Rectovaginal fistula model in the New Zealand white rabbit

Introduction and hypothesis  

The purpose of this study was to create an animal model to study rectovaginal fistula repair.     

Chitosan Sponges to Locally Deliver Amikacin and Vancomycin: A Pilot In Vitro Evaluation

Background

Open orthopaedic wounds are ideal sites for infection. Preventing infection in these wounds is critical for reducing patient morbidity and mortality, controlling antimicrobial resistance and lowering the cost of treatment. Localized drug delivery has the potential to overcome the challenges associated with traditional systemic dosing. A degradable, biocompatible polymer sponge (chitosan) that can be loaded with clinician-selected antibiotics at the point of care would provide the patient and clinician with a desirable, adjunctive preventive modality.

Questions/purposes

We asked (1) if an adaptable, porous chitosan matrix could absorb and elute antibiotics for 72 hours for potential use as an adjunctive therapy to débridement and lavage; and (2) if the sponges could elute levels of antibiotic that would inhibit growth of Staphylococcus aureus and Pseudomonas aeruginosa?

Methods

We fabricated a degradable chitosan sponge that can be loaded with antibiotics during a 60-second hydration in drug-containing solution. In vitro evaluation determined amikacin and vancomycin release from chitosan sponges at six time points. Activity tests were used to assess the release of inhibitory levels of amikacin and vancomycin.

Results

Amikacin concentration was 881.5 μg/mL after 1 hour with a gradual decline to 13.9 μg/mL after 72 hours. Vancomycin concentration was 1007.4 μg/mL after 1 hour with a decrease to 48.1 μg/mL after 72 hours. Zone of inhibition tests were used to verify inhibitory levels of drug release from chitosan sponges. A turbidity assay testing activity of released amikacin and vancomycin indicated inhibitory levels of elution from the chitosan sponge.

Clinical Relevance

Chitosan sponges may provide a potential local drug delivery device for preventing musculoskeletal infections.     

Review article: Renal support in critical illness

Purpose

This review provides a focused and comprehensive update on established and emerging evidence in acute renal replacement therapy (RRT) for critically ill patients with acute kidney injury (AKI).

Principal findings

There have been considerable technological innovations in the methods and techniques for provision of extracorporeal RRT in critical illness. These have greatly expanded our capability to provide both renal and non-renal life-sustaining organ support for critically ill patients. Recent data suggest earlier initiation of RRT in AKI may confer an advantage for survival and renal recovery. Two large trials have recently shown no added benefit to augmented RRT dose delivery in AKI. Observational data have also suggested that fluid accumulation in critically ill patients with AKI is associated with worse clinical outcome. However, several fundamental clinical questions remain to be answered, including issues regarding the time to ideally initiate/discontinue RRT, the role of high-volume hemofiltration or other blood purification techniques in sepsis, and extracorporeal support for combined liver-kidney failure. Extracorporeal support with RRT in sepsis, rhabdomyolysis, and liver failure are discussed, along with strategies for drug dosing and management of RRT in sodium disorders.

Conclusions

We anticipate that this field will continue to expand to promote research and innovation, hopefully for the benefit of sick critically ill patients.     

Acute kidney injury and its association with in-hospital mortality among children with acute infections

Background

We investigated prevalence of acute kidney injury (AKI) at hospitalization and its association with in-hospital mortality among Ugandan children hospitalized with common acute infections, and predictors of mortality among AKI children.

Methods

We enrolled 2,055 children hospitalized with primary diagnoses of acute gastroenteritis, malaria, or pneumonia. Serum creatinine, albumin, electrolytes, hemoglobin, and urine protein were obtained on admission. Participants were assessed for AKI based on serum creatinine levels. Demographic and clinical data were obtained using a primary care provider survey and medical chart review. Logistic regression was used to determine predictors of in-hospital mortality.

Results

A total of 278 (13.5 %) of children had AKI on admission; for 76.2 %, AKI was stage 2 (98/278) or stage 3 (114/278) defined as serum creatinine >2- or 3-fold above normal upper limit for age, respectively. AKI prevalence was particularly high in gastroenteritis (28.6 %) and underweight children (20.7 %). Twenty-five percent of children with AKI died during hospitalization, compared to 9.9 % with no AKI (adjusted odds ratio (aOR) 3.5 (95 % CI, 2.2–5.5)). In-hospital mortality risk did not differ by AKI stage. Predictors of in-hospital mortality among AKI children included primary diagnosis of pneumonia, aOR 4.5 (95 % CI, 1.8–11.2); proteinuria, aOR = 2.1 (95 % CI, 1.0–4.9) and positive human immunodeficiency virus (HIV) status, aOR 5.0 (95 % CI, 2.0–12.9).

Conclusions

Among children hospitalized with gastroenteritis, malaria, or pneumonia, AKI at admission was common and associated with high in-hospital mortality.     

