Objective: To study the effects of underlying bed softness versus stiffness on the effectiveness of chest compressions in CPR. Methods: For a wide range of bed stiffness constants, mathematical models describing compression of the human chest supported by a hospital bed were created for an adult thorax experiencing either a sinusoidal compressive force or a sinusoidal sternal displacement. Results: With 5 cm peak displacement, sternum-to-spine compression fell from 4.3 to 1.0 cm, and peak power fell from 59 to 23 Watts, as bed stiffness decreased from 50,000 to 5,000 N/m. Less than 35% of maximal chest compression occurred at a typical bed stiffness of 10,000 N/m. With 400 N peak force, sternum-to-spine compression decreased from 5.0 to 2.0 cm, and peak power increased from 82 to 226 Watts, as bed stiffness decreased from 50,000 to 5,000 N/m. However, greater than 85% of maximal chest compression was obtained at a typical bed stiffness of 10,000 N/m. Conclusion: The deterioration of chest compression performed on soft beds is technique dependent. If necessary, CPR can be performed effectively on a softer surface using a constant peak force technique. However, a firm surface is most desirable.
Bed, Cardiac Arrest, Cardiopulmonary Resuscitation, Chest Compression, Computers, Hospital, Mathematical Model, Mechanics
Date of this Version
Boe, John M. and Babbs, Charles F., "Mechanics of CPR Performed with the Patient on a Soft Bed Versus a Hard Surface" (1999). Weldon School of Biomedical Engineering Faculty Publications. Paper 68.