Hemodynamics during laparoscopic cholecystectomy under general anesthesia (isoflurane in N2O/O2 (50%)) were investigated in 15 nonobese ASA Class I patients by using invasive hemodynamic monitoring including a flow-directed pulmonary artery catheter. During surgery, intraabdominal pressure was maintained automatically at 14 mm Hg by a CO2 insufflator, and minute ventilation was controlled and adjusted to avoid hypercapnia. Hemodynamics were measured before anesthesia, after the induction of anesthesia, after tilting into 10 degrees head-up position, 5 min, 15 min, and 30 min after peritoneal insufflation, and 30 min after exsufflation. Induction of anesthesia decreased significantly mean arterial pressure and cardiac index (CI). Tilting the patient to the head-up position reduced cardiac preload and caused further reduction of CI. Peritoneal insufflation resulted in a significant increase (+/- 35%) of mean arterial pressure, a significant reduction (+/- 20%) of CI, and a significant increase of systemic (+/- 65%) and pulmonary (+/- 90%) vascular resistances. The combined effect of anesthesia, head-up tilt, and peritoneal insufflation produced a 50% decrease in CI. Administration of increasing concentrations of isoflurane, via its vasodilatory activity, may have partially blunted these hemodynamic changes. These results demonstrate that laparoscopy for cholecystectomy in head-up position results in significant hemodynamic changes in healthy patients, particularly at the induction of pneumoperitoneum.

Vasopressin and catecholamines probably mediate the increase in systemic vascular resistance observed during PNO. Clonidine before PNO reduces catecholamine release and attenuates hemodynamic changes during laparoscopy.

We have compared metabolic and respiratory changes after laparoscopic cholecystectomy (n = 15) with those after open cholecystectomy (n = 15). The durations of postoperative i.v. therapy, fasting and hospital stay were significantly shorter in the laparoscopy group. During the first and second days after operation, analgesic consumption but not pain scores (visual analogue scale) were significantly smaller after laparoscopy, while vital capacity, forced expiratory volume in 1 s, and PaO2 were significantly greater. The metabolic and acute phase responses (glucose, leucocytosis, C-reactive protein) were less after laparoscopy compared with laparotomy. Although plasma cortisol and catecholamine concentrations were not significantly different between the two groups, after surgery interleukin-6 concentrations were less in the laparoscopy group.

A first approach to laparoscopic placement of the adjustable silicone gastric band (ASGB) was begun in our institution in 1992. This work started on an animal model first. In the animal lab, details of laparoscopic dissection around the stomach have been defined. A new prototype of the adjustable silicone band for laparoscopic use has been devised. Four voluntary patients underwent this operation on the 1st, 2nd, and 3rd of September 1993. All the patients were female and the average weight was 116 kg (102-120 kg). The mean body mass index was 43 kg/m2 (36-49 kg/m2). No major operative difficulty was encountered. Immediate postoperative outcome was uneventful.

Steam explosion is a thermomechanicochemical pretreatment which allows the breakdown of lignocellulosic structural components by the action of heating, organic acids formed during the process and shearing forces resulting to the expansion of the moisture.Two distinct stages compose the steam explosion process: vapocracking and explosive decompression which include modification of the material components: hydrolysis of hemicellulosic components (mono and oligosaccharides released), modification of the chemical structure of lignin, modification of the cellulose cristallinity index… These effects allow the opening of lignocellulosic structures and influence the enzymatic hydrolysis yield of the material.