Intraluminal magnetisation of bowel by ferromagnetic particles for retraction and manipulation by magnetic probes.

Feasibility studies are needed to demonstrate that safe and effective manipulation of bowel during Minimal Access Surgery (MAS) can be obtained by use of magnetic force. This paper characterises two classes of magnetic particles: stainless steel microparticles (SS-µPs) and iron oxide nanoparticles (IO-nPs) in terms of their magnetisation, chemical composition, crystallinity, morphology and size distribution. Both magnetic particles were dispersed in a high viscosity biological liquid for intraluminal injection of bowel. Ex vivo porcine bowel segments were then retracted by permanent magnetic probes of 5.0 and 10mm diameter. Strong retraction forces reaching 6N maximum were obtained by magnetic fluid based on dispersion of SS-µPs. In contrast, the IO-nP-based magnetic liquid generated less attraction force, due to both lower magnetic and solution properties of the IO-nPs. The comparison of the two particles allowed the identification of the rules to engineer the next generation of particles. The results with SS-µPs provide proof on concept that intraluminal injection of magnetic fluid can generate sufficient force for efficient bowel retraction. Thereafter we shall carry out in vivo animal studies for efficacy and safety of both types of ferrofluids.

Technical review of the da Vinci surgical telemanipulator.

BACKGROUND: The da Vinci robotic surgical telemanipulator has been utilized in several surgical specialties for varied procedures, and the users' experiences have been widely published. To date, no detailed system technical analyses have been performed. METHODS: A detailed review was performed of all publications and patents about the technical aspects of the da Vinci robotic system. RESULTS: Published technical literature on the da Vinci system highlight strengths and weaknesses of the robot design. While the system facilitates complex surgical operations and has a low malfunction rate, the lack of haptic (especially tactile) feedback and collisions between the robotic arms remain the major limitations of the system. Accurate, preplanned positioning of access ports is essential. CONCLUSION: Knowledge of the technical aspects of the da Vinci robot is important for optimal use. We confirmed the excellent system functionality and ease of use for surgeons without an engineering background. Research and development of the surgical robot has been predominant in the literature. Future trends address robot miniaturization and intelligent control design.

BNNT-mediated irreversible electroporation: its potential on cancer cells.

Irreversible lethal electroporation (IRE) is a new non-thermal ablation modality that uses short pulses of high amplitude static electric fields (up 1000 V/cm) to create irreversible pores in the cell membrane, thus, causing cell death. Recently, IRE has emerged as a promising clinical modality for cancer disease treatment. Here, we investigated the responses of tumour human HeLa cells when subjected to IRE in the presence of BNNTs. These consist of tiny tubes of B and N atoms (arranged in hexagons) with diameters ranging from a 1 to 3 nanometres and lengths < 2 µm. BNNTs have attracted wide attention because of their unique electrical properties. We speculate that BNNTs, when interacting with cells exposed to static electrical fields, amplify locally the electric field, leading to cell death. In this work, electroporation assays were performed with a commercial electroporator using the cell- specific protocol suggested by the supplier (exponential decay wave, time constant 20 ms) with the specific aim to compare IRE in absence and in presence of BNNTs. We observed that BNNTs have the capacity to decrease substantially the voltage required for IRE. When cells were pulsed at 800 V/cm, we observed a 2,2-fold reduction in cell survival in the presence of BNNTs compared to controls. We conclude that the death of the tumour cells exposed to IRE is strongly enhanced in the presence of BNNTs, indicating their potential therapeutic application.

Errors in laparoscopic surgery: what surgeons should know.

