Sizing the lung in dogs: the inspiratory capacity defines the tidal volume

Donati, Pablo; Gogniat, Emiliano; Madorno, Matías; Guevara, Juan Manuel; Guillemi, Eliana Carolina; Lavalle, María del Carmen; Scorza, Francisco Patricio; Mayer, Germán Federico; Rodríguez, Pablo

doi:10.5935/0103-507x.20180028

Cited by 9 publications

(8 citation statements)

References 33 publications

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“…The mRCV variation across breeds was statistically insignificant. The closest report to this finding observed differences in inspiratory capacities normalised to body weights in dogs (Donati et al, 2018). Inspiratory capacity does not necessarily correspond with total chest volume may be the differential factor in comparison to this study.…”

Section: Discussioncontrasting

confidence: 70%

A Retrospective Study Correlating Modified Radiological Chest Volume and ‎Vertebral Heart Score with Pulmonary Patterns in Dogs

Tan

Okene

Hashim

2020

SJVS

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Veterinary practices rely on the Vertebral Heart Score (VHS) to determine cardiac silhouette size. In addition to cardiac silhouette, pulmonary patterns are examined to determine if clinical signs such as coughing are of cardiac or respiratory origin. Concept of interpreting pulmonary patterns are based on the anatomical structure involved within the lung parenchyma to make assumptions of manifestation of diseases. Modified Radiographic Chest Volume (mRCV) and Vertebral Heart Score (VHS) were retrospectively evaluated for correlation with pulmonary patterns in dogs. Patient data and thoracic radiographs were obtained from the digital repository of selected veterinary clinics in Malaysia. Findings revealed that there are wide variations in VHS and are significantly associated with pulmonary patterns (p < 0.05). Mean VHS values of 10.5 ± 1.2, and variations in mean mRCV across breed (26.74 ± 16.71) were observed. The mRCV weakly correlated with VHS denoting that changes in cardiac sizes does not necessarily synergise with lung volume. Therefore, it is recommended to evaluate pulmonary patterns alongside VHS while interpreting thoracic radiographs for cardiorespiratory diseases.

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Section: Discussioncontrasting

confidence: 70%

A Retrospective Study Correlating Modified Radiological Chest Volume and ‎Vertebral Heart Score with Pulmonary Patterns in Dogs

Tan

Okene

Hashim

2020

SJVS

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“…We only included healthy beagle dogs undergoing general anesthesia in the supine position. It is possible that different breeds as well as obesity will develop different magnitudes and distribution of regional strains at a given V T ( 39 ). Furthermore, the distribution of aeration will differ between prone and supine position, which may result in different regional strains ( 15 ).…”

Section: Discussionmentioning

confidence: 99%

Distribution and Magnitude of Regional Volumetric Lung Strain and Its Modification by PEEP in Healthy Anesthetized and Mechanically Ventilated Dogs

et al. 2022

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The present study describes the magnitude and spatial distribution of lung strain in healthy anesthetized, mechanically ventilated dogs with and without positive end-expiratory pressure (PEEP). Total lung strain (LSTOTAL) has a dynamic (LSDYNAMIC) and a static (LSSTATIC) component. Due to lung heterogeneity, global lung strain may not accurately represent regional total tissue lung strain (TSTOTAL), which may also be described by a regional dynamic (TSDYNAMIC) and static (TSSTATIC) component. Six healthy anesthetized beagles (12.4 ± 1.4 kg body weight) were placed in dorsal recumbency and ventilated with a tidal volume of 15 ml/kg, respiratory rate of 15 bpm, and zero end-expiratory pressure (ZEEP). Respiratory system mechanics and full thoracic end-expiratory and end-inspiratory CT scan images were obtained at ZEEP. Thereafter, a PEEP of 5 cmH2O was set and respiratory system mechanics measurements and end-expiratory and end-inspiratory images were repeated. Computed lung volumes from CT scans were used to evaluate the global LSTOTAL, LSDYNAMIC, and LSSTATIC during PEEP. During ZEEP, LSSTATIC was assumed zero; therefore, LSTOTAL was the same as LSDYNAMIC. Image segmentation was applied to CT images to obtain maps of regional TSTOTAL, TSDYNAMIC, and TSSTATIC during PEEP, and TSDYNAMIC during ZEEP. Compliance increased (p = 0.013) and driving pressure decreased (p = 0.043) during PEEP. PEEP increased the end-expiratory lung volume (p < 0.001) and significantly reduced global LSDYNAMIC (33.4 ± 6.4% during ZEEP, 24.0 ± 4.6% during PEEP, p = 0.032). LSSTATIC by PEEP was larger than the reduction in LSDYNAMIC; therefore, LSTOTAL at PEEP was larger than LSDYNAMIC at ZEEP (p = 0.005). There was marked topographic heterogeneity of regional strains. PEEP induced a significant reduction in TSDYNAMIC in all lung regions (p < 0.05). Similar to global findings, PEEP-induced TSSTATIC was larger than the reduction in TSDYNAMIC; therefore, PEEP-induced TSTOTAL was larger than TSDYNAMIC at ZEEP. In conclusion, PEEP reduced both global and regional estimates of dynamic strain, but induced a large static strain. Given that lung injury has been mostly associated with tidal deformation, limiting dynamic strain may be an important clinical target in healthy and diseased lungs, but this requires further study.

