Computer-assessed performance of psychomotor skills in endoscopic otolaryngology surgery: construct validity of the Dundee Endoscopic Psychomotor Otolaryngology Surgery Trainer (DEPOST).

BACKGROUND: This study was undertaken to introduce and establish the value of the Dundee Endoscopic Psychomotor Otolaryngology Surgery Trainer (DEPOST) as a customisable, objective real-time scoring system for trainee assessment. The construct validity of the system was assessed by comparing the performance of experienced otolaryngologists with that of otolaryngology trainees, junior doctors and medical students. METHODS: Forty two subjects (13 Consultants, 8 senior trainees, 13 junior trainees and 8 junior doctors/medical students) completed a single test on DEPOST. The test involved using a 30° rigid endoscope and a probe with position sensor, to identify a series of lights in a complex 3-dimensional model. The system scored subjects for time, success rate, and economy of movement (distance travelled). An analysis of variance and correlation analysis were used for the data analysis, with statistical significance set at 0.05. RESULTS: Increasing experience led to significantly improved performance with the DEPOST (p < 0.01). Senior trainees' results were significantly better than those of consultant otolaryngologists in success rate and time (p < 0.05 & p < 0.05). Consultants were the most efficient in their movement (p = 0.051) CONCLUSIONS: The system provides an accurate and customisable assessment of endoscopic skill in otolaryngologists. The DEPOST system has construct validity, with master surgeons and senior trainees completing the tasks more accurately without sacrificing execution time, success rate or efficiency of movement.

Automatic glare removal in endoscopic imaging.

BACKGROUND: Glare from surgical instruments and tissue surfaces often occurs during endoscopic procedures and can be disturbing to the operator. The brightness level of the light source can be reduced, but at the expense of overall image clarity, so alternative solutions are needed for removing glare. Digital image-processing methods offer the opportunity to lessen or eliminate glare by reducing the intensity of the affected parts of the image. This study investigated a new automated method for glare reduction that uses two different intensity thresholds as a basis for applying glare reduction processes and it also reduces unpleasant artifacts at the glare region boundaries. METHODS: The new glare-reduction method was compared with a previous method. Three variants of each method, each with different color biases in the glare regions, were applied to a 20-s surgical recording containing substantial amounts of glare. The six versions and the original recording were evaluated subjectively by a group of 10 experienced surgeons using a paired-comparisons method, in which each version was compared for preference with all the other versions. RESULTS: The new double-threshold intensity-subtraction method scored significantly higher than the previously developed glare-reduction method (p < 0.05). It also scored higher than the original (unprocessed) version, but not significantly. The color bias was important, with combinations of pink and grey performing better than yellow tints. CONCLUSIONS: The findings show the new method to be a significant improvement in automatic glare reduction compared with earlier methods. The method is not computationally demanding, so it can in the future be evaluated clinically in high-definition endoscopic imaging systems and developed further in this environment.

Measurement of osteotomy force during endoscopic sinus surgery.

Greater understanding of the surgeon's task and skills are required to improve surgical technique and the effectiveness of training. Currently, neither the objective measurement of osteotomy forces during endoscopic sinus surgery (ESS) nor the validity of the properties of cadaver materials, are well documented. Measurement was performed of peak axial osteotomy force during ESS. A comparison was made of results with previously published cadaver data to validate the force properties of cadaver models. A prospective, consecutive cohort of 25 patients was compared with data from 15 cadaver heads. A modified Storz sinus curette measured osteotomy force from uncinate, bulla ethmoidalis, and ground lamella. Independent variables were osteotomy site, age, gender, indication for surgery, and side. Corresponding cadaver data were analyzed for the independent variables of osteotomy site, side, and gender and then compared with the live patient data. Mean osteotomy force in live patients was 9.6 N (95% CI, 8.9-10.4 N). Mean osteotomy force in the cadaver heads was 6.4 N (95% CI, 5.7-7.0 N). Ethmoid osteotomy of live patients required 3.2 N (95% CI, 2.1-4.3 N) more force than the cadaver heads (p = 0.0001). This relationship was statistically significant at the bulla ethmoidalis (p = 0.002) and the ground lamella (p = 0.0001) but not at the uncinate (p = 0.068). Osteotomy in female live subjects required 1.6 N (95% CI, 0.1-3.1 N) more force than male live subjects (p = 0.03). Cadaver tissue may underestimate the mean osteotomy force required in osteotomy of living ethmoid sinus lamellae by a factor of 1.5 times. Caution may be required in extrapolating force estimates from cadaver tissue to those required in living patients.

Surgical instrument force exerted during endoscopic sinus surgery: differences within the ethmoid sinus complex.

BACKGROUND: Endoscopic sinus surgery (ESS) has been the most important technical advance in surgical rhinology in the last 25 years. The technique is now used beyond its initial sinus confines but knowledge of the forces required to perform ESS is limited. Greater understanding of these forces will lead to improved surgical training and safety. The aim of this study was to quantify the magnitude of the forces exerted during punch osteotomy of the bony lamella of the paranasal sinuses and surrounding bony structures during ESS. METHODS: Fifteen formalin-fixed cadaveric heads underwent simulated ESS. Peak axial forces were measured using a pair of modified Blakesley forceps. Measurements were recorded during osteotomy of the paranasal sinus complex, skull base, and crests of the optic nerve and internal carotid artery. Statistical comparison between the mean forces was performed. RESULTS: A mean force of 6.06 N was required to breach the lamellae of the ethmoid sinus complex. This was significantly less than the mean force required to breach the skull base, excluding the olfactory cleft (17.80 N; p < 0.0001), crests of the optic nerve (15.43 N; p < 0.001), and internal carotid artery (13.15 N; p < 0.001). There was no significant difference between the ethmoid lamella and the lamina papyracea (6.13; p = 0.67). CONCLUSION: Significantly greater force was required to breach the skull base and other safety critical areas encountered in ESS, than the bony lamellae of the ethmoid sinus complex. Although this result is reassuring, in vivo studies are now required to validate this relationship in the operative patient.