Compression force-depth relationship during out-of-hospital cardiopulmonary resuscitation

Resuscitation. 2007 Mar;72(3):364-70. doi: 10.1016/j.resuscitation.2006.07.017. Epub 2006 Dec 4.

Abstract

Background: Recent clinical studies reporting the high frequency of inadequate chest compression depth (<38 mm) during CPR, have prompted the question if adult human chest characteristics render it difficult to attain the recommended compression depth in certain patients.

Material and methods: Using a specially designed monitor/defibrillator equipped with a sternal pad fitted with an accelerometer and a pressure sensor, compression force and depth was measured during CPR in 91 adult out-of-hospital cardiac arrest patients.

Results: There was a strong non-linear relationship between the force of compression and depth achieved. Mean applied force for all patients was 30.3+/-8.2 kg and mean absolute compression depth 42+/-8 mm. For 87 of 91 patients 38 mm compression depth was obtained with less than 50 kg. Stiffer chests were compressed more forcefully than softer chests (p<0.001), but softer chests were compressed more deeply than stiffer chests (p=0.001). The force needed to reach 38 mm compression depth (F38) and mean compression force were higher for males than for females: 29.8+/-14.5 kg versus 22.5+/-10.2 kg (p<0.02), and 32.0+/-8.3 kg versus 27.0+/-7.0 kg (p<0.01), respectively. There was no significant variation in F38 or compression depth with age, but a significant 1.5 kg mean decrease in applied force for each 10 years increase in age (p<0.05). Chest stiffness decreased significantly (p<0.0001) with an increasing number of compressions performed. Average residual force during decompression was 1.7+/-1.0 kg, corresponding to an average residual depth of 3+/-2 mm.

Conclusion: In most out-of-hospital cardiac arrest victims adequate chest compression depth can be achieved by a force<50 kg, indicating that an average sized and fit rescuer should be able to perform effective CPR in most adult patients.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Ambulances*
  • Cardiopulmonary Resuscitation / instrumentation*
  • Elasticity
  • England
  • Equipment Design
  • Female
  • Heart Arrest / physiopathology
  • Heart Arrest / therapy*
  • Heart Massage / instrumentation*
  • Humans
  • Male
  • Middle Aged
  • Norway
  • Outpatients*
  • Pressure
  • Risk Factors
  • Sweden
  • Thorax / physiopathology
  • Treatment Outcome