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  • Kitchen, Marcus J.  (3)
  • Lee, Katie  (3)
  • Biology  (3)
  • 1
    Online Resource
    Online Resource
    Increased end-expiratory pressures improve lung function in near-term newborn rabbits with elevated airway liquid volume at birth
    American Physiological Society ; 2021
    In:  Journal of Applied Physiology Vol. 131, No. 3 ( 2021-09-01), p. 997-1008
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 131, No. 3 ( 2021-09-01), p. 997-1008
    Abstract: Approximately 53% of near-term newborns admitted to intensive care experience respiratory distress. These newborns are commonly delivered by cesarean section and have elevated airway liquid volumes at birth, which can cause respiratory morbidity. We investigated the effect of providing respiratory support with a positive end-expiratory pressure (PEEP) of 8 cmH 2 O on lung function in newborn rabbit kittens with elevated airway liquid volumes at birth. Near-term rabbits (30 days; term = 32 days) with airway liquid volumes that corresponded to vaginal delivery (∼7 mL/kg, control, n = 11) or cesarean section [∼37 mL/kg; elevated liquid (EL), n = 11] were mechanically ventilated (tidal volume = 8 mL/kg). The PEEP was changed after lung aeration from 0 to 8 to 0 cmH 2 O (control, n = 6; EL, n = 6), and in a separate group of kittens, PEEP was changed after lung aeration from 8 to 0 to 8 cmH 2 O (control, n = 5; EL, n = 5). Lung function (ventilator parameters, compliance, lung gas volumes, and distribution of gas within the lung) was evaluated using plethysmography and synchrotron-based phase-contrast X-ray imaging. EL kittens initially receiving 0 cmH 2 O PEEP had reduced functional residual capacities and lung compliance, requiring higher inflation pressures to aerate the lung compared with control kittens. Commencing ventilation with 8 cmH 2 O PEEP mitigated the adverse effects of EL, increasing lung compliance, functional residual capacity, and the uniformity and distribution of lung aeration, but did not normalize aeration of the distal airways. Respiratory support with PEEP supports lung function in near-term newborn rabbits with elevated airway liquid volumes at birth who are at a greater risk of suffering respiratory distress. NEW & NOTEWORTHY Term babies born by cesarean section have elevated airway liquid volumes, which predisposes them to respiratory distress. Treatments targeting molecular mechanisms to clear lung liquid are ineffective for term newborn respiratory distress. We showed that respiratory support with an end-expiratory pressure supports lung function in near-term rabbits with elevated airway liquid volumes at birth. This study provides further physiological understanding of lung function in newborns with elevated airway liquid volumes at risk of respiratory distress.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.00918.2020
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2021
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Elevated airway liquid volumes at birth: a potential cause of transient tachypnea of the newborn
    American Physiological Society ; 2017
    In:  Journal of Applied Physiology Vol. 123, No. 5 ( 2017-11-01), p. 1204-1213
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 123, No. 5 ( 2017-11-01), p. 1204-1213
    Abstract: 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; n = 7) or 30 ml/kg of liquid re-added to the airways [liquid added (LA); n = 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 cmH 2 O, P 〈 0.001). LA kittens required greater time to achieve lung aeration (106 ± 14 vs. 60 ± 6 inflations, P = 0.03) and had expanded chest walls, as evidenced by an increased total chest area (32 ± 9%, P 〈 0.0001), lung height (17 ± 6%, P = 0.02), and curvature of the diaphragm (19 ± 8%, P = 0.04). LA kittens had lower functional residual capacity during stepwise changes in positive end-expiratory pressures (5, 3, 0, and 5 cmH 2 0). 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. NEW & NOTEWORTHY 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.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.00464.2017
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2017
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Improving lung aeration in ventilated newborn preterm rabbits with a partially aerated lung
    American Physiological Society ; 2020
    In:  Journal of Applied Physiology Vol. 129, No. 4 ( 2020-10-01), p. 891-900
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 129, No. 4 ( 2020-10-01), p. 891-900
    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 of 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 (200 mg/kg; Curosurf) 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 cmH 2 O, P = 0.01) and had higher dynamic lung compliances (0.54 ± 0.3 vs. 0.40 ± 0.3 cmH 2 O·mL −1 ·kg −1 , 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. NEW & NOTEWORTHY 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. Using phase contrast X-ray imaging, we showed that combining a long inflation time (1.0 s) with surfactant improved lung mechanics and aeration in the immediate newborn period. The current clinical practice of using short inflation times during iPPV might be suboptimal and a different approach is needed.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.00426.2020
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2020
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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