Investigation of the brain stem function using three different parameters analyzing the relation among respiration, heart rate variability, and direct arterial pressure.

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1st year :We developed analytical procedures using 3 different parameters from patients monitor ; heart rate variability (HRV) by measuring R-R interval segments from electrocardiogram (ECG), direct arterial pressure (DAP), and respiratory airway pressure (RAP) and endtidal CO2. We also started to develop computer program for this analysis. This analytical procedures are based on the fast Fourier analysis and impulse response analysis. With this computer program, we investigated the effects between RAP on HRV and HRV on DAP in the experimental animals and in the clinical conditions.2nd year :With this computer program, we continued to investigate the effects between RAP on HRV and HRV on DAP in the experimental animals and in the clinical conditions. In the model of brain-damaged rabbits, it was turned out that artificial respiration did not produce any effect of RAP on HRV,although HRV on DAP was dependent on the condition of brain damage. In clinical investigation in the intensiv care, HRV on DAP was apparent with the level of consciousness, while any effect of RAP on HRV was not observed. We have to improve the analytical procedure using RAP on HRV because the parameters represented by RAP and endtidal CO2 were not sufficient enough for the investigation. Instead of these parameters, thoracic impedance would be appropriate in the next step investigation.Conclusion :It was concluded that HRV was seriously depending on the respiratory condition although the subjects were artificially ventilated. However, it was not apparent that relation between RAP and HRV in both animal models and human studies. It is therefore further needed to investigate the relation between RAP and HRV,and between HRV and DAP for clinical application.