271 - Continuous Chest Compressions with High Frequency Jet Ventilation Improves Gas Exchange in Asphyxiated Cardiac Arrested Preterm Lambs

Poster Number: 271
Publication Number: 271.3313

Background: Gas exchange is severely impaired during cardiopulmonary resuscitation (CPR) in neonatal cardiac arrested. Optimizing gas exchange during neonatal CPR may improve cerebral oxygen delivery (cDO2) and prevent fluctuations in PaCO2.

Objective: We hypothesize that continuous chest compressions (CCC) with high frequency jet ventilation (HFJV) in preterm lambs in cardiac arrest will result in improved gas exchange and cDO2 compared to 3:1 compression-to-ventilation resuscitation and continuous chest compressions with asynchronous ventilation.

Design/Methods: Time-dated extremely preterm (124-126 days gestation; equivalent human ~25 weeks) fetal lambs were intubated and instrumented. Lambs were asphyxiated by umbilical cord occlusion until asystole and delivered. Initial resuscitation started with positive pressure ventilation via T-piece device at an FiO2 of 0.3 for 30 seconds. If heart rate did not improve, chest compressions (CC) were started and FiO2 was increased to 1.0. Lambs were assigned to 3:1 C:V resuscitation following the Neonatal Resuscitation Program algorithm (3:1 C:V group), CCC (120CC/min) with asynchronous ventilation (CCCaV group), or CCC (120CC/min) with HFJV (CCC + HFJV group). First dose of epi (epinephrine) was given at 3 minutes and repeated every 3 min until return of spontaneous circulation (ROSC). Lambs in the 3:1 C:V and CCCaV groups that achieved ROSC were managed on conventional ventilation and lambs in the CCC + HFJV group were maintained on HFJV. Ventilation parameters and FiO2 were adjusted to maintain SpO2 at 88-95% and PaCO2 between 40-60 mmHg.

Results: 24 lambs were studied. Baseline characteristics were similar and all lambs achieved ROSC. 23 lambs achieved ROSC after one dose of epi; one of the CCCaV lambs achieved ROSC after two doses. The CCC + HFJV group had quicker time to ROSC than the CCCaV group but similar to the 3:1 C:V group (Table).

PaCO2 was lower in the CCC + HFJV group at time of ROSC and post-ROSC compared to the 3:1 C:V and CCCaV groups (Figure 1). Oxygenation was better in the CCC + HFJV group compared to the other groups (Table). Carotid flow during CPR and at time of ROSC was the same between groups. However, the CCC + HFJV group had a higher cDO2 (Table). Blood pressure during CPR was lower in the 3:1 C:V group (Figure 2).

Conclusion(s): Resuscitation using CCC during HFJV is feasible with similar success of ROSC, quicker time to ROSC, and improved gas exchange and cDO2 during CC and at ROSC in asphyxiated cardiac arrested preterm lambs. Further studies are required to validate our results and to assess biomarkers and lung injury by histology.