Causes of small bowel obstruction after laparoscopic gastric bypass.

BACKGROUND: Small bowel obstruction after laparoscopic Roux-en-Y gastric bypass is not a rare complication, occurring in approximately 3% of patients. The goal of this study was to review the causes and timing of small bowel obstruction as an aid to diagnosis, treatment, and prevention. METHODS: The records of consecutive patients who underwent laparoscopic Roux-en-Y gastric bypass at the authors' center from 4/99 to 7/03 were retrospectively reviewed. All the patients had a laparoscopic handsewn gastrojejunostomy and a stapled jejunojejunostomy. The Roux limb was placed retrocolically in the first 405 patients and antecolically in the next 1,310 patients. RESULTS: Altogether, 1,715 patients underwent a total laparoscopic Roux-en-Y gastric bypass at the authors' bariatric center. In 51 patients, 55 small bowel obstructions occurred (3%) during a median follow-up period of 21 months (range, 1-52 months). Small bowel obstruction developed in 27 (7%) of the retrocolic patients, as compared with 24 (2%) of the antecolic patients (p < 0.001, chi-square). The causes of small bowel obstruction were adhesive bands (n = 14), obstruction at the jejunojejunostomy from kinking or narrowing (n = 13), internal hernia or external compression at the transverse mesocolon (n = 11), internal hernia through the jejunal mesentery (n = 8) incarcerated abdominal wall hernia (n = 4), and other (n = 5). For patients in whom small bowel obstruction developed in the first 3 weeks after their bypass surgery bowel resection was required in 19 of 24 patients, as compared with 6 of 31 patients in whom obstruction develop after 3 weeks (p < 0.001, chi-square). CONCLUSIONS: Early small bowel obstructions tend to result from technical problems with the Roux limb and require revision of the bypass or small bowel resection significantly more often than late obstructions. The latter group of obstructions usually result from adhesions or hernias, which could be handled laparoscopically without bowel resection. The position of the Roux limb (retrocolic vs antecolic) appeared to influence the incidence of small bowel obstruction. In the current series, changing the position of the jejunal bypass limb from retrocolic to antecolic significantly decreased the overall incidence of small bowel obstruction because it eliminated one of the most common sites for obstruction: the mesocolon.

Laparoscopic right donor nephrectomy: technique and comparison with left nephrectomy.

BACKGROUND: Laparoscopic donor nephrectomy (LDN) preferentially involves the left kidney to optimize vessel length, but occasionally, right nephrectomy is preferred. Right LDN differs markedly in anatomic relations and the need for a fourth port. This retrospective study compares donor outcomes and graft function of right and left LDN and describes the technique. METHODS: Consecutive patients undergoing right LDN from March 26, 1996 to December 31, 2000 were compared with those undergoing left LDN. Age, height, weight, body mass index, creatinine, creatinine clearance, operative time, warm ischemia time, analgesic requirements, serial postoperative creatinine, time to diet resumption, and hospital stay were compared. A second cohort matched for age, gender, race, and temporal left LDN also were compared with the group undergoing right LDN. RESULTS: No significant differences were found for any of the parameters measured. CONCLUSION: This study demonstrates that despite substantial differences in the procedures, donor outcome and graft survival are similar for right and left LDN.

Plasma complement C5 protects endothelial cells from polymorphonuclear neutrophil-derived, H2O2-mediated cytotoxicity.

BACKGROUND: In vitro studies suggest that polymorphonuclear neutrophils (PMN) can damage endothelial cells (EC) by releasing hydrogen peroxide. In vivo this can lead to anasarca secondary to capillary leakage of fluid, protein, and electrolytes. The result is multiple organ dysfunction syndrome, which is associated with high mortality. In vivo, circulating PMN-EC interactions take place in the presence of plasma, and we have shown previously that plasma affords protection to EC from PMN-mediated damage. METHODS: Human umbilical vein endothelial cells were primed with cytokines, cultured to a confluent monolayer, and coincubated with normal human PMNs. Cytotoxicity was assayed by gamma scintigraphy, plasma C5 was determined by sepharose column elution, and H(2)O(2) was assayed by R-Phycoerythrin fluorescence. RESULTS: Addition of C5, but not C3, to RPMI resulted in EC cytoprotection equivalent to adding whole serum. Removal of C5 from serum using F(ab')(2) rabbit IgG anti-human C5 coupled to CNBr-activated 4 sepharose beads resulted in significant loss of EC cytoprotection against H(2)O(2)-mediated damage, whereas adding back C5 restored the cytoprotection. C5 also reduced H(2)O(2)-mediated destruction of R-Phycoerythrin. CONCLUSIONS: The data suggest that the protection of EC against hydrogen peroxide-mediated damage is partly mediated through complement component C5.

