Endoscopic endocrine neck surgery with carbon dioxide insufflation: the effect on intracranial pressure

Abstract Background The endoscopic approach to the thyroid and parathyroid glands requires insufflation with carbon dioxide at 10–15 mmHg. This may decrease the cerebral venous return and increase intracranial pressure (ICP). The aim of this study was to evaluate the effect of carbon dioxide neck insufflation on ICP and haemodynamic variables. Methods Twelve 25-kg pigs underwent endoscopic thyroid dissection using carbon dioxide insufflation at 0 mmHg (sham), 10 mmHg (G10), 15 mmHg (G15) and 20 mmHg (G20). Three pigs were used in each group. ICP, mean arterial pressure, central venous blood pressure (CVP), cardiac output and blood gas were measured at baseline, 30, 60 and 120 min. Results There were no differences in mean ICP between the sham group and G10. However, ICP significantly increased in G15 and G20. The partial pressure of carbon dioxide was similar in G10 and G15 (mean(s.d.) 49·8(2·4) and 49·8(5·2) mmHg respectively at 120 min), while it was dramatically increased in G20 (63·1(6·9) mmHg at 120 min). Haemodynamic parameters were stable in all groups except for G20 in which CVP significantly increased with respect to baseline (8·5(2·1) versus 1·3(1·5) mmHg; P < 0·01). Jugular vein collapse occurred during endoscopic dissection at all insufflation pressures, but pigs operated at 10 mmHg were able to maintain an intermittent blood flow. Conclusion A severe increase in ICP occurs with insufflation pressures higher than 15 mmHg, possibly owing to decreased cervical venous blood flow. Carbon dioxide insufflation up to 10 mmHg does not alter ICP, and is recommended for clinical application in endoscopic endocrine neck surgery.