Importance of cutaneous cooling during photothermal epilation: theoretical and practical considerations

BACKGROUND AND OBJECTIVES: Sapphire contact cooling is widely used to prevent non-specific epidermal injury from occurring during selective laser treatment of unwanted hair and vascular lesions. This small study was performed to examine the clinical response of the skin to 800-nm laser irradiation with varying extent of cutaneous sapphire contact cooling. Observed clinical responses are compared to those predicted by theoretical analysis in an attempt to construct a more complete picture of sapphire contact cooling and its role in preventing non-targeted tissue devitalization during laser treatment of the skin using a wavelength, pulse duration, and radiant exposure commonly used for laser hair removal. STUDY DESIGN/MATERIALS AND METHODS: Three subjects each received a total of three pulses of laser light (800 nm) of equal radiant exposure (60 J/cm(2)), pulse duration (30 msec), and spot size (9 mm x 9 mm), but with varying extent of cutaneous cooling. One site was pre-cooled and heat-sinked with a chilled (5 degrees C) sapphire window in contact with the skin; another site was heat-sinked only with a room-temperature (20 degrees C) sapphire window in contact with the skin; and a third site received no pre-cooling or heat-sinking. Each site was examined immediately after treatment and at intervals throughout a 3-month period. The thermal response of the tissue was calculated in each case using a Monte Carlo model for light transport in multi-layered tissues coupled with an axisymmetric finite-difference heat diffusion model. Thermal injury was modeled as a first-order kinetic rate process using an Arrhenius expression. RESULTS: In all three subjects, the sites that were pre-cooled and heat-sinked showed no evidence of epidermal or dermal devitalization. The three sites that were heat-sinked only had a few patches of perifollicular epidermal devitalization and subsequent desquamation without any permanent epidermal or dermal injury, as would be evidenced by pigmentary alteration or textural change. In each subject, the site that received no pre-cooling or heat-sinking sustained epidermal and dermal devitalization, appearing as ulceration and resulting in sustained erythema and textural alteration. Clinical responses predicted by theoretical analysis agree with the clinical observations and show that the dominant effect of sapphire contact cooling for pulse durations of 30 msec or less is the reduction of fluence within the epidermis resulting from index matching at the skin surface. CONCLUSIONS: The results of this small study suggest that by judiciously selecting the laser pulse duration and pre-cooling and heat-sinking the epidermis in a manner that provides index matching and compression of the skin, epidermal damage can be avoided while administering the highest, most effective radiant exposures.     

Measurement of laparoscopic skills in microgravity anticipates the space surgeon

BACKGROUND: There clearly must be a surgical capability to support the exploration of the solar system by humans. We hypothesized that microgravity would impair surgical task performance and sought to measure degree and criticality of task erosion. METHODS: Twenty subjects performed basic laparoscopic exercises (grasping, cutting, clipping, and suturing) in an inanimate trainer on the ground and during the microgravity phase of a parabolic flight. Skill assessment involved time, accuracy, and force transfer. RESULTS: A decrease in the total number of on-target task completions was observed in microgravity compared with the ground performance for all tasks. The ratio between the total number of attempts and the number of completions was higher in microgravity. The amount of force introduced into the system was not significantly higher in microgravity. CONCLUSIONS: We conclude that although tasks are performed with much greater deliberation and work in microgravity, there is no barrier to accurate and effective laparoscopic surgery.     

Evaluation of face-mounted binocular video display for laparoscopy: outcomes of psychometric skills testing and surgeon satisfaction

