Healing of rectal advancement flaps for anal fistulas in patients with and without Crohn's disease: a retrospective cohort analysis

Background

Surgical closure of anal fistulas with rectal advancement flaps is an established standard method, but it has a high degree of healing failure in some cases. The aim of this study was to identify risk factors for anal fistula healing failure after advancement flap placement between patients with cryptoglandular fistulas and patients with Crohn’s disease (CD).

Methods

From January 2010 to October 2020, 155 rectal advancement flaps (CD patients = 55, non-CD patients = 100) were performed. Patients were entered into a prospective database, and healing rates were retrospectively analysed.

Results

The median follow-up period was 189 days (95% CI: 109–269). The overall complication rate was 5.8%. The total healing rate for all rectal advancement flaps was 56%. CD patients were younger (33 vs. 43 years, p < 0.001), more often female (76% vs. 30%, p < 0.001), were administered more immunosuppressant medication (65% vs. 5%, p < 0.001), and had more rectovaginal fistulas (29% vs. 8%, p = 0.001) and more protective stomas (49% vs. 2%, p < 0.001) than patients without CD. However, no difference in healing rate was noted between patients with or without CD (47% vs. 60%, p = 0.088).

Conclusions

Patients with anal fistulas with and without Crohn’s disease exhibit the same healing rate. Although patients with CD display different patient-specific characteristics, no independent factors for the occurrence of anal fistula healing failure could be determined.

Trial registration Not applicable due to the retrospective study design.

Assessment of Risk Factors for the Occurrence of a High-Output Ileostomy

Background: Ileostomy is often required in patients undergoing bowel resections for inflammatory bowel diseases (IBD), colorectal cancer, and emergencies. Unfortunately, some patients develop a high-output stoma (HOS). This condition affects homeostasis and may be life threatening. We aimed to identify possible risk factors for the development of HOS. Patients and methods: From 2012 to 2018, 296 patients who underwent ileostomy at Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin were retrospectively analyzed. Emergency operations were included. Diverting ileostomy, end ileostomies and anastomotic stomata with at least part ileum, were examined. HOS was defined as stoma output of more than 1,000 mL per day for more than 3 days. Univariate and multivariable analyses were used to detect potential risk factors for the development of HOS. Results: 41 of 296 patients developed HOS (13.9%). Mortality was 0.3%. In the univariate analysis, age (p < 0.002), diagnosis (Crohn's disease, p = 0.005), arterial hypertension (p = 0.023), surgical procedure (right-sided colectomy, small bowel resection, p < 0.001), open technique (p < 0.002), emergencies (p = 0.014), and anastomotic ileostomy (p < 0.001) were identified as risk factors. In the multivariable logistic regression, older age, diagnosis (Crohn's disease) and surgical procedure (right-sided colectomy, separate ileostomy, small bowel resection) remained significant risk factors. Conclusion: The occurrence of HOS is a relevant problem after ileostomy. The identification of risk factors for a high-output may be helpful for monitoring, early diagnosis and initiation of therapy as well as in the planning of close follow-up care.

Microscopic inflammation in ileocecal specimen does not correspond to a higher anastomotic leakage rate after ileocecal resection in Crohn's disease

Background

Patients with Crohn’s disease suffer from a higher rate of anastomotic leakages after ileocecal resection than patients without Crohn’s disease. Our hypothesis was that microscopic inflammation at the resection margins of ileocecal resections in Crohn’s disease increases the rate of anastomotic leakages.

Patients and methods

In a retrospective cohort study, 130 patients with Crohn’s disease that underwent ileocecal resection between 2015 and 2019, were analyzed. Anastomotic leakage was the primary outcome parameter. Inflammation at the resection margin was characterized as “inflammation at proximal resection margin”, “inflammation at distal resection margin” or “inflammation at both ends”.

Results

46 patients (35.4%) showed microscopic inflammation at the resection margins. 17 patients (13.1%) developed anastomotic leakage. No difference in the rate of anastomotic leakages was found for proximally affected resection margins (no anastomotic leakage vs. anastomotic leakage: 20.3 vs. 35.3%, p = 0.17), distally affected resection margins (2.7 vs. 5.9%, p = 0.47) or inflammation at both ends (9.7 vs. 11.8%, p = 0.80). No effect on the anastomotic leakage rate was found for preoperative hemoglobin concentration (no anastomotic leakage vs. anastomotic leakage: 12.3 vs. 13.5 g/dl, p = 0.26), perioperative immunosuppressive medication (62.8 vs. 52.9%, p = 0.30), BMI (21.8 vs. 22.4 m²/kg, p = 0.82), emergency operation (21.2 vs. 11.8%, p = 0.29), laparoscopic vs. open procedure (p = 0.58), diverting ileostomy (31.9 vs. 57.1%, p = 0.35) or the level of surgical training (staff surgeon: 80.5 vs. 76.5%, p = 0.45).

Conclusion

Microscopic inflammation at the resection margins after ileocecal resection in Crohn’s disease is common. Histologically inflamed resection margins do not appear to affect the rate of anastomotic leakages. Our data suggest that there is no need for extensive resections or frozen section to achieve microscopically inflammation-free resection margins.

