Appropriate timing and velocity of infusion for the selective staining of parathyroid glands by intravenous methylene blue.

BACKGROUND

Intraoperative parathyroid gland (PTG) identification by selective staining using methylene blue dye (MB) infusion has been shown effective but the degree of gland staining is inconsistent.

METHODS

The effect of timing and rate of MB infusion on gland uptake was investigated in a canine model by infusing MB either rapidly over 3 to 5 minutes (n = 8) or slowly over 30 minutes (n = 4). The pattern of dye uptake in an exposed PTG was determined by standardized serial photography.

RESULTS

Earliest uptake occurred between 10 and 20 minutes after infusion, and maximum uptake averaged 21 minutes, earlier than previously described. Rate of infusion did not affect staining.

CONCLUSIONS

This rapid uptake of methylene blue by the parathyroid glands suggests that its selective intraoperative use when glands are difficult to locate intraoperatively, rather than a routine preoperative infusion, is possible without significant operative delay. Clinical experience has confirmed this impression.