**9. Conclusions**

*Animal Models in Medicine and Biology*

The purpose of inflations during CC is to deliver an adequate tidal volume to facilitate gas exchange [38], however limited information exists regarding tidal volume delivery during CC. Therefore, Li et al. examined the changes in tidal volume during CC and their effect on lung aeration in the porcine model of hypoxiaasphyxia [39]. Li et al. shows that when resuscitating using the SI with CC technique, passive lung ventilation/aeration can be achieved. In contrast, although use of the 3:1 C:V technique delivered tidal volume, it also resulted in a relative loss of tidal volume per 3:1 C:V cycle of up to 4.5 mL/kg [39]. This suggests that tidal volume delivery is greater when using SI with CC to resuscitate compared to the standard 3:1 C:V technique; this may lead to better alveolar oxygen delivery and lung aeration [39]. Using an objective method to evaluate recovery or predict the outcome of resuscitation may help decision-making during resuscitation. Therefore, Li et al. examined the temporal changes in end-tidal CO2 (ETCO2), volume of expired CO2 (VCO2), and the partial pressure of exhaled CO2 (PECO2) and their relationship with survivability and hemodynamic changes during CPR in the neonatal porcine model [40]. Li et al. reported that surviving piglets had significantly higher values of ETCO2, VCO2, and PECO2 during CPR compared to non-surviving piglets, suggesting that continuously monitoring ETCO2, VCO2, and PECO2 during CC has the potential to be a non-invasive method to indicate ROSC [40]. To further investigate if other parameters could be used as early outcome predictors after CPR, Solevåg et al. examined if cerebral and renal tissue oxygen saturation was different between surviving piglets and non-surviving piglets that were resuscitated after asphyxiainduced cardiac arrest [41]. The relationship of the tissue oxygen saturations with cardiac output, blood pressure, and biochemical variables was also examined [41]. No correlation between cardiac output or blood pressure and cerebral or renal tissue

Espinoza et al. examined the changes in HR during adequate PPV following severe bradycardia in the porcine model of hypoxia-asphyxia [42]. The Neonatal Resuscitation Program (NRP) states that if adequate PPV is given for low HR, then the infant's HR should increase within the first 15 s of PPV. However in contrast to the NRP, Espinoza et al. showed that adequate PPV does not increase HR within 15 s of ventilation in piglets with asphyxia-induced bradycardia; after 30 s of PPV only half of piglets had an increase in HR. This study challenges the current NRP statement and suggests that clinicians should not expect an increase in HR after 15 s of

Current neonatal resuscitation guidelines recommend the administration of intravenous epinephrine during if HR persists below 60 bpm despite CC and 100% oxygen [2–4]. However there is currently a lack of data evaluating the hemodynamic effects of epinephrine during neonatal resuscitation. Wagner et al. utilized the porcine model of hypoxia-asphyxia to examine hemodynamic changes after epinephrine administration during resuscitation and compare surviving and non-surviving piglets; epinephrine was administered at a dose of 0.01 mg/kg [43]. Epinephrine had no effect on either HR or cardiac output in survivors versus non-survivors during resuscitation; it did not increase survival

**8.5 Respiratory parameters**

oxygen saturation was observed.

PPV if there is severe bradycardia [42].

**8.6 Hemodynamics**

**8.7 Epinephrine**

rates or ROSC [43].

**176**

Animal models that reliably reproduce the events surrounding neonatal resuscitation in the delivery room are imperative to improve the outcome of newborn infants requiring CPR and may also lead to benefits for the pediatric population. Due to its many advantages, the porcine model of neonatal hypoxia-asphyxia is one of the most commonly used large animal models for neonatal resuscitation studies. Not only has this model provided a further understanding of the effects of various resuscitation interventions, but it has also enabled the study of an increasingly important clinical situation in the laboratory setting – pulseless electrical activity. Using this animal model will further accelerate knowledge on neonatal resuscitation that will ultimately benefit patients.
