סמינר מחלקתי

DEVELOPMENT OF AWEARABLE CHEST STRAP FOR MONITORING LUNGS’ VENTILATION AND AN ALGORITHM TO DETECT THE RESPIRATORY COMPENSATION POINT

Guiora Harel

Background: The second Lactate Threshold (LT2) also known as the Anaerobic Threshold is a fundamental physiologic measure for assessing exercise intensity and improving cardiorespiratory (aerobic) fitness level by training/rehabilitation. Currently, the principal methods for the detection of LT2 are performed in the laboratory and require blood samples (for lactate level) or noninvasive detection of the equivalent Respiratory Compensation Point (RCP) by Cardio-Pulmonary Exercise Test (CPET).

Aim: Develop a new, non-invasive, non-laboratory wearable chest strap for measuring pulmonary ventilation (VE) at field conditions and a mathematical algorithm for detecting the RCP on the chest strap VE equivalent data.

Methods: An advanced chest strap consisting of vertical accelerometer, heart rate monitor and a stretch sensor for measuring the breathing frequency (BF) and the relative tidal volume (VT, driven by thorax expansion). The product of BF and VT, calculated by the processing unit, equals the pulmonary ventilation (VE) equivalent. 20 normal healthy adults age 20-35 wearing the advanced Chest-Strap and running on a treadmill, performed maximal incremental ramp tests (CPET) to compare between the two methods.

 Results:  Correlation between the equivalent of VE measured by the advanced chest-strap and VE measured by CPET in the treadmill running test was very high (r = 0.94). The average deviation between the RCPs detected by mathematical algorithm and the RCPs identified by an expert on the VE curves recorded by the CPET was as low as 1% and was 2% when identified by the expert on the VE equivalent curves recorded by the advanced chest strap.

Conclusions: The advanced Chest-Strap accurately measures pulmonary attributes (BF, relative VT, and VE equivalent) relevant to the detection of RCP noninvasively, during running exercise. Further research is needed to verify the feasibility and reliability of the new chest-strap for detecting RCP under field conditions.