Neonatal resuscitation with continuous chest compressions and high frequency percussive ventilation in preterm lambs

Abstract

Background: Cerebral oxygen delivery (cDO₂) is low during chest compressions (CC). We hypothesized that gas exchange and cDO₂ are better with continuous CC with high frequency percussive ventilation (CCC + HFPV) compared to conventional 3:1 compressions-to-ventilation (C:V) resuscitation during neonatal resuscitation in preterm lambs with cardiac arrest induced by umbilical cord compression.

Methods: Fourteen lambs in cardiac arrest were randomized to 3:1 C:V resuscitation (90CC + 30 breaths/min) per the Neonatal Resuscitation Program guidelines or CCC + HFPV (120CC + HFPV continuously). Intravenous epinephrine was given every 3 min until return of spontaneous circulation (ROSC).

Results: There was no difference in the incidence and time to ROSC between both groups. Median (IQR) PaCO₂ was significantly lower with CCC + HFPV during CC, at ROSC and 15 min post-ROSC-[104 (99-112), 83 (77-99), and 43 (40-64)], respectively compared to 3:1 C:V-[149 (139-167), 153 (143-168), and 153 (138-178) mmHg. PaO₂ and cDO₂ were higher with CCC + HFPV during CC and at ROSC. PaO₂ was similar 15 min post-ROSC with a lower FiO₂ in the CCC + HFPV group 0.4 (0.4-0.5) vs. 1 (0.6-1).

Conclusion: In preterm lambs with perinatal cardiac-arrest, continuous chest compressions with HFPV does not improve ROSC but enhances gas exchange and increases cerebral oxygen delivery compared to 3:1 C:V during neonatal resuscitation.

Impact statement: Ventilation is the most important intervention in newborn resuscitation. Currently recommended 3:1 compression-to-ventilation ratio is associated with hypercarbia and poor oxygen delivery to the brain. Providing uninterrupted continuous chest compressions during high frequency percussive ventilation is feasible in a lamb model of perinatal cardiac arrest, and demonstrates improved gas exchange and oxygen delivery to the brain. This is the first study in premature lambs evaluating high frequency percussive ventilation with asynchronous chest compressions and lays the groundwork for future clinical studies to optimize gas exchange and hemodynamics during chest compressions in newborns.

Fig. 1. Picture of the TXP-5 ventilator and Phasitron next to a ruler in inches for comparison.

The TXP-5 is a compact, pneumatically powered, high frequency percussive ventilator. Using its unique circuit, called the Phasitron, this ventilator generates a constant distending pressure intertwined with high frequency, sub-tidal, pressure-limited, and time-cycled breaths. The three knobs rotate to control the only three parameters: amplitude, frequency, and mean airway pressure.

Fig. 2. Changes in preductal PaCO₂ in CCC + HFPV group and 3:1 C:V group at baseline, after asphyxia, during chest compressions, at time of ROSC, and 15 min post-ROSC.

CCC on HFPV: continuous chest compressions on high frequency percussive ventilation. ROSC: return of spontaneous circulation. * p < 0.01 (Mann-Whitney U test).

Fig. 3. Changes in preductal PaO₂ and FiO₂ in CCC + HFPV group and 3:1 C:V group at baseline, after asphyxia, during chest compressions, at time of ROSC, and 15 min post-ROSC.

CCC on HFPV: continuous chest compressions on high frequency percussive ventilation. ROSC return of spontaneous circulation. *p < 0.01 (Mann-Whitney U test).

Fig. 4. Changes in cerebral oxygen delivery in CCC + HFPV group and 3:1C:V group at baseline, after asphyxia, during chest compressions, at time of ROSC, and 15 min post-ROSC.

CCC on HFPV: continuous chest compressions on high frequency percussive ventilation. ROSC: return of spontaneous circulation. *p < 0.05 (Mann-Whitney U test). ^an = 5 and ^bn = 6 for CCC on HFPV owing to probe malfunction.