Nigel Standfield

Patients with critical ischemia of the lower limb are at risk of developing kidney dysfunction.

BACKGROUND The aim of this study is to establish a relationship between critical ischemia of the lower limb and kidney dysfunction. MATERIALS AND METHODS At rest, urine samples were collected from three groups: group A, 16 patients with critical ischemia; group B, 22 patients with stable intermittent claudication; and group C, 12 normal individuals. Urinary N-acetyle-beta-D-glucosaminidase (NAG) enzyme was measured using spectrophotometer. Microalbuminuria was measured by radioimmunoassay. RESULTS There was a significant difference in the NAG activity between groups A and B, P = 0.001. Also, between group A and C, P = 0.01. There was no significant difference between groups B and C, P = 0.13. Microalbuminuria was not significantly different among the three groups: A versus B, P = 0.27; A versus C, P = 0.22; B versus C, P = 0.11. CONCLUSIONS Elevated levels of NAG enzyme in patients with critical ischemia of the lower limb suggest that they are at greater risk of developing kidney dysfunction. This could be caused by the release of more free radicals into the systemic circulation.

Training safer orthopedic surgeons. Construct validation of a virtual-reality simulator for hip fracture surgery.

Background and purpose — Virtual-reality (VR) simulation in orthopedic training is still in its infancy, and much of the work has been focused on arthroscopy. We evaluated the construct validity of a new VR trauma simulator for performing dynamic hip screw (DHS) fixation of a trochanteric femoral fracture. Patients and methods — 30 volunteers were divided into 3 groups according to the number of postgraduate (PG) years and the amount of clinical experience: novice (1–4 PG years; less than 10 DHS procedures); intermediate (5–12 PG years; 10–100 procedures); expert (> 12 PG years; > 100 procedures). Each participant performed a DHS procedure and objective performance metrics were recorded. These data were analyzed with each performance metric taken as the dependent variable in 3 regression models. Results — There were statistically significant differences in performance between groups for (1) number of attempts at guide-wire insertion, (2) total fluoroscopy time, (3) tip-apex distance, (4) probability of screw cutout, and (5) overall simulator score. The intermediate group performed the procedure most quickly, with the lowest fluoroscopy time, the lowest tip-apex distance, the lowest probability of cutout, and the highest simulator score, which correlated with their frequency of exposure to running the trauma lists for hip fracture surgery. Interpretation — This study demonstrates the construct validity of a haptic VR trauma simulator with surgeons undertaking the procedure most frequently performing best on the simulator. VR simulation may be a means of addressing restrictions on working hours and allows trainees to practice technical tasks without putting patients at risk. The VR DHS simulator evaluated in this study may provide valid assessment of technical skill.

Validation of open inguinal hernia repair simulation model: a randomized controlled educational trial

BACKGROUND A hernia repair open surgical simulation computer software was developed at Imperial College London. A randomized controlled educational trial was conducted to investigate the benefit of the simulation on the development of procedural knowledge. METHODS Medical students in their clinical years were invited to participate in the trial. Students were block randomized to 4 groups: G1--Interactive Simulation; G2--Non-interactive Simulation; G3--Video Tutorial; G4--Control. On completion, they were objectively assessed on their ability to recall the tasks involved in an open inguinal hernia repair in the form of a multiple choice question (MCQ) and a simulated discussion with a consultant surgeon. RESULTS Fifty-six students completed the study. Each arm carries similar baseline scores (pre-intervention MCQ) with means 43.33, 38.92, 38.33, and 39.57 in G1 to G4, respectively. MCQ score improvements and final assessment scores proved better in the intervention groups (1, 2, and 3) compared to controls. CONCLUSION The interactive simulation has shown an objective benefit in teaching medical students the anatomical and procedural knowledge in performing an open inguinal hernia repair.

Impaired Hyperaemic and Rhythmic Vasomotor Response in Type 1 Diabetes Mellitus Patients: A Predictor of Early Peripheral Vascular Disease

OBJECTIVES The smooth muscle of distal vascular networks exhibits periodical contraction and relaxation known as rhythmical vasomotion. The nature of microvascular vasomotion has been shown to correlate with severity of peripheral vascular disease. We present basal and post-ischaemic hyperaemic laser doppler flowmetry vasomotion in control and type 1 adult diabetic patients. DESIGN Prospective case control study. METHODS Laser Doppler flowmetry was used to measure vasomotion and hyperaemic responses in age and body mass index matched male subjects (25 type 1 Diabetes Mellitus and 13 controls), all with ankle/brachial pressure index (ABPI) >1.0 but <1.2. RESULTS The frequency of resting vasomotion was raised in diabetics compared to controls 8 (5-9)min(-1) vs. 5 (4-6)min(-1) (median (range); p<0.0001). The post ischaemic hyperaemia response was significantly higher in the diabetic group compared to the controls 11 (7-12)min(-1) vs. 6 (5-7)min(-1) (median (range); p<0.05). Post ischaemic hyperaemic flux (expressed as percent increase from resting) was significantly lower in the diabetic group compared to controls (234+/-62 vs. 453+/-155%, p<0.01). The time to achieve peak post ischaemic response was also significantly increased in the diabetic group compared to control: 21.4+/-0.4 vs. 12.8+/-5.4sec (mean+/-SD, p<0.05). CONCLUSIONS Vasomotion frequency and its change during hyperaemic insult is significantly different in Type 1 Diabetes Mellitus subjects compared to controls. The results are similar to patients with macrovascular atherosclerosis. Long term studies of these groups of patients will be required to determine the significance of these findings and whether these changes could be used as a non invasive screening test to predict peripheral early vascular disease in type 1 diabetic patients.

