Physiological responses to different ischemic periods during laparoscopic infrarenal aortic cross-clamping: evaluation in an experimental animal model.

Our aim was to study the physiological repercussions of varying ischemic times during laparoscopic aortic surgery. After quarantine, laparoscopy was performed in 24 healthy pigs, which were randomly allocated to four study groups: group I (n=6), laparoscopic infrarenal abdominal aortic surgery with 30 min of crossclamping; group II (n=6), laparoscopic infrarenal abdominal aortic surgery with 60 min of cross-clamping; group III (n=6), laparoscopic infrarenal abdominal aortic surgery with 120 min of cross-clamping; group IV (n=6), 120 min pneumoperitoneum in the absence of aortic cross-clamping (control group). Hematological, biochemical, hormone, hemodynamic, and ventilatory studies were conducted during and after surgery; and a postoperative neurological evaluation was performed 10 days after surgery. Group III evidenced an increase in arterial blood pressure and heart rate that was significantly higher than those present in the other groups. Significant decreases in pH were observed in groups II and III, whereas no changes in this parameter were seen in groups I and IV. Catecholamine levels during surgery were similar in all groups (a significant [p<0.001] increase in plasmatic adrenaline and noradrenaline was seen immediately after pneumoperitoneum creation in all groups). A positive association was found between the duration of aortic clamping and hormone values at 30 and 60 min after declamping but not after 24hr. A significant increase in the renal resistive index (RRI) and a significant decrease in urine output were evidenced during laparoscopy, with significantly lower RRI values seen in group IV immediately after surgery. Thus, a synergic effect of pneumoperitoneum and aortic cross-clamping was seen in this study. These two factors together cause a hemodynamic compromise, with decreased renal perfusion and acidosis, thus negatively affecting the patient's general state during this type of surgery. Despite being well tolerated in healthy pigs, a laparoscopic aortic cross-clamping time over 60min produces significant hemodynamic, metabolic, and hormonal changes. Careful patient selection is mandatory to avoid any severe complications.