Randomized clinical trial of mesh versus sutured wound closure after open abdominal aortic aneurysm surgery.

BACKGROUND: Incisional herniation is a common complication of abdominal aortic aneurysm (AAA) repair. This study investigated whether prophylactic mesh placement could reduce the rate of postoperative incisional hernia after open repair of AAA. METHODS: This randomized clinical trial was undertaken in three hospitals. Patients undergoing elective open AAA repair were randomized to routine abdominal mass closure after AAA repair or to prophylactic placement of polypropylene mesh in the preperitoneal plane. RESULTS: Eighty-five patients with a mean age of 73 (range 59-89) years were recruited, 77 (91 per cent) of whom were men. There were five perioperative deaths (6 per cent), two in the control group and three in the mesh group (P = 0.663), none related to the mesh. Sixteen patients in the control group and five in the mesh group developed a postoperative incisional hernia (hazard ratio 4.10, 95 per cent confidence interval 1.72 to 9.82; P = 0.002). Hernias developed between 170 and 585 days after surgery in the control group, and between 336 and 1122 days in the mesh group. Four patients in the control group and one in the mesh group underwent incisional hernia repair (P = 0.375). No mesh became infected, but one was subsequently removed owing to seroma formation during laparotomy for small bowel obstruction. CONCLUSION: Mesh placement significantly reduced the rate of postoperative incisional hernia after open AAA repair without increasing the rate of complications.

Antigen receptor V-segment usage in mucosal T cells.

In the accepted model of lymphocyte intestinal homing, naïve T cells recirculate via organized lymphoid tissues, whilst induced effector/memory cells home to the intestinal mucosa. In order to assess the T-cell-receptor repertoire in the intestine and gut-associated lymphoid tissue (GALT), spectratyping was performed on the proximal and the distal intestine, spleen and mesenteric lymph node tissue from six PVG rats. The products were analysed with an automated sequencer and statistical analyses were performed with hierarchical cluster analysis. This demonstrated the presence of a restricted T-cell repertoire in the small intestine compared with that in the mesenteric lymph nodes and the spleen. It also demonstrated marked differences in repertoire between individual, fully inbred rats maintained under apparently identical conditions in the same cage and fed identical diets. In addition, this work demonstrated marked differences between repertoires in the proximal and the distal intestine. Such marked differences are likely to reflect the end result of increasing divergence over time produced by relatively subtle effects of environment and antigenic load. Equally, marked differences in repertoire between small intestinal segments within individual rats indicate selective recruitment or retention of specific clones, presumably antigen-driven.

Intestinal adaptation after massive intestinal resection.

Patients with short bowel syndrome require long term parenteral nutrition support. However, after massive intestinal resection the intestine undergoes adaptation and nutritional autonomy may be obtained. Given that the complications of parenteral nutrition may be life threatening or result in treatment failure and the need for intestinal transplantation, a more attractive option is to wean patients off nutrition support by optimising the adaptive process. The article examines the evidence that after extensive small bowel resection adaptation occurs in humans and focuses on the factors that influence adaptation and the strategies that have been used to optimise this process. The review is based on an English language Medline search with secondary references obtained from key articles. There is evidence that adaptation occurs in humans. Adaptation is a complex process that results in response to nutrient and non-nutrient stimuli. Successful and reproducible strategies to improve adaptation remain elusive despite an abundance of experimental data. Nevertheless given the low patient survival and quality of life associated with other treatments for irreversible intestinal failure it is imperative that clinical research continues into the optimisation of the adaptation.

Comparison of microemulsion and conventional formulations of cyclosporine A in preventing acute rejection in de novo kidney transplant patients. The U.K. Neoral Renal Study Group.

BACKGROUND: The microemulsion preconcentrate formulation of cyclosporine A (CsA) (Neoral) exhibits more uniform pharmacokinetics than the conventional formulation (Sandimmun; SIM). This randomized, open-label, U.K. multicenter study compared the efficacy, safety, and tolerability of Neoral and SIM in preventing acute rejection in de novo renal transplant recipients. METHODS: Adult cadaveric kidney recipients (n=293) received Neoral or SIM twice daily for 12 months. Initially identical Neoral and SIM doses were titrated, maintaining trough CsA levels within locally defined therapeutic limits. RESULTS: In the year after transplantation, acute rejection occurred in 34% of the Neoral and 47% of the SIM recipients (P=0.037). In the intent-to-treat population, fewer treatment failures (defined as acute rejection, graft loss, withdrawal, or death) occurred in the Neoral (45%) than the SIM recipients (58%) (P=0.015) and therapeutic CsA levels (> or =250 microg/L) were reached faster with Neoral than SIM (P=0.0017). Antibody treatment of refractory rejection was used slightly less in the Neoral group (Neoral: 10%; SIM: 12%). One-year patient and graft survival rates (excluding deaths with functioning grafts) were 95% and 88%, respectively, for Neoral and 96% and 89% for SIM. Both formulations were well tolerated. No differences were observed between therapies in the nature, frequency, or severity of adverse events. Neoral use was not associated with increased nephrotoxicity or excessive immunosuppression. CONCLUSIONS: Neoral reduced the incidence of acute rejection compared with SIM, without significant increases in adverse events. This was achieved without altering existing SIM protocols and was attributed to improved absorption of CsA from Neoral and less variability in whole blood CsA concentrations.

