Factors affecting the prognosis following cardiac arrest
| Duration of arrest | Precise duration of cessation of blood flow to the brain is the most important factor in determining outcome (ie, for 6 min or longer indicates poor prognosis) |
| Age | Older patients have worse prognosis |
| Comorbidity | Poor prognosis associated with comorbidities, including cardiac and cerebrovascular disease, diabetes, obesity and renal disease |
| Circumstances of arrest | Out of hospital cardiac arrest carries a much worse prognosis than in-hospital arrest |
| Witness/immediate bystander resuscitation | Prolonged unwitnessed pulseless arrest suggests a poor prognosis |
| Effective cardiopulmonary resuscitation | Effective chest compression is needed to maintain effective cardiac output |
| Early attendance of paramedics | Early defibrillation is associated with an improved prognosis |
| Cardiac rhythm | Ventricular tachycardia/fibrillation are associated with a better prognosis than pulseless electrical activity or asystole |
| Resuscitation | Duration, number of defibrillations, boluses of norepinephrine or atropine, regaining pulse during the first 10 min of resuscitation |
| Fever within first 48 h | Associated with worse prognosis |
| Advanced directive | Advanced directives will influence the extent and duration of resuscitation, and so the outcome |