This study was conducted to investigate the importance of the depth of chest compression in producing effective cardiopulmonary resuscitation (CPR) in animals, as indicated by cardiac output and mean arterial blood pressure. Cardiac output was measured by a modified indicator dilution technique in 8 anesthetized dogs, 6 to 12 kg body weight, during repeated 2-minute episodes of electrically induced ventricular fibrillation and CPR provided by a mechanical chest compressor and ventilator (Thumper®). Chest compression exceeding a threshold value (x0) between 1.5 and 3.0 cm was required in each animal to produce measurable cardiac output. In particular, cardiac output (CO) was linearly related to chest compression depth (x) by an expression of the form CO = a(x-x0) for x > x0, and CO = 0 for x £ x0. The mean value of x0 was 2.3 cm. A similar threshold for measurable blood pressure was observed in 7 of the 8 dogs, with a mean value of 1.8 cm. For chest compression of 2.5 cm or greater, relatively modest increases in chest compression depth caused relatively large changes in cardiac output.


This is the author accepted manuscript of Babbs C.F., WD Voorhees, KR Fitzgerald, HR Holmes, LA Geddes. "Relationship of blood pressure and flow during CPR to chest compression amplitude: Evidence for an effective compression threshold," Annals of Emergency Medicine 12, 527-532, 1983. Copyright Elsevier, it is made available here CC-BY-NC-ND, and the version of record is at http://dx.doi.org/10.1016/S0196-0644(83)80290-X.


defibrillation, myocardial damage, toxicity, ventricular fibrillation, waveform

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