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Endoscopic endocrine neck surgery with carbon dioxide insufflation: the effect on intracranial pressure in a large animal model.

BACKGROUND
Endoscopic endocrine neck surgery requires insufflation with carbon dioxide (CO(2)) at 10 to 15 mm Hg, which may decrease the cerebral venous return and increase intracranial pressure. This study evaluated the effect of CO(2) neck insufflation on intracranial pressure (ICP) and hemodynamic parameters.


METHODS
Fifteen pigs underwent endoscopic thyroid dissection. Insufflation was performed with CO(2) at 0 (sham), 10, 15, and 20 mm Hg and with helium at 20 mm Hg with 3 pigs in each group. ICP, mean arterial pressure, central venous pressure (CVP), cardiac output, and blood gas were measured at baseline, 30, 60, and 120 minutes.


RESULTS
There were no differences in mean ICP between the sham group and CO(2) insufflation at 10 mm Hg. Mean ICP increased significantly with CO(2) at 15 and 20 mm Hg and with helium at 20 mm Hg. A significant increase in CVP occurred in pigs operated with CO(2) at 20 mm Hg. We observed jugular vein collapse under all insufflation pressures; however, pigs operated at 10 mm Hg were able to maintain an intermittent blood flow.


CONCLUSIONS
A severe increase in ICP occurs with insufflation pressures higher than 15 mm Hg, possibly as a result of decreased cervical venous blood flow. Carbon dioxide insufflation up to 10 mm Hg does not alter ICP and is recommended for clinical application in endoscopic neck surgery.