PREDICTIVE FACTORS IN V1 FAILURE DURING INTRA OPERATIVE NEURO MONITORING (IONM)

AUTHORS:
D. Inversini (Varese, Italy) , A. Vigezzi (Varese, Italy) , A. Palillo (Varese, Italy) , W. Sirco (Varese, Italy) , F. Gambero (Varese, Italy) , S. Gianazza (Varese, Italy) , A. Leotta (Varese, Italy) , G. Ietto (Varese, Italy) , G. Carcano (Varese, Italy)
Background:
Intra operative neuro-monitroing (IONM) failure is an unfrequent event during thyroid surgery that could lead into a change in surgycal strategy. We tried to evaluate in our series predictors of failure of a valid V1 signal.
Methods:
In this preliminary phase we evaluated 50 patients candidated to Total Thyroidectomy in the department of General Sugery of Ospedale di Circolo di Varese - Universita' degli studi Insubria. Specific items regarding pre-operative diagnosis, impedance values at IONM, respiratory variation and Tap-Test were collected. The data extension is still in progress.
Results:
In 11 patients (22%) the first Vagal Stimulation (V1) had values lower than 500 µV. Out of this cluster in 10 (90,9%) cases we obtained a valid V1 signal after using IONM problem solving guidelines. In 6 (60%) cases we observed a tube displacement, in 2 (20%) cases a tube - rotation, in one case (10%) breakage of surface electrodes and in one case (10%) the patient was still under the effect of succinylcholine. Respiratory variation (p=0,6852), Tap-Test (p=0,1498) and impedance value (p= 0,3704) were not predictive for non valid V1 value.
Conclusions:
This study is not able to identify predictor factors for V1 failure. Videolaryngoscopic verification of correct tube position associated to a standard use of IONM could prevent and decrease the incidence of this eventuality.