The effect of rejection and graft-versus-host disease on small intestinal microflora and bacterial translocation after rat small bowel transplantation.

Bacterial translocation and the development of sepsis after small bowel transplantation may be promoted by immunological damage to the intestinal mucosa or by quantitative and qualitative changes in intestinal microflora. This study assessed the effects of rejection, graft-versus-host disease (GVHD) and immunosuppression on intestinal microflora and bacterial translocation after heterotopic rat small bowel transplantation. Isografts, allografts with and without CsA immunosuppression, and the semi-allogeneic parent to the F1 hybrid GVHD model were studied. Intestinal microflora in graft and host loops and bacterial translocation to host organs and the graft mesenteric lymph node were determined. Bacterial colonies were counted and individual colonies identified using API 20E nutrient and fermentation indicator techniques. Colony counts in isografts and allografts were significantly higher than in the native intestine, whereas there was a massive overgrowth in the native intestine in the GVHD group. The species profile for the host and graft loops was similar in animals that had received isografts, allografted animals receiving CsA, and animals undergoing GVHD. However, there was a large increase in Staphylococcus epidermidis in animals with rejection. Bacterial translocation was not detected in isografted animals, but was observed in all other animal groups, with S. epidermidis being the most prevalent organism. These findings demonstrate that rejection and GVHD are associated with shifts in intestinal microflora toward potentially pathogenic organisms and that bacterial translocation into recipient tissues poses a major threat for the development of sepsis.

Restoration of allograft responsiveness in B rats. II. Requirements for lymphoid populations and lymphokine.

B rats, produced by lethal x-irradiation of thymectomized animals that are then reconstituted with bone marrow cells from syngeneic, thymectomized, and thoracic-duct-drained donors, are unable to reject histoin-compatible heterotopic cardiac allografts. In these studies, we have continued to investigate the role of immune competent cells and lymphokine in restoring acute allograft rejection in these animals, noting that adoptive transfer of 10(8) sensitized splenocytes (sSL) plus Interleukin-2-rich conditioned medium, IL-2 (CM) will reproducibly produce acute responsiveness toward long-standing, well-functioning, heart grafts. We have now noted that sensitized lymph node cells or thoracic duct lymphocytes can also reverse the unresponsive state, with IL-2 rich conditioned supernatants increasing the effectiveness of small numbers of cells from these populations in inducing allograft rejection. Furthermore, the major cellular components within the spleen have been separated using antibody techniques, and their individual role in the rejection reaction has been assessed. Although 10(8) sSL plus IL-2 (CM) can produce acute rejection in a time comparable to that occurring in unmodified recipients (n = 20, MST +/- SD = 8.4 +/- 1.3 days), neither the T cell fraction (6 x 10(7] of 10(8) SL + IL-2 (CM) (n = 10, MST +/- SD = 17.4 +/- 7.3 days), nor addition of the adherent cell fraction to the T cell component (MST +/- SD = 18 +/- 2 days) or addition of the B cell fraction (MST +/- SD = 15.5 +/- 2.1 days) could restore acute responsiveness. However, increasing the numbers of T cells to 10(8) and transferring concomitantly with IL-2 (CM) again produced acute rejection (n = 4, MST +/- SD = 9 +/- 1.1 days). These data suggest that T cells form the essential element of transfer in the B rat, although other cells present in SL appear necessary to provide an optimal milieu. Our experiments also suggest that this response is independent of the route of administration or of higher doses of IL-2. Finally, using a dual allograft model, it appears that graft destruction is determined by the specific sensitivity of transferred SL; IL-2 (CM) being a nonspecific factor in the response.

Small intestine transplantation in the rat--immunology and function.

Heterotopic, vascularized small intestine transplants were performed in inbred strains of rats to investigate the structural, functional, and immunologic consequences of intestinal transplantation with and without immunosuppression with cyclosporine (CyA). Lewis X Brown Norway F1 intestine was rejected by untreated Lewis recipients in 7 to 10 days. Structurally, rejected intestine was characterized by shortened crypts and villi lined by damaged attenuated epithelial cells. Functionally, rejection was associated with impaired epithelial active ion transport as indicated by decreased potential difference and with diminished epithelial barrier function as reflected by decreased transepithelial resistance. Administration of CyA for 7 days prevented clinical rejection and partially prevented the structural and functional defects. Lewis intestine transplanted into Lewis X Brown Norway F1 recipients caused fatal graft versus host disease (GVHD) in 9 to 17 days. Treatment with CyA for 7 days failed to prevent GVHD routinely, but prolonged administration delayed fatal GVHD until CyA was discontinued. Intestine from Lewis "B" rats made deficient of T cells by thymectomy, irradiation, and reconstitution with syngeneic T cell-depleted bone marrow failed to cause GVHD in Lewis recipients. Reconstitution of the "B" rats with T cells before transplantation restored the GVHD response. These results may be relevant in the consideration of clinical small intestinal transplantation.

