Manual vs Mechanical External Cardiac Massage

To the Editor:—  I would like to comment on your report (196, April 4, 1966, adv p 36), comparing manual and mechanical external cardiac massage. We have been engaged in a study of mechanical resuscitation aids, and both our methods and our results differ from the one reported.Much of our data derive from direct on-line recording, which takes place automatically during clinical resuscitation of humans. Our experience in using instrumented manikins for trials suggests that the substantial difference in weight, measurable phenomena, physical results derived, and completely different psychological response to the manikin make this an ineffective comparison method. Effective studies cannot be carried out on most animals because of differences in anatomy of the mediastinum and thorax.Manually lever-operated plungers possess all of the disadvantages of manual and mechanical external cardiac massage with the advantages of neither. Some are more time-consuming and difficult to set up than pneumatically