[Transanal total mesorectal excision-a critical appraisal]

INTRODUCTION

Total mesorectal excision (TME) is the international standard for rectal cancer surgery. In addition to laparoscopic TME (lapTME), transanal TME (taTME) was developed in recent years to reduce the rate of incomplete TME, conversion to open surgery and postoperative functional impairment. Despite limited evidence, this technique is becoming increasingly more popular and is already routinely used by many hospitals for rectal cancer in varying tumor level locations. The aim of this review was to evaluate the taTME compared to anterior rectal resection with lapTME as the standard of care in rectal cancer surgery based on currently available evidence.

METHOD

The databases PubMed and Medline were systematically searched for publications on transanal total mesorectal excision (taTME) and transanal minimally invasive surgery (TAMIS). Relevant studies were selected and further research based on the reference lists was undertaken.

RESULTS

A total of 16 studies analyzing 3782 patients were identified. The taTME does not lead to a higher rate of complete TME-resected specimens compared to the standard procedure. So far, superiority could not be demonstrated for complication rates or for functional or oncological results. Serious complications secondary to dissection in incorrect planes were observed. The anastomotic level generally seems to be closer to the sphincter after taTME versus anterior lapTME.

CONCLUSION

Considering current evidence, taTME failed to show superiority compared to conventional anterior lapTME. Although taTME has some potential advantages, it carries substantial risks. If performed outside of clinical trials, it should therefore only be used in carefully selected patients with a high possibility of conversion, following adequate patient informed consent and after intense and systematic training of the surgeon.

Minimal vascular flows cause strong heat sink effects in hepatic radiofrequency ablation ex vivo

BACKGROUND

The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo.

METHODS

Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry.

RESULTS

Flow rates of 1 ml/min already caused a significant cooling effect (P ≤ 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min.

CONCLUSIONS

Minimal vascular flows of ≥1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels.

[Are there too many conferences for general and visceral surgery in Germany? : A survey of DGAV members]

BACKGROUND

Human and financial resources are increasingly bound due to economic pressure and the working hours Act whereby the already restricted further training times are further limited. The industry also has less funding available for sponsorship of conferences and workshops. Against this background the question arises whether a reduction or focusing of the conferences is necessary; therefore, the aim of this survey was to obtain an opinion from members of the German Society of General and Visceral Surgery (DGAV) and possibly to derive a need for action to submit to the board members.

METHODS

From 7 February to 18 March 2015 an online survey was conducted by the DGAV with their members regarding the number of necessary congress events in Germany.

RESULTS

A total of 670 responses were received (return rate 16 %). In total, 56 % of participants felt that there are too many conferences. A differentiation according to the position of the respondent and the level of the associated hospital resulted in the following: 69.3 % of the participating head physicians (HP) shared this opinion, compared to 48.6 % of senior physicians (SP) and 34.4 % of residents (RP). Of the participants from basic and standard care hospitals (B/SC) 50 % shared this opinion, compared to 59.2 % from maximum care hospitals (MC) and 63.6 % from university hospitals (UH). In addition, a total of 75 % of the participants (HP 82.9 %, SP 78.4 %, RP 70.5 %) were in favor of keeping the congress of the DGAV (annual meeting of the German Society for Digestive and Metabolic Diseases in conjunction with the Autumn meeting of the DGAV) in its previous form, regardless of the underlying level of care of the associated hospital (B/SC 77 %, MC 79 %, UC 68 %).

CONCLUSION

More experienced surgeons in particular tended to favor a reduction of events with a focus on the major conferences; however, younger colleagues preferred a wider spectrum of meetings. In order to comply with both positions a wide range of events should be continued to be provided in the future so that surgeons can choose which to attend according to the individual preferences.

Management of Complications Following Emergency and Elective Surgery for Diverticulitis

BACKGROUND

The clinical spectrum of sigmoid diverticulitis (SD) varies from asymptomatic diverticulosis to symptomatic disease with potentially fatal complications. Sigmoid colectomy with restoration of continuity has been the prevailing modality for treating acute and recurrent SD, and is often performed as a laparoscopy-assisted procedure. For elective sigmoid colectomy, the postoperative morbidity rate is 15-20% whereas morbidity rates reach up to 30% in patients who undergo emergency surgery for perforated SD. Some of the more common and serious surgical complications after sigmoid colectomy are anastomotic leaks and peritonitis, wound infections, small bowel obstruction, postoperative bleeding, and injuries to the urinary tract structures. Regarding the management of complications, it makes no difference whether the complication is a result of an emergency or an elective procedure.

METHODS

The present work gives an overview of the management of complications in the surgical treatment of SD based on the current literature.

RESULTS

To achieve successful management, early diagnosis is mandatory in cases of deviation from the normal postoperative course. If diagnostic procedures fail to deliver a correlate for the clinical situation of the patient, re-laparotomy or re-laparoscopy still remain among the most important diagnostic and/or therapeutic principles in visceral surgery when a patient's clinical status deteriorates.

CONCLUSION

The ability to recognize and successfully manage complications is a crucial part of the surgical treatment of diverticular disease and should be mastered by any surgeon qualified in this field.

[Stump closure in laparoscopic appendectomy. Influence of endoloop or linear stapler on patient outcome]

BACKGROUND

Even though laparoscopic appendectomy is one of the most frequent procedures in abdominal surgery, the technique of appendiceal stump closure is still not standardized. The aim of this retrospective study was to analyze the effect of the use of endoloops or linear staplers for appendiceal stump closure concerning surgical site infections (SSI) and intra-abdominal abscesses (IAA).

PATIENTS AND METHODS

All laparoscopic appendectomies between January 1st 2007 and May 31st 2010 were split into an endoloop group (ELG) and a linear stapler group (LSG). The groups were compared with respect to the outcome parameters SSI and IAA.

