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Abstract

We investigated endocrine correlates of the hemodynamic changes induced by carbon dioxide pneumoperitoneum (PNO). We then studied whether clonidine might modulate the hemodynamic changes induced by PNO by reducing release of catecholamines and vasopressin. Both mechanical and neurohumoral factors contribute to the hemodynamic changes induced by carbon dioxide PNO. Several mediators have been proposed, but no study has correlated hemodynamic changes with changes in levels of these potential mediators. We conducted two studies, each including 20 healthy patients scheduled for elective laparoscopic cholecystectomy. In the first study serial measurements of hemodynamics (thermodilution technique) were done during laparoscopy and after exsufflation. Plasma concentrations of cortisol, catecholamines, vasopressin, renin, endothelin and prostaglandins were measured at the same time points. In the second study patients were randomly allocated to receive 8 microg/kg clonidine infused over 1 h or placebo before PNO. Hemodynamics and plasma levels of cortisol, catecholamines and vasopressin were measured during PNO and after exsufflation. Peritoneal insufflation resulted in a significant reduction of cardiac output (18+/-4%) and increases in mean arterial pressure (39+/-8%) and systemic (70+/-12%) and pulmonary (98+/-18%) vascular resistances. Laparoscopy resulted in progressive and significant increases in plasma concentrations of cortisol, epinephrine, norepinephrine and renin. Vasopressin plasma concentrations markedly increased immediately after the beginning of PNO (before PNO 6+/-4 pg/ml; during PNO 129+/-42 pg/ml; p < 0.05). The profile of vasopressin release paralleled the time course of changes in systemic vascular resistance. Prostaglandins and endothelin did not change significantly. Clonidine significantly reduced mean arterial pressure, heart rate and the increase in systemic vascular resistance. Clonidine also significantly reduced catecholamine concentrations but did not alter vasopressin and cortisol plasma concentrations. 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.

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Reduced narcotic requirement by clonidine with improved hemodynamic and adrenergic stability in patients undergoing coronary bypass surgery.

William W. Stead, B C Bloor, W FLACKE … (1987)

The authors examined the effect of clonidine, a preferential alpha 2-adrenergic agonist, upon narcotic requirements, hemodynamics, and adrenergic responses during the perioperative period in patients undergoing CABG surgery. Anesthesia was provided by sufentanil supplemented with isoflurane; sodium nitroprusside was given as needed for hemodynamic control. Ten patients received oral clonidine preoperatively at the time of premedication, and again intraoperatively by nasogastric tube. Another group of ten untreated patients were otherwise managed identically. Intergroup differences in required anesthetic and vasoactive drug doses and recovery times were measured and evaluated, as well as hemodynamics and plasma catecholamines prior to induction, after intubation, and at intervals intra- and postoperatively. Patients who received clonidine required less diazepam prior to induction, and received 40% less sufentanil during the anesthetic period, than did untreated controls. More control patients required the addition of isoflurane to prevent hypertension. Mean blood pressures and heart rates were elevated at many sampling points in patients not treated with clonidine. Four of the clonidine-treated group required atropine for treatment of bradycardia in the pre-incision period. Plasma catecholamines were significantly lower throughout most of the study period in patients treated with clonidine. After cardiopulmonary bypass and postoperatively, cardiac outputs were significantly higher in the treated group. Patients who had received clonidine were extubated significantly earlier, and fewer of them shivered postoperatively. We conclude that perioperative treatment with clonidine reduced narcotic and anesthetic requirements, improved hemodynamics, reduced plasma catecholamines, and shortened the period of postoperative ventilation in patients undergoing coronary artery surgery.

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Hemodynamic changes during laparoscopic cholecystectomy.

N Jacquet, Peter Joris, M Lamy … (1993)

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.