Nicolas Jacquet

Hemodynamic changes during laparoscopic cholecystectomy.

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° 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 pre-load 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.

Hemodynamic changes induced by laparoscopy and their endocrine correlates: effects of clonidine

OBJECTIVES 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. BACKGROUND 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

Early stage results after oesophageal resection for malignancy — colon interposition vs. gastric pull-up

OBJECTIVE The aims of our study were to determine if using the colon as a digestive transplant after oesophagectomy for cancer was associated with increased postoperative complications, and to assess the impact of preoperative radiochemotherapy on postoperative hospital outcome. METHODS From January 1990 to December 1998, 130 patients underwent oesophageal resection for malignancy. There were 103 males and 27 females (age: 61.3+/-11.5 years). Indications were squamous cell carcinoma in 69 patients and adenocarcinoma in 61. Preoperatively 30 patients (eight in stage IIB, 18 in stage III, and four in stage IV) received radiochemotherapy. There were 84 subtotal oesophagectomies, with anastomosis in the neck in 44 patients and at the thoracic inlet in 40, and 46 distal oesophageal resections. Digestive continuity was restored with the stomach in 92 patients (age: 63.4+/-10.2 years) and the colon in 38 (age: 52.3+/-12.8 years). With the exception of age (P<0.0001), there was no significant preoperative difference between gastric and colonic groups. RESULTS Hospital mortality was 8.5% (11 patients), decreasing from 18.5% (before 1993) to 3.8% (since 1993). One patient (2.5%) died in the colonic graft group and ten (11%) in the gastric pull-up group (P=0.17). Postoperative complications occurred in 40 patients (31%), respectively, in ten (26%) and 30 (33%) patients after colonic and gastric transplants (P=0.48), and were pulmonary insufficiency or infection in 29 patients, anastomotic fistula in six, myocardial infarction in five, recurrent nerve palsy in four, renal insufficiency in three, and cerebrovascular accident in one. All fistulas occurred in the gastric pull-up group. The incidence of postoperative pulmonary complications was 70% (21/30 patients) in the subgroup who received preoperative radiochemotherapy, as compared to 11% (5/44 patients) in the subgroup of comparable staging, but without preoperative treatment (P<0.001). CONCLUSIONS Colonic grafts are not associated with increased postoperative mortality or complications. Our results suggest that preoperative neoadjuvant treatment significantly increases postoperative pulmonary complications.

Misdiagnosed malignancy in transplanted organs

The case reports of three patients who received cancer-bearing organs at this institution are presented. A fourth recipient, who was to be transplanted with a cancerous kidney, was spared this disastrous complication. The relevant data regarding the donors is also alluded to, with special reference to the type and site of the primary malignancy. Following these case reports, the implications of these issues, their possible prevention, and further management are discussed.

Influence of steam explosion on physicochemical properties and hydrolysis rate of pure cellulose fibers

The aim of this study is to compare the effect of different steam explosion treatments on the physicochemical properties and the hydrolysis rate of a pure bleached cellulose. The results showed that moderate steam explosion treatments (severity factor below 5.2) did not appear to improve the enzymatic hydrolysis rate of the cellulose fibers. However, characterization of the samples showed a modification of the physicochemical properties of the cellulose, resulting in an increase of the water retention values (WRV) coupled to an increase of the overall crystallinity. For higher treatment intensities, an important thermal degradation of the cellulose was highlighted. This thermal degradation caused an important modification of the cellulose composition which leads to a decrease of the hydrolysis rate.

Characterization of sugar beet pectic-derived oligosaccharides obtained by enzymatic hydrolysis.

Three pectic oligosaccharides (POS) obtained by enzymatic hydrolysis of sugar beet pectin by combining endopolygalacturonase and pectinmethylesterase, were characterized using high performance liquid chromatography, thermogravimetric analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray diffraction. According to chromatographic analyses, POS are composed of mixture of polymers with different molecular weights and different galacturonic acid contents. The thermal analysis showed no major variation in thermal behavior regarding POS composition but showed that POS were more sensitive to thermal degradation than the parent pectin as well as the deesterified pectin. No change in composition of the gaseous products was obtained through TGA-FTIR analysis. The X-ray pattern of POS clearly indicated a considerable decrease in crystallinity when compared to the native pectin. Thus, thermal characterization of POS may have practical repercussions if the formulation in which POS is incorporated is submitted to a high temperature treatment.

