Impedance Threshold Devices and Mechanical CPR in Out-of-Hospital Cardiac Arrest: Does Any Combination Increase ROSC?

Introduction—Impedance threshold devices (ITDs) have been used in the treatment of out-of-hospital cardiac arrest (OHCA) by increasing circulation through negative pressurization during CPR. Mechanical CPR (mCPR) devices have also seen increased usage, despite questionable utility. Few studies have examined the concurrent use of both adjuncts in OHCA.

Objective—To determine whether the use of an ITD coupled with either mechanical or manual CPR during the management of an OHCA increases the probability of return of spontaneous circulation (ROSC).

Methods—A retrospective analysis of OHCA patients from July 2012 to June 2014 was conducted using data from the North Carolina Prehospital Medical Information System (PreMIS). Patients greater than 18 years old who suffered an OHCA before or after EMS arrival were included. Descriptive statistics were used to analyze the overall sample, while logistic regression was used to analyze the relationship between ROSC and combinations of receipt of an ITD and type of CPR (mechanical vs. manual), while controlling for potential confounders.

Results—A total of 15,395 patients met inclusion criteria, of which 9,241 (60.03%) were male; 10,507 (68.24%) were Caucasian; 5,947 (38.62%) received bystander CPR; 2,802 (18.2%) had a shockable presenting rhythm; and 5,832 (37.88%) achieved ROSC. ROSC was three times more likely in patients with shockable presenting rhythms (OR 3.00, p<0.001) and 2.17 times more likely with the receipt of lay person and/or first responder CPR (OR 2.17, p<0.001). The odds of ROSC were 19% less likely with males (OR 0.81, p<0.001) and 35% and 29% less likely with the provision of mCPR with (OR 0.65, p<0.001) or without (OR 0.71, p=0.007) the use of an ITD respectively. Patient age and use of standard CPR in conjunction with an ITD were not statistically significant in this cohort.

Conclusion—The achievement of ROSC was shown to be less likely in patients who received mCPR with or without the use of an ITD. As has been seen in previous studies, patients in this cohort directly benefited from the provision of lay person and/or first responder CPR and were twice as likely to achieve ROSC when presenting in an initially shockable rhythm. These results might be useful for EMS resource allocation.