RESULTS

A total of 430 appendectomies were performed in the study period of which 105 operations were conducted laparoscopically. In this study 47.6 % (n = 50) were alloted to the LSG and 52.4 % (n = 55) to ELG. In LSG 3.1 % (n = 1) developed an SSI versus 10.0 % (n = 4, p = 0.254) in ELG. No IAAs occurred in LSG compared to 2 (5.1 %, p = 0.499) in ELG.

CONCLUSION

The use of EL for appendiceal stump closure is safe and cost effective for low-grade appendicitis but high-grade appendicitis should be treated with LS.

[Simulation training in surgical education - application of virtual reality laparoscopic simulators in a surgical skills course]

BACKGROUND

Training and simulation are gaining importance in surgical education. Today, virtual reality surgery simulators provide sophisticated laparoscopic training scenarios and offer detailed assessment methods. This also makes simulators interesting for the application in surgical skills courses. The aim of the current study was to assess the suitability of a virtual surgery simulator for training and assessment in an established surgical training course.

MATERIALS AND METHODS

The study was conducted during the annual "Practical Course for Visceral Surgery" (Warnemuende, Germany). 36 of 108 course participants were assigned at random for the study. Training was conducted in 15 sessions over 5 days with 4 identical virtual surgery simulators (LapSim) and 2 standardised training tasks. The simulator measured 16 individual parameters and calculated 2 scores. Questionnaires were used to assess the test persons' laparoscopic experience, their training situation and the acceptance of the simulator training. Data were analysed with non-parametric tests. A subgroup analysis for laparoscopic experience was conducted in order to assess the simulator's construct validity and assessment capabilities.

RESULTS

Median age was 32 (27 - 41) years; median professional experience was 3 (1 - 11) years. Typical laparoscopic learning curves with initial significant improvements and a subsequent plateau phase were measured over 5 days. The individual training sessions exhibited a rhythmic variability in the training results. A shorter night's sleep led to a marked drop in performance. The participants' different experience levels could clearly be discriminated ( ≤ 20 vs. > 20 laparoscopic operations; p ≤ 0.001). The questionnaire showed that the majority of the participants had limited training opportunities in their hospitals. The simulator training was very well accepted. However, the participants severely misjudged the real costs of the simulators that were used.

CONCLUSIONS

The learning curve on the simulator was successfully mastered during the course. Construct validity could be demonstrated within the course setting. The simulator's assessment system can be of value for the assessment of laparoscopic training performance within surgical skills courses. Acceptance of the simulator training is high. However, simulators are currently too expensive to be used within a large training course.

Sigmoid diverticulitis in young patients--a more aggressive disease than in older patients?

INTRODUCTION

There is controversy over whether sigmoid diverticulitis (SD) is more aggressive with a higher risk of perforation in younger than in older patients. The aim of this study was to assess the clinical presentation and outcome of patients ≤40 and >40 years old with acute diverticulitis.

PATIENTS AND METHODS

Consecutive admissions of all patients with acute SD were prospectively recruited from January 1998 to June 2010.

RESULTS

A total of 1,019 patients were included: 513 (69 ≤40 years and 444 >40 years) presented with their first episode, while 506 (20 ≤40 years, 486 >40 years) had a prior history of SD. The percentage of patients with severe SD did not differ between the two age groups either for the first (covered perforation, 30.4% vs. 29.5%, p = 0.875; free perforation, 26.1% vs. 23.9%, p = 0.69) or for the recurrent episode (covered perforation, 15% vs. 8.2%, p = 0.287; free perforation, 5% vs. 4.1%, p = 0.846). Furthermore, the rate of emergency surgery did not differ between both age groups either for the first (26.1% vs. 23.9%, p = 0.690) or the recurrent episode (5% vs. 4.1%, p = 0.846). No differences in the rate of Hartmann's procedure (52.6% vs. 68.3%, p = 0.180) and failure of conservative treatment (3.4% vs. 4.9%, p = 0.607) were observed between younger and older patients.

CONCLUSION

Acute SD in younger patients is not more aggressive and has no higher risk of perforation or need for emergency surgery compared to older patients.

Effectiveness of various thermal ablation techniques for the treatment of nodular thyroid disease--comparison of laser-induced thermotherapy and bipolar radiofrequency ablation

Alternative minimally invasive treatment options such as radiofrequency ablation (RFA) or laser-induced thermotherapy (LITT) are at present under investigation for achieving a nonsurgical targeted cytoreduction in benign and malignant thyroid lesions. So far, studies have not been able to show a secure advantage for neither LITT nor RFA. The aim of this study was to compare the two ablation procedures in terms of their effectiveness. Thermal lesions were induced in porcine thyroid glands either by LITT or bipolar RFA ex vivo (n = 110 each) and in vivo (n = 10 each) using power settings between 10 and 20 W. Temperature spread during application was documented in 5- and 10-mm distance of the applicator. Postinterventional lesion diameters were measured and lesion size was calculated. Furthermore, enzyme histochemical analysis of the thyroid tissue was performed in vivo. Lesion volumes induced by LITT ranged between 0.74 ± 0.18 cm(3) (10 W) and 3.80 ± 0.41 cm(3) (20 W) with a maximum of 5.13 ± 0.16 cm(3) at 18 W. The inducible lesion volumes by RFA were between 2.43 ± 0.68 cm(3) (10 W) and 0.91 ± 0.71 cm(3) (20 W) with a maximum of 2.80 ± 0.85 cm(3) at 14 W. The maximum temperatures were 112.9 ± 9.2°C (LITT) and 61.6 ± 13.9°C (RFA) at a distance of 5 mm and 73.2 ± 6.7°C (LITT) and 53.5 ± 8.6°C (RFA) at a distance of 10 mm. The histochemical analysis demonstrates a complete loss of NADPH dehydrogenase activity in thermal lesions as a sign of irreversible cell damage both for LITT and RFA. This study is the first to compare the effectiveness of laser-induced thermotherapy and radiofrequency ablation of thyroid tissue. LITT as well as RFA are suitable for singular thyroid nodules and induces reproducible clinically relevant lesions in an appropriate application time. The maximum inducible lesion volumes by LITT are significantly larger than by RFA with the devices used herein.

