A new design for high stability pressure-controlled ventilation for small animal lung imaging

Kitchen, Marcus John; Habib, Anowarul; Fouras, Andreas; Dubsky, Stephen; Lewis, Robert A.; Wallace, Megan Jane; Hooper, Stuart B.

doi:10.1088/1748-0221/5/02/t02002

Cited by 41 publications

(32 citation statements)

References 11 publications

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“…18,26). The endotracheal tube was connected to a custombuilt ventilator (36), and ventilation and image acquisition were commenced. Time from intratracheal drug administration to ventilation was ≥5 min but often longer (~8 min).…”

Section: Methodsmentioning

confidence: 99%

“…FITCalbumin-labeled lung liquid was slowly and repeatedly withdrawn and reinjected into the lung ~20 times. The umbilical cord was then cut, and the pup was placed in a warm (40 °C) water-filled plethysmograph (head out) and connected to a mechanical ventilator (36). Pups were ventilated with a tidal volume of 7 ml/kg and a PEEP of 5 cmH 2 O at 24 inflations per minute for 7 min and then killed with sodium pentobarbitone (>100 mg/ kg i.p.).…”

Section: Articles Siew Et Almentioning

confidence: 99%

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The role of lung inflation and sodium transport in airway liquid clearance during lung aeration in newborn rabbits

et al. 2012

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Background: Recent phase-contrast X-ray imaging studies suggest that inspiration primarily drives lung aeration and airway liquid clearance at birth, which questions the role of adrenaline-induced activation of epithelial sodium channels (eNacs). We hypothesized that pressures generated by inspiration have a greater role in airway liquid clearance than do eNacs after birth. Methods: Rabbit pups (30 d of gestation) were delivered and sedated, and 0.1 ml of saline (s) or amiloride (Am; an eNac inhibitor) was instilled into the lungs before mechanical ventilation. Two other groups (30 d of gestation) were treated similarly but were also given adrenaline (s/Ad and Am/Ad) before mechanical ventilation. results: Amiloride and adrenaline did not affect functional residual capacity (FRc) recruitment (P > 0.05). Amiloride increased the rate of FRc loss between inflations (Am: −5.2 ± 0.6 ml/kg/s), whereas adrenaline reduced the rate of FRc loss (s/Ad: −1.9 ± 0.3 ml/kg/s) as compared with saline-treated controls (s: −3.5 ± −0.6 ml/kg/s; P < 0.05). conclusion: These data indicate that inspiration is a major determinant of airway liquid clearance and FRc development during positive pressure ventilation. Although eNac inhibition and adrenaline administration had no detectable effect on FRc development, eNac may help to prevent liquid from re-entering the airways during expiration. a t birth, airway liquid clearance and lung aeration initiate cardiopulmonary changes, and together they underpin the transition to newborn life. Airway liquid clearance is accomplished by a variety of mechanisms (1-3), depending on the mode and timing of delivery. However, cell culture (4,5), animal (6-8), and human (9,10) studies imply that adrenaline-induced activation of pulmonary epithelial sodium channels (ENaCs) is the primary mechanism. This predicts that increased Na + reabsorption from the lung lumen reverses the osmotic gradient across the pulmonary epithelium, favoring liquid movement from the airways into the interstitial tissue (11-13). However, no studies have assessed the independent effects of ENaC inhibition vs. other factors such as increased transpulmonary hydrostatic pressures generated by inspiration. These transpulmonary pressures refer to the pressure difference across the pulmonary epithelium between the distal airways and the surrounding interstitial tissue.Phase-contrast (PC) X-ray imaging exploits the refractive index difference between air and water to generate high-resolution images of the aerating lung after birth. As X-rays pass through the aerated lung, they are refracted at each air-liquid interface, which generates a characteristic "speckle" pattern from which lung gas volumes can be determined (14-16). Together with plethysmography, PC X-ray imaging has demonstrated the dependence of lung aeration on inspiratory activity after birth (17,18). These data have questioned the role of Na + reabsorption and suggest that inspiration may be the primary force promoting airway liquid clearance after birth. However, because ...

