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OBJECTIVE	To improve the quality of chest compression ( CC ) , we developed the assistant-push method , whereby the second rescuer pushes the back of the chest compressor during CC .
OBJECTIVE	We investigated the effectiveness and feasibility of assistant push in achieving and maintaining the CC quality .
METHODS	This was a randomized crossover trial in which 41 subjects randomly performed both of standard CC ( single-rescuer group ) and CC with instructor-driven assistant push ( assistant-push group ) in different order .
METHODS	Each session of CC was performed for 2 minutes using a manikin .
METHODS	Subjects were also assigned to both roles of chest compressor and assistant and together performed CC with subject-driven assistant push .
METHODS	Depth of CC , compression to recoil ratio , duty cycle , and rate of incomplete recoil were quantified .
RESULTS	The mean depth of CC ( 57.0 [ 56.0-59 .0 ] vs 55.0 [ 49.5-57 .5 ] , P < .001 ) was significantly deeper , and the compression force ( 33.8 [ 29.3-36 .4 ] vs 23.3 [ 20.4-25 .3 ] , P < .001 ) was stronger in the assistant-push group .
RESULTS	The ratio of compression to recoil , duty cycle , and rate of incomplete chest recoil were comparable between the 2 groups .
RESULTS	The CC depth in the single-rescuer group decreased significantly every 30 seconds , whereas in the assistant-push group , it was comparable at 60 - and 90-second time points ( P = .004 ) .
RESULTS	The subject assistant-push group performed CCs at a depth comparable with that of the instructor assistant-push group .
CONCLUSIONS	The assistant-push method improved the depth of CC and attenuated its decline , eventually helping maintain adequate CC depth over time .
CONCLUSIONS	Subjects were able to feasibly learn assistant push and performed effectively .