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“…Comparative respiratory physiology studies across different mammal species also indicate that spontaneous breath tidal volumes range from 6 to 8 ml/kg (27,28). Even though, in small animals undergoing general anesthesia, the recommended tidal volumes to be used are in the range of 10 to 15 ml/kg (29,30). It is unknown what the effect of such high tidal volumes and airway pressures is on the pulmonary structure and its possible long-term consequences in healthy cats undergoing general anesthesia and MV for surgical procedures, and studies like this one are important to determine the ideal inspiratory pressure and V T to be clinically used in this species.…”

Section: Discussionmentioning

confidence: 99%

Computed Tomography Assessment of Tidal Lung Overinflation in Domestic Cats Undergoing Pressure-Controlled Mechanical Ventilation During General Anesthesia

Martins¹,

Ambrósio

Fantoni

et al. 2022

Front. Vet. Sci.

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ObjectiveThis study aimed to evaluate lung overinflation at different airway inspiratory pressure levels using computed tomography in cats undergoing general anesthesia.Study DesignProspective laboratory study.AnimalsA group of 17 healthy male cats, aged 1.9–4.5 years and weighing 3.5 ± 0.5 kg.MethodsSeventeen adult male cats were ventilated in pressure-controlled mode with airway pressure stepwise increased from 5 to 15 cmH2O in 2 cmH2O steps every 5 min and then stepwise decreased. The respiratory rate was set at 15 movements per min and end-expiratory pressure at zero (ZEEP). After 5 min in each inspiratory pressure step, a 4 s inspiratory pause was performed to obtain a thoracic juxta-diaphragmatic single slice helical CT image and to collect respiratory mechanics data and an arterial blood sample. Lung parenchyma aeration was defined as overinflated, normally-aerated, poorly-aerated, and non-aerated according to the CT attenuation number (−1,000 to −900 HU, −900 to −500 HU, −500 to −100 HU, and −100 to +100 HU, respectively).ResultAt 5 cmH2O airway pressure, tidal volume was 6.7± 2.2 ml kg−1, 2.1% (0.3–6.3%) of the pulmonary parenchyma was overinflated and 84.9% (77.6%−87.6%) was normally inflated. Increases in airway pressure were associated with progressive distention of the lung parenchyma. At 15 cmH2O airway pressure, tidal volume increased to 31.5± 9.9 ml kg−1 (p < 0.001), overinflated pulmonary parenchyma increased to 28.4% (21.2–30.6%) (p < 0.001), while normally inflated parenchyma decreased 57.9% (53.4–62.8%) (p < 0.001). Tidal volume and overinflated lung fraction returned to baseline when airway pressure was decreased. A progressive decrease was observed in arterial carbon dioxide partial pressure (PaCO2) and end-tidal carbon dioxide (ETCO2) when the airway pressures were increased above 9 cmH2O (p < 0.001). The increase in airway pressure promoted an elevation in pH (p < 0.001).Conclusions and Clinical RelevanceVentilation with 5 and 7 cmH2O of airway pressure prevents overinflation in healthy cats with highly compliant chest walls, despite presenting acidemia by respiratory acidosis. This fact can be controlled by increasing or decreasing respiratory rate and inspiratory time.

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Sizing the lung in dogs: the inspiratory capacity defines the tidal volume

Cited by 9 publications

References 33 publications

A Retrospective Study Correlating Modified Radiological Chest Volume and ‎Vertebral Heart Score with Pulmonary Patterns in Dogs

A Retrospective Study Correlating Modified Radiological Chest Volume and ‎Vertebral Heart Score with Pulmonary Patterns in Dogs

Distribution and Magnitude of Regional Volumetric Lung Strain and Its Modification by PEEP in Healthy Anesthetized and Mechanically Ventilated Dogs

Computed Tomography Assessment of Tidal Lung Overinflation in Domestic Cats Undergoing Pressure-Controlled Mechanical Ventilation During General Anesthesia

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