Is day case surgery the key to basic surgical training?

The logbooks of 5 senior house officers (SHOs) were audited to determine progression of surgical skills on a single vascular firm. Total surgical experience and, in particular, experience in varicose vein and arterio-venous fistula surgery, performed in the day-case unit (DCU), were examined. Trainees were divided into those undertaking their first surgical SHO post (group 1, n = 2) and those who had had previous surgical exposure (group 2, n = 3) on the basic surgical training rotation. SHOs were exposed to a mean of 273 (+/- 41 SD) operative cases in 6 months. Emergency work comprised 15% (+/- 7%) of workload. Day cases accounted for 35% (+/- 3%) of elective workload. A mean of 66 (+/- 5) varicose vein and AVF cases were undertaken in the DCU. This represented 82% (+/- 6%) of day-case operative experience for the firm. SHOs undertook 12 (+/- 6) VV/AVF cases unassisted, 35 (+/- 5) cases with senior assistance, and 20 (+/- 11) as first assistance in the DCU. All SHOs progressed to being able to perform arterial bypass and amputation (with senior assistance) during their time on the firm. There was no significant difference in experience or progression to major vascular surgery between group 1 and group 2 in this study except in lower limb amputation procedures. It is concluded that vascular surgical firms can provide a good introduction to surgical skills. Most experience as first operator was gained in the DCU and we suggest that those undergoing basic surgical training might benefit from an attachment to the DCU early in their rotations.

[Distal femoro-popliteal bypass using Esmarch tourniquet ischemia]. / Der distale femoro-popliteale Bypass unter Verwendung der Esmarchschen Blutleere.

The Esmarch bandage is an effective substitute for vascular clamps in distal femoro-popliteal or tibial bypass surgery. Intimal trauma caused by clamping is avoided, vasa vasorum are preserved due to only semicircumferential dissection of vessels. This method is particularly suitable for heavy calcified rigid vessel walls. We demonstrate this technique, which was employed in 8 patients (10 bypasses). The use of this technique requires neither a longer operation- nor clamping time. The postoperative course of all but one patients develops normally and the technique does not provoke any pathological results in the area of operation. Advantages of the procedure compared to conventional techniques will be discussed.

The impact of training on outcomes in primary vascular access surgery.

BACKGROUND: There is evidence that the outcome of arteriovenous fistula surgery is dependent on the surgeon performing the operation. Vascular access surgery provides excellent technical training for surgical trainees. The effect of surgical trainees on the outcome of fistulas was evaluated. METHODS: The grade of the main operator for all first attempted (primary) upper limb arteriovenous fistulas, between February 1998 and August 2001, was identified. Median follow-up was 18.0 months (IQR, 6.5-30.1 months). Successful use of fistula for dialysis, fistula patency and survival were assessed. RESULTS: 441 primary fistulas were formed in the study period. Median age was 67.5 years (IQR, 54.0-75.2 years). 71% of all fistulas were formed at the wrist. Trainees performed 31.1% of all operations. The two groups (trainees and consultants) were well matched for age, sex, diabetes, and fistula type. Only 70.5% of patients proceeded to long-term haemodialysis. There were no significant differences in the successful use of AVF for dialysis or patency rates between the two groups. One and two year fistula survival in this group was 87.7% and 78.3% for trainees and 80.8% and 71.1% for consultants (P = 0.288 log rank). CONCLUSIONS: Surgical trainees can perform primary AVF surgery without significantly reducing fistula outcomes. Vascular access surgery can be utilised as a training operation.

Haemodynamics of brachial arteriovenous fistula development.

This study observes the development of brachial arteriovenous fistulae, and assesses methods of predicting potential usefulness for haemodialysis. Creation of an adequate brachial fistula causes significant changes in blood flow to the forearm and hand. A prospective study of fifteen consecutive patients undergoing brachial arteriovenous fistula formation for haemodialysis was undertaken. Clinical measurements and coloured flow Doppler measurements were performed pre operatively, immediately post operatively and at two and eight weeks after surgery. The morphology of the fistula was studied and the volume flow was measured. Digital pressure was measured pre and post exercise at each visit. Fourteen fistulae worked well by eight weeks. There was an immediate large increase in brachial artery blood flow and by two weeks all fistulae that went on to develop well had a brachial artery flow of more than 700 mls/minute. The cephalic vein mean diameter pre operatively was 2.39 mm and increased to 5.4 mm by two weeks post operatively. Fistulae with flows over 400 mls/minute at two weeks had a good outcome. There were significant differences in digital pressure after fistula formation (P (2) 0.05). Digital mean arterial pressure dropped from 118 mm Hg pre-operatively to 98 mm Hg post operatively, at rest, and 89 mm Hg after exercise. Four patients developed forearm/hand claudication on exercise or signs of distal ischaemia. Three of these were diabetic with calcified vessels. All patients with a suitable cephalic vein should have attempted fistula formation rather than recourse to use of a synthetic graft. In diabetics creating a shunt in an already marginally competent vascular tree exposes the pa-tient to risk of significant hand ischaemia.