Abstract
Objective Sustained inflation (SI) during chest compression (CC = CC+SI) significantly reduces time to return of spontaneous circulation (ROSC) compared to 3:1 compression-to-ventilation ratio during neonatal resuscitation. However, the optimal peak inflation pressure (PIP) of SI during CC+SI to improve ROSC and hemodynamic recovery in severely asphyxiated piglets is unknown.
Aim To examine if different PIPs of SI during CC+SI will improve ROSC and hemodynamic recovery in severely asphyxiated piglets.
Intervention and measurements Twenty-nine newborn piglets (1-3 days old) were anesthetized, intubated, instrumented and exposed to 30-min normocapnic hypoxia followed by asphyxia. Piglets were randomized into four groups: CC+SI with a PIP of 10 cmH2O (CC+SI_PIP_10, n=8), a PIP of 20 cmH2O (CC+SI_PIP_20, n=8), a PIP of 30 cmH2O (CC+SI_PIP_30, n=8), and a sham-operated control group (n=5). Heart rate, arterial blood pressure, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment.
Main results Baseline parameters were similar between all groups. There was no difference in asphyxiation (duration and degree) between intervention groups. PIP correlated positively with tidal volume and inversely with exhaled CO2 during cardiopulmonary resuscitation. Time to ROSC and rate of ROSC were similar between piglets resuscitated with CC+SI_PIP_10, CC+SI_PIP_20, and CC+SI_PIP_30 cmH2O: median (IQR) 75 (63-193) sec, 94 (78-210) sec, and 85 (70-90) sec; 5/8 (63%), 7/8 (88%), and 3/8 (38%) (p=0.56 and p=0.12, respectively). All piglets that achieved ROSC survived to four hours post-resuscitation. Piglets resuscitated with CC+SI_PIP_30 cmH2O exhibited increased concentrations of pro-inflammatory cytokines interleukin-1β and tumour necrosis factor-α in the frontoparietal cerebral cortex (both p<0.05 vs. sham-operated controls).
Conclusions In asphyxiated term newborn piglets resuscitated by CC+SI, the use of different PIPs resulted in similar time to ROSC, but PIP at 30 cmH2O showed a larger VT delivery, lower exhaled CO2 and increased tissue inflammatory markers in the brain.
Footnotes
↵* Joint first author
Conflict of Interest: None
Funding sources We would like to thank the public for donating money to our funding agencies: GMS is a recipient of the Heart and Stroke Foundation/University of Alberta Professorship of Neonatal Resuscitation, a National New Investigator of the Heart and Stroke Foundation Canada and an Alberta New Investigator of the Heart and Stroke Foundation Alberta. The study was supported by a Grant from the SickKids Foundation in partnership with the Canadian Institutes of Health Research (CIHR - Institute of Human Development, Child and Youth Health (IHDCYH)), New Investigator Research Grant Program (Grant number - No. NI17-033). This research has been facilitated by the Women and Children’s Health Research Institute through the generous support of the Stollery Children’s Hospital Foundation.
Abbreviations
- CC
- Chest compression
- CC+SI
- Chest compression during sustained inflation
- crSO2
- Cerebral oxygenation
- ETCO2
- End-tidal CO2
- IL
- Interleukin
- IQR
- Interquartile range
- PIP
- Peak inflation pressure
- PPV
- Positive pressure ventilation
- ROSC
- Return of spontaneous circulation
- SD
- Standard deviation
- SI
- Sustained inflation
- TNF
- Tumor necrosis factor
- VT
- Tidal volume