Abstract
BackgroundSustained inflations (SI) are advocated for the rapid establishment of FRC after birth in preterm and term infants requiring resuscitation. However, the most appropriate way to deliver a SI is poorly understood. We investigated whether a volume-limited SI improved the establishment of FRC and ventilation homogeneity and reduced lung inflammation/injury compared to a pressure-limited SI.Methods131 d gestation lambs were resuscitated with either: i) pressure-limited SI (PressSI: 0-40 cmH2O over 5 s, maintained until 20 s); or ii) volume-limited SI (VolSI: 0-15 mL/kg over 5 s, maintained until 20 s). Following the SI, all lambs were ventilated using volume-controlled ventilation (7 mL/kg tidal volume) for 15 min. Lung mechanics, regional ventilation distribution (electrical impedance tomography), cerebral tissue oxygenation index (near infrared spectroscopy), arterial pressures and blood gas values were recorded regularly. Pressure-volume curves were performed in-situ post-mortem and early markers of lung injury were assessed.ResultsCompared to a pressure-limited SI, a volume-limited SI had increased pressure variability but reduced volume variability. Each SI strategy achieved similar end-inflation lung volumes and regional ventilation homogeneity. Volume-limited SI increased heart-rate and arterial pressure faster than pressure-limited SI lambs, but no differences were observed after 30 s. Volume-limited SI had increased arterial-alveolar oxygen difference due to higher FiO2 at 15 min (p = 0.01 and p = 0.02 respectively). No other inter-group differences in arterial or cerebral oxygenation, blood pressures or early markers of lung injury were evident.ConclusionWith the exception of inferior oxygenation, a sustained inflation targeting delivery to preterm lambs of 15 mL/kg volume by 5 s did not influence physiological variables or early markers of lung inflammation and injury at 15 min compared to a standard pressure-limited sustained inflation.
Highlights
Sustained inflations (SI) are advocated for the rapid establishment of functional residual capacity (FRC) after birth in preterm and term infants requiring resuscitation
Mean volume recruited at the end of the 20-s sustained inflation was not different between groups higher variability was evident in volumes delivered to PressSI compared to volume (PressSI) or pressures (VolSI) lambs: mean (SD) of inflation volume was 16.0 (6.7) mL/kg for PressSI lambs versus 14.6 (2.5) mL/kg for VolSI lambs (Figure 1A)
We demonstrated the efficacy of volume-limited sustained inflations for lung recruitment in preterm lambs
Summary
Sustained inflations (SI) are advocated for the rapid establishment of FRC after birth in preterm and term infants requiring resuscitation. We investigated whether a volume-limited SI improved the establishment of FRC and ventilation homogeneity and reduced lung inflammation/injury compared to a pressure-limited SI. Initial resuscitation of preterm infants aims to establish a functional residual capacity (FRC) and facilitate initiation of gas-exchange within the immature lung. The initiation of ventilation after preterm birth may be a critical period of susceptibility for the development of lung and brain injury [1,2,3,4]. A sustained inflation is recommended for the initial ventilation of apneic term and preterm infants in the recent European Resuscitation Council Guidelines [7]. The optimal way to deliver a sustained inflation is unknown
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