Changes in Positive End-Expiratory Pressure Alter the Distribution of Ventilation within the Lung Immediately after Birth in Newborn Rabbits

Kitchen, Marcus John; Siew, Melissa Li-Lian; Wallace, Megan Jane; Fouras, Andreas; Lewis, Robert A.; Yagi, Naoto; Uesugi, Kentaro; Pas, Arjan B. te; Hooper, Stuart B.

doi:10.1371/journal.pone.0093391

Cited by 25 publications

(32 citation statements)

References 34 publications

(52 reference statements)

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“…In the current study, more B-lines were observed in the lower chest than in the upper chest at <3 h. A similar observation was reported by Laura Martelius, who suggested that airway liquid clearance may occur later in the lower lobes than in the upper lobes [19]. Others have shown that in preterm rabbit pups, initiating ventilation at birth with 0 PEEP could result in the unequal distribution of air between the upper and lower lobes, with a significantly greater distribution of air toward the upper than the lower lobes at functional residual capacity [30].…”

Section: Discussionsupporting

confidence: 65%

Comprehensive Quantitative Assessment of Lung Liquid Clearance by Lung Ultrasound Score in Neonates with No Lung Disease during the First 24 Hours

Guo

Wang

Xie

et al. 2020

BioMed Research International

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Objectives. To comprehensively and quantitatively assess the process of lung liquid clearance using the lung ultrasound score. This study is to evaluate the whole healthy lungs of neonates during the first 24 h. Methods. Lung ultrasound was performed in neonates with no respiratory symptoms within 3 h after birth, and scans were then repeated at 6 hours and 24 hours, respectively. The entire chest wall was divided into 12 regions. The lung ultrasound scores of the anterior, posterior, upper, and lower regions and sum of all regions were calculated according to the ultrasound pattern of each region examined. Results. The total lung ultrasound score decreased gradually during the first 24 h, with the total lung ultrasound score at 6 h being significantly lower than that at <3 h (P<0.05). At <3 h, B-lines were more abundant in the posterior chest than in the anterior chest (P<0.001), and more B-lines were observed in the lower chest than in the upper chest (P<0.001). At 6 h and 24 h, there were no significant differences among the regions. Conclusion. Changes in the lung ultrasound score may quantitatively reflect the characteristics of different regions and processes of lung liquid clearance during the first 24 h.

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Section: Discussionsupporting

confidence: 65%

Comprehensive Quantitative Assessment of Lung Liquid Clearance by Lung Ultrasound Score in Neonates with No Lung Disease during the First 24 Hours

Guo

Wang

Xie

et al. 2020

BioMed Research International

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“…This has not been previously observed in healthy infants. In premature rabbit pups, ventilated with low or no positive end-expiratory pressure, an uneven distribution of lung aeration with higher air content in the upper lobes has been observed [21]. Our data suggest that liquid clearance from the lungs might occur faster in the upper lobes than in the lower lobes.…”

Section: Discussionmentioning

confidence: 56%

Lung Ultrasound and Static Lung Compliance during Postnatal Adaptation in Healthy Term Infants

et al. 2015

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Background: B-lines in lung ultrasound can be used to estimate lung liquid. B-lines are ring-down artifacts that arise from alterations to subpleural lung parenchyma. Lung ultrasound has been used to differentiate between diseases causing respiratory symptoms in neonates. B-lines are also seen in healthy infants during postnatal adaptation. Static lung compliance is a measure of the elasticity of the lungs. Objectives: Our aim was to document lung ultrasound findings, static lung compliance and their relationship during postnatal adaptation in healthy term infants. Methods: Lung ultrasound and measurement of static lung compliance were performed in 34 infants at ages of 0-4 and 24 h. B-lines in lung ultrasound were scored using a 5-step scale. Separate ultrasound scores for the upper and lower fields were also calculated. Results: A significant decrease in the abundance of B-lines and a concomitant significant improvement in static lung compliance was observed from <4 to 24 h of age. At <4 h the B-lines were significantly more abundant in the lower fields. No significant correlation existed between lung ultrasound and static lung compliance. Conclusion: The concomitant decrease in the B-lines in ultrasound and the increase in lung compliance during the first 24 h are likely to reflect clearance of lung liquid.

