Development of Respiratory Training System Using Individual Characteristic Guiding Waveform / 의학물리

The purpose of this study was to develop the respiratory training system using individual characteristic guiding waveform to reduce the impact of respiratory motion that causes artifact in radiotherapy. In order to evaluate the improvement of respiratory regularity, 5 volunteers were included and their respiratory signals were acquired using the in-house developed belt-type sensor. Respiratory training system needs 10 free breathing cycles of each volunteer to make individual characteristic guiding waveform based on Fourier series and it guides patient's next breathing. For each volunteer, free breathing and guided breathing which uses individual characteristic guiding waveform were performed to acquire the respiratory cycles for 3 min. The root mean square error (RMSE) was computed to analyze improvement of respiratory regularity in period and displacement. It was found that respiratory regularity was improved by using respiratory training system. RMSE of guided breathing decreased up to 40% in displacement and 76% in period compared with free breathing. In conclusion, since the guiding waveform was easy to follow for the volunteers, the respiratory regularity was significantly improved by using in-house developed respiratory training system. So it would be helpful to improve accuracy and efficiency during 4D-RT, 4D-CT.

Respiratory Patterns Associated with Swallowing in Athetoid Cerebral-Palsied Patients

OBJECTIVE: To evaluate the changes of the respiratory patterns associated with swallowing in athetoid cerebral palsied patients (CP), and to understand its relationship with their dysphagia and aspiration. METHOD: Seven adult athetoid CP and seven control subjects were selected for this study. Each subject performed swallowing tasks in upright sitting position, and submental electromyography and respirography by pneumobelt on mid-abdomen were recorded simultaneously. Swallowing tasks were composed of swallowing 5 cc, 75 cc of water, and chewing a cookie. And athetoid subjects performed videofluoroscopic swallowing study (VFSS) for each food texture. RESULTS: 1) In athetoid CP, respiratory patterns during swallowing were variable and more irregular than the resting tidal breathing. 2) In athetoid CP, completion time of the swallowing task and recovery time to the resting tidal breathing after swallow were significantly prolonged (p<0.01). 4) Athetoid subjects had significantly higher rate of postdeglutitive inspiration than that of the controls (p<0.01). 5) In correlation with the VFSS findings, aspirated group of the athetoid subjects had significantly higher rate of postdeglutitive inspiration than that of non-aspirated group (p<0.05). CONCLUSION: Respiratory-swallowing coordination was disrupted in the athtoid CP, and their higher rate of postdeglutitive inspiration suggested the higher risk for aspiration of the food materials, especially in drinking of large amounts of liquid.

Respiratory Variations of Doppler Echocardiographic Parameters in Cardiac Tamponade

BACKGROUND: Cardiac tamponade is associated with the expiratory increase and the expira-tory decrease in left ventricular filling flow. With Doppler echocardiography, we analyzed the respiratory variations of mitral and tricuspid inflows, and pulmonary and hepatic venous flows in patients with cardiac tamponade. METHODS: Respiratory hemodynamic changes in mitral and tricuspid inflows and pulmonary and hepatic venous flows were evaluated using Doppler echocardiography in 13 patients (6 men and 7 women; mean age 51+/-13 years) with large pericardial effusion and clinical cardiac tamponade, and compared the results with those of 11 control subjects (3 men and 8 women, mean age 53+/-13 years). Doppler examination was repeated after pericardiocentesis in 6 patients. RESULTS: Peak velocity of early diastolic mitral inflow (E velocity) decreased during inspiration compared with expiratory increase; the mean percentage change was 40%. Peak velocity of late diastolic mitral inflow (A velocity) decreased 13% during inspiration. E/A ratio decreased 31% during inspiration. Deceleration time (DT) and isovolumic relaxation time (IVRT) increased by 26% and 44%, respectively, during inspiration. But respiratory variations of tricuspid inflow were opposite to those of mitral inflow. Tricuspid E velocity increased during inspiration and decre-ased during expiration. The mean percentage change was 123%, which was larger than thte 40% of mitral inflow. The most characteristic findings of pulmonary venous flow during respiration were the expiratory increases of peak diastolic velocity (DV) and diastolic time-velocity integral (D-TVI). The mean percentage changes of peak systolic velocity (SV), DV and D-TVI during respiration were 27%, 45% and 53% respectively. In contrast, the SV and DV of hepatic venous flow increased during inspiration and decreased during expiration. The respiratory variations of peak systolic reverse flow velocity (SR) and peak diastolic reverse flow velocity (DR) were opposite to those of SV and DV. DR notably increased during expiration, and the mean percentage change was 61%. The ratio of RFI (Inspiratory reverse flow integral) to FFI (forward flow integral) of the tamponade group was 270%. The mean percentage changes of each parameters decreased after pericardiocentesis. CONCLUSION: Patients with cardiac tamponade showed inspiratory increases of diastolic tri-cuspid filling flow and hepatic forward flow. Expiratory increases included diastolic mitral filling flow, pulmonary venous systolic and diastolic flow, and hepatic venous reverse flow. Such res-piratory variations decreased after pericardiocentesis.