Chest Pressure Changes In The Hemodynamic Effects Of Mechanical Principle

Objective l.To investigate the mechanism of the different influence ofthe intrathoracic pressure change (ITPC) on the two ventricular fillings and the motion of interventricular septum. 2.To observe the effects of quiet and resistant respiration on hemodynamics in normal man and and to establish the normal values of this effects and to verify the new proposal of the mechanism of respiratory effects on hemodynamics from clinical point of view. 3. To observe influence of respiration on hemodynamics and interventricular septal (IVS) motion in patients with pericardial effusion (PE) with echocardiography and to provide theoretical basis for its clinical application. 4.To test a new method of measuring pulmonary pressure, which is independent of pulmonary valvular regurgitation, and a new menthod of measuring left ventricular end-diastolic pressure using Doppler echocardiography.Methods1. Simulated experimentsEffects of intrathoracic pressure change on hemodynamicsThree models that simulated the anatomic arrangement of the venous return systems and chest cavity were established to investigate the hydromechanic principle of the different influence of the ITPC on the ventricular fillings.Effects of intrathoracic pressure change on the motion of interventricular septum (IVS)Acuson's Sequoia 512 ultrasonographic system was used in this study to record the M-mode and two-dimensional cineloop images of the simulated interventricular septum movement with different intrathoracic pressurechanges.2. Respiratory Variation Index (RVI) in normal manPulsed-wave Doppler spectra of the four cardiac valves were recorded andcompared with Sequoia 512 and Acuson 128 XP/10 in 79 normal subjects aged 18 to 70 years. Electrocardiogram and respiratory tracing by a nasal thermistor were recorded simultaneously with the echocardiograms. The blood flow velocities of each valve during quiet and resistant respiration were averaged separately and those were again averaged for at least 3 consecutive respiratory cycles, and the RVIs were calculated.3. Effects of intrathoracic pressure change on the hemodynamics and the motion of IVS in patients with PETo observe the respiration-related hemodynamic changes and the IVS motion in 10 patients with PE with or without cardiac tamponade using echocardiographic technique.4. New methods for noninvasively detecting pulmonary pressure and left ventricular end-diastolic pressureManometer that measures megative pressure in mmHg was connected with the examined subject through a mask. The manometer is a remodeled sphygmomanometer for routine peripheral arterial blood pressure measurement that is market-available. The examined subjects were asked to carry out Muller maneuver slowly so that the intrathoracic pressure decreases gradually while the blood flow of the right ventricular outflow tract observed with pulsed Doppler echocardiography at the parasternal short-axis view of the great vessels in the two-dimensional echocardiography.These pressure recordings were compared with the results of thewell-known Doppler method for pulmonary regurgitation data using the simplified Bernoulli's equation.Results1. Simulated experimentsEffects of intrathoracic pressure change on hemodynamicsModel I and II tests demonstrated that the same ITPC had different actions on the simulated ventricular fillings. The ITPC would not change the pressure in the simulated right heart but its volume while it changed the pressure in the simulated left heart without direct influencing on its volume.With the pressure in the simulated right ventricle (SRV) and simulated left ventricle (SLV) kept constant (standard pressure condition for model III), each step of pressure decrease in the SCC from 0 mmHg to -5 mmHg, the SIVS moved leftwards (to the SLV direction) in a corresponding position and from 0 mmHg to +5 mmHg, the SIVS swung left- and rightwards at amplitude of 2.2 mm.Effects of intrathoracic pressure change on the motion of IVSUnde...