Hepatic arterial infusion (HAI) with PEGylated liposomes containing 5-FU improves tumor control of liver metastases in a rat model

PURPOSE

To investigate the cytostatic effect of 5-fluorouracil (5-FU) encapsulated in polyethylene glycol (PEG) liposomes with or without degradable starch microspheres (DSM) in a long-term trial using a rat liver tumor model.

MATERIALS AND METHODS

The cytostatics were applied once either as a hepatic arterial infusion (HAI) or were systemically infused via the tail vein. Seven groups were compared with respect to tumor growth and survival times: 5-FU HAI (group I), 5-FU + DSM HAI (group II), PEG-5-FU HAI (group III), PEG-5-FU + DSM HAI (group IV), NaCl HAI (group V), 5-FU i.v. (group VI), and PEG-5-FU i.v. (group VII).

RESULTS

Seven and 14 days after treatment in groups III and IV, only group IV had significantly inhibited tumor growth on day 21 compared to the groups treated intravenously. On day 28, none of the animals from the intravenously treated groups were still alive compared to a significantly longer survival time of 6 and 8 weeks in groups III and IV.

CONCLUSION

Locoregional therapy with 5-fluorouracil encapsulated in PEGylated liposomes may further improve the treatment success with longer-lasting tumor regression and prolonged survival times.

The German registry for natural orifice translumenal endoscopic surgery: report of the first 551 patients

OBJECTIVE

To analyze patient outcome in the first 14 months of the German natural orifice translumenal endoscopic surgery (NOTES) registry (GNR).

SUMMARY BACKGROUND DATA

NOTES is a new surgical concept, which permits scarless intra-abdominal operations through natural orifices, such as the mouth, vagina, rectum, or urethra. The GNR was established as a nationwide outcome database to allow the monitoring and safe introduction of this technique in Germany.

METHODS

The GNR was designed as a voluntary database with online access. All surgeons in Germany who performed NOTES procedures were requested to participate in the registry. The GNR recorded demographical and therapy data as well as data on the postoperative course.

RESULTS

A total of 572 target organs were operated in 551 patients. Cholecystectomies accounted for 85.3% of all NOTES procedures. All procedures were performed in female patients using transvaginal hybrid technique. Complications occurred in 3.1% of all patients, conversions to laparoscopy or open surgery in 4.9%. In cholecystectomies, institutional case volume, obesity, and age had substantial effect on conversion rate, operation length, and length of hospital stay, but no effect on complications.

CONCLUSIONS

Despite the fact that NOTES has just recently been introduced, the technique has already gained considerable clinical application. Transvaginal hybrid NOTES cholecystectomy is a practicable and safe alternative to laparoscopic resection even in obese or older patients.

Preoperative CT staging in sigmoid diverticulitis--does it correlate with intraoperative and histological findings?

PURPOSE

This study was designed to evaluate whether the computed tomography (CT) reflects the extent of the inflammation in sigmoid diverticulitis (SD) in order to draw conclusions for selecting the appropriate treatment.

METHODS

Two hundred four patients who underwent resection for SD from January 2003 to December 2008 were included. The preoperative CT stage was compared with intraoperative and histological findings. Patients were classified into phlegmonous (Hansen-Stock IIa), abscess-forming (HS IIb), and free perforated (HS IIc) forms of SD. Patients with a recurrent type of diverticulitis were excluded.

RESULTS

In the phlegmonous type (HS IIa; n = 75), we found a correlation with the preoperative stage in 52% (intraoperative) and 56% (histological), an understaging in 12% (intraoperative) and 11% (histological), and an overstaging in 36% (intraoperative) and 33% (histological). In the abscess-forming type (HS IIb, Hinchey I/II; n = 87), we found conformity in 92% (intraoperative) and 90% (histological), understaging in 3% (intraoperative) and 0% (histological), and overstaging in 5% (intraoperative) and 10% (histological). In the presence of a free perforation (HS IIc, Hinchey III/IV; n = 42), we saw conformity in 100% (intraoperative and histological). The positive predictive value for correctly diagnosing of phlegmonous type (HS IIa), abscess-forming type (HS IIb), and free perforation (HS IIc) by CT was intraoperatively (histologically) 52% (56), 92% (90), and 100% (100), respectively.

CONCLUSIONS

The CT is one of the most accurate methods for staging in SD. However, in the phlegmonous type (HS IIa), it leads to an overestimation of the findings in every third patient. It must be clarified whether this pronounced low inflammation should really be regarded as a complicated form of SD. In contrast, the abscess-forming (HS IIb) and free perforated (HS IIc) type of complicated SD is very well reflected by CT.

