BACKGROUND
Effective positive pressure ventilation (PPV) is a critical factor in the successful resuscitation of a depressed newborn. The availability of healthcare personnel with expertise in neonatal endotracheal intubation (ETT) is a practical challenge in resource-limited settings. PPV with a laryngeal mask airway (LMA) is a reasonable alternative. While the current evidence suggests that LMA ventilation can be a secure and viable alternative to manage the airway of a depressed newborn during the initial stages of resuscitation, there is limited evidence for its use during chest compression (CC).
OBJECTIVE
To compare the efficacy of PPV through LMA to ETT during CC in a transitional term lamb model of asphyxial cardiac arrest. We compared the incidence and time to return of spontaneous circulation (ROSC), adequacy of ventilation, systemic and pulmonary hemodynamics.
METHODS
We designed a randomized controlled trial using an asphyxiated lamb model with the ability to study the gas exchange, systemic and pulmonary hemodynamics during resuscitation. Time-dated near-term pregnant ewes underwent C-section under general anesthesia. Fetal lambs were partially exteriorized and instrumented while in the placental circulation. The lambs were asphyxiated by ETT and umbilical cord occlusion. After delivery, ETT was removed, and lambs were randomized into the LMA or ETT ventilation group (controls). Resuscitation was initiated as per NRP recommendations and continued until ROSC or for 20 minutes. A respiratory function monitor was used to measure ventilatory parameters continuously. Chi-squared test and paired t-test were used for data analysis.
RESULTS
Eleven lambs were randomized, asphyxiated, and resuscitated (5 in the LMA group vs. 6 in the ETT group). Gestational age and gender distribution were similar among the groups. Baseline acid-base status and time to asystole were homogenous. (Table 1) The rate of ROSC was 40% in the LMA and 66%in ETT group. The number of epinephrine doses required, and the time to ROSC (7m 30s ± 2m 7s in LMA vs. 9m 3s ± 2m 50s in ETT) were not different. Tidal volumes were similar between the groups utilizing equivalent mean airway pressures (Fig. 1&2) and resulting in comparable PaCO2 between the groups. (Fig. 3) The systemic and pulmonary hemodynamics measured by the mean blood pressure, mean carotid artery flows, and the mean pulmonary artery flows were similar between the groups across various time points during and 30 minutes after resuscitation. (Table 2)
CONCLUSION
Our study demonstrates that LMA provides comparable ventilatory parameters during chest compression in a translational asphyxiated animal model to ETT (standard of care).