Stapled aortic anastomoses: a minimally invasive, feasible alternative to videoscopic aortic suturing?

Widespread applications of totally laparoscopic aortic reconstructions have been limited by the long cross-clamp time required to suture the aortic anastomosis despite improvement in instrumentation. The authors' hypothesis was that a "one-step anastomosis concept" using an intraluminal stapler would allow shorter cross-clamp time but similar patency and imperviousness as videoscopic suturing techniques. An intraluminal stapler (Endopath-ILS, Ethicon) with a modified anvil was used to perform videoscopic-assisted thoracic aorta-to-iliac artery bypass with a 21 mm by 8 mm polytetrafluoroethylene (PTFE) graft in 22 sheep through a minimally invasive approach using a 5 cm thoracotomy. The graft-to-iliac artery anastomoses were hand sutured through a flank incision. Twelve sheep were used to establish the technique and 10 subsequent animals constituted the study group. Aortic cross-clamp time, imperviousness, and need for additional sutures were recorded and compared to previously reported data using videoscopic suturing in pigs. Patency was assessed by comparing lower limb arterial pressures. Macroscopic and microscopic examinations of the anastomoses were performed at different time-points within the first 3 months. Videoscopic-assisted stapled anastomoses were also performed on atherosclerotic aortas of 3 human cadavers. Stapled anastomoses between the thoracic aorta and PTFE graft were completed in 8 of 10 animals. Two animals were euthanized after stapler failure and anastomotic bleeding. Sutures to strengthen the anastomosis had to be used in 4 cases. Mean aortic cross-clamp time in 8 successful cases was 4.3 +/-2.9 minutes (range 2-11 minutes) and was significantly shorter than clamp time of videoscopic suturing technique (48.7 +/-9.4 minutes, p < 0.0001). Imperviousness was good or excellent in 4 animals and fair in 4 animals. All anastomoses were patent at the end of the procedure. Examination of the anastomosis of the 2 failed interventions showed medial aortic tear surrounding the anastomosis in 1 case and misfired staples in the other. No graft occlusion was noted during follow-up ranging from 0 to 12 weeks. At the time of harvest, no bleeding was noted after epinephrine and volume infusion to increase mean arterial pressure to 200 mm Hg for 15 minutes. Macroscopic examination of the anastomoses revealed adequate healing with circumferential stapling of the prosthesis to the aortic wall and no stenosis or thrombus except in 1 false aneurysm (1/7, 14%). Surface electron microscopy showed cells coverage of the anastomosis surface. When applied on human cadaver thoracic and abdominal aorta with atherosclerotic changes, clamping times of less than 5 minutes were achieved. However, imperviousness tested with saline was poor. An automatic stapling device allows performance of a graft-to-aorta anastomosis through a minimally invasive approach with shorter clamping time than a videoscopic suturing technique. However, the current technique of aortic stapling is unreliable and further improvements are needed.     

A pilot study using total colonic manometry in the surgical evaluation of pediatric functional colonic obstruction

Background/purpose

Total colonic manometry (TCM) can directly measure intraluminal pressures and contractile function of the entire colon. The utility of TCM to guide the surgical management of functional colonic obstruction has not been reported.

Methods

Total colonic manometry was performed on all patients referred for surgical evaluation of refractory functional colonic obstruction. Manometric tracings were obtained while fasting, after feeding, and after pharmacologic stimulation.

Results

Nine patients were referred for refractory colonic obstruction. The mean age was 4.8 years, and the mean duration of follow-up was 29 months. Two patients had functional obstruction after repair of Hirschsprung’s disease, and 7 patients had idiopathic functional obstruction. In the idiopathic group, 4 distinct motility patterns were identified: (1) normal colonic motility, (2) dysmotility with massive distension, (3) persistent segmental dysmotility, and (4) global neuropathy/myopathy. Both Hirschsprung’s patients showed globally abnormal motility. Surgical management was guided by TCM results. There was significant improvement in bowel function and weight gain after manometry-guided intervention. An unnecessary laparotomy was avoided in 2 patients.

Conclusions

TCM can be valuable in deciding the need for and timing of diversion, the extent of resection required, and the suitability of the patient for restoring bowel continuity in refractory functional obstruction.     

Is three-dimensional computed tomography reconstruction justified before endovascular aortic aneurysm repair?

