A modeling approach to the effects of force guided versus depth guided compression during cardiopulmonary resuscitation on different chests and back support surfaces

Objectives

To validate an existing theoretical model for the mechanics of chest compression (CC) during constant peak force cardiopulmonary resuscitation (CPR) using experimental human and manikin CC data from the literature. Also, to gain insights into the clinical application of force guided CPR.

Methods

The experimental CC data from the literature were analyzed and compared to theoretical predictions from the constant peak force CPR model. The CPR model was also used to explore how CC rate and peak sternal force may influence CC performance during the clinical application of force guided CPR.

Results

The model predictions matched the human CC data to within an average difference of less than 1.5% at CC rates of 60 cpm and 90 cpm, and 0.6% for the manikin data at a CC rate of 90 cpm. The model predictions also showed that the net sternum-to-spine compression depth achieved during force guided CPR strongly depends on the patient's thoracic stiffness.

Conclusions

Good quantitative agreement between the experimental data from the literature and the theoretical model suggests that the constant peak force CPR model developed by Boe and Babbs provides reasonable prediction of CC mechanics during CPR over a range of clinically relevant CC rates. The model predictions also suggest that the effectiveness of CC during force guided CPR is highly sensitive to the patient's thoracic stiffness and insensitive to the back support stiffness. Patients having high thoracic stiffness (≥100 N cm⁻¹) were found to require higher CC forces, which may exceed the force above which severe chest wall trauma and abdominal injury occurs, in order to achieve the ERC recommended CC depth range. This suggests that the choice of maximum sternal force applied by clinicians during constant peak force CPR ought to be based on a general assessment of the patient's thoracic stiffness.