2631
EA signs were observed in all 7 patients in association with propofol TIVA but did not recur in any of 123 subsequent anesthetics sessions during which low-dose ketamine was added to propofol.
 ( adverse event: observed ,  all 7 patients: Subject, 7: Subject.Population, EA signs: Effect, propofol TIVA: Treatment, low-dose ketamine was added to propofol: Treatment, propofol: Treatment.Drug, ketamine: Treatment.Drug, propofol: Treatment.Drug, TIVA: Treatment.Route, low-dose: Treatment.Dosage, propofol: Combination.Drug, ketamine: Combination.Drug) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: adverse event,potential therapeutic event, Arguments type: Treatment.Disorder,Treatment.Time_elapsed,Treatment.Dosage,Subject.Race,Treatment.Drug,Treatment.Route,Subject.Disorder,Treatment.Freq,Treatment,Effect,Subject.Population,Treatment.Duration,Combination.Drug,Subject,Subject.Age,Subject.Gender. 
Text: {0} 
Answer:
 ( adverse event: observed ,  all 7 patients: Subject, 7: Subject.Population, EA signs: Effect, propofol TIVA: Treatment, low-dose ketamine was added to propofol: Treatment, propofol: Treatment.Drug, ketamine: Treatment.Drug, propofol: Treatment.Drug, TIVA: Treatment.Route, low-dose: Treatment.Dosage, propofol: Combination.Drug, ketamine: Combination.Drug) 