Discussion
The focus of this study was to examine the relation between IOH and POF in children undergoing CI surgery, and to explore their association with local complications. IOH has been previously described by Schwartz A et al. [4], who concluded that patients undergoing CI surgery are susceptible to IOH, without an identified etiology. There was, however, a higher incidence of IOH in CI surgeries compared to anatomically similar surgeries, such as mastoid or ophthalmic surgeries, as well as a significant difference in the length of anesthesia between IOH and NIOH.
In the present study, IOH appears to be a benign phenomenon which does not predispose the patient to POF or to post-operative inflammatory complications, as per the multivariate analysis.
The overall incidence of IOH during CI in the present study (4.7%) is lower than that which was reported by Schwartz A et al. (10%), meaning that the phenomenon became less frequent in recent years. Interestingly, in the more recent cases, there was a larger fraction of bilateral implants, which is the group of patients that initially had a higher rate of IOH. While a bilateral procedure is longer in duration, thus exposing the patient to prolonged anesthesia, intravenous anesthesia has been replacing inhaled anesthesia in the past years [4].
According to the present study, IOH is not associated with the occurrence of POF. Indeed, POF is not unusual in CI surgery; compared to an incidence of 19.2% [9], the incidence of POF in the present study (14.5%) continues to represent a benign entity with no major clinical significance. However, the financial burden of a POF-related work up remains high.
The post-surgical complication rate in the present study was similar to the rate found in the literature [1]. However, while many studies examined complications after CI surgeries, the present study focused on inflammatory complications, with the rationale of a possible common axis that connects IOH, POF and infectious complications.
The present study has several limitations. Being a retrospective study, data on complications that had occurred after patient discharge may be lacking. In addition, sample size in the intra-operative analysis is relatively small: Out of 190 patient records, only 108 had sufficient data across study parameters. Therefore, a robust conclusion regarding a putative correlation between length of anesthesia and hyperthermic events could not be made. A larger study with a more detailed documentation of each parameter per patient would be required in order to learn how factors such as anesthesia, room temperature and heating methods, may affect hyperthermic events in CI surgery.
Taken together, based on the presently studied cohort, IOH and POF are not unusual in children undergoing CI surgery, and are independent of each other. Indeed, here, IOH does not predict the development of POF. Moreover, both hyperthermic events do not seem to influence the development of local complications.