Decreased systemic polymorphonuclear neutrophil (PMN) rolling without increased PMN adhesion in peritonitis at remote sites.

BACKGROUND: Previous in vitro studies have demonstrated that the host response to intra-abdominal infection produces increased generalized polymorphonuclear neutrophil (PMN) adherence to vascular endothelial cells (ECs), which may lead to subsequent endothelial damage, leaky capillaries, and organ dysfunction. There are scant data to demonstrate this enhanced systemic PMN adherence in vivo or the influence of PMN rolling on PMN endothelial adherence. HYPOTHESIS: Systemic PMN adherence in the animal with sepsis is increased. DESIGN: In vivo murine model of a 2-front infection using intravital microscopy of the cremasteric muscle to quantify PMN-EC adherence in a septic response. SETTING: Basic science laboratory and animal surgical facility. PATIENTS OR OTHER PARTICIPANTS: One hundred CD1 male mice. INTERVENTIONS: Animals underwent cecal ligation and puncture peritonitis, cremasteric muscle Escherichia coli infection, both infections, or neither (controls). Eighteen hours later, the mice underwent exteriorization of the cremasteric muscle under an intravital microscope for measurement of PMN-EC interactions. Blood was then drawn for calculation of circulating PMN counts. MAIN OUTCOME MEASURES: Adherence of PMNs, PMN rolling flux, PMN rolling velocity, and circulating PMN counts. RESULTS: Circulatory mechanics did not differ between the groups. Unlike static in vitro systems, we could not detect an increase in PMN adherence after peritonitis with this dynamic in vivo model. A local (cremasteric) infection was associated with marked PMN adherence. Peritonitis was associated with reduced PMN adherence at a local infection site as well as reduced rolling adhesion and PMN rolling velocity. CONCLUSIONS: The data suggest that intra-abdominal infection does not increase remote PMN adherence, and may actually result in reduction of systemic adherence via modulation of PMN rolling.

Polymorphonuclear neutrophil (PMN) recruitment in a 2-front murine injury model: triage of PMNs to competing stimuli of recruitment.

BACKGROUND: Intensive care unit patients as a group have the highest rate of nosocomial infections, such as pneumonia, urinary tract infections, and wound infections. The triage of polymorphonuclear neutrophils (PMNs) during an acute inflammatory response was investigated to determine if the severity of injury or infection contributes to PMN delivery. METHODS: A murine cecal ligation and puncture-induced peritonitis model with polyvinyl sponge discs were used to collect the PMNs in the abdomen (primary site) and in the subcutaneous tissue of the dorsum (remote site). Eighty CD1 male mice--20 in each of 4 groups--were assigned to the following: cecal ligation and puncture (CLP), sham laparotomy with cecal manipulation (CM), polyvinyl sponge placement in the abdomen and back only (SP), and sponge placement in the back alone (CON [control]). After 24 hours, the sponges were harvested, and the PMNs were collected and counted on a hemocytometer. RESULTS: These data, reported as mean PMN cells x 10(5) +/- SEM, demonstrated that back sponges contained significantly fewer PMNs in the CLP group (3.29 +/- 1.1) than in the CM group (7.77 +/- 1.61, P = .04), the SP group (8.69 +/- 1.67, P = .01), and the CON group (11.04 +/- 1.91, P < .001). CONCLUSIONS: These results demonstrate that PMN delivery to sites of secondary injury are inversely correlated to the severity of the primary injury or peritonitis.

Reduction in neutrophil cell surface expression of tumor necrosis factor receptors but not Fas after transmigration: implications for the regulation of neutrophil apoptosis.