Microscopic findings in sigmoid diverticulitis--changes after conservative therapy

INTRODUCTION

The indications for prophylactic surgery for phlegmonous and covered perforated type of acute sigmoid diverticulitis (SD) are currently matters of debate, and a more conservative approach has been advocated. However, it has not yet been clarified to what extent CT findings indicative of acute SD correlate with histological findings, and it is still uncertain how these findings change in the time interval between initial antibiotic treatment and late elective surgery. The aim of this study was to record time-course changes of inflammation in phlegmonous and abscess-forming diverticulitis after conservative treatment in order to check the indication for surgery.

MATERIAL AND METHODS

This study included all patients who underwent surgery for CT morphologically phlegmonous and covered perforated SD from January 2002 to June 2007. Two groups were formed to record time-course changes: early elective surgery (7-10 days after antibiotic treatment) and late elective surgery (4-6 weeks after conservative treatment). Exclusion criteria were emergency interventions, free perforations (Hinchey III and IV), recurrent inflammations, and contrast allergy. The extent of the inflammation recorded preoperatively by CT scan was compared with histological findings.

RESULTS

A total of 257 patients (142 male and 115 female; mean age, 56.6 years) underwent surgery (116 early elective and 141 late elective) for phlegmonous and covered perforated SD. Phlegmonous SD was seen in 127 cases and covered perforated SD in 130 cases. In the phlegmonous type of SD, early surgery led to conformity with the preoperative stage in 56%, to more extensive findings in 11%, and to subsided inflammation in 33%. Late surgery led to conformity in 0% and to signs of subsided inflammation in 100%. In the covered perforated type of SD, early surgery led to conformity in 90%, to subsided inflammation in 10%, and to milder manifestation in 0%. In contrast, late surgery here led to conformity in 26% of the cases and to subsided inflammation in 74%. Considerable histological changes can be detected under conservative therapy. The acute inflammation subsides under antibiotic therapy as awaited. It must be clarified whether the phlegmonous form of SD should, in principal, be regarded as an indication for surgery, since it shows early and nearly complete regression of the inflammation. Otherwise, the covered perforated type of SD still shows marked inflammatory changes after conservative therapy in a high percentage of patients and should thus preferably be treated by surgery. However, the clinical appearance of the patient with sigmoid diverticulitis still remains the most important part of decision making.

Fluid resuscitation with human albumin or hydroxyethyl starch--are there differences in the healing of experimental intestinal anastomoses?

OBJECTIVES

Restoration of the macro- and microcirculation is important for the healing of gastrointestinal anastomoses. Colloids and crystalloids are widely used for blood volume therapy. We evaluated the effects of human albumin, hydroxyethyl starch (HES) 130/0.4 and saline on the microcirculation and on wound healing in colon anastomoses in rats.

MATERIAL AND METHODS

Male Wistar rats received a colonic end-to-end anastomosis. The animals were randomized into three groups and a single 3-ml dose of either 20% human albumin, 6% HES 130/0.4 or 0.9% saline was applied intravenously. Six, 24, 48, 96 h and 2 weeks after the procedure, 10 animals per group were reanesthetized. Measurements of capillary blood flow, vessel permeability and anastomosis bursting pressure were performed. The amounts of vascular endothelial growth factor (VEGF) and IL-6 in the plasma were determined by enzyme-linked immunosorbent assays, and the mRNA levels of VEGF and collagen types I and III were measured by real-time polymerase chain reaction.

RESULTS

No significant differences were found between albumin, HES 130/0.4 and saline in capillary blood flow, vessel permeability and anastomotic bursting pressure in this rat model. Concentrations of collagen I and III mRNA were significantly elevated after 96 h in animals that had received HES 130/0.4 or albumin. RNA and protein levels of VEGF and interleukin-6 were unaffected by therapy.

CONCLUSIONS

Human albumin, which is still widely used in the clinical setting, had no advantage over HES 130/0.4 and saline with regard to anastomotic healing in this animal model. Nevertheless, we prefer HES 130/0.4 because it is more effective for volume therapy than saline and has a better availability and is less expensive than human albumin.

Pilot study of bipolar radiofrequency-induced anastomotic thermofusion-exploration of therapy parameters ex vivo

PURPOSE

Vessel sealing has been well-established in surgical practice in recent years. Bipolar radiofrequency-induced thermofusion (BIRTH) of intestinal tissue might replace traditionally used staples or sutures in the near future. In this experimental study, the influence of compressive pressure, fusion temperature, and duration of heating on the quality of intestinal anastomosis was investigated to obtain the relevant major parameters for the in vivo use of this system.

METHODS

An experimental setup for a closed-loop temperature-controlled bipolar radiofrequency-induced thermofusion of porcine intestinal tissue was developed. Twenty-four colon samples were harvested from nine different Saalower-Kräuter pigs and then anastomosed altering compressive pressure on five different levels to explore its influence on anastomotic bursting pressure.

RESULTS

The anastomotic bursting strength depends on the compressive pressure applied to the colonic fusion site. An optimal interval of compressive pressure (CP = 1.125 N/mm(2)) in respect of a high amount of burst pressure was detected. A correlation (r = 0.54, p = 0.015) of burst pressure to delta compression indicated that increasing colonic wall thickness probably strengthens the anastomotic fusion.

CONCLUSION

This study is a first step to enlighten the major parameters of tissue fusion, though effects and interactions of various main parameters of bipolar radiofrequency-induced thermofusion of colonic tissue remain unclear. Further studies exploring the main effects and interactions of tissue and process parameters to the quality of the fusion site have to follow.

