Exhaled CO(2) Parameters as a Tool to Assess Ventilation-Perfusion Mismatching during Neonatal Resuscitation in a Swine Model of Neonatal Asphyxia

BACKGROUND: End-tidal CO(2) (ETCO(2)), partial pressure of exhaled CO(2) (PECO(2)), and volume of expired CO(2) (VCO(2)) can be continuously monitored non-invasively to reflect pulmonary ventilation and perfusion status. Although ETCO(2) ≥14mmHg has been shown to be associated with return of an adequate heart rate in neonatal resuscitation and quantifying the PECO(2) has the potential to serve as an indicator of resuscitation quality, there is little information regarding capnometric measurement of PECO(2) and ETCO(2) in detecting return of spontaneous circulation (ROSC) and survivability in asphyxiated neonates receiving cardiopulmonary resuscitation (CPR). METHODS: Seventeen newborn piglets were anesthetized, intubated, instrumented, and exposed to 45-minute normocapnic hypoxia followed by apnea to induce asphyxia. Protocolized resuscitation was initiated when heart rate decreased to 25% of baseline. Respiratory and hemodynamic parameters including ETCO(2), PECO(2), VCO(2), heart rate, cardiac output, and carotid artery flow were continuously measured and analyzed. RESULTS: There were no differences in respiratory and hemodynamic parameters between surviving and non-surviving piglets prior to CPR. Surviving piglets had significantly higher ETCO(2), PECO(2), VCO(2), cardiac index, and carotid artery flow values during CPR compared to non-surviving piglets. CONCLUSION: Surviving piglets had significantly better respiratory and hemodynamic parameters during resuscitation compared to non-surviving piglets. In addition to optimizing resuscitation efforts, capnometry can assist by predicting outcomes of newborns requiring chest compressions.