Olfactory function testing before and after anesthesia

Abstract

This study aimed to determine whether anesthesia would affect olfactory function. Patients who were admitted for surgical intervention that did not include the nasal cavity and paranasal sinuses were included in this prospective cohort study. Structured medical history was taken from the patients, including the following: age, sex, smoking history, alcohol intake, current medications, and sleep deficits prior to surgery. Before surgery, patients were asked for a self-rating of their olfactory function. Olfactory function was also measured using Sniffin’ Sticks comprising measures of odor threshold, discrimination, and identification. The mean interval between olfactory tests was 6 days (range 3–12 days). Seventy-three patients were included in the study, 34 men and 39 women. Olfactory scores were consistent before and after surgery as indicated by correlative analyses (p < 0.05). Odor thresholds, discrimination, identification, and composite TDI scores did not change significantly, whereas odor identification scores increased (p = 0.011) after surgery. In conclusion, post-operative olfactory scores remained stable. However, identification scores exhibited a slight increase which can be attributed to a retest effect. Overall, the present results indicate that surgery outside of the nasal and paranasal sinus region performed in general anesthesia has no major effect on the sense of smell.

Isoflurane impairs olfaction by increasing neuronal activity in the olfactory bulb

“…While many studies have reported cognitive impairments after general anesthesia, 1,2,6,7 only a few studies have investigated changes in olfactory behavior after exposure to anesthetics. Although reports have suggested that general anesthesia has no major effect on olfaction, 17,18 other studies have indicated impaired olfactory identification and loss of olfaction in patients receiving anesthetic agents. [13][14][15]17 Consistent with previous studies, cognitive impairment was observed in mice exposed to repeated isoflurane in the present study.…”

“…Although reports have suggested that general anesthesia has no major effect on olfaction, 17,18 other studies have indicated impaired olfactory identification and loss of olfaction in patients receiving anesthetic agents. [13][14][15]17 Consistent with previous studies, cognitive impairment was observed in mice exposed to repeated isoflurane in the present study. More importantly, we showed that although olfactory preference/avoidance was not affected, olfactory detection and odor threshold were impaired by repeated isoflurane exposure in mice, providing important insights into the effects of repeated anesthetic exposure on olfaction of adult rodents.…”

“…[12][13][14][15][16] Conversely, several studies have indicated that general anesthesia has no effect on olfaction. 17,18 Therefore, whether and how general anesthesia affects olfactory behaviors remains poorly understood. In clinical studies, it is very difficult to separate the effects of anesthesia from other factors such as disease, drugs, and inflammation, so animal studies are necessary to investigate the effects of general anesthesia on olfactory behaviors.…”

“…Many human studies have also reported olfactory dysfunction after general anesthesia 12–16 . Conversely, several studies have indicated that general anesthesia has no effect on olfaction 17,18 . Therefore, whether and how general anesthesia affects olfactory behaviors remains poorly understood.…”