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 in sufflation in the neck exist owing to reports of potential adverse metaboli c and hemodynamic changes. Hypothesis: Carbon dioxide insufflation in the neck may cause adverse effec ts on hemodynamic and blood gas levels. These adverse effects may reflect t he level of pressure and duration of insufflation. Methods: Fifteen pigs, 5 per group, underwent endoscopic thyroidectomy at 1 0, 15, and 20 mm Hg. Partial pressure of carbon dioxide (arterial), pH, car diac output, central venous pressure, heart rate, and mean arterial pressur e (MAP) were measured at baseline, 1 and 2 hours after carbon dioxide insuf flation, and 30 minutes after desufflation. Results: At 10 mm Hg, PaCO2 increased slightly but not significantly, and n either acidosis nor adverse hemodynamic changes were observed. Hypercarbia, moderate acidosis, and a slight increase in MAP occurred in pigs undergoin g surgery at 15 mm Hg (MAP increased to 88 =/- 2.4 mm Hg from a baseline va lue of 78 +/- 3.53 mm Hg; P<.05). Pigs undergoing surgery at 20 mm Hg exper ienced sea ere hypercarbia and acidosis, as well as a significant decrease in MAP (P<.05). Central venous pressure decreased at 1 hour (P<.05) and inc reased at 2 hours (P<.05) in pigs undergoing surgery at 15 and 20 mm Hg. Af ter desufflation, PaCO2 and pH levels were normal for the 10 and 15 mm Hg g roups, 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.