Comparison of the effects of TIVA and inhalation anesthetic techniques on olfactory functions and olfactory memory: a randomized prospective study

Purpose: This study aimed to investigate the effects of different general anesthesia procedures on postoperative olfactory functions and olfactory memory.Materials and Methods: This prospective study was conducted with 97 patients. Patients were divided into three groups based on anesthesia induction and maintenance technique: Group P (induction and maintenance with propofol), Group PS (induction with propofol, maintenance with sevoflurane), and Group S (induction with sevoflurane, maintenance with sevoflurane). Butanol threshold and olfactory identification tests were administered 30 minutes (min) before the operation (T1) and 30 min (T2), 8 hours (h) (T3) and 24 h (T4) after the operation.Results: Butanol threshold values were increased at the T2 time point compared to baseline in all groups, which returned to baseline values at T3 only in Group P. There was a significant difference between Group P and Group S in terms of butanol threshold values at all time points except T1. When olfactory identification increased at T3 and T4 compared to baseline in Group P, there was a significant difference between T2, T3, and T4 time points in Group S, and between T2 and T3 time points in Group PS as compared to Group P.Conclusion: Propofol only causes a temporary impairment in olfactory functions in the early period and does not alter olfactory memory.