MECHANISM OF CLOSED-CHEST CARDIOPULMONARY-RESUSCITATION INVESTIGATED BY TRANSESOPHAGEAL ECHOCARDIOGRAPHY

Transoesophageal echocardiography (TOE) was performed during closed ch est cardiopulmonary resuscitation (CPR) in 18 subjects in cardiac arre st. Compression of all four cardiac chambers resulted in forward flow in the pulmonary and systemic circulations, retrograde pulmonary vein flow and incomplete mitral valve closure. Antegrade pulmonary vein flo w and left ventricular filling occurred exclusively during the relaxat ion phase. These findings support the cardiac pump theory of CPR and a re incompatible with the thoracic pump mechanism. TOE merits further i nvestigation as a device to monitor and guide resuscitation efforts du ring CPR.