SEVENTY-TWO HOURS HYPOTHERMIC INTESTINAL PRESERVATION STUDY USING A NEW PERFLUOROCARBON EMULSION

We investigated the effect of a perfluorocarbon emulsion (FC) added to the University of Wisconsin (UW) solution on hypothermic (4°C, 12–72h) preservation of rat small bowel grafts. The FC was 90%w/v perfluorooctylbromide, 2%w/v egg yolk phospholipids and 1.4%w/v mixed fluorocarbon-hydrocarbon molecular dowels. Four groups were defined: [1] UW flush and UW storage; [2] UW flush and FC storage; [3] flush with FC diluted 2 times with UW (FU) and FU storage; [4] FU flush and storage in oxygenated FU. Preservation was estimated with a histological score based on villus epithelium adhesion, on villus sloughing and on crypt cell adhesion to the basal membrane. Antioxidant potential was estimated by measurement of total thiol functions (SH) and activities of glutathione-peroxidase (GSH-P), superoxide dismutase (SOD) and catalase. FC in flush improved preservation during the first 24h (p<0.01). Storage in FC appeared superior to UW for the first 24h (p<0.01). Oxygenation (100% O2) of the storage medium yielded superior results at 12h and 24h (p<0.01 and p<0.001 versus group [1] respectively). After 72h, SOD and catalase activities increased in groups [3] and [4], and SOD decreased in group [1] (p<0.05). SH progressively decreased in group [1] (p<0.05) and GSH-P increased at 24 and 48h in groups [3] and [4] (p<0.01). The increase of O2 in the perfusion flush or storage medium ameliorated the preservation status and protected the antioxidant potential of the small bowel.

Acute diverticulitis in heart transplant recipients

Immunosuppressed patients are susceptible to complicated diverticulitis, but reports of this complication are scarce in heart graft recipients. To estimate the prevalence of acute diverticulitis in heart graft recipients, we retrospectively reviewed the cases of diverticulitis in a series of 143 patients who underwent orthotopic heart transplantation in a period of 10 years. Six (4%) of these developed acute diverticulitis and required colectomy. All of them were male patients and were older than 50 years. Four patients underwent urgent laparotomy and colon resection with end colostomy (Hartmann procedure). The two other patients suffered from diverticulitis without generalized peritonitis and underwent laparoscopic sigmoidectomy with direct transanal end-to-end anastomosis. The postoperative outcomes of these six patients were satisfactory. As are other immunosuppressed patients, heart graft recipients are susceptible to diverticulitis. Early surgical management may be safe in well-compensated patients.

Strictureplasty in Crohn's disease: short- and long-term follow-up.

Abstract Strictureplasty for obstructive Crohn’s disease is still controversial because lesions are left in place and the suture is performed on a diseased bowel. Many surgeons prefer to perform bowel resection, hoping for fewer complications and a lower recurrence rate. In this paper, the authors report their strictureplasty experience. They performed a systematic retrospective review of the patients suffering from Crohn’s disease who underwent strictureplasties during a 10-year period in the abdominal surgery department of the University Hospital of Liège Sart Tilman, and studied the short-and long-term clinical results of 68 strictureplasties performed in 18 patients. Median follow-up was 63 months (range 12 to 144). Mortality was 0% and septic morbidity was 11% (one wound abscess and one leakage). Among the 16 patients available for the latest follow-up, symptomatic stenotic recurrence had to be medically treated in hospital for 4 patients (25%) with a recurrence delay range of 19 to 49 months. Stenosis recurrence needed re-intervention in one patient 48 months after surgery: stenosis occurred at a distance from the corrected site. These results confirmed that strictureplasty is a safe and efficient procedure in selected patients undergoing surgery for obstructive Crohn’s disease.

Cytokines and organ transplantation. A review

Cytokines regulate both aspecific inflammatory responses and specific immune responses. Inflammatory changes occur in the organ transplant as a result of tissue trauma and ischemia/reperfusion in the organ donor and at the time of transplant operation. There is a possibility that cytokines play a role in mediating theses changes. These aspecific inflammatory changes may not only affect graft function but also influence graft immunogenicity (enhanced MHC and adhesion molecule expression) and thus, vulnerability to rejection. Cytokines orchestrate the specific immune response elicited by organ transplantation. Relevance of cytokines to the rejection reaction is multifactorial in nature: 1) promotion of the proliferation an differentiation of specific alloreactive T and B cells clones and differentiation and activation of CTL and NK cells, 2) chemotactic effect and induction of the expression of adhesion molecules, 3) enhancement of MHC class I and II expression, and 4) direct cytotoxic effect on the target grafted cells. Therefore, modulation of cytokine activity either specifically (monoclonal antibody, soluble receptor, etc.) or aspecifically (cyclosporin, FK 506, Rapamycin, steroids, etc.) is essential in controlling graft rejection. Determination of circulating cytokines and cytokines measurement within the biological fluids produced by an organ transplant may help in the diagnosis of rejection episodes and other complications following organ transplantation.