Some two decades after its introduction, minimal access surgery (MAS) is still evolving. Undoubtedly, its significant uptake world wide is due to its clinical benefits to patient outcome. These benefits include reduced traumatic insult, reduction of pain, earlier return to bowel function, decrease disability, shorter hospitalization and better cosmetic results. Nonetheless complications due to the laparoscopic approach are not rare as documented by several studies on task specific or procedure related MAS morbidity. In all these instances, error analysis research has demonstrated that an understanding of the underlying causes of these complications requires a comprehensive approach addressing the entire system related to the procedure for identification and characterization of the errors ultimately responsible for the morbidity. The present review covers definition, taxonomy and incidence of errors in medicine with special reference to MAS. In addition, possible root causes of adverse events in laparoscopy are explored and existing methods to study errors are reviewed. Finally specific areas requiring further human factors research to enhance safety of patients undergoing laparoscopic operations are identified. The hope is that awareness of causes and mechanisms of errors may reduce incidence of errors in clinical practice for the final benefit of the patients.

Progress in nanotechnology for healthcare.

This review based on the Wickham lecture given by AC at the 2009 SMIT meeting in Sinaia outlines the progress made in nano-technology for healthcare. It describes in brief the nature of nano-materials and their unique properties which accounts for the significant research both in scientific institutions and industry for translation into new therapies embodied in the emerging field of nano-medicine. It stresses that the potential of nano-medicine to make significant inroads for more effective therapies both for life-threatening and life-disabling disorders will only be achieved by high-quality life science research. The first generation of passive nano-diagnostics based on nanoparticle contrast agents for magnetic resonance imaging is well established in clinical practice and new such contrast agents are undergoing early clinical evaluation. Likewise active (second generation) nano-therapies, exemplified by targeted control drug release systems are undergoing early clinical evaluation. The situation concerning other nano-materials such as carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs) is less advanced although considerable progress has been made on their coating for aqueous dispersion and functionalisation to enable carriage of drugs, genes and fluorescent markers. The main problem related to the clinical use of these nanotubes is that there is no consent among scientists on the fate of such nano-materials following injection or implantation in humans. Provided carbon nanotubes are manufactured to certain medical criteria (length around 1 mum, purity of 97-99% and low Fe content) they exhibit no cytotoxicity on cell cultures and demonstrate full bio-compatibility on in vivo animal studies. The results of recent experimental studies have demonstrated the potential of technologies based on CNTs for low voltage wireless electro-chemotherapy of tumours and for electro-stimulation therapies for cardiac, neurodegenerative and skeletal and visceral muscle disorders.

Hand-assisted laparoscopic surgery is associated with enhanced depth perception in novices.

BACKGROUND: The visual information obtained in hand-assisted laparoscopic surgery (HALS) and total laparoscopy is based on two-dimensional depth cues. This study was designed to test the hypothesis that intracorporeal hand improves depth perception in HALS. METHODS: Ten subjects were divided into two groups using HALS or total laparoscopy. The first task was passing a 10-cm thread through four small metallic loops five times; the second was tying 30 square three-throw intracorporeal laparoscopic knots. End points were (1) number of past pointing as an index of movement accuracy and reflection of depth perception, (2) execution time, and (3) knot quality score. RESULTS: The HALS group was significantly faster than total laparoscopy with a median (interquartile range (IQR)) of 117 s (75.5) vs. 179 s (235.5; P = 0.001) for the thread passing task and 97 s (43.3) vs. 130 s (68.3; P < 0.0005) for knot tying. The number of past-pointing events was significantly lower with HALS compared with total laparoscopy with a median (IQR) of 12 (8) vs. 23 (24; P = 0.001) for the thread passing task and 7 (5) vs. 13 (10; P < 0.0005) for knot tying. There was a significant main effect of whether the targeted object was in contact with the other instrument in knot tying task when past-pointing occurred (P = 0.031). No difference in a knot quality score was found between the HALS and total laparoscopy. CONCLUSIONS: The accuracy of instrument movement was significantly better in the HALS group compared with total laparoscopy. The study confirmed the hypothesis that intracorporeal hand improves depth perception in HALS. Also, the touch of the assisting instrument with the target object enhances spatial orientation in the laparoscopic operative field. However, further study is needed to test the hypothesis in experts.

Enhanced low voltage cell electropermeabilization by boron nitride nanotubes.

