Establishment Of Functional Residual Capacity Research Articles

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

Aim of the studyEstablishing 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. MethodsObservational 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. Results19,587 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. ConclusionsThe 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.

The relation between given volume and heart rate during newborn resuscitation

BackgroundDuring 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. ObjectivesThe 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. MethodsIn 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. Results215 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. ConclusionsThere 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.

Delivery room end tidal CO2 monitoring in preterm infants

ObjectivesTo determine the feasibility of end tidal (EtCO2) monitoring of preterm infants in the delivery room, to determine EtCO2 levels during delivery room stabilisation, and to examine the incidence of...

Effect of sustained inflation vs. stepwise PEEP strategy at birth on gas exchange and lung mechanics in preterm lambs

Sustained inflation (SI) at birth facilitates establishment of functional residual capacity (FRC) in the preterm lung, but the ideal lung recruitment strategy is unclear. We have compared the effect of SI and a stepwise positive end-expiratory pressure (PEEP; SEP) strategy in a preterm model. 127 d gestation lambs received either 20-s SI (n = 9) or 2 cmH2O stepwise PEEP increases to 20 cmH2O every 10 inflations, and then decreases to 6 cmH2O (n = 10). Ventilation continued for 70 min, with surfactant administered at 10 min. Alveolar-arterial oxygen gradient (AaDO2), compliance (C(dyn)), end-expiratory thoracic volume (EEVRIP; respiratory inductive plethysmography), and EEV and C(dyn) in the gravity-dependent and nondependent hemithoraces (electrical impedance tomography) were measured throughout. Early mRNA markers of lung injury were analyzed using quantitative real-time PCR. From 15 min of life, AaDO2 was lower in SEP group (P < 0.005; two-way ANOVA). SEP resulted in higher and more homogeneous C(dyn) (P < 0.0001). Mean (SD) EEVRIP at 5 min was 18 (9) ml/kg and 6 (5) ml/kg following SEP and SI, respectively (P = 0.021; Bonferroni posttest); this difference was due to a greater nondependent hemithorax EEV. There was no difference in markers of lung injury. An SEP at birth improved gas exchange, lung mechanics, and EEV, without increasing lung injury, compared to the SI strategy used.

Short- and intermediate-term outcomes of preterm infants receiving positive pressure ventilation in the delivery room.

Although recent advances in neonatal care have improved survival rates, rates of bronchopulmonary dysplasia remain unchanged. Although neonatologists are increasingly applying gentle ventilation strategies in the neonatal intensive care unit, the same emphasis has not been applied immediately after birth. A lung-protective strategy should start with the first breath to help in the establishment of functional residual capacity, facilitate gas exchange, and reduce volutrauma and atelectotrauma. This paper will discuss techniques and equipment during breathing assistance in the delivery room.

New concepts in neonatal resuscitation

There has been a substantial increase in the number of studies of neonatal resuscitation and it is timely to review the accumulating evidence. There have been major changes in the way that newly born infants are managed in the delivery room. Colour is no longer recommended as a useful indicator of oxygenation or effectiveness of resuscitation. Pulse oximetry provides rapid, continuous and accurate information on both oxygenation and heart rate. Resuscitation of term infants should begin with air, with the provision of blended oxygen to maintain oxygen saturations similar to those of term infants requiring no resuscitation. Positive end-expiratory pressure during initial ventilation aids lung aeration and establishment of functional residual capacity. Respiratory function monitoring allows operators to identify factors adversely affecting ventilation, including leak around the face mask and airway obstruction. Clamping of the umbilical cord should be delayed for at least 1 min for infants not requiring resuscitation. The International Liaison Committee on Resuscitation guidelines on the management of newborn infants were updated in 2010 and incorporate much of the newly available evidence. The use of intensive care techniques in the delivery room is promising but requires further evaluation. Monitoring techniques and interventions need to be adapted for use in developing countries.

Effect of Peep and Tidal Volume on Aeration of the Preterm Neonatal Lung

Previous studies suggest that positive end expiratory pressure (PEEP) promotes aeration of the preterm lung. The role of tidal volume has been less clear. We aimed to study the effects of different PEEPs (0, 5, 8 and 10 cm H2O) and VTs (4, 8, and 12 mL/kg) on the establishment of functional residual capacity (FRC). 27d preterm rabbit pups (equivalent to a surfactant deficient extremely preterm infant) were anaesthetised and surgically intubated. Volume targeted intermittent positive pressure ventilation (IPPV) was provided at each permutations of the above PEEPs and VTs. The primary outcome was FRC after 160 inflations, measured by plethysmography. Secondary outcomes included static compliance and homogeneity of tidal ventilation assessed using synchrotron based techniques (Spring8, Japan). Mean (SE) FRC and static compliance after 160 inflations are shown below: Table Linear regression of both FRC and compliance was statistically significant against both VT and PEEP separately (p≤0.01). No pup developed a pneumothorax. Video imaging demonstrates more homogeneous tidal ventilation in pups with better established FRC. PEEP and VT both played a role in the establishment of FRC in fully ventilated infants. Future studies should assess which strategies promote aeration at birth whilst minimising lung injury.

Part 11: Neonatal Resuscitation

Part 11: Neonatal Resuscitation

Establishment of functional residual capacity in infants delivered vaginally and by elective cesarean section

Functional residual capacity (FRC) was measured with an open circuit N 2 washout method in 20 vaginally born infants and 15 delivered by cesarean section, 30 and 120 min after birth. Umbilical artery blood was collected and analyzed for pH and catecholamine concentration. FRC was significantly higher in the cesarean section infants than in the vaginally delivered infants at 120 min of age (23.8 versus 16.8 ml/kg). The cesarean section infants also tended to have lower tidal volumes and higher respiratory frequencies than infants delivered vaginally. No significant correlation was found between catecholamine levels in umbilical artery and FRC in either group although there was a significant correlation between catecholamine level at birth and the increase of FRC from 30 to 120 min in the cesarean section group. It is suggested that the higher FRC, higher respiratory frequency and lower tidal volume in the cesarean section infants is an adaptation to a higher pulmonary water content to ensure an efficient gas exchange with the least respiratory work.