397 - NRP vs. PALS During Newborn Resuscitation Using a Term Ovine Model of Cardiac Arrest

Publication Number: 397.5957

Mausma I. Bawa, University At Buffalo, Buffalo, NY, United States; Sylvia Gugino, SUNY at Buffalo, Buffalo, NY, United States; Justin Helman, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Nicole Bradley, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Lori Nielsen, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Clarence Center, NY, United States; Mary Divya Kasu, University of Maryland Children's Hospital, Baltimore, MD, United States; Hamza Abbasi, John R. Oishei Children’s Hospital, East Amherst, NY, United States; Sheetal Chepuri, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Srinivasan Mani, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States; Munmun Rawat, University at Buffalo, Buffalo, NY, United States; Praveen Chandrasekharan, Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, Buffalo, NY, United States

Background: A newborn baby requiring resuscitation born in the hospital compared to the one born at home and brought to the emergency room may receive NRP or PALS-recommended cardiopulmonary resuscitation (CPR). Other than data from the piglet model (Morin et al. 2024), there are no studies in a transitioning model with asphyxia that have evaluated the effect of NRP vs. PALS and it's immediate outcomes.

Objective: To evaluate the effect of performing CPR, based on NRP vs. PALS recommended guidelines using a term asphyxiated cardiac arrest model on
1) incidence and time to return of spontaneous circulation (ROSC)
2) hemodynamics and gas exchange

Design/Methods: After IACUC approval, near-term lambs 139-141d gestation were instrumented to measure hemodynamics (carotid (Ca), pulmonary (Pa) & coronary (Co) blood flows) and gas exchange. Fig1a shows the NRP and PALS protocols algorithm. The snapshot with carotid (Ca) and pulmonary (Pa) flows highlights the differences in chest compressions (CC) & positive pressure ventilation (PPV) in the ratio of 3:1 in NRP vs. continuous CC&PPV in PALS with pauses Q2 min to check the rhythm. To avoid bias, epinephrine (EPI) was administered via IV @ 0.03mg/kg/dose Q3min until ROSC (defined as HR≥100bpm, diastolic blood pressure≥20mmHg) with 100% oxygen used during CC in both the groups. Chi-square, unpaired t-test, and ANOVA were used to analyze data.

Results: Characteristics of the lambs are shown in Fig1b. With NRP (4/6), 66.7% achieved ROSC, and with PALS (1/6), 16% briefly achieved ROSC before going to arrest after 3 min. The time of attaining ROSC in the NRP group was 7± 4 min. The only lamb that achieved ROSC in PALS took 18.9 min and went into arrest after 3 min. Since only one lamb briefly achieved ROSC with PALS, no comparison/analyses was made with the four lambs that achieved ROSC with the NRP algorithm. Fig2a,2b,2c shows the graphs of peak Co, Ca & Pa blood flows in lambs that did not achieve ROSC: NRP (N=2/6) & PALS (N=5/6). The blood flows were similar, and there were no differences in blood pressure during CPR. On average, there were ten pauses with PALS compared to 4 (before EPI administration) with NRP to check the rhythm. No differences in gas exchange were observed in ROSC lambs with both algorithms (Fig3a,3b,3c).

Conclusion(s): The NRP algorithm had higher ROSC rates than PALS, although this difference was not significant. PALS suggested EPI dose of 0.01mg/kg could have worsened the ROSC rate further. Frequent pauses in the PALS algorithm can explain the lower rates of ROSC observed in our study. Our study suggests using the NRP protocol for newborn resuscitation.

Figure 1a shows the difference between the NRP & PALS protocols, with a snapshot of NRP vs. PALS. Figure 1b shows the characteristics of 12 lambs – NRP=6, PALS=6. *pH was significantly higher in PALS group before resuscitation.
Figure 1a shows the NRP and PALS resuscitation: In NALS protocol, ventilation & chest compression: A T-piece device with peak inspiratory pressures (PIP) of 35/5 cm H2O will be used to deliver breaths with 21% oxygen via an endotracheal tube (ETT). Once CC is initiated, PPV is coordinated in the ratio of 3:1 with 100% oxygen. Tidal volume (TV) is targeted between 7-9ml/kg during resuscitation. In all groups, the first dose of epinephrine (0.03 mg/kg) will be administered via jugular venous line (JVC) 5 minutes from the onset of resuscitation if ROSC is not achieved. This time point for EPI is chosen to approximate the time to administer venous EPI in clinical scenarios. Subsequent EPI administration at the same dose will be given every three minutes until ROSC or for four doses/20 min of resuscitation. In the PALS protocol, ventilation & chest compression: With advanced airway (endotracheal tube), start with 100 -120 chest compressions: 20 – 30 breaths (with a T-piece device & TV/PIP similar to NRP protocol), which are not synchronized. There will be pauses every 2 min to assess rhythm. The first dose of EPI 0.03mg/kg (instead of 0.01mg/kg to avoid introducing a variable that can interfere with the outcome) will be started at 5 min and continued every three minutes until ROSC or for four doses/20 min of resuscitation. With the pauses every 2 min, if there is a shockable rhythm, heart start (Phillips) will deliver 2J/kg followed by 4, 6, and 8J/kg for a maximum of 4 shocks (modified)


Figure 2
Figure 2: a,b,c – shows the peak coronary, carotid & pulmonary blood flows in lambs that did not achieve ROSC with NRP (N=2) & PALS (N=5) during resuscitation for 20 min. There were no differences in blood flows.

Figure 3
Figure 3: a,b,c – shows the pH, arterial carbon dioxide & oxygen in lambs that did not achieve ROSC with NRP (N=2) & PALS (N=5) during resuscitation for 20 min. There were no differences in gas exchange during resuscitation.