Boron nitride nanotubes (BNNTs) are a structural analogue of carbon nanotubes (CNTs), with alternating B and N atoms which entirely substitute for C atoms in a graphitic-like sheet with almost no change in atomic spacing. BNNTs have generated considerable interest within the scientific community by virtue of their unique properties. Very recently, biomedical applications of BNNTs have also been proposed. In the present in vitro study, we demonstrate that BNNTs can be used as nanotools to enable cell electropermeabilization with very low electric fields (40-60 V cm(-1)). An explanation of this behaviour based on the dielectric response of BNNTs to static electric fields is proposed.

Thermal spread and heat absorbance differences between open and laparoscopic surgeries during energized dissections by electrosurgical instruments.

BACKGROUND: The reported literature suggests a higher incidence of collateral damage during energized dissections in laparoscopic surgery than in open surgery, probably because the ambient environment of the two approaches causes different heat absorbance and thermal spread during energized dissection. METHODS: The experimental design involved randomized allocation of the surgical approach (4 open and 4 laparoscopic procedures) for eight adult pigs. A bipolar electrosurgery system (LigaSure) was used to perform 40 standardized regional dissections and procedures (5 per animal in randomized order). During these procedures, both white light and infrared thermographic imaging (3-5 mum) were recorded, and biopsy specimens were procured for histology. RESULTS: The core body temperatures were significantly different between the two approaches. The laparoscopic group had a smaller temperature drop (3.08 +/- 0.98 degrees C vs 1.9 +/- 0.72 degrees C; p = 0.03). Differences also were observed in the thermal spread between the laparoscopic and open groups during portal vein dissection with the Advance (1.7 +/- 0.2 mm vs 2.3 +/- 1.7 mm; p = 0.07). Both thermography and histology confirmed the safety of the LigaSure system in limiting thermal spread and necrosis at the fusion line. Significant degradation of the instruments began after 10 activations. The deterioration was faster and more extensive in laparoscopic surgery. CONCLUSIONS: Heat absorbance and thermal spread during bipolar electrosurgery are significantly different between open and laparoscopic surgery. Device performance degradation with repeat activations is more marked in laparoscopic surgery.

Influence of compression pressure from the hand access device on hand microcirculation during hand-assisted laparoscopic surgery.

BACKGROUND: Hand access devices in hand-assisted laparoscopic surgery depend on compression pressure to prevent air leakage. Surgeons frequently experience hand ache during surgery. This study aimed to test whether the pressure with such a device affects the microvascular function of the hand. METHODS: Eight healthy volunteers participated in this experimental study. The hand access device, applied to the forearm, was inflated to 0, 8, 12, and 16 mmHg in a random order, and the microvascular activity of the skin of the hand dorsum was quantified using laser Doppler and iontophoresis of increasing doses of acetylcholine (endothelial-dependent vasodilator) and sodium nitroprusside (endothelial-independent vasodilator). The end point was skin erythrocyte flux ratio as a measure of microvascular skin activity. RESULTS: No significant differences in microvascular responses to iontophoresis of acetylcholine and sodium nitroprusside were found at the four doses used when the hand access device was inflated at different pressures. The peak values for the hand allocated to acetylcholine were 3.48 +/- 1.33, 3.42 +/- 2.33, 3.38 +/- 2.55, and 2.84 +/- 3.10 arbitrary units, and the peak values for the hand allocated to sodium nitroprusside were 2.79 +/- 1.60, 2.00 +/- 1.60, 2.30 +/- 1.50, and 2.40 +/- 1.62 arbitrary units at cuff pressures of 0, 8, 12, and 16 mmHg, respectively. CONCLUSION: The pressure in the hand access device up to 16 mmHg does not affect the hand cutaneous microcirculation.

Cell creeping and controlled migration by magnetic carbon nanotubes.

