J Korean Soc Emerg Med.  2003 Dec;14(5):522-528.

Effects of Compression Rate and Compression/Relaxation Ratio on the Hemodynamics of Simultaneous Sterno-Thoracic Cardiopulmonary Resuscitation in the Canine Model of Cardiac Arrest

• Lee SY
• Hwang SO
• Kim H
• Jang YS
• Choi HJ
• Oh SB
• Cha KC
• Lee KH
• Yoon JH
• Yoo BS
• Lee SH
• Choe KH

Abstract

PURPOSE
This study was designed to determine the compression rate and the compression/relaxation ratio to produce the optimal hemodynamic effect with simultaneous sterno-thoracic cardiopulmonary resuscitation (SST-CPR)and to investigate the mechanism for the blood flow generated by SST-CPR.
METHODS
A canine model of ventricular fibrillation was used. Twelve mongrel dogs were divided into two groups. In the first six animals were resuscitated by using SST-CPR with the compression duration varied randomly at 2-minute intervals, 30%, 40%, and 50% of the CPR cycle, at a constant rate of 80/min. In the other six dogs, SST-CPR was performed with a randomly varied compression rate, 60, 80, 100, and 120/minute, at a 50:50 compression/relaxation ratio.
RESULTS
During SST-CPR, increasing the compression relaxation ratio from 30:70 to 50:50 increased the end tidal CO2 from 10+/-2 mmHg to 15+/-3 mmHg. Increasing the compression rate from 60 to 100/minute tended to improve the carotid blood flow.
CONCLUSION
The maximal hemodynamic effects with SSTCPR was generated when the compression rate was 100/minute and the compression/relaxation ratio was 50:50. A combination of the cardiac and the thoracic pump theories may be the mechanism for the blood flow produced by SST-CPR.

Keyword

Cardiopulmonary resuscitation; Cardiac arrest

MeSH Terms

Animals
Cardiopulmonary Resuscitation*
Dogs
Heart Arrest*
Hemodynamics*
Relaxation
Ventricular Fibrillation