Parathyroid Autofluorescence Visualization in Thyroid Surgery: Impact on Postoperative Hypocalcemia

Parathyroid Autofluorescence Visualization in Thyroid Surgery: Impact on Postoperative Hypocalcemia. A Randomized Controlled Trial

This Multicenter, Randomized Controlled Trial evaluates the clinical impact of parathyroid autofluorescence visualization using near infrared light (NIR) during total thyroidectomy (TT). It compares patients who undergo TT associated or not with lymph node dissection (LND) with NIR vs without NIR use during surgery.

Total thyroidectomy (TT) is responsible for postoperative hypocalcemia in 20-30% of patients, which is definitive in 1-4% of operated patients (1). This complication is mainly due to surgery-induced parathyroid dysfunction, which could be improved by a better intraoperative identification of the parathyroids. Intraoperative parathyroid auto-fluorescence visualization (without any dye injection) using near infrared light (NIR) is an emerging technique, which allows correct identification of normal parathyroids in almost all cases (2), but the clinical impact of NIR is unknown. The aim of this prospective, comparative randomized study, is to compare 2 groups of patients: patients operated with NIR (NIR+) vs patients operated without NIR (NIR-). The main objective of this study is to assess the impact of intraoperative use of NIR camera on postoperative hypocalcemia. Secondary objectives are to assess the impact of NIR on the visualization, autotransplantation and inadvertent resection rates during TT.

Patients who undergo conventional total thyroidectomy (TT)+/- lymph node dissection (LND). Parathyroid identification was done with the use of NIR (intervention group, NIR+ group)

Patients who undergo conventional total thyroidectomy (TT)+/- lymph node dissection (LND) without the use of NIR - parathyroid identification was done by naked eye only (no intervention group, NIR- group)

Surgical field is examined with NIR, during a few minutes (<5') with room lights switched off, to avoid parasite lights, then open thyroidectomy is resumed conventionally. Real-time images, evocative of autofluorescent parathyroids, are checked visually. NIR consists of a 750 nm class 1 laser excitation, with a power <20mW/cm2 (5 times less than the limit of 100mw/cm2, fixed by the international standard IEC 60601-2-41). It is provided by the Fluobeam® camera, which is inserted into a sterile cover and hold at a 15-20 cm distance from the patient. The system has an FDA 510(k) authorization for clinical use in parathyroid surgery and a European Community certification (Class 2A device).

Postoperative day 1 and day 2 corrected calcemia (hypocalcemia when calcemia <2mmol/l). If hypocalcemia, calcium is measured at 1 month and 6 months

when parathyroids cannot be left in situ, they are fragmented and reinserted in a sterno-cleido-mastoid muscle

Inclusion Criteria: All patients eligible for one-stage total thyroidectomy, associated or not to lymph node dissection (TT +/- LND). Exclusion Criteria: Combined parathyroid and thyroid disease (including patients with enlarged parathyroids incidentally found during surgery and resected)

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