Establishment of functional residual capacity at birth: Observational study of 821 neonatal resuscitations.

AIM OF THE STUDY: Establishing functional residual capacity (FRC) during positive pressure ventilation (PPV) of apnoeic neonates is critical for survival. This may be difficult due to liquid-filled airways contributing to low lung compliance. The objectives were to describe initial PPV, changes in lung compliance and establishment of FRC in near-term/term neonates ≥36 weeks gestation at birth. METHODS: Observational study of all neonatal resuscitations between 01.07.13 and 30.06.18 in a Tanzanian referral hospital. Perinatal events and characteristics were observed and recorded by trained research assistants. PPV were performed using self-inflating bag-masks without positive end-expiratory pressure (PEEP). Ventilation signals (pressure/flow), expired CO2 (ECO2) and heart rate were recorded by resuscitation monitors. RESULTS: 19,587 neonates were born, 1451 received PPV, of these 821 of median (p25, p75) birthweight 3180 (2844, 3500) grams and gestation 38 (37, 40) weeks had ≥20 ventilations and complete datasets. There was a significant increase in expired volume (from 3.3 to 6.0 ml/kg), ECO2 (0.3-2.4%), lung compliance (0.13-0.19 ml/kg/mbar) and heart rate (109-138 beats/min) over the first 20 PPVs. Inflation volume, time, and peak inflation pressure (PIP) were stable around 12-13 ml/kg, 0.45 s, and 36 mbar, respectively. CONCLUSIONS: The combination of increasing expired volumes, ECO2, and heart rate with decreasing inflation/expired volume ratios and constant PIP, suggests establishment of FRC during the first 20 PPVs in near-term/term neonates using a self-inflating bag-mask without PEEP, the most common device worldwide for ventilating non-breathing neonates. Initial lung compliance is low, and with short inflation times, higher than recommended PIP seem necessary to deliver adequate tidal volumes.

Predictors of 24-h outcome in newborns in need of positive pressure ventilation at birth.

BACKGROUND: Birth asphyxia, defined as 5-minute Apgar score <7 in apneic newborns, is a major cause of newborn mortality. Heart rate (HR) response to ventilation is considered an important indicator of effective resuscitation. OBJECTIVES: To describe the relationship between initial HR in apneic newborns, HR responses to ventilation and 24-h survival or death. METHODS: In a Tanzanian hospital, data on all newborns ≥34 weeks gestational age resuscitated between June 2013-January 2017 were recorded using self-inflating bags containing sensors measuring ventilation parameters and expired CO2, dry-electrode electrocardiography sensors, and trained observers. RESULTS: 757 newborns of gestational age 38 ±â€¯2 weeks and birthweight 3131 ±â€¯594 g were included; 706 survived and 51 died. Fetal HR abnormalities (abnormal, undetectable or not assessed) increased the risk of death almost 2-fold (RR = 1.77; CI: 1.07, 2.96, p = 0.027). For every beat/min increase in first detected HR after birth the risk of death was reduced by 2% (RR = 0.98; CI: 0.97, 0.99, p < 0.001). A decrease in HR to <100 beats/minute when ventilation was paused increased the risk of death almost 2-fold (RR = 1.76; CI: 0.96, 3.20, p = 0.066). An initial rapid increase in HR to >100 beats/min in response to treatment reduced the risk of dying by 75% (RR = 0.25; CI: 0.14, 0.44, p < 0.001). A 1% increase in expired CO2 was associated with 28% reduced risk of death (RR = 0.72; CI: 0.62,0.85, p < 0.001). CONCLUSIONS: The risk of death in apneic newborns can be predicted by the fetal HR (absent or abnormal), initial newborn HR (bradycardia), and the HR response to ventilation. These findings stress the importance of reliable fetal HR monitoring during labor and providing effective ventilation following birth to enhance survival.

The relation between given volume and heart rate during newborn resuscitation.

BACKGROUND: During delivery room resuscitation of depressed newborns, provision of appropriate tidal volume (TV) with establishment of functional residual capacity (FRC) is essential for circulatory recovery. Effective positive pressure ventilation (PPV) is associated with a rapid increase in heart rate (HR). The relationship between delivery of TV and HR responses remains unclear. OBJECTIVES: The study objectives were to determine (1) the relationship between a given TV during initial PPV and HR responses of depressed newborns, and (2) the optimal delivered TV associated with a rapid increase in HR. METHODS: In a Tanzanian rural hospital, ventilation and ECG signals were recorded during neonatal resuscitation and stored in Neonatal Resuscitation Monitors. Resuscitators without positive end-expiratory pressure were used for PPV. No oxygen was used. Perinatal events were observed and recorded by research assistants. RESULTS: 215 newborns of gestational age 37.3±1.9 weeks and birth weight 3115±579g were included. There was a non-linear relationship between delivered TV and HR increase. TV of 9.3ml/kg produced the largest increase in HR during PPV. Frequent interruptions of PPV sequences to provide stimulation/suctioning occurred in all cases and were associated with further HR increases, especially for newborns with initial HR<100 beats/minute. CONCLUSIONS: There was a consistent positive relationship between HR increase and delivered TV. The unanticipated finding of a further increase in HR with PPV pauses to provide stimulation/suctioning suggests that most newborns were in primary rather than secondary apnea.