Improving lung aeration in ventilated newborn preterm rabbits with a partially aerated lung

Abstract

Preterm newborns commonly receive intermittent positive pressure ventilation (iPPV) at birth, but the optimal approach that facilitates uniform lung aeration is unknown, particularly in a partially aerated lung. As both inflation time and exogenous surfactant facilitate uniform lung aeration, we investigated whether they can improve lung aeration and lung mechanics in a partially aerated lung immediately after birth. Preterm rabbit kittens (29 days gestation, term ~32 days) were delivered by caesarean section and partial lung aeration was created by intubating and mechanically ventilating the right lung. The tube was then withdrawn to ventilate both lungs using inflation times of 0.2 s or 1.0 s, with or without exogenous surfactant (Curosurf 200 mg/kg), and a tidal volume (Vt) of 8 mL/kg. Simultaneous phase contrast X-ray imaging and plethysmography were used to measure lung aeration and mechanics. Kittens ventilated with longer inflation times (1.0 s) reached their target Vt with fewer inflations, required lower inflation pressures (28.5 ± 1.1 vs. 33.5 ± 1.3 cmH2O, p=0.01) and had higher dynamic lung compliances (0.54 ± 0.3 vs. 0.40 ± 0.3 cmH2O/mL/kg, p=0.003). Surfactant increased functional residual capacity (FRC; 31.9 ± 3.2 vs. 18.0 ± 3.9 mL/kg, p=0.02) and the proportion of the Vt entering the previously unaerated lung but had no effect on dynamic lung compliance. Combining early surfactant treatment with longer inflation times increases FRC levels, improves dynamic lung compliance, reduces inflation pressures and markedly increases the proportion of the lungs being ventilated during iPPV in preterm kittens with a partially aerated lung.

Accurate measures of changes in regional lung air volumes from chest x-rays of small animals

“…Future biomedical studies utilising this technique could be complemented by simultaneous physiological measures such as blood oxygen saturation. For current experiments involving synchrotron radiation, this work can be readily applied to determine large regional volume changes to a high degree of accuracy using a linear calibration, which is useful for any biomedical experiments studying air volume changes (Pryor et al 2020, Dekker et al 2019.…”

Accurate measures of regional lung air volumes from chest X-rays of small animals

“…Future studies will seek to apply this method using typical lab-based sources (polychromatic, low brilliance) to test the applicability in a clinical scenario, as well as in synchrotron-based experiments involving larger animals. For current experiments involving synchrotron radiation, this work can be readily applied to determine large regional volume changes to a high degree of accuracy, which is useful for any biomedical experiments studying air volume changes [27,29].…”

Lung Ultrasound in Neonates: An Emerging Tool for Monitoring Critically Ill Infants

“…[9][10][11] In neonates, the relatively under-aerated lungs permit better sonic evaluation of various pathologies with higher sensitivity and specificity than in adults. [12][13][14][15] Lung ultrasound can help in bedside diagnosis/evaluation of respiratory distress syndrome (RDS), pneumonia, transient tachypnea of the newborn (TTN), pleural effusion, and pneumothorax. 1,5,[16][17][18][19][20][21][22] Compared to chest radiographs, LUS is more convenient as it can be readily available at the bedside, is safer as there is no radiation exposure, and has the potential to improve care by allowing quick interpretation and repeated testing to monitor the course of disease and response to therapy.…”