OBJECTIVES: The endovascular management of abdominal aortic aneurysm (AAA) relies on accurate preoperative imaging for proper patient selection and operative planning. Three-dimensional (3-D) computed tomography (CT) with reformatted images perpendicular to blood flow has gained popularity as a method of AAA assessment and image-based planning before endovascular aneurysm repair (EVAR). The current study was undertaken to determine the interobserver agreement of AAA measurements obtained with axial CT and reformatted 3-D CT and to compare the consistency of the 2 methods in selecting patients for EVAR. METHODS: Eight observers assessed the axial CT and reformatted 3-D CT scans for 5 patients with AAAs to determine whether the patients were candidates for EVAR. 3-D CT with multiplanar reformatted images was performed by Medical Media Systems (MMS). Each observer measured the length and diameter of the proximal neck, maximal AAA, aortic bifurcation, common iliac diameter, and aortic angulation. The proximal neck and common iliac arteries were also assessed for thrombus, calcification, and tortuosity. Agreement of the measurements on axial CT scans was compared with those on MMS CT scans by calculating the kappa statistic. Complete agreement was defined as kappa = 1.0. The limits of agreement between observers were also calculated. RESULTS: The cumulative interobserver agreement of MMS CT scans (kappa =.81) was greater than for axial CT scans (kappa =.59). The kappa value for each of the diameter measurements was greater with the MMS CT scans. In 79% of cases the observers' measurements were less than 2 mm from the mean with MMS CT, compared with 59% for axial CT. The kappa value for deciding whether a patient was an endograft candidate on the basis of aortic neck was greater with the MMS CT (0.92 vs 0.63). The limits of agreement between observers were also better with the MMS CT. CONCLUSIONS: The interobserver agreement in planning EVAR is significantly better with MMS CT compared with traditional axial CT. The routine use of MMS CT appears justified before EVAR to improve the accuracy and consistency of patient selection.     

Comparison of C4d Detection on Erythrocytes and PTC‐C4d to Histological Signs of Antibody‐Mediated Rejection in Kidney Transplantation

C4d on erythrocytes (EC4d), C4d peritubular capillary deposition (PTC‐C4d) staining and histology were compared in a cross‐sectional cohort of 146 renal allograft biopsies (132 patients). EC4d levels paralleled PTC‐C4d staining, but were more predictive of peritubular capillaritis (PTC). Donor‐specific antibodies (DSA), PTC‐C4d, EC4d and PTC were analyzed in an independent longitudinal follow‐up cohort (96 biopsies, 76 patients). Seventy‐six samples were PTC and EC4d concordant, 11 positive and 65 negative, 7 PTC‐EC4d+ and 13 PTC+EC4d?. EC4d levels were related to DSA occurrence. With ABMR defined by PTC and DSA, all apparently discordant patients, EC4d negative, were correctly reassigned comparing EC4d level curves with rejection kinetics, with positive EC4d samples predating biopsy or late biopsies compared with ABMR flare‐ups. All EC4d‐positive patients without PTC or DSA had permanent high EC4d levels unrelated to rejection. EC4d was more abundant in PTC‐positive (mean = 108.5%± 3.4; n = 50) than PTC‐negative samples (mean = 88.1%± 1.3; n= 96; p < 0.0001). Sensitivity, specificity, positive predictive value and negative predictive value of PTC‐C4d and EC4d for PTC were, respectively, 75%, 79%; 64%, 76% (p < 0.05); 28%, 46% (p < 0.05) and 93%, 94%. Values were similar for DSA. A noninvasive blood test, EC4d, and particularly longitudinally monitoring EC4d levels, may increase surrogate ABMR testing options.     

Hounsfield units on computerized tomography predict stone-free rates after extracorporeal shock wave lithotripsy

PURPOSE: Studies suggest that HU values on non-contrast computerized tomography may predict the ability to fragment urinary calculi. We determined whether the HUs of in vivo urinary stones could be used to predict the stone-free rates after extracorporeal shock wave lithotripsy. MATERIALS AND METHODS: We evaluated 50 patients who underwent extracorporeal shock wave lithotripsy for 5 to 10 mm. upper urinary tract stones. Chemical analyses and HU calculations were performed for each stone and posttreatment radiographic assessment categorized patients into a stone-free or a residual stone group. Statistical analysis was performed using the Student t test to compare mean HU values in the 2 groups. RESULTS: Of the patients 32 (64%) were stone-free and 18 (36%) had residual stones. Mean values +/- SEM for the stone-free and residual stone groups were significantly different (551.20 +/- 46.66 versus 926.20 +/- 51.42 HU, p <0.0001). A total of 30 calculi (60%) were located in the ureter, including 21 in the stone-free group and 9 in the residual stone group with a mean value of 505.10 +/- 46.66 and 888.70 +/- 102.00 HU, respectively, which was significantly different (p = 0.0005). A total of 20 calculi (40%) were located in the kidney, including 11 in the stone-free group and 9 in the residual stone group with a mean value of 558.40 +/- 62.38 and 905.10 +/- 61.49 HU, respectively, which was significantly different (p = 0.001). CONCLUSIONS: These findings suggest that HU measurement of urinary calculi on pretreatment non-contrast computerized tomography may predict the stone-free rate. This information may be beneficial for selecting the preferred treatment option for patients with urinary calculi.