Continuous End-Tidal Carbon Dioxide Monitoring during Resuscitation of Asphyxiated Term Lambs.

BACKGROUND: The Neonatal Resuscitation Program (NRP) recommends close monitoring of oxygenation during the resuscitation of newborns using a pulse oximeter. However, there are no guidelines for monitoring carbon dioxide (CO2) to assess ventilation. Considering that cerebral blood flow (CBF) correlates directly with PaCO2, continuous capnography monitoring of end-tidal CO2 (ETCO2) may limit fluctuations in PaCO2 and, therefore, CBF during resuscitation of asphyxiated infants.

OBJECTIVE: To evaluate whether continuous monitoring of ETCO2 with capnography during resuscitation of asphyxiated term lambs with meconium aspiration will prevent fluctuations in PaCO2 and carotid arterial blood flow (CABF).

METHODS: Fifty-four asphyxiated term lambs with meconium aspiration syndrome were mechanically ventilated from birth to 60 min of age. Ventilatory parameters were adjusted based on clinical observation (chest excursion) and frequent arterial blood gas analysis in 24 lambs (control group) and 30 lambs (capnography group) received additional continuous ETCO2 monitoring. Left CABF was monitored. We aimed to maintain PaCO2 between 35 and 50 mm Hg and ETCO2 between 30 and 45 mm Hg.

RESULTS: There was a significant correlation between ETCO2 and PaCO2 (R = 0.7, p < 0.001), between PaCO2 and carotid flow (R = 0.52, p < 0.001) and between ETCO2 and carotid flow (R = 0.5, p < 0.001). PaCO2 and CABF during the first 60 min of age showed significantly higher fluctuation in the control group compared to the capnography group.

CONCLUSION: Continuous monitoring of ETCO2 using capnography with mechanical ventilation during and after resuscitation in asphyxiated term lambs with meconium aspiration limits fluctuations in PaCO2 and CABF and may potentially limit brain injury.