Comparison of mechanical characteristics of the human and porcine chest during cardiopulmonary resuscitation.
BACKGROUND
Most studies investigating cardiopulmonary resuscitation (CPR) interventions or functionality of mechanical CPR devices have been performed using porcine models. The purpose of this study was to identify differences between mechanical characteristics of the human and porcine chest during CPR.


METHODS
CPR data of 90 cardiac arrest patients was compared to data of 14 porcine from two animal studies. Chest stiffness k and viscosity mu were calculated from acceleration and pressure data recorded using a Laerdal Heartstart 4000SP defibrillator during CPR. K and mu were calculated at chest compression depths of 15, 30 and 50mm for three different time periods.


RESULTS
At a depth of 15mm porcine chest stiffness was comparable to human chest stiffness at the beginning of resuscitation (4.8 vs. 4.5N/mm) and clearly lower after 200 chest compressions (2.9 vs. 4.5N/mm) (p<0.05). At 30 and 50mm porcine chest stiffness was higher at the beginning and comparable to human chest stiffness after 200 chest compressions. After 200 chest compressions porcine chest viscosity was similar to human chest viscosity at 15mm (108 vs. 110Ns/m), higher for 30mm (240 vs. 188Ns/m) and clearly higher for 50mm chest compression depth (672 vs. 339Ns/m) (p<0.05).


CONCLUSIONS
In conclusion, human and porcine chest behave relatively similarly during CPR with respect to chest stiffness, but differences in chest viscosity at medium and deep chest compression depth should at least be kept in mind when extrapolating porcine results to humans.
Neurauter
Andreas
A
Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Anichstrasse 35, 6020 Innsbruck, Austria.
Nysaether
Jon
J
Kramer-Johansen
Jo
J
Eilevstjønn
Joar
J
Paal
Peter
P
Myklebust
Helge
H
Wenzel
Volker
V
Lindner
Karl H
KH
Schmölz
Werner
W
Pytte
Morten
M
Steen
Petter A
PA
Strohmenger
Hans-Ulrich
HU
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D016887:Cardiopulmonary Resuscitation; D004548:Elasticity / Q000502:physiology; D004554:Electric Countershock; D004562:Electrocardiography; D006323:Heart Arrest / Q000503:physiopathology / Q000628:therapy*; D006336:Heart Massage; D006801:Humans; D008875:Middle Aged; D013552:Swine; D013909:Thorax / Q000503:physiopathology*; D014783:Viscosity; D055815:Young Adult