August 31st, 2011
New Resuscitation Strategies Fail to Improve Outcomes After Cardiac Arrest
Two trials from the Resuscitation Outcomes Consortium (ROC) investigators were unable to demonstrate meaningful improvements to resuscitation strategies after cardiac arrest. The two trials, one testing an impedance threshold device and the other examining a strategy of early versus late rhythm analysis, have been published in the New England Journal of Medicine.
In the first trial, 8718 patients were randomized to treatment with an active or sham impedance threshold device (ITD) intended to improve venous return and cardiac output during CPR. There was no significant difference between the groups in the percentage of subjects who survived to hospital discharge with satisfactory function:
- 6.0% (260 patients) in the sham-ITD group and 5.8% (254 patients) in the active-ITD group
In the second trial, which utilized a cluster-randomized design, 9933 patients with out-of-hospital cardiac arrest received either CPR for 30-60 seconds or CPR for 180 seconds prior to ECG analysis. Once again, no difference in the primary outcome of survival to hospital discharge with satisfactory functional status was observed:
- 5.9% (273 patients) in the later-analysis group and 5.9% (310 patients) in the early-analysis group
There were no significant differences in any of the secondary outcomes or among subgroups in either of the trials.
In an accompanying editorial, Arthur Sanders writes that although the early versus late rhythm analysis trial ruled out any significant difference between the two groups, it did not answer “the more critical question” of whether any CPR before rhythm analysis is beneficial.
More generally, Sanders argues that “there are fundamental tensions between the principles of randomized trial design and the practice of resuscitation that make the conduct of any clinical trial of out-of hospital cardiac arrest challenging.” Out-of-hospital cardiac arrest should be considered a public health problem rather than a disease process and might be better tackled with a continuous-quality-improvement model, he writes.