OBJECTIVES: To test the hypothesis that loss of polymorphonuclear neutrophil tumor necrosis factor alpha (TNF-alpha) receptors during transmigration renders the exudate neutrophil refractory to TNF-alpha-mediated stimulation of apoptosis; and to investigate the surface expression of Fas on both circulating and exudate neutrophils. DESIGN: A prospective cohort study. SETTING: Surgical laboratory of a tertiary care hospital. PARTICIPANTS: Twenty-one healthy human volunteers. INTERVENTIONS: All subjects had circulating neutrophils and exudate neutrophils collected by venipuncture and skin window methods, respectively. MAIN OUTCOME MEASURES: Circulating and exudate neutrophils were incubated in culture medium (1.0x10(6) neutrophils per milliliter) alone or with TNF-alpha (100 ng/mL). Apoptosis was evaluated by flow cytometry (annexin V-fluorescein isothiocyanate and propidium iodide). Tumor necrosis factor alpha-phycoerythrin and anti-human Fas-fluorescein isothiocyanate were used to evaluate neutrophil TNF-alpha receptors and surface expression of Fas. RESULTS: Exudate neutrophils had a significant delay in apoptosis rates when compared with circulating neutrophils. The percentage of neutrophils expressing TNF-alpha receptors was significantly diminished after exudation (80%+/-15% vs 33%+/-9%; P<.001), as was the median channel number of TNF-alpha phycoerythrin fluorescence (8.1+/-1.6 vs 5.2+/-0.5; P=.001). However, the expression of Fas was unchanged after transmigration (percentage positive for Fas: 98.7%+/-0.7% vs 92.8%+/-3.4%, P=.89; Fas antibody-fluorescein isothiocyanate median channel fluorescence: 12.2+/-1.1 vs 13.1+/-1.2; P=.80). Exposure of exudate neutrophils to TNF-alpha failed to increase their rate of apoptosis. CONCLUSIONS: Exudate polymorphonuclear neutrophils are confirmed to have delayed apoptosis. Loss of TNF-alpha receptors during transmigration is necessary for neutrophil survival in the extravascular inflammatory milieu.

Perioperative mortality after pneumonectomy: analysis of risk factors and review of the literature.

OBJECTIVE: To determine risk factors for perioperative death associated with pneumonectomy. DESIGN: A retrospective case-control study in which a perioperative death group was compared with a survivor group, and a review of the English literature on the subject. SETTING: The Montreal General Hospital, a tertiary-care teaching institution. PATIENTS AND INTERVENTION: Ninety-two consecutive patients who underwent pneumonectomy between April 1989 and 1994. MAIN OUTCOME MEASURES: The effects of age, sex, smoking history, tumour size, type and stage, pulmonary function, cardiovascular risks, comorbidity, preoperative blood values and volume of fluids administered perioperatively. Values from the literature were reported for comparison. RESULTS: The perioperative death rate was 10.9%. Selection bias and in-hospital values reported in the literature have underestimated the death rate, with actual rates ranging from 7% to 11%. Age (odds ratio 2.48, p = 0.04), the presence of 1 or more comorbid diseases (odds ratio 7.92, p = 0.05) and amount of fluids given in the first 12 hours postoperatively (odds ratio 2.21, p = 0.06) were found to be significant risk factors for death. Multivariate logistic regression demonstrated that the volume of fluids given remains an independent risk factor whereas age and comorbid disease are dependent variables. CONCLUSIONS: The results were consistent with previously reported death rates and risk factors. Patient age and concomitant disease are not modifiable risk factors, but perioperative fluid administration and other means to prevent postpneumonectomy pulmonary edema may reduce the perioperative death rate.

Posterolateral lumbar and lumbosacral fusion with and without pedicle screw internal fixation.

Forty-seven patients who had lumbar or lumbosacral fusion with or without pedicle screw internal fixation by one surgeon for treatment of degenerative lumbar disease with clinical instability were retrospectively reviewed by an independent observer. Eighteen of the 21 patients whose fusions were internally fixed with the Variable Spinal Plating (VSP) system were available for review. A control group consisted of 27 patients who had fusion without internal fixation. The rate of pseudarthrosis did not significantly differ between the two groups (VSP group, 22%; versus control group, 26%). Twelve (67%) of the 18 patients treated with fusion and VSP instrumentation were considered to have had a good or excellent outcome, whereas 19 (70%) of the 27 patients treated by fusion without internal fixation had good or excellent results. Two VSP-instrumented patients had postoperative leg dysesthesias, whereas this complication was not observed in the control group. Bilateral posterolateral lumbar or lumbosacral fusion without internal fixation is as effective as and safer than fusion with pedicle screw instrumentation.