Ex vivo and in vivo evaluation of laser-induced thermotherapy for nodular thyroid disease

BACKGROUND AND OBJECTIVE

The prevalence of thyroid nodules ranges between 2% and 60% depending on the population studied. However, minimally invasive procedures like laser-induced thermotherapy (LITT) are increasingly used to treat tumors of parenchymatous organs and seem to be suitable for singular thyroid nodules as well. Their successful clinical application depends on the induction of sufficiently large lesions and a knowledge of the energy parameters required for complete thermal ablation. The aim of this study was to establish a dose-response relationship for LITT of thyroid nodules.

MATERIALS AND METHODS

Thermal lesions were induced in healthy porcine thyroid glands ex vivo (n = 110) and in vivo (n = 10) using an Nd:YAG laser (1,064 nm). Laser energy was applied for 300 seconds in a power range of 10-20 W. During the ablation, continuous temperature measurement at a distance of 5 and 10 mm from the applicator was performed. The lesions were longitudinally and transversally measured, and the volume was calculated. Furthermore, enzyme histochemical analysis of the thyroid tissue was performed.

RESULTS

The maximum inducible lesion volumes were between 0.74 +/- 0.18 cm(3) at a laser power of 10 W and 3.80 +/- 0.41 cm(3) at 20 W. The maximum temperatures after ablation were between 72.9 +/- 2.9 degrees C (10 W) and 112.9 +/- 9.2 degrees C (20 W) at a distance of 5 mm and between 49.5 +/- 2.2 degrees C (10 W) and 73.2 +/- 6.7 degrees C (20 W) at a distance of 10 mm from the applicator. The histochemical analysis demonstrates a complete loss of NADPH dehydrogenase activity in thermal lesions as a sign of irreversible cell damage.

CONCLUSIONS

This study is the first to demonstrate a dose-response relationship for LITT of thyroid tissue. LITT is suitable for singular thyroid nodules and induces reproducible clinically relevant lesions with irreversible cell damage in an appropriate application time.

Bipolar radiofrequency ablation for nodular thyroid disease--ex vivo and in vivo evaluation of a dose-response relationship

BACKGROUND

The prevalence of thyroid nodules ranges between 2% and 60% depending on the population studied. However, minimally invasive procedures like radiofrequency ablation (rfA) are increasingly used to treat tumors of parenchymatous organs, and seem to be suitable for singular thyroid nodules as well. Their successful clinical application depends on the induction of sufficiently large lesions and a knowledge of the energy parameters required for complete thermal ablation. The aim of this study was to establish a dose-response relationship for rfA of thyroid nodules.

MATERIAL AND METHODS

Thermal lesions were induced in healthy porcine thyroid glands ex vivo (n=110) and in vivo (n=10) using a bipolar radiofrequency system; rf was applied in a power range of 10-20 watts. During the ablation, continuous temperature measurement at a distance of 5 and 10 mm from the applicator was performed. The transversal and axial lesion diameters were measured, and the volume was calculated. Furthermore, enzyme histochemical analysis of the thyroid tissue was performed.

RESULTS

The inducible lesion volumes were between 0.91±0.71 cm(3) at 20W and 2.80±0.85 cm(3) at 14W. The maximum temperatures after rf ablation were between 44.0±9.7°C and 61.6±13.9°C at a distance of 5 mm and between 30.0±8.6°C and 53.5±8.6°C at a distance of 10 mm from the applicator. The histochemical analysis demonstrates a complete loss of nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) dehydrogenase activity in thermal lesions as a sign of irreversible cell damage.

CONCLUSION

This study is the first to demonstrate a dose-response relationship for rfA of thyroid tissue. rfA is suitable for singular thyroid nodules and induces reproducible, clinically relevant lesions with irreversible cell damage in an appropriate application time.

Portal vein segmentation of a 3D-planning system for liver surgery--in vivo evaluation in a porcine model

BACKGROUND

Computer systems allow the planning of complex liver operations. The segmentation of intrahepatic vessels builds the basis for the calculation of liver segments and resection proposals. For surgical use, it is essential to know the capabilities and limitations of the segmentation. The aim of this study was to determine the sensitivity and precision of the portal vein segmentation of a computer planning system for liver surgery in vivo.

METHODS

Segmentations were performed with the software system HepaVision on computed tomography (CT) scan data of domestic pigs. An in situ corrosion cast of the portal vein served as the gold standard. The segmentation results of the portal vein and the corrosion cast were compared with regard to sensitivity, precision, and amount of short-circuit segmentations.

RESULTS

The methodology demonstrated high resolution ex situ. The in vivo sensitivity of the portal vein segmentation was 100% for vessels of more than 5 mm in diameter and 82% for vessels of 3-4 mm. All segment branches were detected as well as 84% of the first subsegment branches with a diameter of more than 3 mm. The precision of the system was 100% for segment branches and 89% for the first subsegment vessels. The amount of internal short-circuit segmentations was less than 3.0%. No external short-circuits were found.

CONCLUSION

The system has a high precision and sensitivity under clinical conditions. The segmentation is suitable for portal vein branches of the first and second order and for vessels of >/=3 mm in diameter.

