Tidal Volume Delivery and Endotracheal Tube Leak during Cardiopulmonary Resuscitation in Intubated Newborn Piglets with Hypoxic Cardiac Arrest Exposed to Different Modes of Ventilatory Support

Ventilation With or Without Endotracheal Tube Leak in Prolonged Neonatal Asphyxia

Background Severe and prolonged asphyxia can result in either intrauterine fetal death and stillbirth or multiorgan failure in surviving neonates. Establishing effective ventilation is the primary aim of resuscitation in newborns with asphyxia. The objective of this study was to compare the outcome of resuscitation by applying an endotracheal tube (ETT) with less, an ETT with moderate, and an ETT with high leakage during mechanical ventilation in swine neonates after prolonged perinatal asphyxia. Materials and methods A prospective, randomized controlled laboratory study was performed. Thirty Landrace/large white pigs, aged one to four days and weighted 1.754±218 gr, were randomly allocated into three groups depending on the ETT size: Group C (less leak: ETT no 4.0, n=10); Group A (high leak: ETT no 3.0, n=10); and Group B (moderate leak: ETT no 3.5, n=10). Mechanical asphyxia was performed until their heart rate was less than 60 bpm or their mean arterial pressure was below 15 mmHg. All animals with return of spontaneous circulation (ROSC) were monitored for four hours for their hemodynamic parameters, arterial oxygen saturation, and lactate acid levels. Results We demonstrate that 70% of the surviving animals were ventilated with an ETT with a leak (no. 3.5 and 3). A statistically significant difference was noted in PO₂ (p=0.032) between Group B (126.4±53.4 mmHg) compared to Group A (72.28±29.18 mmHg) and Group C (94.28±20.46 mmHg) as well as in the right atrial pressure (p<0.001) between Group C (4.5 mmHg) vs Groups A (2 mmHg) and B (2 mmHg) during ROSC time. Lactate levels were statistically significantly lower (p=0.035) in Group C (mean=0.92 ± 0.07mmol/L) as compared to Group A (mean=1.13 ± 0.1 mmol/L) and Group B (mean= 1.08 ± 0.07 mmol /L; p = 0.034) at 4h post-ROSC. Conclusion We provide preliminary evidence that ventilation with ETT with moderate leakage improves survival after 2h of ROSC, along with oxygenation and hemodynamic parameters, in a porcine model of neonatal asphyxia and resuscitation, compared to less leakage ETT.

[Paediatric Life Support]

The European Resuscitation Council (ERC) Paediatric Life Support (PLS) guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations of the International Liaison Committee on Resuscitation (ILCOR). This section provides guidelines on the management of critically ill or injured infants, children and adolescents before, during and after respiratory/cardiac arrest.

European Resuscitation Council Guidelines 2021: Paediatric Life Support

These European Resuscitation Council Paediatric Life Support (PLS) guidelines, are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the management of critically ill infants and children, before, during and after cardiac arrest.

Asynchronous ventilation at 120 compared with 90 or 100 compressions per minute improves haemodynamic recovery in asphyxiated newborn piglets

OBJECTIVE

To determine whether different chest compression (CC) rates during continuous CC with asynchronous ventilations (CCaV) reduce time to return of spontaneous circulation (ROSC) and improved haemodynamic recovery in piglets aged 24-72 hours with asphyxia-induced asystole.

METHODS

Thirty piglets (aged 24-72 hours) were anaesthetised, intubated, instrumented and exposed to 30 min normocapnic hypoxia followed by asphyxia. Piglets were randomised into four groups: CCaV with CC rate of 90 (CCaV+90, n=8), 100 (CCaV+100, n=8) or 120 compressions per minute (CCaV+120, n=8), and a sham-operated group (n=6). Cardiac function, carotid blood flow, cerebral and renal oxygenation and respiratory parameters were continuously recorded. Cerebral cortical tissue was harvested and assayed for inflammatory and injury markers.

