Effects of carbon dioxide pneumoperitoneum on cerebral hemodynamics in pigs

Previous studies have shown that laparoscopic interventions are associated with increases in intracranial pressure. However, the consequences on cereb ral blood flow (CBF) are unknown. This study investigates the effects of ca rbon dioxide (CO2) pneumoperitoneum on CBF in pigs. Ten pigs (weight, 20-26 kg) were anesthetized with 1.4% isoflurane and fentanyl (1 mug/kg per minu te). Mechanical ventilation (fraction of inspired oxygen = 0.4) was set to maintain normocapnia (end-tidal CO2 tension = 35 mm Hg). Arterial and centr al venous catheters were placed for measurement of mean arterial blood pres sure and central venous pressure. Bilateral internal carotid artery blood f low was measured using two transient time flow probes placed around both ca rotid arteries (with ligated external carotid arteries). Cortical and subco rtical cerebral blood flow was measured using laser Doppler flowmetry. Sagi ttal sinus pressure was measured via a superior sagittal sinus catheter. Af ter baseline measurements, the peritoneal cavity of the animals was insuffl ated with CO2 to achieve an intraabdominal pressure of 12-mm Hg. After 10 m inutes of stable CO2, pneumoperitoneum measurements were repeated. Increase s in central venous pressure (6.3 +/- 2.1 to 11.1 +/- 3.0 mm Hg) and sagitt al sinus pressure (8.0 +/- 2.8 to 11.9 +/- 3.0 mm Hg) were noted during CO2 pneumoperitoneum (P < .05). Bilateral internal carotid artery blood flow ( 46.0 +/- 7.4 vs 47.7 +/- 7.1 mL/100g per minute), cortical CBF (263 +/- 115 vs 259 +/- 158 tissue perfusion units), and subcortical CBF (131 +/- 145 v s 133 +/- 149 tissue perfusion units) did not change during CO2 pneumoperit oneum. The current data show that CO2 pneumoperitoneum increases sagittal s inus pressure without changing CBF. Increases in sagittal sinus pressure ar e likely related to decreases in cerebral venous drainage caused by increas es in intraabdominal pressure.