The origin of adaptive support ventilation.
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Biomedical subjects
F T Tehrani
Publications and source records attributed to F T Tehrani.
A model study of periodic breathing, stability of the neonatal respiratory system, and causes of sudden infant death syndrome.
A mathematical model of the neonatal respiratory system has been modified and used to examine the system under various physiological conditions at different stages of maturity. The respiratory responses in hypoxia, periodic breathing and following a sign have been analyzed. The effects of different respiratory parameters on the stability of the system for normal and premature infants have been investigated. The causes of periodic breathing, apnea spells and sudden infant death syndrome for full-term and premature infants have been studied, and the results compared with the available experimental findings. The response of the infant respiratory system has been found to be highly sensitive to several parameters of the system, as indicated by the results of this study. These significant parameters are sensitivity factor of central receptors to carbon dioxide, sensitivity factor of arterial receptors to carbon dioxide, sensitivity factor of arterial receptors to oxygen, functional residual capacity of the lungs, the alveolar-arterial oxygen difference and the lungs shunt ratio. It has been shown that different parts of the respiratory controller have antagonistic effects on hypoxic periodic breathing and apnea of infancy.
Computer Simulation↗
A feedback controller for supplemental oxygen treatment of newborn infants: a simulation study.
A microcomputer control system has been developed for supplemental oxygen therapy of newborn infants. The system uses feedback of arterial oxygen saturation to adjust the concentration of oxygen in the incubator or under the hood. The control system has been tested under different physiological conditions, using a detailed simulation model of the neonatal respiratory system. Some of the simulation results of this study are presented to illustrate the performance of the controller.
Acute Disease↗
Mathematical analysis and computer simulation of the respiratory system in the newborn infant.
A mathematical model of neonatal respiratory control is proposed which can be used to stimulate the system under different physiological conditions. The model consists of a continuous plant and a discrete controller. Included in the plant are lungs, body tissue, brain tissue, a cerebrospinal fluid compartment, and central and peripheral receptors. The effect of shunt in the lungs is included in the model and the lung volume and the dead space are time varying. The controller utilizes outputs from peripheral and central receptors to adjust the depth and rate of breathing and the effects of prematurity of peripheral receptors are included in the system. Hering-Breuer type reflexes are embodied in the controller to accomplish respiratory synchronization. The model is examined and its simulation results under test conditions in hypoxia and hypercapnia are presented.
Blood Gas Analysis↗
A microcomputer oxygen control system for ventilatory therapy.
A computer-based feedback system has been developed to adjust the concentration of oxygen in the inspired gas of a patient under artificial respiration. The system uses a proportional plus integral controller and feedback of arterial oxygen saturation to adjust the inspired oxygen fraction. The effectiveness of the controller has been tested using a dynamic, mathematical model of the human respiratory system. This relatively sophisticated model has been developed and examined in the past, and it has been shown that it can realistically describe the human respiratory system for a wide variety of test conditions. The performance of the oxygen control system has been evaluated using the simulation model. The response of the controller to different disturbances is always stable, with arterial pressure of oxygen returning to normal in less than 12 minutes. Some of the simulation results are presented to illustrate the dynamic behavior and robustness of the controller.
Computer Simulation↗
A mathematical model of the human respiratory system.
A model of the human respiratory system is proposed which has a satisfactory performance under different physiological conditions. The model comprises a continuous plant and a discrete controller which generates and updates the drive signal to the plant at the end of every breath to represent the Hering-Breuer reflex. Arterial and central medullary sensors are included. The lung volume, dead space volume, cardiac output and cerebral blood flow are time varying. The respiratory work is minimized. The model is examined and simulation results of its performance in hypercapnia, hypoxia, periodic breathing and moderate exercise are presented. The responses presented include the relatively fast transients of Cheyne-Stokes breathing and the slower transients associated with carbon dioxide inhalation.
Blood Circulation↗
On the regulation of cardiac output and cerebral blood flow.
Algebraic presentations are used to describe the steady-state relationships for cardiac output and cerebral blood flow in terms of arterial blood levels of oxygen and carbon dioxide and the metabolic rate ratio. A possible application of the results is briefly discussed with regard to their use in modelling of the respiratory control system.
Carbon Dioxide↗