RESULTS

All three intervention groups had a similar number of piglets achieving ROSC (6/8, 5/8 and 5/8 for CCaV+120, CCaV+100 and CCaV+90, respectively) and mean ROSC time (120, 90 and 90 s for CCaV+120, CCaV+100 and CCaV+90, respectively). The haemodynamic recovery (indicated by carotid flow, cerebral and renal perfusion) was similar between CCaV+120 and sham by the end of experiment. In comparison, CCaV+90 and CCaV+100 had significantly reduced haemodynamic recovery compared with sham operated (p≤0.05). Inflammatory (interleukin [IL]-6 and IL-1β) and injury markers (lactate) were significantly higher in the frontoparietal cortex of CCaV+90 and CCaV+100 compared with sham, whereas brain injury markers were similar between CCaV+120 and sham.

CONCLUSIONS

Although there was no difference between the groups in achieving ROSC, the haemodynamic recovery of CCaV+120 was significantly improved compared with CCaV+90 and CCaV+100, which were also associated with higher cerebral inflammatory and brain injury markers.

Hypoxia - Reoxygenation in neonatal cardiac arrest: Results from experimental models

In this review, we summarize the results of studies that investigated the effects of hypoxia and reoxygenation in cardiac arrest, including the use of different fractions of inspired oxygen, in neonatal animals. The studies were heterogenous in terms of anaesthetic regimens, and definitions of cardiac arrest and circulatory recovery. Cardiopulmonary resuscitation with 100% oxygen increased oxidative stress in maturing rats. Studies in fetal/neonatal lambs and post-transitional neonatal piglets indicate no consistent differences between ventilation with 21% vs. 100% oxygen with regards to recovery times, oxygen damage or adverse events. If 21% oxygen is as effective as 100% oxygen in newborn infants with cardiac arrest requiring chest compression, the use of 21% instead of 100% oxygen could reduce morbidity and mortality in asphyxiated infants. Unanswered questions include what is the most optimal cerebral oxygen delivery during reperfusion, as well as oxygenation targets after return of spontaneous circulation.

Chest Compressions during Sustained Inflations Improve Recovery When Compared to a 3:1 Compression:Ventilation Ratio during Cardiopulmonary Resuscitation in a Neonatal Porcine Model of Asphyxia

BACKGROUND

Recently, sustained inflations (SI) during chest compression (CC) (CC+SI) have been suggested as an alternative to the current approach during neonatal resuscitation. No previous study compared CC+SI using CC rates of 90/min to the current 3:1 compression:ventilation ratio (C:V).

OBJECTIVE

To determine whether CC+SI versus a 3:1 C:V reduces the time to the return of spontaneous circulation (ROSC) and improves hemodynamic recovery in newborn piglets with asphyxia-induced bradycardia.

INTERVENTION AND MEASUREMENTS

Term newborn piglets were anesthetized, intubated, instrumented, and exposed to 45-min normocapnic hypoxia followed by asphyxia. Cardiopulmonary resuscitation (CPR) was initiated when the heart rate decreased to 25% of baseline. Piglets were randomized into 3 groups: CC during SI at a rate of 90 CC/min (SI+CC 90, n = 8), a 3:1 C:V using 90 CC and 30 inflations (3:1, n = 8), or a sham group (n = 6). Cardiac function, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment.

RESULTS

CC+SI significantly reduced the median (IQR) time of ROSC, i.e., 34 s (28-156 s) versus 210 s (72-300 s) in the 3:1 group (p = 0.048). CC+SI also significantly reduced the requirement for 100% oxygen, improved respiratory parameters, and resulted in a similar hemodynamic recovery.

CONCLUSIONS

CC+SI during CPR significantly improved ROSC in a porcine model of neonatal resuscitation. This is of considerable clinical relevance because improved respiratory and hemodynamic parameters potentially minimize morbidity and mortality in newborn infants.