An Experimental Study on the Relationship Among Airway Pressure, Pneumoperitoneum Pressure, and Central Venous Pressure in Pure Laparoscopic Hepatectomy

Objectives: To determine optimal settings for airway pressure (AWP), pneumoperitoneum pressure (PPP), and central venous pressure (CVP) in pure laparoscopic hepatectomy. Background: High PPP is often employed to control bleeding from the hepatic vein during pure laparoscopic hepatectomy; however, there is a risk of pulmonary gas embolism. We noted that decreases in AWP were often effective. Methods: After establishing carbon dioxide pneumoperitoneum in 6 male piglets and maintaining PPP at 25 mmHg, CVP was measured 3 times at each of 9 levels of airway pressure, which was increased in increments of 5 cmH(2)O from 0 to 40cmH(2)O. CVP was measured in the same manner by maintaining PPP at 20, 15, 10, 5, and 0 mmHg, and in laparotomy. Correlation and regression analyses were performed among airway pressure, CVP, and pneumoperitoneum pressure. Results: Positive correlations were observed between AWP and CVP and between PPP and CVP (P<0.001). Under high airway pressure, CVP was persistently higher than pneumoperitoneum pressure. Under low airway pressure, CVP did not increase or often decreased when PPP was higher than CVP. Conclusions: By increasing pneumoperitoneum pressure, bleeding from the hepatic vein cannot be controlled under high airway pressure, but can be controlled under low airway pressure. However, under low airway pressure, the risk of pulmonary gas embolism increases when PPP is higher than CVP. We consider that reducing AWP is also effective for controlling bleeding from the hepatic vein and safer than increasing pneumoperitoneum pressure.