Changes in vascular flow after transdermal oestradiol therapy for prostate cancer: a mechanism for cardiovascular toxicity and benefit?

To report the influence of transdermal oestradiol therapy on the vascular dynamics of men with advanced prostate cancer.

Variation in duplex peak systolic velocity measurement in a multi-site vascular service

Objective: Duplex US (DUS) is increasingly utilised as a first-line investigation for the assessment of carotid disease. For clinical decision-making, DUS assessment must be accurate and reproducible to ensure reliability. We aimed to investigate the variability in peak systolic velocity (PSV) measurement in a multi-site vascular network. Methods: DUS measurements of PSV were taken from continuous and pulsatile flow, generated by a high fidelity phantom, by 12 experienced vascular scientists across four hospitals. Participants were blinded to the actual PSV value (50 cm/s). Results: We observed an average error of 13.2% (± 8.3) and 11.6% (± 7.5) in PSV measurements taken from pulsatile and continuous waveforms, respectively. Measurements of PSV using the pulsatile waveform demonstrated statistically significant variation across all hospitals; ((hospital/mean) A 43.9 cm/s, B 61.7 cm/s, C 57.4 cm/s, D 47.7 cm/s, p=0.001). Further analysis demonstrated statistically significant variation in 4 instrumentation-related factors when measuring from a pulsatile waveform (Doppler angle, angle of insonation, velocity range, scale range). Conclusion: We observed a significant level of error and variation in PSV measurements across four sites within our vascular network. Variation in instrumentation-related factors may be accountable for this. In light of the centralisation of vascular services, it is increasingly important to unify and implement scanning protocols in order to reduce error and inter-site variability.

Training safer surgeons: How do patients view the role of simulation in orthopaedic training?

BackgroundSimulation allows training without posing risk to patient safety. It has developed in response to the demand for patient safety and the reduced training times for surgeons. Whilst there is an increasing role of simulation in orthopaedic training, the perception of patients and the general public of this novel method is yet unknown. Patients and the public were given the opportunity to perform a diagnostic knee arthroscopy on a virtual reality ARTHRO Mentor simulator. After their practice session, participants answered a validated questionnaire based on a 5-point Likert Scale assessing their opinions on arthroscopic simulation. Primary objective was observing perception of patients on orthopaedic virtual reality simulation.FindingsThere were a total of 159 respondents, of which 86% were of the opinion that simulators are widely used in surgical training and 94% felt that they should be compulsory. 91% would feel safer having an operation by a surgeon trained on simulators, 87% desired their surgeon to be trained on simulators and 72% believed that additional simulator training resulted in better surgeons. Moreover, none of the respondents would want their operation to be performed by a surgeon who had not trained on a simulator. Cronbach’s alpha was 0.969.ConclusionsThere is also a clear public consensus for this method of training to be more widely utilised and it would enhance public perception of safer training of orthopaedic surgeons. This study of public perception provides a mandate to increase investment and infrastructure in orthopaedic simulation as part of promoting clinical governance.

The Effect of a Simulation Training Package on Skill Acquisition for Duplex Arterial Stenosis Detection

OBJECTIVES In vascular surgery, duplex ultrasonography is a valuable diagnostic tool in patients with peripheral vascular disease, and there is increasing demand for vascular surgeons to be able to perform duplex scanning. This study evaluates the role of a novel simulation training package on vascular ultrasound (US) skill acquisition. MATERIALS AND METHODS A total of 19 novices measured predefined stenosis in a simulated pulsatile vessel using both peak systolic velocity ratio (PSVR) and diameter reduction (DR) methods before and after a short period of training using a simulated training package. The training package consisted of a simulated pulsatile vessel phantom, a set of instructional videos, duplex ultrasound objective structured assessment of technical skills (DUOSATS) tool, and a portable US scanner. Quantitative metrics (procedure time, percentage error using PSVR and DR methods, DUOSAT scores, and global rating scores) before and after training were compared. RESULTS Subjects spent a median time of 144 mins (IQR: 60-195) training using the simulation package. Subjects exhibited statistically significant improvements when comparing pretraining and posttraining DUOSAT scores (pretraining = 17 [16-19.3] vs posttraining = 30 [27.8-31.8]; p < 0.01), global rating score (pretraining = 1 [1-2] vs posttraining = 4 [3.8-4]; p < 0.01), percentage error using both the DR (pretraining = 12.6% [9-29.6] vs posttraining = 10.3% [8.9-11.1]; p = 0.03) and PSVR (pretraining = 60% [40-60] vs posttraining = 20% [6.7-20]; p < 0.01) methods. CONCLUSION In this study, subjects with no previous practical US experience developed the ability to both acquire and interpret arterial duplex images in a pulsatile simulated phantom following a short period of goal direct training using a simulation training package. A simulation training package may be a valuable tool for integration into a vascular training program. However, further work is needed to explore whether these newly attained skills are translated into clinical assessment.