OBJECTIVES: Improved digital video cameras and high-resolution video displays have greatly enhanced laparoscopic surgery. However, the size and distance of the video display and the location of the monitor continue to be impediments in laparoscopy, providing unsatisfactory operative visualization and causing the development of neck and back strain in surgeons performing long procedures. The purpose of this study was to evaluate the use of a face-mounted binocular high-resolution video display by means of standardized measurements of laparoscopic skill, and to compare procedure speed and surgeon satisfaction with the binocular display, open operative visualization, and standard laparoscopic monitor views. METHODS: The surgical faculty and resident trainees (n = 22) underwent two standardized laparoscopic psychometric skills tests of fine motor control and bimanual operative facility. Testing was performed first with the use of laparoscopic instruments in direct view of the participants; sufficient repetitions were allowed so that plateau levels were obtained in task speed. Video camera-based imaging displayed on the face-mounted binocular video display and a standard video monitor were then used to repeat identical tests. Test times were compared between the open view, face-mounted display (FMD) view, and standard laparoscopic monitor view groups. A Likert-scale based assessment was conducted to examine operator impressions of neck and back strain, visual acuity, and overall satisfaction. RESULTS: Performance with the standard laparoscopic monitor was significantly slower than with the direct view on both fine motor (mean, 85.0 +/- 7.1 s vs. 56.4 +/- 5.7 s; P <.0001) and bimanual (mean, 80.8 +/- 7.0 s vs. 40.2 +/- 2.6 s; P =.009) psychometric skills tests. The FMD view performance was significantly faster than the standard laparoscopic monitor performance for both the bimanual (mean, 72.2 +/- 7.6 s vs. 85.0 +/- 7.2 s; P =.001) and fine motor (mean, 59.3 +/- 4.7 s vs. 80.8 +/- 7.0 s; P =.004) tests. The scores on a Likert Scale satisfaction survey of the use of the FMD unit for neck and back strain (mean, 4.27 +/- 0.20), visual acuity (mean, 3.93 +/- 0.10), and overall satisfaction (mean, 4.16 +/- 0.20) were high (scale: 1, worst; 5, ideal). CONCLUSIONS: A face-mounted high-resolution video display unit reduces neck and back strain and improves both visualization and overall satisfaction in comparison with standard laparoscopic display monitors; surgical performance is better than with standard laparoscopic imaging as assessed by standardized psychometric skills testing.     

Evaluation of laparoscopic skills: a 2-year follow-up during residency training.

OBJECTIVE: To evaluate laparoscopic technical skill in surgical residents over a 2-year period. DESIGN: The laparoscopic technical skills of general surgical residents were evaluated using the MISTELS program. This provides an objective evaluation of laparoscopic skill, taking into account precision and speed. SETTING: Inanimate laparoscopic skills centre. PARTICIPANTS: Ten general surgical residents (5 PGY1, 3 PGY2 and 2 PGY3 residents) who were required to complete 3 structured laparoscopic tasks. OUTCOME MEASURES: A composite score incorporating precision and timing was assigned to each task. The paired t-test was used to compare performance of each resident at the 2 levels of their residency training for each task. Linear regression analysis was used to correlated level of training and total score (sum of all tasks). RESULTS: Linear regression analysis demonstrated a highly significant correlation between level of training and total score (r = 0.82, p < 0.01). There was a significant increase in scores in the cutting and suturing task over the 2-year period (p < 0.01). Transferring skills did not improve significantly (p = 0.11). CONCLUSIONS: Performance in the simulator improved over residency training and was correlated highly with postgraduate year. This simulator model is a valuable teaching tool for training and evaluation of basic laparoscopic tasks in laparoscopic surgery.     

Evaluation of students' physical examination skills during their surgery clerkship

BACKGROUND: Faculty often presume that students possess adequate physical examination skills upon graduation. Yet assessments of their performance with these skills often reveal deficiencies. This study was designed to determine if students' physical examination skills improved during their clerkship year. METHODS: Sixty-six students performed four specific physical examinations on patients during the first and last week of their surgery clerkship. Four consecutive clerkship rotations were examined. Encounters were videotaped and evaluated by faculty members. RESULTS: Posttest mean percent correct scores significantly improved for three examinations (P <0.01). Analysis of variance found no significant differences between clerkship mean percent correct scores. CONCLUSIONS: Students' physical examination skills improved slightly during their clerkship, however, no relationship was found between clerkship rotation and performance. These findings suggest unsupervised experiences during the third year do not positively influence student performance with physical examination skill proficiency.     

