To realize the measurement of the chest compression depth during the administration of manual cardiopulmonary resuscitation, two 3-axis digital accelerometers were applied for chest compression acceleration and environment acceleration acquisition, with one placed in the chest compression sensor pad, and the other placed in the back sensor pad. Then double integration was made for the acceleration-to-depth conversion with both of the accelerations after preprocessing. The method further included integration reset mechanism based on compression force, with the force point of a pre-determined threshold and the maximum force point as the starting point and the ending point of the integration, respectively. Moreover, a software compensation algorithm was implemented to further increase the accuracy of the depth estimation and reliability of the acceleration. The final performance of the compression depth estimation is within +/- 0.6 cm with 95% confidence of a total of 283 compressions. Accurate and real-time estimation of chest compression depth greatly facilitates the control of compression depth for the lifesaver during manual cardiopulmonary resuscitation.
Acceleration ; Cardiopulmonary Resuscitation ; instrumentation ; methods ; Heart Arrest ; therapy ; Heart Massage ; methods ; standards ; Humans ; Pressure ; Thorax

No study has examined the effectiveness of backboards and air deflation for achieving adequate chest compression (CC) depth on air mattresses with the typical configurations seen in intensive care units. To determine this efficacy, we measured mattress compression depth (MCD, mm) on these surfaces using dual accelerometers. Eight cardiopulmonary resuscitation providers performed CCs on manikins lying on 4 different surfaces using a visual feedback system. The surfaces were as follows: A, a bed frame; B, a deflated air mattress placed on top of a foam mattress laid on a bed frame; C, a typical air mattress configuration with an inflated air mattress placed on a foam mattress laid on a bed frame; and D, C with a backboard. Deflation of the air mattress decreased MCD significantly (B; 14.74 +/- 1.36 vs C; 30.16 +/- 3.96, P < 0.001). The use of a backboard also decreased MCD (C; 30.16 +/- 3.96 vs D; 25.46 +/- 2.89, P = 0.002). However, deflation of the air mattress decreased MCD more than use of a backboard (B; 14.74 +/- 1.36 vs D; 25.46 +/- 2.89, P = 0.002). The use of a both a backboard and a deflated air mattress in this configuration reduces MCD and thus helps achieve accurate CC depth during cardiopulmonary resuscitation.
Beds ; Cardiopulmonary Resuscitation/*instrumentation/methods ; *Compressive Strength ; Equipment Design ; Heart Massage/*instrumentation/methods ; Humans ; Intensive Care Units ; Manikins ; Prospective Studies