Non-Contact Measurement of Respiratory Function for Judging the Effect of Respiratory Rehabilitation in Patients With SMID

Patients with SMID (severe motor and intellectual disabilities) are “patients having severe limbs disorder and severe mental disabilities”. They are bedridden and have symptoms such as body deformation. More than half of their deaths are due to respiratory disorders. Therefore, respiratory rehabilitation is important. The effect of respiratory rehabilitation is generally determined by measuring respiratory volume and respiratory rate with an expired gas analyzer. However, it is difficult to use the equipment because it is expensive, often refuses contact due to intellectual disability, and there is a risk of infection and dermatitis due to the contact. And now it is only a clinical evaluation from the disease phase.

In previous studies, there was a method that could measure the respiratory volume of adult males at low cost and without contact using a three-dimensional camera. However, applications to patients with SMID include issues such as undeveloped physique, specificity of symptoms such as posture distortion and body deformation, and unstable breathing. The purpose of this study is to develop a non-contact measurement system of respiratory volume for judging respiratory rehabilitation effect of patients with SMID using a three-dimensional camera.

We performed respiratory rehabilitation for patients with SMID using an RTX respirator for the purpose of expectoration. The RTX respirator is a biphasic external cuirass-style ventilator that supports both inspiration and expiration at various cycle rates and pressures, as well as allowing application of the vibration and cough modes. Then, we performed a simultaneous measurement experiment of respiratory volume using a three-dimensional camera “Kinect” and an expired gas analyzer “Cpex-1” to verify the effect of the RTX respirator and the validity of the non-contact measurement system of respiratory volume using Kinect. The experimental results showed that the effects of the RTX respirator can be evaluated in three items: the magnitude of respiratory volume, the variation in respiratory volume, and the apnea time. In addition, when the RTX respirator is used in normal times, it was found that, it is difficult to measure the change in the respiratory state even with Cpex-1 if the respiratory state is relatively good, but it is possible to measure the improvement in the respiratory state if the respiratory state is bad. Corresponding results were obtained with Kinect. Therefore, it was shown that if the effect of rehabilitation could be judged by the expired gas analyzer, the rehabilitation effect could be judged by a three-dimensional camera. Although the measurement of respiratory volume using Kinect was still under analysis, the results correlated with the measurement of respiratory volume using Cpex-1. We plan to do a detailed analysis in the future.