Laser-induced thermotherapy for lung tissue—evaluation of two different internally cooled application systems for clinical use

Thermal ablation techniques like radiofrequency or laser-induced thermotherapy (LITT) are increasingly used to treat tumors of parenchymatous organs. Minimal access, parenchymal preservation, and a low complication rate render them suitable for pulmonary tumors as well. Their successful clinical application depends on the induction of sufficiently large lesions and a knowledge of the energy parameters required for complete thermal ablation. The aim of this study was to establish a dose-response relationship for a percutaneous and an intraoperative system for LITT of lung tissue. Thermal lesions were induced in healthy porcine lungs using an Nd:YAG laser (1,064 nm). LITT was performed with a percutaneous application system in group I (n = 18) and an intraoperative application system in group II (n = 90). Laser energy was applied for 600-1,200 s in a power range of 20-32 W (12,000-38,400 J). The lesions were longitudinally and transversally measured, and the volume was calculated after the intervention. Furthermore, an open application system was used to perform LITT under in vivo conditions during lung perfusion and ventilation in domestic pigs. Lesion volumes in both groups showed a plateau-like curve when the laser power increased from an initial level of 25 W. With the percutaneous puncture system (group I), the application of 28 W (16,800 J) for 10 min generated the largest lesions with a volume of 12.54 +/- 1.33 cm(3), an axial diameter of 39.33 +/- 2.52 mm, and a diametrical diameter of 24.67 +/- 1.15 mm. A longer application time was not possible due to thermal instability of the applicator. Moreover, group I started developing extensive carbonizations at a laser power of 22 W (13,200 J). The intraoperative application system (group II) achieved the largest lesion volumes of 11.03 +/- 2.54 cm(3) with diameters of 34.6 +/- 4.22 mm (axial) and 25.6 +/- 2.51 mm (diametrical) by an exposure time of 20 min and a power of 32 W (38,400 J). Here extensive carbonizations only started to occur at 28 W (33,600 J). Under in vivo conditions, all pigs tolerated the LITT procedure well without complications. Besides a typical cooling effect in the vicinity of blood vessels, the thermal lesions were about three times smaller than the ex vivo lesions. Both the percutaneous and the open LITT application system induced reproducible, clinically relevant lung lesions. The percutaneous puncture set generated large relevant lesions, although its usability is limited by its restricted capacity and high carbonization risk. It is suitable for powers up to 22 W. The intraoperative application system allows higher energy exposure to induce larger lesion volumes. This study elucidates the dose-effect relation of two clinically relevant puncture sets.

Improving laser-induced thermotherapy of liver metastases--effects of arterial microembolization and complete blood flow occlusion

INTRODUCTION

A prerequisite for an oncologically curative application of laser-induced thermotherapy (LITT) of liver metastases is complete tumor destruction. This increased effectiveness was achieved experimentally by combining LITT with interrupted hepatic perfusion. The aim of this study was to evaluate whether an interventional selective arterial microembolization might be as effective as complete blood flow occlusion using an open Pringle's maneuver.

PATIENTS AND METHODS

We included patients with unresectable colorectal liver metastases. LITT was performed without interrupted hepatic perfusion (control group) compared to LITT in combination with interrupted perfusion either by embolization of intraarterial degradable starch microspheres (DSM) (percutaneous access) or by complete hepatic inflow occlusion (Pringle's maneuver; open access). Online monitoring was performed using intraoperative ultrasound or MRI. Volumetric techniques were used to assess metastases and postinterventional lesions.

RESULTS

Fifty-six patients with 104 metastases (control group (25), DSM (37), and Pringle (42)) were treated. The preinterventional tumor volumes were significantly smaller than the postinterventional lesion volumes (control group: 9.8 vs. 25.3 cm3; DSM: 9.5 vs. 65.4 cm3; Pringle: 12.9 vs. 76.5 cm3). The morbidity rate was 21.4% without treatment-related mortalities. After 6 months follow-up, tumor recurrence was diagnosed in 6 patients (control group (4), LITT with DSM (1), and Pringle (1)).

CONCLUSIONS

Combining LITT with blood flow occlusion leads to a significant increase in lesion size. The application of DSM offers a safe and effective alternative to the open access with Pringle's maneuver. Compared to LITT-monotherapy, this modality achieves significantly larger thermal lesions with the need of fewer applications.

Optical properties of adenocarcinoma and squamous cell carcinoma of the gastroesophageal junction

