One-fifth of out-of-hospital cardiac arrest survivors have non-shockable rhythm
MedWire News: Results from a Swedish study indicate that 20% of patients surviving out-of-hospital cardiac arrest (OHCA) have a non-shockable rhythm at first contact.
The findings also show that survivors of this type of rhythm are more likely to exhibit poorer cerebral performance than those with a shockable initial rhythm.
This may be due to "prolonged anoxia from cardiac arrest until the return of spontaneous circulation," say the study authors.
Christina Holmgren (NU Hospital Organisation, Trollhättan) and colleagues analyzed data from 2165 OHCA survivors recorded in the Swedish Cardiac Arrest Registry between 1992 and 2007.
All patients were reported to have received cardiopulmonary resuscitation (CPR) after cardiac arrest, and were alive 1 month post-OHCA.
Writing in the journal Heart, the researchers report that over the 16-year period, the percentage of surviving OHCA patients with an initially shockable rhythm, as determined by electrocardiogram (ECG) on first contact with a health professional, remained at a level close to 80%. All other patients (20%) had a non-shockable rhythm.
In all, a bystander witnessed the OHCA in 54% and 59% of patients with shockable and non-shockable initial rhythms, respectively.
Non-shockable rhythms were more common in women than men, at 27% and 18%, respectively (p<0.0001).
Holmgren and team also report that cerebral performance, defined by Cerebral Peformance Categories score on a scale of 1 (good function) to 5 (brain dead), was better among survivors who had a shockable initial rhythm than those with a non-shockable rhythm (p=0.0006).
The team identified several factors associated with survival to 1 month post-OHCA. These factors included OHCA occurring outside the patient's home, CPR given before arrival of ambulance, and arrest witnessed by a bystander.
In a related commentary, Douglas Chamberlain, from the University of Brighton in the UK, advised that the findings of Holmgren et al should not provide cause to equate patients with a low chance of survival after OHCA as having no chance of survival.
He concluded that such a pessimistic attitude "can have a demotivating effect on management... with the result that we have fewer successes than our present knowledge base can justify."
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By Lauretta Ihonor