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3. Tidal changes in PaO2 and their relationship to cyclical lung recruitment/derecruitment in a porcine lung injury model

Author

Crockett, D. C., Cronin, J. N., Bommakanti, N., Chen, R., Hahn, C. E. W., Hedenstierna, Göran, Larsson, Anders, Farmery, A. D., Formenti, F., Crockett, D. C., Cronin, J. N., Bommakanti, N., Chen, R., Hahn, C. E. W., Hedenstierna, Göran, Larsson, Anders, Farmery, A. D., and Formenti, F.

Abstract

Background: Tidal recruitment/derecruitment (R/D) of collapsed regions in lung injury has been presumed to cause respiratory oscillations in the partial pressure of arterial oxygen (PaO2). These phenomena have not yet been studied simultaneously. We examined the relationship between R/D and PaO2 oscillations by contemporaneous measurement of lung-density changes and PaO2. Methods: Five anaesthetised pigs were studied after surfactant depletion via a saline-lavage model of R/D. The animals were ventilated with a mean fraction of inspired O-2 (FiO(2)) of 0.7 and a tidal volume of 10 ml kg(-1) Protocolised changes in pressure-and volume-controlled modes, inspiratory: expiratory ratio (I:E), and three types of breath-hold manoeuvres were undertaken. Lung collapse and PaO2 were recorded using dynamic computed tomography (dCT) and a rapid PaO2 sensor. Results: During tidal ventilation, the expiratory lung collapse increased when I: E <1 [mean (standard deviation) lung collapse = .7 (8.7)%; P<0.05], but the amplitude of respiratory PaO2 oscillations [ 2.2 (0.8) kPa] did not change during the respiratory cycle. The expected relationship between respiratory PaO2 oscillation amplitude and R/D was therefore not clear. Lung collapse increased during breath-hold manoeuvres at end-expiration and end-inspiration (14% vs 0.9-2.1%; P<0.0001). The mean change in PaO2 from beginning to end of breath-hold manoeuvres was significantly different with each type of breath-hold manoeuvre (P<0.0001). Conclusions: This study in a porcine model of collapse-prone lungs did not demonstrate the expected association between PaO2 oscillation amplitude and the degree of recruitment/derecruitment. The results suggest that changes in pulmonary ventilation are not the sole determinant of changes in PaO2 during mechanical ventilation in lung injury.

Published
2019
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4. Tidal changes in PaO2 and their relationship to cyclical lung recruitment/derecruitment in a porcine lung injury model

Author

Crockett, D. C., Cronin, J. N., Bommakanti, N., Chen, R., Hahn, C. E. W., Hedenstierna, Göran, Larsson, Anders, Farmery, A. D., and Formenti, F.

Subjects
Male, Recruitment, Neurophysiological, Pulmonary Atelectasis, Anestesi och intensivvård, Swine, diagnostic imaging, Acute Lung Injury, Oxygen Consumption, Tidal Volume, Animals, pulmonary atelectasis, lung injury, Therapeutic Irrigation, dynamic computed tomorgraphy, Anesthesiology and Intensive Care, ventilation, respiratory system, Respiration, Artificial, respiratory tract diseases, Respiratory Mechanics, Female, Respiration and the airway, Blood Gas Analysis, Tomography, X-Ray Computed, respiration, circulatory and respiratory physiology
Abstract

