Resuscitation of term and near-term newborns in low-resourced settings : Studies of positive end-expiratory pressure and expired CO2 during bag-mask ventilation at birth

Background: An estimated 0.7 million newborns die due to perinatal asphyxia each year, most are born at or near term. The major burden of preventable newborn deaths occur in low-resourced settings. A self-inflating bag is the most used and available equipment to save newborn lives globally. To aerate the lungs is key to survival. Expired CO2 (ECO2) may be an indicator for lung aeration, and positive end-expiratory pressure (PEEP) may facilitate aeration of the lungs. Research aiming to improve ventilation in term and near-term newborns using a self-inflating bag is needed. Aims: To investigate interpretation of ECO2 measured during bag-mask ventilation in the immediate newborn period, and assess whether this can be used as a marker for lung aeration, effective ventilation technique and prognosis. To study the effects of PEEP during bag-mask ventilation at or near term. Methods: Two observational studies and one randomized clinical trial were performed at Haydom Lutheran Hospital in Tanzania. Data were collected using direct observation, side-stream CO2-monitoring, respiratory function monitoring and dry-electrode ECG. In the randomized trial, newborns in need of ventilation were assigned in blocks based on weeks to receive ventilations by self-inflating bag with or without a PEEP-valve. Results: ECO2 during bag-mask ventilation at birth was significantly associated with both ventilation factors and clinical factors. Tidal volumes of 10-14 ml/kg and a low ventilation frequency of around 30 inflations/minute were associated with the fastest rise and highest levels of ECO2. ECO2 increased before heart rate, and measured levels of ECO2 during resuscitation could, similar to heart rate, predict 24-hours survival. Adding a PEEP-valve to the self-inflating bag did not improve heart rate, ECO2 or outcomes in term and near-term newborns despite delivery of an adequate PEEP. Conclusions: ECO2 may be seen as a combined marker for lung aeration, airway patency and pulmonary circulation at birth. Tidal volumes of 10-14 ml/kg and ventilation frequencies of around 30 inflations/minute may be favorable to achieve a fast lung aeration. We found no clinical benefit of adding a PEEP-valve during bag-mask ventilation at birth in term and near-term newborns, and our study does not support routine use