg) compared to the 15 (18.8 (10.9-22.4) mL/kg) cm H2O groups (p = 0.003). Fewer kittens achieved FRC > 15 mL/kg in the 0 (20%), compared to 8 (36%), 12 (60%) and 15 (73%) cm H2O groups (p = 0.008). While breathing rates were not different (p = 0.096), apnoea tended to occur more often with CPAP < 8 cm H2O (p = 0.185). CPAP belly and lung bulging rates were similar whereas pneumothoraces were rare. Lowering CPAP from 15 to 5, but not 15 to 8 cm H2O, decreased FRC and breathing rates.CONCLUSION: In all, 15 cm H2O of CPAP improved lung aeration and reduced apnoea, but did not increase the risk of lung over-expansion, pneumothorax or CPAP belly immediately after birth. FRC and breathing rates were maintained when CPAP was decreased to 8 cm H2O.Show less

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Higher CPAP levels improve functional residual capacity at birth in preterm rabbits