Head up CPR is based upon the laws of physics.

Competing Interests: Declaration of competing interest Keith G. Lurie is a co-inventor of the active compression-decompression CPR device, the impedance threshold device, and an automated head-up CPR device. Dr. Lurie is the CEO of AdvanedCPR Solutions. The remainder of the authors have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.