Pre-operative prediction of ‘dry taps’

Abstract

In our study population, the proportion of dry taps at myringotomy was 18 per cent. The presence of a dry tap was rarely due to the induction of anaesthesia. Multivariate analysis revealed that the combination of factors most likely to predict a dry tap were non type B tympanogram and delay to operation.

Resolved effusion on myringotomy: A study of dry tap without general anesthesia

“…Previous reports that DT is increased with a time delay also demonstrates that DT is a sign of the natural resolution of OME, and the natural resolution can manifest as non-B-type tympanometry that yields more DT. Non-B tympanometry has been recommended as the most likely predictor of DT [1], but this study showed that non-B-type tympanometry was not predictive of DT. B-tympanometry was also imperfect for the diagnostic of positive effusion, which is expected because tympanometry is not the gold standard for determining the presence of effusion, but myringotomy is the gold standard for presence of effusion.…”

“…However, a recent study estimated that a very small proportion of DTs, only 6%, were attributable to anesthetics; thus, the authors commented that GA is rarely a cause of DT and that the time delay to operation was the main reason [1]. Therefore, DT can also be taken as a measure of a problematic surgery because DT is more common when the child is not assessed on the day of surgery.…”

“…The second aim of this study focused on whether OME would recur if the insertion of the tube was aborted because the common preference for DT under GA is tube insertion, even when no effusion exists [12]. It has been recommended that DT with type C tympanometry still need VT because DT results from the easy penetration of anesthetics into the middle ear due to the negative pressure [1]. However, regarding DT as a natural resolution of OME, we determined that DT might be a misdiagnosis from a poor preoperative assessment and wanted to conclude that VT insertion is not necessary for DT.…”

“…The reported frequency of DT ranged from 13% to 34% [1,2], but surgeons usually ignored it because DT was usually attributed to the confounding artifact of gaseous GA or an problematic surgery [3,4]. However, recent reports have suggested that DT is rarely due to GA. DT presents a difficult situation for the surgeon because it is unclear whether or not to continue tube insertion [1,5]. A minimization of the time delay before the operation, and the careful selection of non-B-type tympanometry were recommended to reduce the rate of DT.…”

“…The objectives of the present study are (1) to clarify the clinical nature of DT without the confounding effect of GA and the time delay from a preoperative diagnosis and (2) to determine if OME recurs when VT is aborted for DT.…”