Carbon nanotubes (CNTs) are tubular nanostructures that exhibit magnetic properties due to the metal catalyst impurities entrapped at their extremities during fabrication. When mammalian cells are cultured in a CNT-containing medium, the nanotubes interact with the cells, as a result of which, on exposure to a magnetic field, they are able to move cells towards the magnetic source. In the present paper, we report on a model that describes the dynamics of this mammalian cell movement in a magnetic field consequent on CNT attachment. The model is based on Bell's theory of unbinding dynamics of receptor-ligand bonds modified and validated by experimental data of the movement dynamics of mammalian cells cultured with nanotubes and exposed to a magnetic field, generated by a permanent magnet, in the vicinity of the cell culture wells. We demonstrate that when the applied magnetic force is below a critical value (about Fc ≈ 10-11 N), the cell 'creeps' very slowly on the culture dish at a very low velocity (10-20 nm/s) but becomes detached from the substrate when this critical magnetic force is exceeded and then move towards the magnetic source.

Extent of innate dexterity and ambidexterity across handedness and gender: Implications for training in laparoscopic surgery.

BACKGROUND: As innate dexterity is considered one of the important predictors of eventual operative competence, an experimental human factors study was conducted to determine innate dexterity and ambidexterity across handedness and gender. METHODS: 50 medical students (right-handed males, left-handed males, and right-handed females) were recruited as participants in a study designed to assess innate dexterity and degree of ambidexterity for endoscopic manipulations in a validated virtual-reality simulator. All participants performed unilateral and bilateral tasks with both dominant and nondominant hands in random sequence. The outcome measures were execution time, extent of ambidexterity (ambidexterity index), aiming errors, and maximum tissue damage. RESULTS: Right-handed males exhibited a greater level of ambidexterity than left-handed males (p = 0.02 for path length, p = 0.001 for angular path) and right-handed females (p = 0.01 for path length, p = 0.02 for angular path), and more-efficient task performance as measured by execution time (p = 0.001 for males and p = 0.03 across gender). The task quality when executed by the dominant hand was best in right-handed males (p = 0.001 vs. left-dominant males and p = 0.03 across gender). No significant difference was observed in terms of precision control and fine movements (aiming errors and maximum tissue damage) between the three groups. CONCLUSIONS: These findings indicate that training surgical curricula in laparoscopic surgery should be more flexible to accommodate the innate differences across handedness and gender.

Ideal manipulation angle and instrument length in hand-assisted laparoscopic surgery.

BACKGROUND: This study aimed to investigate the impact of manipulation angles and instrument length on task performance and muscle workload in hand-assisted laparoscopic surgery. METHODS: The standard task was to close a 5-cm enterotomy of porcine small bowel inside a hand-assisted laparoscopic trainer. Surgeons were instructed to place the sutures 3 to 5 mm apart and from the enterotomy edge. Ten surgeons participated in each experiment. In the first experiment, each surgeon performed one task for each of the following manipulation angles: 45 degrees , 60 degrees , 75 degrees , and 90 degrees . In the second experiment, each surgeon performed two sessions of three tasks using either standard-length (330 mm) or short (250 mm) needle holders in the external hand. Outcome measures were execution time (s), placement error score (mm deviation from exact placement), leaking pressure (mmHg), and muscle workload by upper extremities as measured by integrated electromyography (mV s). RESULTS: In the first experiments, the mean execution time was significantly longer with 90 degrees angles than with 45 degrees and 60 degrees manipulation angles (1,074.9 vs 715.9 s and 657.9 s with p < 0.05 and p < 0.01, respectively). The 90 degrees manipulation angle had the greatest muscle workload by the deltoid and trapezius of the extracorporeal and intracorporeal limbs and the extracorporeal dominant arm extensor and flexor groups. In the second experiment, the short instruments had a shorter mean execution time than the standard-length instrument (572.05 vs 618.75 s; p < 0.01). There was less muscle workload with the short than with the standard-length instrument by the extracorporeal dominant forearm extensor and flexor muscle groups and the deltoid of extracorporeal dominant and intracorporeal limbs. There were no significant differences in leaking pressure or placement error score between the different manipulation angles and instrument lengths. CONCLUSION: The best ergonomic setup in hand-assisted laparoscopic surgery entails a manipulation angle of 45 degrees to 60 degrees and use of an instrument with a shorter shaft than standard laparoscopic length.

