Unconstrained respiration measurement and respiratory arrest detection by dynamic threshold in transferring patients by stretcher

General anesthesia used for surgery may cause an unstable postoperative condition of patients, which could lead to respiratory arrest. Under such circumstances, nurses could fail to recognize changes of condition, and other errors could also occur. It is highly possible that such errors may occur while transferring a patient from the ICU to the room on a stretcher. Monitoring the change in the blood oxygen saturation concentration and other vital signs to detect respiratory arrest is not easy when transferring a patient on a stretcher. We present several noise reduction systems and algorithms to detect respiratory arrest while transferring patients, based on the unconstrained air pressure method that the authors presented previously. It was found that when the stretcher noise was at an acceleration level of 0.5 G, the respiratory arrest detection ratio by this novel method was 65%, while that with the conventional method was 0%.