A toolbox for a structured risk-based prehabilitation program in major surgical oncology.

Prehabilitation is a multimodal concept to improve functional capability prior to surgery, so that the patients' resilience is strengthened to withstand any peri- and postoperative comorbidity. It covers physical activities, nutrition, and psychosocial wellbeing. The literature is heterogeneous in outcomes and definitions. In this scoping review, class 1 and 2 evidence was included to identify seven main aspects of prehabilitation for the treatment pathway: (i) risk assessment, (ii) FITT (frequency, interventions, time, type of exercise) principles of prehabilitation exercise, (iii) outcome measures, (iv) nutrition, (v) patient blood management, (vi) mental wellbeing, and (vii) economic potential. Recommendations include the risk of tumor progression due to delay of surgery. Patients undergoing prehabilitation should perceive risk assessment by structured, quantifiable, and validated tools like Risk Analysis Index, Charlson Comorbidity Index (CCI), American Society of Anesthesiology Score, or Eastern Co-operative Oncology Group scoring. Assessments should be repeated to quantify its effects. The most common types of exercise include breathing exercises and moderate- to high-intensity interval protocols. The program should have a duration of 3-6 weeks with 3-4 exercises per week that take 30-60 min. The 6-Minute Walking Testing is a valid and resource-saving tool to assess changes in aerobic capacity. Long-term assessment should include standardized outcome measurements (overall survival, 90-day survival, Dindo-Clavien/CCI®) to monitor the potential of up to 50% less morbidity. Finally, individual cost-revenue assessment can help assess health economics, confirming the hypothetic saving of $8 for treatment for $1 spent for prehabilitation. These recommendations should serve as a toolbox to generate hypotheses, discussion, and systematic approaches to develop clinical prehabilitation standards.

Impact of sleep deprivation on medium-term psychomotor and cognitive performance of surgeons: prospective cross-over study with a virtual surgery simulator and psychometric tests.

BACKGROUND: Despite recent work hour restrictions, 24-hour calls remain an important part of patient care. The aim of this study was to assess the impact of 24-hour night calls on the psychomotor and cognitive skills of surgeons with a virtual surgery simulator (VSS) and psychometric tests. We hypothesized that sleep loss impairs surgical skills and concentration performance. METHODS: Seventeen surgery residents (test group) and 13 medical students (reference group) performed a 5-day training program on the VSS. The test group was then assessed during a night call on 4 test points (8 am and 4 pm on the on-call day, 8 am on the postcall day, and 8 am on the recovery day) to assess the effects of sleep loss on these surgery residents. The reference group performed the same tests but without a night call. RESULTS: The training resulted in a homogenous performance level for both groups. The average time for the test group was 26 minutes. The analysis between rested and sleep-deprived participants (6.5 +/- 0.9 vs 2.9 +/- 1.4 hours of night sleep) in the on-call part showed no performance differences. No impairment was found for the VSS and the cognitive tests within the test group between the start of the working day and the start of the postcall day after the night of relative sleep loss. The subgroup analysis showed no significant differences regarding the amount of night sleep and laparoscopic experience. CONCLUSION: No performance impairment was found for surgeons with a VSS and standardized cognitive tests after a night of relative sleep loss. Although there is no doubt that sleep deprivation ultimately impairs human functioning, typical surgical skills do not necessarily deteriorate with a limited amount of sleep loss under clinical conditions.

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.

Oral vs intravenous antibiotic prophylaxis in elective laparoscopic cholecystectomy: an exploratory trial.

INTRODUCTION: The application of perioperative intravenous antibiotic prophylaxis is often considered a necessary routine procedure. The only way to decide whether an antibiotic prophylaxis is necessary in elective gallbladder surgery is to conduct a multicenter randomized trial. The aim of this exploratory trial was to clarify whether an oral application of an antibiotic prophylaxis is a feasible and safe procedure compared to intravenous application. This exploratory trial was conducted prospective randomized, using a double-dummy design. The main target criteria included tolerance, adverse effects, pharmacokinetics, and cost of treatment. MATERIAL AND METHODS: Patients undergoing elective laparoscopic cholecystectomy were randomized double-blinded to an oral or intravenous application group of one antibiotic (gyrase inhibitor) using a double-dummy design. Exclusion criteria were acute cholecystitis, icterus, and choledocholithiasis. In addition to a tolerance analysis, the antibiotic concentration was determined in serum and bile by high-pressure liquid chromatography (HPLC). RESULTS: One hundred fifty one patients (75 patients with oral and 76 with intravenous prophylaxis) were evaluated for the tolerance analysis. Four patients (1 p.o., 3 i.v.) had adverse reactions to the antibiotics. The antibiotic serum concentration was 0.83 mg/l (p.o.) vs 8.44 mg/l (i.v.) before surgery, 0.81 mg/l (p.o.) vs 4.43 mg/l (i.v.) during surgery, and 0.69 mg/l (p.o.) vs 2.77 mg/l (i.v.) after surgery. The bile concentration was higher after oral administration with 9.20 mg/l than after intravenous application with 5.79 mg/l. The costs of medication for intravenous application were 20 times higher than those for oral application. CONCLUSION: The oral application of an antibiotic (gyrase inhibitor) was feasible and safe for perioperative antibiotic prophylaxis in laparoscopic cholecystectomy in this exploratory trial.

