Smolich Joseph J, Kenna Kelly R, Sourial Magdy, Black Don, Lavizzari Anna, Tingay David G
Heart Research Group, Murdoch Children's Research Institute, Parkville, VIC, Australia.
Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.
Pediatr Res. 2025 Jun 13. doi: 10.1038/s41390-025-04183-x.
Sustained inflation (SI) and dynamic PEEP recruitment (dynPEEP) aim to facilitate preterm lung aeration, but the effect of dynPEEP on pulmonary arterial (PA) blood flow after birth is unknown.
Preterm (128 ± 1 day) fetal lambs instrumented with left PA and ductus arteriosus flow probes underwent positive-pressure ventilation (PEEP 8 cmHO) after early cord clamping, preceded by either (1) SI at 40 cmHO for 35 ± 3 s (n = 7) or (2) dynPEEP (n = 9) over 275 ± 23 s, comprising 2 cmHO step rises in PEEP from 6 to 18 cmHO followed by 2 cmHO decrements to 6 cmHO PEEP, then lung re-recruitment at 18 cmHO PEEP. Hemodynamics were recorded for 30 min after birth.
During dynPEEP, PA blood flow increased linearly (P < 0.001) except for plateaus (1) between 12 cmHO PEEP on the escalation limb and 14 cmHO PEEP on the de-escalation limb, and (2) during lung re-recruitment. By contrast, PA flow increased during SI (P < 0.02), and was then briefly unchanged before rising linearly (P < 0.001). Consequently, post-birth rises in PA flow diverged between groups (P < 0.001), with this flow lower during dynPEEP by lung re-recruitment (P ≤ 0.048), but subsequently similar between groups.
Only transient temporal differences in PA blood flow occur between SI and dynPEEP lung recruitment maneuvers at birth.
This study shows that a dynamic escalation and de-escalation positive end-expiratory pressure (PEEP) lung recruitment maneuver applied during the phase of rapidly-increasing pulmonary blood flow in the immediate period after preterm birth does not impede the peak of this flow increase, although transient plateauing of pulmonary flow occurs at high levels of PEEP This response contrasts with a sustained reduction of pulmonary blood flow reported during and after elevations in PEEP following stabilization of increased pulmonary perfusion after birth This preclinical study provides evidence that dynamic PEEP lung recruitment immediately after birth does not impair subsequent pulmonary perfusion.
持续充气（SI）和动态呼气末正压通气肺复张（dynPEEP）旨在促进早产肺通气，但dynPEEP对出生后肺动脉（PA）血流的影响尚不清楚。
对128±1日龄的早产胎羊，在早期脐带结扎后进行正压通气（呼气末正压8cmH₂O），在此之前，一组（n = 7）接受40cmH₂O的SI持续35±3秒，另一组（n = 9）接受dynPEEP持续275±23秒，dynPEEP包括呼气末正压从6cmH₂O逐步升至18cmH₂O，然后从18cmH₂O逐步降至6cmH₂O，随后在18cmH₂O呼气末正压下进行肺再次复张。出生后记录血流动力学30分钟。
在dynPEEP期间，除了（1）在上升支的12cmH₂O呼气末正压和下降支的14cmH₂O呼气末正压之间的平台期，以及（2）肺再次复张期间，肺动脉血流呈线性增加（P < 0.001）。相比之下，SI期间肺动脉血流增加（P < 0.02），然后短暂不变，之后呈线性上升（P < 0.001）。因此，出生后两组间肺动脉血流的上升出现差异（P < 0.001）；在dynPEEP期间，肺再次复张时血流较低（P≤0.048），但随后两组间相似。
出生时，SI和dynPEEP肺复张操作之间仅在肺动脉血流上存在短暂的时间差异。
本研究表明，在早产出生后即刻肺血流快速增加阶段应用动态上升和下降的呼气末正压（PEEP）肺复张操作，尽管在高呼气末正压水平时肺血流会出现短暂平台期，但不会阻碍血流增加的峰值。这种反应与出生后肺灌注增加稳定后呼气末正压升高期间及之后肺动脉血流持续减少的报道相反。这项临床前研究提供了证据，表明出生后立即进行动态PEEP肺复张不会损害随后的肺灌注。
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