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“…Following delivery, kittens were immediately placed, head out, in a warmed (39°C) water-filled plethysmograph (custom-made) located within the experimental imaging hutch, as previously described (12,19). The ET tube was connected to a purpose-built pressure limited ventilator (16) that also triggered image acquisition to synchronize the imaging and lung inflation/deflation.…”

Section: Ventilation Protocolmentioning

confidence: 99%

“…This cutting-edge synchrotron imaging technology has been used to reveal the airways at the micron scale in living, breathing animals, which no other imaging modality can currently achieve. PC X-ray images were acquired as previously described using a synchrotron source tuned to 24 keV (19,35). The X-ray source-to-sample distance was ϳ210 m, and the sample-to-detector distance was 2 m. A Hamamatsu ORCA flash C11440-22C detector was coupled to a 25-m thick gadolinium oxysulfide (Gd2O2S:Tbϩ) powdered phosphor and a tandem lens system that provided an effective pixel size of 15. each sequence to correct for variations in the beam intensity and detector dark current signal.…”

Section: Pc X-ray Imagingmentioning

confidence: 99%

Elevated airway liquid volumes at birth: a potential cause of transient tachypnea of the newborn

McGillick

Lee

Yamaoka

et al. 2017

Journal of Applied Physiology

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Excessive liquid in airways and/or distal lung tissue may underpin the respiratory morbidity associated with transient tachypnea of the newborn (TTN). However, its effects on lung aeration and respiratory function following birth are unknown. We investigated the effect of elevated airway liquid volumes on newborn respiratory function. Near-term rabbit kittens (30 days gestation; term ~32 days) were delivered, had their lung liquid-drained, and either had no liquid replaced (control; = 7) or 30 ml/kg of liquid re-added to the airways [liquid added (LA); = 7]. Kittens were mechanically ventilated in a plethysmograph. Measures of chest and lung parameters, uniformity of lung aeration, and airway size were analyzed using phase contrast X-ray imaging. The maximum peak inflation pressure required to recruit a tidal volume of 8 ml/kg was significantly greater in LA compared with control kittens (35.0 ± 0.7 vs. 26.8 ± 0.4 cmHO, < 0.001). LA kittens required greater time to achieve lung aeration (106 ± 14 vs. 60 ± 6 inflations, = 0.03) and had expanded chest walls, as evidenced by an increased total chest area (32 ± 9%, < 0.0001), lung height (17 ± 6%, = 0.02), and curvature of the diaphragm (19 ± 8%, = 0.04). LA kittens had lower functional residual capacity during stepwise changes in positive end-expiratory pressures (5, 3, 0, and 5 cmH0). Elevated lung liquid volumes had marked adverse effects on lung structure and function in the immediate neonatal period and reduced the ability of the lung to aerate efficiently. We speculate that elevated airway liquid volumes may underlie the initial morbidity in near-term babies with TTN after birth. Transient tachypnea of the newborn reduces respiratory function in newborns and is thought to result due to elevated airway liquid volumes following birth. However, the effect of elevated airway liquid volumes on neonatal respiratory function is unknown. Using phase contrast X-ray imaging, we show that elevated airway liquid volumes have adverse effects on lung structure and function in the immediate newborn period, which may underlie the pathology of TTN in near-term babies after birth.

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Changes in Positive End-Expiratory Pressure Alter the Distribution of Ventilation within the Lung Immediately after Birth in Newborn Rabbits

Cited by 25 publications

References 34 publications

Comprehensive Quantitative Assessment of Lung Liquid Clearance by Lung Ultrasound Score in Neonates with No Lung Disease during the First 24 Hours

Comprehensive Quantitative Assessment of Lung Liquid Clearance by Lung Ultrasound Score in Neonates with No Lung Disease during the First 24 Hours

Lung Ultrasound and Static Lung Compliance during Postnatal Adaptation in Healthy Term Infants

Elevated airway liquid volumes at birth: a potential cause of transient tachypnea of the newborn

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