LEADING Australian cardiologists have called on hospitals to re-examine their use of automated external defibrillators (AEDs) for patients with cardiac arrest after US research showed their use in hospitals lowered survival rates.
Professor Peter Thompson, cardiologist and director of research development at Sir Charles Gairdner Hospital in Perth, said the important data revealed by the study should be studied carefully by hospital resuscitation teams to reassess the positioning of AEDs in hospital.
“Critical care areas with well trained staff do not need AEDs,” he said.
“On the other hand, wards well away from the main part of the hospital and outpatient areas where the resuscitation team may not be able to get to them rapidly may still have a need for AEDs.”
The JAMA study of 11 695 patients with cardiac arrests at 204 US hospitals found AED use was associated with a lower rate of survival compared with no AED use (16.3% vs 19.3%).(1)
Among cardiac arrests due to non-shockable rhythms, such as asystole or pulseless electrical activity, AED use was associated with lower survival (10.4% vs 15.4%).
Such events accounted for more than four of five cardiac arrests in the hospital setting.
The authors said this finding was of particular concern.
They said the time required to use an AED to assess non-shockable cardiac arrest rhythms could lead to longer interruptions of continuous chest compressions during the first few minutes of resuscitation, when effective cardiac perfusion to vital organs was most critical.
The study also showed that for cardiac arrests due to shockable rhythms, such as pulseless ventricular tachycardia or ventricular fibrillation, AED use was not linked to survival (38.4% vs 39.8%).
A JAMA editorial said the compelling conclusions from the study should lead to consideration of a change in practice for in-hospital cardiac arrest.(2)
Professor Thompson said excessive dependence on any new technology was always a bad idea.
“Properly used, AEDs are very useful in the community and in parts of the hospital where there are fewer staff skilled in resuscitation than in critical care areas,” he said.
“The JAMA study has shown that if AEDs are used for the wrong reasons, such as cardiac arrest not due to ventricular fibrillation, they are not helpful and they can delay the correct type of resuscitation.”
Most Australian hospitals still used manual defibrillators in critical care areas, partly because of reservations about time to apply leads and delays in identifying shockable rhythm, as exposed by the study, he said.
Professor Ben Freedman, professor of cardiology at Concord Repatriation General Hospital in Sydney, said hospitals should promulgate the finding that AEDs reduced survival in non-shockable rhythms, which were the majority of in-hospital cardiac arrests, and might do this by delaying the onset of compressions.
Instead of using an AED in hospital, patients should be shocked first with a manual defibrillator, Professor Freedman said.
Professor Geoffrey Tofler, cardiologist and medical director of the North Shore Heart Research Foundation in Sydney, said the study was a timely reminder that initiatives that intuitively seemed to be of benefit should be subjected to scrutiny in carefully designed trials.
There were some lessons from the study which might influence practice, including the reminder that prompt and ongoing cardiac compression was important in an arrest situation.
An MJA survey in 2003 found 43% of 665 Australian hospitals had one or more AEDs.(3)
Posted 22 November 2010