Prognostic significance of acute pain preceding out-of-hospital cardiac arrest.

Background: Sudden loss of consciousness (LOC) and chest pain are common manifestations of out-of-hospital cardiac arrest (OHCA). History of acute pain may be helpful in estimating aetiology and prognosis of OHCA victims. The objective of this study was to evaluate the relationship between acute pain at various locations preceding collapse and outcome.
Methods: Clinical data of 250 witnessed, non-traumatic OHCA victims were reviewed, and the incidence of pain based on anatomical distribution was documented. The focus was on identifying the difference between those collapsing with LOC alone and those collapsing with chest pain (CP). Clinical variables predictive of survival were identified using a logistic regression model.
Results: Among the 250 victims, 55.2% collapsed with LOC alone. The incidence of acute pain was: 28.0% for CP, 3.2% for headache, 2.8% for abdominal pain and 2.4% for back pain. The overall 6-month survival rate was 7.2%. The LOC group had a significantly higher return of spontaneous circulation (ROSC) rate compared with the CP group (48.6% vs 31.4%, p<0.05). The rate was elevated in the LOC group; however, only when the initial rhythm was non-shockable. There was no significant intergroup difference in the survival rate. Initial shockable rhythm positively and history of cardiovascular diseases negatively predicted survival. None of the victims in the headache, abdominal pain or back pain groups survived.
Conclusion: The LOC group's seemingly higher ROSC rate may be due to its aetiological heterogeneity. Complaint of a headache, abdominal pain or back pain in OHCA victims carries a poor prognosis.