Funnel plots and spine surgery: unit level and surgeon level outcome data

European Spine Journal -     

Residents lack knowledge and practical skills in handling the difficult airway

BACKGROUND: Full-scale simulators have been developed in anaesthesia. We aimed at assessing Danish anaesthesia residents' knowledge and management of a standardized difficult airway situation in an advanced airway simulator. The reliability of the assessment was also determined. METHODS: Thirty-six residents answered a questionnaire testing their knowledge on difficult airway management and practice patterns. Secondly, all residents attempted management of a standardized 'cannot ventilate, cannot intubate' airway scenario. Three observers independently assessed a video recording of the performance. RESULTS: Only 17% of the residents passed the written test. Ninety-seven per cent stated that they had difficulties recalling the American Society of Anesthesiologists'(ASA) difficult airway algorithm and 53% did not know how to oxygenate through the cricothyroid membrane. Seventeen per cent had previously been involved in emergency situations with severe complications due to insufficient airway management. In the scenario 75% of the residents established ventilation using a laryngeal mask airway. After establishing ventilation, 26% would continue with surgery without a definitive airway, despite the risk of aspiration. Analysis of the interobserver agreement showed good (Kappa = 0.63) to excellent (Kappa = 0.78) consistency for objective parameters in the scoring scheme. Inter-observer reliability was satisfactory (R = 0.43) for trained Crisis Resource Management evaluators. CONCLUSIONS: Theoretical and practical education in difficult airway management needs to be improved among Danish anaesthesia residents. Simulator assessment should only be performed using well-defined objective parameters and trained assessors.     

Expert practical operative skills teaching in Trauma and Orthopaedics at a nominal cost

Background and purposeThe AO Foundation Operative Fracture Management course is the gold standard in training courses currently available for trainees at ST3 level. We have devised a low cost operative skills course comprising instructional lectures, demonstrations and practical dry bone workshops. To assess the quality of teaching, candidates’ feedback was analysed in two cohorts for the running of the course over two consecutive years: 2008 and 2009.MethodsTrainees were given short instructional lectures by consultant surgeons followed by workshops, with a trainer to candidate ratio of 1:4. A trauma inventory was provided by Stryker Trauma UK, ensuring a nominal fee for each candidate (£50). Feedback was anonymously collected according to a Likert scale and analysed using non-parametric methods appropriate for ranked data.Main findingsTwenty one of 22 (95%) candidates gave feedback in 2008 and 18 out of 18 candidates (100%) in 2009. The teaching provided was highly rated consistently for both years, apart from an informal session on theatre tips and tricks in 2008. This was not repeated in 2009 to allow more practical time. Only one session, an intramedullary nailing lecture, had a significant difference in scores between the 2 years (p = 0.044) because of improved scores in 2009.ConclusionsDue to changes in training, trainees have reduced exposure in theatre and this has implications for the early stages of acquiring practical operative skills. As an adjunct to the AO course, practical skills teaching by consultants in the format of a low cost skills workshop outside of a theatre environment can be achieved with support from a trauma implant supplier.     

Perceived effects of deployments on surgeon and physician skills in the US Army Medical Department

Background

The military health care system is unique in that almost every physician deploys for ≥6 months to a combat or far-forward setting. The aim of this study was to determine the perceived changes in clinical skills in this deployed population.

Methods

A survey was sent out to all specialty consultants to the Army Surgeon General to query active duty staff physicians in their specialty areas who have deployment experience in August 2007. Questions concerning specialty, length of deployment, perceived changes in skills, skill use while deployed, and time to get back to baseline clinically after deployment were asked.

Results

Surveys were sent to approximately 1,500 physicians, of which 673 were usable, for a 45% response rate. More than 70% of respondents were deployed for >6 months. Fifty-nine percent reported that they were used in their specialties <40% of the time deployed. Surgeons rated surgical skills before and after deployment as 6.0 ± 1.0 and 4.0 ± 1.5, respectively (on a 7-point, Likert-type scale ranging from 1 = worst to 7 = best; P = .001). Most felt that the time needed to get back to predeployment skill levels was 1 to 6 months.

Conclusions

There was significant perceived degradation in both the surgical and clinical skills of those deploying for >6 months, and the degradation was correlated with the length of time deployed. Most surgical specialists felt that it took them 3 to 6 months to return to their clinical and surgical performance baseline upon returning from a deployment and that 6 months was the most amount of time they could be deployed without a significant decrement in skills.     

Cinoxacin in urinary tract infections theoretical and practical considerations

In dogs we found that cinoxacin concentrations in prostatic tissue, secretion, and interstitial fluid always were lower than the simultaneous serum concentrations, during constant infusion experiments. The cinoxacin concentrations in urethral and vaginal secretions were similar to those found in prostatic interstitial fluid, approximately one third to one fourth of the simultaneous serum concentrations. The concentrations of cinoxacin in human prostatic tissue after single or multiple doses of 500 mg. were found to be in the range of minimum inhibitory concentrations for most microorganisms found in urinary tract infections. Cinoxacin was found to have a half-life of 2.7 hours in patients with normal renal function, but increased to 8.5 hours in patients with impaired renal function. We found little or no drug accumulation during a seven-day treatment of patients with impaired renal function.