Cardiac arrest victims given three minutes of CPR by EMS providers before having their heart rhythm analyzed (and defibrillation when called for) were no more likely to survive than those given only one minute of CPR, new research shows. The study, in the Sept. 1 issue of the New England Journal of Medicine, included nearly 10,000 out-of-hospital cardiac arrests that were not the result of trauma. The data were gathered from 10 U.S. and Canadian universities and their regional EMS systems involved in the Resuscitation Outcomes Consortium.
About 5,300 patients were given 30 seconds to one minute of chest compressions/ventilations before receiving an electrocardiogram heart rhythm analysis and defibrillation; 4,600 were given three minutes of CPR first. In both groups, 5.9 percent survived to hospital discharge with “satisfactory functional status.”
What’s more, there’s evidence that longer CPR may be detrimental. An analysis of a subgroup of patients who received both bystander CPR and three minutes of CPR by EMS personnel and who had a shockable rhythm fared worse.
The American Heart Association-International Liaison Committee on Resuscitation’s (AHA-ILCOR) 2005 guidelines recommend two minutes of CPR by EMS personnel before checking heart rhythm. But the evidence for delaying cardiac rhythm analysis has been mixed, according to background information in the study, and the 2010 guidelines say there is “inconsistent evidence to support or refute” a delay in analysis.
That’s led to significant uncertainty in EMS about how much CPR to do before heart rhythm analysis/defibrillation, a controversy these findings should help put to rest, the study reports. “This finding suggests that there is no advantage of delaying the analysis of cardiac rhythm during EMS-administered CPR,” the researchers write. “Indeed, the data suggest that there may be a disadvantage of delaying the rhythm analysis in the subgroup of patients with a first rhythm of either ventricular tachycardia or ventricular fibrillation who have received CPR from a bystander. Overall, our data suggest that the administration of 2 minutes of CPR by EMS personnel before the first analysis of rhythm, which was suggested in the 2005 guidelines of the AHA-ILCOR, is unlikely to provide a greater benefit than CPR of shorter duration.”
EMS participants included firefighters, paramedics and EMTs; all were trained to give uninterrupted chest compressions using a 30:2 compression/ventilation ratio. The average age of the patients was about 67, approximately 64 percent were male, and about 40 percent had CPR administered by a bystander.
Impedance Threshold Device During CPR Doesn’t Improve Survival
Impedance threshold devices (ITDs) don’t appear to be of much benefit in saving the lives of patients in sudden cardiac arrest, according to a second study by the Resuscitation Outcomes Consortium reported in the same issue of the New England Journal of Medicine.
CPR with manual chest compressions provides only a small fraction of normal cardiac output. Animal studies have shown that by preventing air from flowing back into the chest during recoil, ITDs improve blood flow to vital organs and, hence, survival. The hope was ITDs would show a similar benefit in humans.
More than 8,700 patients who experienced out-of-hospital cardiac arrest were given CPR using either an ITD or a sham device designed to look identical to the real thing. About 5.8 percent of those in the ITD group survived to hospital discharge with “satisfactory function” compared to 6 percent of those in the sham group.
“This large effectiveness trial did not confirm a survival advantage with the use of an active ITD during standard CPR in patients with nontraumatic, out-of-hospital cardiac arrest,” the researchers report.
Yet they did not rule out the possibility that ITDs could be beneficial. A 2006 study, they note, showed that using an ITD with active compression-decompression CPR (a handheld device that uses suction to compress and decompress the chest) significantly increased survival compared to standard CPR.
More Firefighter Retirements After 9/11 Attacks
Retirements, especially those due to disability, spiked among New York City firefighters during the seven years following the World Trade Center attacks.
In the seven years leading up to 9/11, 3,261 FDNY firefighters retired, 48 percent due to disability. In the seven years after 9/11, 4,502 retired, 66 percent due to disability. Of the disability retirements, 47 percent were associated with terrorist attack-related injuries or illnesses, primarily respiratory illnesses, according to the study published in a special Sept. 11 issue of the American Journal of Industrial Medicine.
