Sett Arun, Truong Jennifer, Crotty Anna, Douglas Ellen, Hodder Joel, Poh Qi Hui, Kenna Kelly R, Sourial Magdy, Fatmous Monique, Pereira-Fantini Prue M, Tingay David Gerald
Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
Newborn Services, Joan Kirner Women's and Children's, Sunshine Hospital, Western Health, Melbourne, Victoria, Australia.
Arch Dis Child Fetal Neonatal Ed. 2025 May 13. doi: 10.1136/archdischild-2024-328401.
Stepwise positive end-expiratory pressure at birth (dynamic PEEP) reduces lung injury in preterm lambs; however, the impact of dynamic PEEP on pulmonary blood flow (PBF) during immediate (ICC) and deferred cord clamping (DCC) is unknown.
To determine the impact of dynamic PEEP on PBF during DCC and ICC.
Preterm lambs (n=22) received a ventilation strategy with either dynamic PEEP (between 8 and 14 cmHO) or static PEEP (8 cmHO) after birth. Lambs were managed with either DCC or ICC (30 s clamp to ventilation) (n=5-6 per group). Left pulmonary artery flow was measured using echocardiography as a surrogate for PBF. Ventilation parameters and PBF were measured every 20 s until 180 s and at 5, 10 and 15 min from ventilation onset.
There was no significant difference in PBF between dynamic and static PEEP applied during DCC (mean (SD) 183 (66) vs 125 (43) mL/kg/min, mean (SD) difference=-58 (103) mL/kg/min, p=0.09) or ICC (124 (26) vs 120 (31) mL/kg/min, mean difference=-4(184), p=0.94). PBF significantly increased over time (p<0.01; mixed effects) in all groups regardless of cord management. This was associated with an increase in the velocity time integral (p<0.01) but no difference in heart rate. Cerebral blood flow reduced over time during DCC (p<0.01) with no change observed during ICC. There was no difference in lung mechanics apart from higher respiratory system compliance in the ICC Dynamic PEEP group (mean difference 0.08 (0.05) mL/kg/cmHO, p<0.01).
Elective lung recruitment after birth using a dynamic PEEP does not impede PBF in preterm lambs.
出生时逐步增加呼气末正压（动态呼气末正压）可减少早产羔羊的肺损伤；然而，动态呼气末正压对即刻断脐（ICC）和延迟断脐（DCC）期间肺血流（PBF）的影响尚不清楚。
确定动态呼气末正压对DCC和ICC期间PBF的影响。
早产羔羊（n = 22）出生后接受动态呼气末正压（8至14 cmH₂O之间）或静态呼气末正压（8 cmH₂O）的通气策略。羔羊采用DCC或ICC（夹闭脐带30秒后通气）进行处理（每组n = 5 - 6）。使用超声心动图测量左肺动脉血流作为PBF的替代指标。每20秒测量一次通气参数和PBF，直至180秒，并在通气开始后5、10和15分钟测量。
DCC期间应用动态呼气末正压和静态呼气末正压时，PBF无显著差异（均值（标准差）183（66）对125（43）mL/kg/min，均值（标准差）差异 = -58（103）mL/kg/min，p = 0.09）或ICC期间（124（26）对120（31）mL/kg/min，均值差异 = -4（184），p = 0.94）。无论脐带处理方式如何，所有组的PBF均随时间显著增加（p < 0.01；混合效应）。这与速度时间积分增加（p < 0.01）相关，但心率无差异。DCC期间脑血流随时间减少（p < 0.01），ICC期间未观察到变化。除ICC动态呼气末正压组呼吸系统顺应性较高外（均值差异0.08（0.05）mL/kg/cmH₂O，p < 0.01），肺力学无差异。
出生后使用动态呼气末正压进行选择性肺复张不会阻碍早产羔羊的PBF。