A biomechanical study of the fatigue characteristics of thoracolumbar fixation implants in a calf spine model.

Clinical failures of internal fixation implants for the treatment of the thoracolumbar spine are generally attributed to fatigue. Few studies, however, have characterized changes in fixation rigidity with time or subjected spine-implant fixation constructs to fatigue loading until failure. Fatigue characteristics of five dorsally applied spinal fixation implants were determined using lumbosacral calf spines, with an L3 vertebrectomy, loaded cyclically in combined compression (maximum 605 N) and flexion (maximum 16 Nm) for up to 100,000 cycles. Displacement transducers monitored motion at the site of instability and at the segment above the implants. Flexibility and strain at these segments were then calculated. A one-way analysis of variance showed that there were no significant differences in flexibility of the five fixation constructs (P greater than .05). A multiple Bonferroni test revealed that the AO and Kluger fixateur interne and Steffee plates, with fixation at L2 and L4, allowed significantly more strain (P less than .01) across the site of instability than did Harrington rods and Luque plates with fixation at L1, L2, L4, and L5. There were no significant differences between fixation constructs in initial strain above the implants. After 10,000 cycles, however, there were significant increases in strain across the segment above the Luque and Harrington implants (P less than .05). Failure of the AO Schanz screw occurred in three of six constructs at a mean of 73,300 cycles. The Steffee screws failed in four of five constructs at a mean of 20,800 cycles. The rods of the Kluger fixateur interne broke in four of five constructs at a mean of 47,800 cycles, and one screw slipped at 11,000 cycles. There were no metal failures in the Harrington or Luque implants.(ABSTRACT TRUNCATED AT 250 WORDS)

Importance of bone mineral density in instrumented spine fusions.

The effect of equivalent mineral density on pedicular screw fixation strength was investigated. The equivalent mineral density of human vertebral bodies was correlated highly with the pullout force of Kluger screws (r2 = 0.61, P less than 0.02). A moderate to high correlation existed between density and vertical force (r2 = 0.42 for Kluger screws, r2 = 0.55 for Steffee screws, P less than 0.02). In calf vertebral bodies of higher density (146 +/- 14 mg/cc), the forces were significantly higher than in the human vertebral bodies (P less than 0.05). Human lumbosacral spines were instrumented with three different fixators: Steffee plates, AO fixateur interne, and Kluger fixateur interne. Of five specimens with a mean density of 88 +/- 11 mg/cc, one screw loosened. More than one screw loosened in six specimens with a mean density of 63 +/- 12 mg/cc, and no screw loosened in four specimens with a mean density of 114 +/- 38 mg/cc. Measurement of equivalent mineral density correlates with the fixation strength of the intrapedicular screws in vitro and should be considered in patients with signs of osteopenia before using pedicular screws for spinal fusions. It is also concluded that calf spines are a good model for testing implants because they tend to focus failure processes in the implant rather than in the implant-bone interface.

Physical and mechanical properties of calf lumbosacral trabecular bone.

The physical and mechanical properties of calf lumbar and sacral trabecular bone were determined and compared with those of human trabecular bone. The mean tissue density (1.66 +/- 0.12 g cm-3), equivalent mineral density (169 +/- 36 mg cm-3), apparent density (453 +/- 89 mg cm-3), ash density (194 +/- 59 mg cm-3), ash content (0.6 +/- 0.05%), compressive strength (7.1 +/- 3.0 MPa) and compressive modulus (173 +/- 97 MPa) of calf trabecular bone are similar to those of young human. There were moderate, positive linear correlations between apparent density and equivalent mineral density, ash density, and compressive strength; and between compressive strength and equivalent mineral density (R2 ranging from 0.35 to 0.48, p less than 0.001). Apparent density, ash density, and equivalent mineral density did not differ significantly in different regions. In contrast to humans, the compressive strength increased from posterior, near the facet, to the anterior vertebral body. These comparisons of physical and mechanical properties, as well as anatomical comparisons by others, indicate that the calf spine is a good model of the young non-osteoporotic human spine and thus useful for the testing of spinal instrumentation.