Background: Tidal recruitment/derecruitment (R/D) of collapsed regions in lung injury has been presumed to cause respiratory oscillations in the partial pressure of arterial oxygen (PaO 2 ). These phenomena have not yet been studied simultaneously. We examined the relationship between R/D and PaO 2 oscillations by contemporaneous measurement of lung-density changes and PaO 2 . Methods: Five anaesthetised pigs were studied after surfactant depletion via a saline-lavage model of R/D. The animals were ventilated with a mean fraction of inspired O 2 (FiO 2 ) of 0.7 and a tidal volume of 10 ml kg −1 . Protocolised changes in pressure- and volume-controlled modes, inspiratory:expiratory ratio (I:E), and three types of breath-hold manoeuvres were undertaken. Lung collapse and PaO 2 were recorded using dynamic computed tomography (dCT) and a rapid PaO 2 sensor. Results: During tidal ventilation, the expiratory lung collapse increased when I:E 2 oscillations [2.2 (0.8) kPa] did not change during the respiratory cycle. The expected relationship between respiratory PaO 2 oscillation amplitude and R/D was therefore not clear. Lung collapse increased during breath-hold manoeuvres at end-expiration and end-inspiration (14% vs 0.9–2.1%; P2 from beginning to end of breath-hold manoeuvres was significantly different with each type of breath-hold manoeuvre (P2 oscillation amplitude and the degree of recruitment/derecruitment. The results suggest that changes in pulmonary ventilation are not the sole determinant of changes in PaO 2 during mechanical ventilation in lung injury.

Published
2018

5. Tidal changes in PaO 2 and their relationship to cyclical lung recruitment/derecruitment in a porcine lung injury model.

Author

Crockett DC, Cronin JN, Bommakanti N, Chen R, Hahn CEW, Hedenstierna G, Larsson A, Farmery AD, and Formenti F

Subjects
Acute Lung Injury diagnostic imaging, Animals, Blood Gas Analysis, Female, Male, Pulmonary Atelectasis metabolism, Pulmonary Atelectasis physiopathology, Respiration, Artificial, Respiratory Mechanics, Swine, Therapeutic Irrigation, Tidal Volume, Tomography, X-Ray Computed, Acute Lung Injury metabolism, Acute Lung Injury physiopathology, Oxygen Consumption, Recruitment, Neurophysiological
Abstract

Background: Tidal recruitment/derecruitment (R/D) of collapsed regions in lung injury has been presumed to cause respiratory oscillations in the partial pressure of arterial oxygen (PaO 2 ). These phenomena have not yet been studied simultaneously. We examined the relationship between R/D and PaO 2 oscillations by contemporaneous measurement of lung-density changes and PaO 2 ., Methods: Five anaesthetised pigs were studied after surfactant depletion via a saline-lavage model of R/D. The animals were ventilated with a mean fraction of inspired O 2 (FiO 2 ) of 0.7 and a tidal volume of 10 ml kg -1 . Protocolised changes in pressure- and volume-controlled modes, inspiratory:expiratory ratio (I:E), and three types of breath-hold manoeuvres were undertaken. Lung collapse and PaO 2 were recorded using dynamic computed tomography (dCT) and a rapid PaO 2 sensor., Results: During tidal ventilation, the expiratory lung collapse increased when I:E <1 [mean (standard deviation) lung collapse=15.7 (8.7)%; P<0.05], but the amplitude of respiratory PaO 2 oscillations [2.2 (0.8) kPa] did not change during the respiratory cycle. The expected relationship between respiratory PaO 2 oscillation amplitude and R/D was therefore not clear. Lung collapse increased during breath-hold manoeuvres at end-expiration and end-inspiration (14% vs 0.9-2.1%; P<0.0001). The mean change in PaO 2 from beginning to end of breath-hold manoeuvres was significantly different with each type of breath-hold manoeuvre (P<0.0001)., Conclusions: This study in a porcine model of collapse-prone lungs did not demonstrate the expected association between PaO 2 oscillation amplitude and the degree of recruitment/derecruitment. The results suggest that changes in pulmonary ventilation are not the sole determinant of changes in PaO 2 during mechanical ventilation in lung injury., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Published
2019
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6. Medicine among the American Indians.

Author

Crockett DC

Subjects
Attitude to Health, Child, Preschool, Culture, Folklore, Humans, Infant, Infant Mortality, Morbidity, Mortality, Superstitions, United States, United States Public Health Service, Indians, North American, Medicine, Traditional, Personal Health Services supply & distribution
Published
1971

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