Long-term comparative outcome between laparoscopic total Nissen and Toupet fundoplication: Symptomatic relief, patient satisfaction and quality of life.

BACKGROUND: Laparoscopic antireflux surgery has become an established method of treatment of gastroesophageal reflux disease. This study compares the long-term outcome of total (Nissen) and partial (Toupet) fundoplication, performed in a single institution, by evaluating symptoms and quality of life. METHODS: 266 patients who underwent laparoscopic Nissen or Toupet fundoplication completed a preoperative reflux symptom questionnaire. Postsurgery symptom evaluation, patient satisfaction and quality of life in reflux and dyspepsia (QOLRAD) questionnaires were sent to these patients in December 2004. The two groups were compared for each item nonparametrically. RESULTS: Completed questionnaires were received from 161 patients (61%) of whom 99 had a laparoscopic Nissen fundoplication and 62 laparoscopic Toupet fundoplication. Both procedures were equivalent in improving reflux symptom scores in the long term, 79/99 (80%) and 56/62 (90%) were either symptom free or had obtained significant symptomatic relief. Both groups had equivalent QoL scores on the QOLRAD questionnaire. An equivalent number of patients (86% and 83.9% after Nissen and Toupet, respectively) were sufficiently satisfied to recommend antireflux surgery to a friend or relative complaining of reflux symptoms. CONCLUSION: In conclusion, in patients who have returned the questionnaire, long-term satisfaction, general symptom scores, and quality of life are equivalent after laparoscopic Nissen (complete) or Toupet (partial) fundoplication. There is however, a significant increased prevalence of persistent heartburn after laparoscopic Toupet fundoplication.

Artificial neural network: predicted vs observed survival in patients with colonic cancer.

PURPOSE: An Internet-web-based artificial neural network has been developed for practicing clinical oncologists and medical researchers as part of an ongoing program designed for the implementation of advanced neural networks for prognostic estimates and eventually for management/treatment decisions in individual patients with colonic cancer. METHODS: An interdisciplinary team of academic oncologists and physicists has configured and implemented a Partial Logistic Artificial Neural Network and trained it to predict cancer-related survival in patients with confirmed colorectal cancer by using a database (1,558 patients) made available for the study by the Information & Statistics Division of National Health Service Scotland. The reliability of the trained network was evaluated against Kaplan-Meier observed survival plots of a random sample of 300 patients not used in the training but forming part of the same data set. RESULTS: The predicted survival curves obtained as the output from the artificial neural network showed close agreement with observed actual survival rates of a cohort of 300 patients with four grades of risk of dying from the cancer within five years of diagnosis. CONCLUSIONS: The web-based Partial Logistic Artificial Neural Network system accurately predicts survival after staging and treatment of colonic cancer. It can be made web-accessible where it is powerful enough to serve hundreds of users simultaneously.

Optimum view distance for laparoscopic surgery.

