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Canadian researchers have devised a three-point test to help emergency medical technicians (EMTs) in the field determine whether they should continue or end cardiopulmonary resuscitation (CPR) efforts for a patient in cardiac arrest.

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Survival rates for patients suffering out-of-hospital cardiac arrest are very low. Among 1,240 patients in the Canadian study who suffered a cardiac arrest outside a hospital, just 41 (3%) survived. From a retrospective analysis, researchers say their termination of resuscitation (TOR) rule accurately predicted when CPR would be futile.


All patients in the study were adults who experienced cardiac arrest outside a hospital. They were treated in the field according to standard guidelines and transported to the hospital. Afterward, EMTs filled out a form that collected data on each case. Based on this data, researchers found that three criteria reliably predicted the futility of resuscitation efforts:


* no return of spontaneous circulation before transportation


* no shock given before transportation


* cardiac arrest not witnessed by EMT personnel.



In 776 cases where all three criteria were met, only 4 patients (0.5%) survived. This survival rate is well below 1%, which is generally accepted as indicating medical futility. When researchers applied two more criteria-paramedic arrival time of more than 8 minutes and cardiac arrest not witnessed by a bystander-the survival rate was 0%.


Researchers say that applying the TOR rule in the field would significantly reduce the number of patients taken to the hospital. Preventing unnecessary hospital transfers frees EMTs and ED personnel to help other patients, reduces the risk of accidents and other hazards related to transport, and allows families to come to terms with the death outside the hospital setting.


An editorial accompanying the study calls for additional research to answer two key questions: How long should CPR continue before a determination of "no spontaneous circulation" is made, and how should TOR be modified for special patients, such as an infant or someone who's hypothermic?


Sources: Validation of a rule for termination of resuscitation in out-of-hospital cardiac arrest, The New England Journal of Medicine, LJ Morrison, et al., August 3, 2006; Cardiac resuscitation-When is enough enough? The New England Journal of Medicine, GA Ewy, August 3, 2006.