STUDY OBJECTIVE: This study associated survival from prehospital cardiac arrest to patient historical variables including presenting complaint, medications used, and medical history as a secondary end point in a trial evaluating the effect of bicarbonate administration. This raises issues concerning extensive prehospital historical assessment that may potentially delay care and transport. METHODS: This prospective multicentre trial enrolled 874 prehospital cardiac arrest patients encountered by urban, suburban, and rural emergency medical services. This group underwent conventional ACLS intervention followed by empiric early administration of sodium bicarbonate (1mEq/l). Survival was measured as the presence of vital signs on emergency department arrival. Data analysis used Student's t test, Fisher's exact test, chi2 with Pearson correlation, and logistic regression (p<0.05). Secondary end points were analysed including an association with common historical variables such as medical history, presenting complaint, or drugs used. RESULTS: The overall survival rate was 13.9% (110 of 793) of prehospital arrest patients. There was no correlation between historical factors, such as chief complaint or history of present illness (p = 0.277), medical history (p = 0.425), presence of specific disease conditions (p = 0.1125-0.956), or overall drug use (p = 0.002-0.9848). However, there was an adverse association between specific antiarrhythmic use (p = 0.003) and outcome. CONCLUSION: There is little relation of patient historical factors on the outcome from prehospital cardiac arrest raising issues of efficiency with history taking in prehospital care and transport.