BACKGROUND: Proper visualization of the surgical field without fatigue is essential in laparoscopic surgery and reduces the risk of iatrogenic injuries. One of the important factors influencing visualization is the viewing distance between the surgeon and the monitor. This was the subject of the current investigation. METHODS: For this study, 14 surgeons participated in experiments designed to determine two working distances from a standard 34-cm (14 in. diagonal) cathode ray tube (CRT) monitor: (a) the maximum view distance permitting small prints of a near vision chart to be identified clearly by sight, (b) and the minimum view distance (of a standard resolution chart) just short of flicker, image degradation, or both. The range of the monitor optimal working distance for laparoscopic surgery was extrapolated from these data sets. RESULTS: The maximum view distance allowing identification of detail averaged 221 cm (range, 166-302 cm). The mean minimal view distance short of flicker/image degradation was 136 cm (range, 102-168 cm). The coefficient of variation for the two view distances was almost identical (18% vs 17%, respectively), and a frequency histogram confirmed the normality of the two data sets. Thus, for most surgeons, the extrapolated monitor view distances for laparoscopic surgery using a 14-in. diagonal (34-cm) monitor range from 139 to 303 cm (57-121 in.) for maximal distance viewing and from 90 to 182 cm (36-73 in.) for close-up viewing (i.e., a monitor optimal working distance ranging from 90 to 303 cm (36-121 in.). CONCLUSIONS: For most surgeons operating from a 14-in. diagonal CRT monitor, both the maximal and minimal (close-up) view distances are individually variable, but the surgeon should never be farther than 3 m (10 ft) or less than 0.9 m (3 ft) from the monitor. However, within limits, the maximal view distance increases with increasing monitor size. The limit for close-up distance is 0.9 m, irrespective of monitor size.

Mechanical properties of the human abdominal wall measured in vivo during insufflation for laparoscopic surgery.

BACKGROUND: Carbon dioxide insufflation of the peritoneal cavity for laparoscopic surgery offers a unique opportunity to measure some mechanical properties of the human abdominal wall that hitherto have been difficult to obtain. METHODS: The movement and change of the abdominal wall during insufflation to a pressure of 12 mmHg was studied in 18 patients undergoing laparoscopic surgery using a remote motion analysis system that does not compromise the sterility of the operative filed. These data together with the known abdominal wall thickness of each patient (measured by preoperative ultrasound scanning) enabled estimates of mechanical stiffness. RESULTS: The findings showed that the abdominal wall changes from a cylinder to a dome during inflation, and that its area is increased by 15%. A volume, averaging 1.27 x 10(-3)m(3), results from expansion, reshaping of the abdominal wall, and displacement of the diaphragm. The abdominal wall is stiffer in the transverse plane than in the sagittal plane (Young's modulus, 42.5 +/- 9.0 kPa vs 22.5 +/- 2.6 kPa; p = 0.03; paired t-test). CONCLUSIONS: Measurements of mechanical properties of the abdominal wall in patients undergoing laparoscopic surgery were obtained using a remote motion analysis system.

Free radical production in the esophago-gastro-duodenal mucosa in response to acid and bile.

Several studies have demonstrated the role of free radicals in causing esophagus-gastro-duodenal mucosal injury. The present study has been designed to investigate: whether acid, bile salts and a combination of bile + acid could determine the production of O2-derived free radicals by oesophageal, gastric and duodenal mucosa; which agent is capable of producing more free radicals and if O2-derived free radicals production depends on the duration of contact with acid, bile salts and their combination. Wistar rats' gastro-intestinal mucosa were perfused with bile, acid and a combination of bile + acid at pH4 and pH2 for 1 hour and 2 hours. Free radical production (FRP) was assessed by chemoluminescence. After 1 hour, the increase in FRP in comparison with control reached statistical significance (P < 0.05) at all tested pH levels in the duodenum, at pH1, 2 and 3 in the esophagus, and at pH1 in the stomach. Comparing different segments, both the esophagus and duodenum behaved similarly, producing more free radicals than the stomach at all pH values. However, this difference reached statistical significance at pH1 and 2 only. In comparison to control, FRP was increased by bile (pH7) infusion after 1 and 2 hours. There was increased FRP in all segments after the infusion of bile at pH2 and 4 in comparison to control. Infusion of bile at pH2 stimulates more FRP than infusion of bile at pH4 in all segments. This increased FRP reaches statistical significance in the esophagus after 2 hours of infusion, in the stomach after 1 and 2 hours of infusion, but in the duodenum it does not reach statistical significance. Acid, bile and bile + acid at pH2 and 4 can cause free radical production in esophageal, gastric and duodenal mucosa. Their role in producing free radicals is different according to the segment and the chemical composition of the solution.