Arterial PCO2 and cardiovascular function during endoscopic neck surgery with carbon dioxide insufflation.

BACKGROUND Endoscopic parathyroidectomy and thyroidectomy were introduced into clinical practice in 1995. Concerns about the use of carbon dioxide insufflation in the neck exist owing to reports of potential adverse metabolic and hemodynamic changes. HYPOTHESIS Carbon dioxide insufflation in the neck may cause adverse effects on hemodynamic and blood gas levels. These adverse effects may reflect the level of pressure and duration of insufflation. METHODS Fifteen pigs, 5 per group, underwent endoscopic thyroidectomy at 10, 15, and 20 mm Hg. Partial pressure of carbon dioxide (arterial), pH, cardiac output, central venous pressure, heart rate, and mean arterial pressure (MAP) were measured at baseline, 1 and 2 hours after carbon dioxide insufflation, and 30 minutes after desufflation. RESULTS At 10 mm Hg, PaCO2 increased slightly but not significantly, and neither acidosis nor adverse hemodynamic changes were observed. Hypercarbia, moderate acidosis, and a slight increase in MAP occurred in pigs undergoing surgery at 15 mm Hg (MAP increased to 88 +/- 2.4 mm Hg from a baseline value of 78 +/- 3.53 mm Hg; P<.05). Pigs undergoing surgery at 20 mm Hg experienced severe hypercarbia and acidosis, as well as a significant decrease in MAP (P<.05). Central venous pressure decreased at 1 hour (P<.05) and increased at 2 hours (P<.05) in pigs undergoing surgery at 15 and 20 mm Hg. After desufflation, PaCO2 and pH levels were normal for the 10 and 15 mm Hg groups, while pigs undergoing surgery at 20 mm Hg developed a higher degree of hypercarbia and acidosis (P =.001). CONCLUSIONS Carbon dioxide neck insufflation is safe at 10 mm Hg. The use of insufflation pressures higher than 15 mm Hg should be avoided due to the potential risk for metabolic and hemodynamic complications.