Minimization of lung pressure swings during high-frequency ventilation: a model. 1989

M C Khoo, and S M Yamashiro, and P Yamashiro
Department of Biomedical Engineering, University of Southern California, Los Angeles 90089.

The goal of this theoretical study was to develop a simple computational model for determining the lung pressure excursions that accompany the maintenance of adequate gas transport through high-frequency airway oscillations applied via the trachea (HFAO) and by transthoracic means (HFTO). Respiratory mechanics and gas transport parameters estimated from the preceding companion study (J. Appl. Physiol. 67: 985-992, 1989) were used in the model for computing tracheal, alveolar, pleural, and transpulmonary pressure swings. Comparison of model predictions with corresponding data obtained in dogs showed close agreement. The specification of eucapnia as a constraint led to results that were significantly different from previous findings which had assumed constant airflow. We used the model to identify "quasi-optimal" strategies for HFAO and HFTO application in which all pressure excursions were kept below the corresponding levels produced by conventional mechanical ventilation operating at 15 breaths/min. The model suggests the application of both HFAO and HFTO at frequencies substantially lower than the settings commonly employed in high-frequency ventilation. Application of HFAO at frequencies ranging from 1 to 4 Hz is recommended, whereas for HFTO the quasi-optimal range lies between 1 and 1.7 Hz. In patients with chronic obstructive pulmonary disease, pressure costs during HFAO or HFTO are minimized in the vicinity of 1 Hz.

UI MeSH Term Description Entries
D008168 Lung Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood. Lungs
D008170 Lung Compliance The capability of the LUNGS to distend under pressure as measured by pulmonary volume change per unit pressure change. While not a complete description of the pressure-volume properties of the lung, it is nevertheless useful in practice as a measure of the comparative stiffness of the lung. (From Best & Taylor's Physiological Basis of Medical Practice, 12th ed, p562) Compliance, Lung,Compliances, Lung,Lung Compliances
D008954 Models, Biological Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment. Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D011312 Pressure A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Pressures
D011659 Pulmonary Gas Exchange The exchange of OXYGEN and CARBON DIOXIDE between alveolar air and pulmonary capillary blood that occurs across the BLOOD-AIR BARRIER. Exchange, Pulmonary Gas,Gas Exchange, Pulmonary
D012119 Respiration The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration ( Breathing
D012137 Respiratory System The tubular and cavernous organs and structures, by means of which pulmonary ventilation and gas exchange between ambient air and the blood are brought about. Respiratory Tract,Respiratory Systems,Respiratory Tracts,System, Respiratory,Tract, Respiratory
D006612 High-Frequency Ventilation Ventilatory support system using frequencies from 60-900 cycles/min or more. Three types of systems have been distinguished on the basis of rates, volumes, and the system used. They are high frequency positive-pressure ventilation (HFPPV); HIGH-FREQUENCY JET VENTILATION; (HFJV); and high-frequency oscillation (HFO). High-Frequency Oscillation Ventilation,High-Frequency Positive Pressure Ventilation,Ventilation, High-Frequency,High Frequency Oscillation Ventilation,High Frequency Positive Pressure Ventilation,High Frequency Ventilation,Ventilation, High Frequency,High Frequency Ventilations,High-Frequency Oscillation Ventilations,High-Frequency Ventilations,Oscillation Ventilation, High-Frequency,Oscillation Ventilations, High-Frequency,Ventilation, High-Frequency Oscillation,Ventilations, High Frequency,Ventilations, High-Frequency,Ventilations, High-Frequency Oscillation
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000403 Airway Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Airway Resistances,Resistance, Airway,Resistances, Airway

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