What is the optimal time of surgical intervention after an acute attack of sigmoid diverticulitis: early or late elective laparoscopic resection?

PURPOSE: This prospective study was designed to check the ideal time of surgical intervention by comparing the results of early elective laparoscopic sigmoid resection after an inflammatory attack with those of late elective resection during the inflammation-free interval. METHODS: A total of 210 patients (114 males) underwent laparoscopic resection for acute sigmoid diverticulitis between 1999 and 2005. They were prospectively divided into two groups: Group I with an early elective sigmoid resection (5-8 days after initial antibiotic treatment); Group II in the inflammation-free interval (4-6 weeks after initial hospitalization). RESULTS: There was no difference between the groups with regard to age (55.7 years), American Society of Anesthesiologists score (1.86), previous diseases, and extent of inflammation. After surgery, 156 patients (74.3 percent) were complication-free. There was a total of ten conversions (Group I, 9; Group II, 1; P<0.05). Minor complications developed in 42 patients (abdominal wall abscess=24, intestinal atony=6, hematoma=9, urinary tract infection=2). Eight patients in Group I (P<0.05) developed anastomotic leaks. None of the patients died. CONCLUSIONS: In the majority of patients, laparoscopic sigmoid resection in sigmoid diverticulitis can be performed without conversion. Patients who underwent surgery in the inflammation-free interval had a lower complication rate than those submitted to early elective resection. In our patient population, we were able to show that surgery in the inflammation-free interval significantly reduces postoperative morbidity. It is thus preferable for patients with sigmoid diverticulitis to receive initial antibiotic treatment and then undergo late elective laparoscopic sigmoid resection.

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).

In-vivo evaluation of a novel bipolar radiofrequency device for interstitial thermotherapy of liver tumors during normal and interrupted hepatic perfusion.

BACKGROUND: Only monopolar systems have thus far been available for radiofrequency ablation of liver tumors, whose application is restricted because of the incalculable energy flow, reduction of electrical tissue conduction, and limited lesion size. The aim of this study was to evaluate a novel internally cooled bipolar radiofrequency application device under in vivo conditions and to compare the effect of this system on lesion size when combined with hepatic arterial microembolization or complete hepatic blood flow occlusion. MATERIALS AND METHODS: In a porcine liver model, RFA (60 W, 12 min) was performed with either normal (n = 12), partially interrupted (arterial microembolization via a hepatic artery catheter n = 12) or completely interrupted hepatic perfusion (Pringle's maneuver, n = 12). RFA parameters (impedance, power output, temperature, applied energy) were determined continuously during therapy. RFA lesions were macroscopically assessed after liver dissection. RESULTS: Bipolar RFA induced clinical relevant ellipsoid thermal lesions without complications. Hepatic inflow occlusion led to a 4.3-fold increase in lesion volume after arterial microembolization and a 5.8-fold increase after complete interruption (7.4 cm(3)versus 31.9 cm(3)versus 42.6 cm(3), P < 0.01). CONCLUSIONS: The novel bipolar RFA device is a safe and effective alternative to monopolar RFA-systems. Interrupting hepatic perfusion significantly increases lesion volumes in bipolar RFA. This beneficial effect can also be achieved in the percutaneous application mode by RFA combined with arterial microembolization via a hepatic artery catheter.

A prospective randomized study to test the transfer of basic psychomotor skills from virtual reality to physical reality in a comparable training setting.

OBJECTIVE: To test whether basic skills acquired on a virtual endoscopic surgery simulator are transferable from virtual reality to physical reality in a comparable training setting. SUMMARY BACKGROUND DATA: For surgical training in laparoscopic surgery, new training methods have to be developed that allow surgeons to first practice in a simulated setting before operating on real patients. A virtual endoscopic surgery trainer (VEST) has been developed within the framework of a joint project. Because of principal limitations of simulation techniques, it is essential to know whether training with this simulator is comparable to conventional training. METHODS: Devices used were the VEST system and a conventional video trainer (CVT). Two basic training tasks were constructed identically (a) as virtual tasks and (b) as mechanical models for the CVT. Test persons were divided into 2 groups each consisting of 12 novices and 4 experts. Each group carried out a defined training program over the course of 4 consecutive days on the VEST or the CVT, respectively. To test the transfer of skills, the groups switched devices on the 5th day. The main parameter was task completion time. RESULTS: The novices in both groups showed similar learning curves. The mean task completion times decreased significantly over the 4 training days of the study. The task completion times for the control task on Day 5 were significantly lower than on Days 1 and 2. The experts' task completion times were much lower than those of the novices. CONCLUSIONS: This study showed that training with a computer simulator, just as with the CVT, resulted in a reproducible training effect. The control task showed that skills learned in virtual reality are transferable to the physical reality of a CVT. The fact that the experts showed little improvement demonstrates that the simulation trains surgeons in basic laparoscopic skills learned in years of practice.