Photodynamic therapy (PDT) is an alternative to radical surgical resection for T1a or nonresectable carcinomas of the gastroesophageal junction. Besides the concentration of the photosensitizer, the light distribution in tissue is responsible for tumor destruction. For this reason, knowledge about the behavior of light in healthy and dysplastic tissue is of great interest for careful irradiation scheduling. The aim of this study is to determine the optical parameters (OP) of healthy and carcinomatous tissue of the gastroesophageal junction in vitro to provide reproducible parameters for optimal dosimetry when applying PDT. A total of 36 tissue samples [adenocarcinoma tissue (n=21), squamous cell tissue (n=15)] are obtained from patients with carcinomas of the gastroesophageal junction. The optical parameters are measured in 10-nm steps using new integrating sphere spectrometers in the PDT-relevant wavelength range of 300 to 1140 nm and evaluated by inverse Monte-Carlo simulation. Additional examinations are done in healthy tissue from the surgical safety margin. In the wavelength range of frequently applied photosensitizers at 330, 630, and 650 nm, the absorption coefficient in tumor tissue (adenocarcinoma 1.22, 0.16, and 0.15 mm(-1); squamous cell carcinoma 1.48, 0.13, and 0.11 mm(-1)) is significantly lower than in healthy tissue (stomach 3.34, 0.26, and 0.20 mm(-1); esophagus 2.47, 0.21, and 0.18 mm(-1)). The scattering coefficient of all tissues decreases continuously with increasing wavelength (adenocarcinoma 22.8, 12.99, and 12.52 mm(-1); squamous cell carcinoma 19.44, 9.35, and 8.98 mm(-1); stomach 20.55, 13.96, and 13.94 mm(-1); esophagus 20.34, 12.56, and 12.22 mm(-1). All tissues show an anisotropy factor between 0.80 and 0.94 over the entire spectrum. The maximum optical penetration depth for all tissues is achieved in the range of 800 to 1100 nm. At the wavelength range of 330, 630, and 650 nm, the optical penetration depth is significantly higher in carcinoma tissue (adenocarcinoma 0.27, 1.54, and 1.66 mm; squamous cell carcinoma 0.23, 1.71, and 1.84 mm) than in healthy tissue (stomach 0.16, 1.10, and 1.26 mm; esophagus 0.17, 1.47, and 1.65 mm; p<0.05). Above 1000 nm, a higher absorption coefficient of tumor tissue results in a lower optical penetration depth than in healthy tissue (p<0.05). The higher absorption and scattering of the tumor tissue in the wavelength range of available photosensitizer is associated with a low optical penetration depth. This necessitates higher energy doses and long application times or repeated applications to effectively treat large tumor volumes. Photosensitizers optimized for larger wavelength range need to be developed to increase the efficacy of PDT.

Colorectal tumors and hepatic metastases differ in their optical properties—relevance for dosimetry in laser-induced interstitial thermotherapy

BACKGROUND AND OBJECTIVES

The therapeutic application of laser light is a promising alternative to surgical resection of colorectal liver metastases. The extent of tumor destruction achieved by this strategy depends primarily on light distribution in the target tissue. Knowledge about optical properties is necessary to predict light distribution in the tissue for careful irradiation planning. The aim of this study was to compare the optical behavior of healthy colon tissue with that of colorectal carcinomas and their hepatic metastases in the native and coagulated state in order to test the effect of malignant degeneration, metastasis, and thermal coagulation on optical parameters.

MATERIALS AND METHODS

Ninety tissue samples were taken from patients with a colorectal carcinoma and concomitant liver metastases: healthy colon tissue (n = 30); colon carcinoma (n = 30); liver metastases (n = 30). Optical properties were measured according to the single integrating sphere principle in the native state and after thermal coagulation in the wavelength range of 800-1,100 nm and analyzed by inverse Monte Carlo simulation.

RESULTS

The highest optical penetration depth for all tissue types was obtained at the end of the spectral range investigated. The highest penetration depths of 4.13 mm (healthy colon), 7.47 mm (colon carcinoma tissue), and 4.08 (liver metastases) were at 1,060 nm, although the values decreased significantly after thermal coagulation. Comparing healthy colon-to-colon carcinoma always revealed a significantly lower absorption and scattering coefficient in the tumor tissue. This resulted in a higher optical penetration depth of the laser light in the colon carcinoma tissue (P < 0.05). A direct comparison disclosed no agreement between the optical properties of the primary tumor and the liver metastases. In the native state, colon carcinoma tissue had a lower scattering coefficient (P < 0.05), higher anisotropy factor, and optical penetration depth than liver metastases (P < 0.05). The absorption coefficient did not differ significantly. The differences in the native state were equalized by tissue coagulation.

CONCLUSIONS

Colon carcinoma tissue has a higher optical penetration depth than healthy colon tissue, which speaks in favor of tumor selectivity for interstitial laser application, since large treatment volumes can be obtained in the tumor. The lack of agreement between primary tumors and their concomitant liver metastases indicates a modification of optical behavior through metastasis. Thermal coagulation of tissue leads to changes in the optical properties, which are clearly less pronounced in carcinoma tissue. The data obtained in this study clearly show that an individual irradiation schedule is necessary for effective and safe dosimetry in laser-induced thermotherapy (LITT).

Indirect calorimetry during treadmill walking--a study of two methods

Walking is a complex process and the physiotherapist must focus on physical signs as well as functional and practical tests to evaluate treatment. Measurement of energy expenditure during level walking is a useful objective parameter for assessing walking as being a valuable supplement to evaluate the outcome of physiotherapy. This study had two purposes. The first purpose was to investigate whether sampling and measurement of oxygen consumption were reproducible when using two different devices during walking on a treadmill. A second purpose was to find out whether the measurements were sensitive enough to reveal differences in energy expenditure and respiratory quotient (RO) during different walking speeds. Ten healthy students (mean age 22 years; range 20-25 years) volunteered in the test-retest of a slightly adjusted Deltatrac metabolic monitor. Thirteen volunteers (mean age 45 years; range 31-57 years) participated in the test-retest of Sensormedics 2900. In the first test, the subjects walked for 10 min in order to get a steady state both at an individual comfortable speed and at a preset speed. The retest was done with the same design and within 2 weeks. Nobody experienced any discomfort during the tests. The repeatability of measuring energy expenditure and RQ was acceptable for both methods and the methods were sensitive in revealing differences in energy expenditure during different walking speeds. The RQ were, however, too low when using the Deltatrac monitor, probably as a result of low air flow. We therefore conclude that only the method using Sensormedics 2900 may be used for the evaluation of energy expenditure during walking on a treadmill.