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Section: Methodsmentioning

confidence: 99%

Section: Articles Siew Et Almentioning

confidence: 99%

The role of lung inflation and sodium transport in airway liquid clearance during lung aeration in newborn rabbits

et al. 2012

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“…The ET tube was connected to a purpose-built, time-cycled, pressure-controlled ventilator (16) and simultaneous ventilation and image acquisition began as soon as possible.…”

Section: Methodsmentioning

confidence: 99%

Surfactant Increases the Uniformity of Lung Aeration at Birth in Ventilated Preterm Rabbits

et al. 2011

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Surfactant deficiency is a major cause of respiratory failure in newborns. We have investigated the roles of surfactant and positive end-expiratory pressure (PEEP) in the development of a functional residual capacity (FRC) and the distribution of ventilation at birth. Preterm rabbit pups (28 d GA) were delivered and received either saline or surfactant and then ventilated with (3PEEP) or without (0PEEP) 3 cm H 2 O PEEP (groups: saline/0PEEP, surfactant/ 0PEEP, saline/3PEEP, surfactant/3PEEP). Lung gas volumes were measured using plethysmography, and the uniformity of ventilation was analyzed using phase contrast (PC) x-ray imaging. Surfactant/ 0PEEP pups had greater FRCs and the lungs were more uniformly ventilated than saline/0PEEP pups; FRC at inflation 19 -21 was 2.46 Ϯ 0.52 mL/kg versus 0.91 Ϯ 0.95 mL/kg (p Ͻ 0.05). Saline/ 3PEEP pups developed an FRC of 7.54 Ϯ 1.68 mL/kg at inflation 19 -21 (p Ͻ 0.05), but the distribution of ventilation was initially nonuniform. Surfactant/3PEEP pups had an FRC of 8.50 Ϯ 0.80 mL/kg (at inflation 19 -21), and the distribution of ventilation was more uniform than with saline/3PEEP (p Ͻ 0.05). In ventilated preterm newborn rabbits, PEEP has a greater effect on FRC than surfactant, although the two are additive. Surfactant, administered at birth, markedly improved the uniformity of ventilation irrespective of whether PEEP was applied.

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“…This allows precise alignment and rotation of the sample to reduce artefacts in the subsequent tomographic reconstructions. A customdesigned ventilator, based on the device described by Kitchen et al [23] provides stable, pressure-controlled ventilation, and provides triggering to the imaging system for synchronization with the ventilation cycle.…”

Section: Imagingmentioning

confidence: 99%

Synchrotron-based dynamic computed tomography of tissue motion for regional lung function measurement

Dubsky

Hooper

Siu

et al. 2012

J. R. Soc. Interface.

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During breathing, lung inflation is a dynamic process involving a balance of mechanical factors, including trans-pulmonary pressure gradients, tissue compliance and airway resistance. Current techniques lack the capacity for dynamic measurement of ventilation in vivo at sufficient spatial and temporal resolution to allow the spatio-temporal patterns of ventilation to be precisely defined. As a result, little is known of the regional dynamics of lung inflation, in either health or disease. Using fast synchrotron-based imaging (up to 60 frames s 21 ), we have combined dynamic computed tomography (CT) with cross-correlation velocimetry to measure regional time constants and expansion within the mammalian lung in vivo. Additionally, our new technique provides estimation of the airflow distribution throughout the bronchial tree during the ventilation cycle. Measurements of lung expansion and airflow in mice and rabbit pups are shown to agree with independent measures. The ability to measure lung function at a regional level will provide invaluable information for studies into normal and pathological lung dynamics, and may provide new pathways for diagnosis of regional lung diseases. Although proof-of-concept data were acquired on a synchrotron, the methodology developed potentially lends itself to clinical CT scanning and therefore offers translational research opportunities.

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A new design for high stability pressure-controlled ventilation for small animal lung imaging

Cited by 41 publications

References 11 publications

The role of lung inflation and sodium transport in airway liquid clearance during lung aeration in newborn rabbits

The role of lung inflation and sodium transport in airway liquid clearance during lung aeration in newborn rabbits

Surfactant Increases the Uniformity of Lung Aeration at Birth in Ventilated Preterm Rabbits

Synchrotron-based dynamic computed tomography of tissue motion for regional lung function measurement

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