Surgical Trainee Opinions in the United Kingdom Regarding a Three-Dimensional Virtual Mentoring Environment (MentorSL) in Second Life: Pilot Study

Background Medical mentoring is becoming increasingly complex with the evolving needs of trainees and the complexities of their personal and social lives. The Internet is an enabling technology, which increasingly facilitates interaction with multiple people at a distance. Web 2.0 and 3.0 technology shows promise in furthering this facilitation. Objective The objective of our study was to establish opinions among doctors in postgraduate surgical training regarding mentoring and whether these doctors would readily accept virtual mentoring following a brief experience. Methods On the 12th of February 2012, an introductory teaching class was arranged by The London Postgraduate School of Surgery for doctors in training. Participants were introduced to a novel virtual mentoring system and asked to complete a questionnaire regarding their opinions before and after the demonstration. Results A total of 57 junior doctors attended. Among them, 35 completed questionnaires pre- and postdemonstration. Regarding usefulness of a 3D virtual environment for mentoring, 6/35 (17%) agreed or strongly agreed and 20/35 (57%) were unsure prior to the session. Following 20 minutes using MentorSL, this significantly increased to 14/35 (40%) agreeing or strongly agreeing with 11/35 (31%) unsure (P<.001). Prior to using MentorSL, regarding usefulness of voice communication for virtual mentoring, 11/35 (31%) agreed or strongly agreed and 18/35 (51%) were unsure. Following 20 minutes using MentorSL, 19/35 (54%) agreed or strongly agreed and 10/35 (29%) were unsure of usefulness. Regarding ease of use of navigation, search mentor, meeting scheduling, and voice communication features, 17/35 (49%), 13/35 (37%), 15/35 (43%), and 16/35 (46%) participants agreed or strongly agreed, respectively. Regarding usefulness of telementoring, 24/35 (69%) agreed or strongly agreed, increasing to 28/35 (80%) following the introduction. For usefulness of multiple mentors, initially 24/35 (69%) agreed or strongly agreed increasing to 29/35 (83%). For overall satisfaction, 30/35 (86%) reported good or adequate and 19/35 (54%) agreed or strongly agreed with using the system again. Conclusions These data suggest that a short introduction on how to use virtual systems may result in significant participation and use of virtual mentoring systems.

The Transferability of Generic Minimally Invasive Surgical Skills: Is There Crossover of Core Skills Between Laparoscopy and Arthroscopy?

OBJECTIVE The primary objective was observing transferability of minimally invasive surgical skills between virtual reality simulators for laparoscopy and arthroscopy. Secondary objectives were to assess face validity and acceptability. DESIGN Prospective single-blinded crossover randomized controlled trial. SETTING MSk Laboratory, Imperial College London. PARTICIPANTS Student doctors naïve to simulation and minimally invasive techniques. METHODS A total of 72 medical students were randomized into 4 groups (2 control groups and 2 training groups), and tested on haptic virtual reality simulators. Group 1 (control; n = 16) performed a partial laparoscopic cholecystectomy and Group 2 (control; n = 16) performed a diagnostic knee arthroscopy. Both groups then repeated the same task a week later. Group 3 (training; n = 20) completed a partial laparoscopic cholecystectomy, followed by an arthroscopic training program, and repeated the laparoscopic cholecystectomy a week later. Group 4 (training; n = 20) performed a diagnostic knee arthroscopy, followed by a laparoscopic training program, and then repeated the initial arthroscopic test a week later. The time taken, instrument path length, and speed were recorded for each participant and analyzed. RESULTS Time taken for task: All 4 cohorts were significantly quicker on their second attempt but the 2 training groups outperformed the 2 control groups, with the laparoscopy-trained group improving the most (p < 0.05). Economy of movement: All cohorts had a significant improvement in left hand path length (p < 0.01) but there was no difference for right hand path length. Left hand speed: Only the 2 training groups showed significant improvement with the laparoscopy-trained group improving the most (p < 0.05). Right hand speed: All cohorts improved significantly with the laparoscopy-trained group improving the most (p < 0.05). Face validity and acceptability were established for both simulators. CONCLUSION This study showed that minimally invasive surgical skills learnt on a laparoscopy simulator are transferable to arthroscopy and vice versa, with greater effect after training on the laparoscopy simulator.