Abstrakt Ostatní Říjen 2010

“Developing expertise in surgery.”

Alderson, D. (2010).

Medical Teacher 32(10): 830-836.

 

The concept of expertise is widely embraced but poorly defined in surgery. Dictionary definitions differentiate between authority and experience, while a third view sees expertise as a mind-set rather than a status. Both absolute and relative models of expertise have been developed, and each allows a richer understanding of the application of these concepts to emerge. Trainees must develop both independent and interdependent expertise, and an appreciation of the essentially constructivist and uncertain nature of medical knowledge. Approach may be more important than innate talent; the concepts of ‘flow’, sustained ‘deliberate practice’ and ‘adaptive expertise’ are examples of expert approaches to learning. Non-analytical reasoning plays a key role in decision making at expert levels of practice. A technically gifted surgeon may be seen as a safety hazard rather than an expert if inter-dependent expertise has not been developed. Key roles of a surgical educator are to facilitate the development of an expert approach to education and to enable entry into and movement towards the centre of an expert community of practice. © 2010 Informa UK Ltd.

 

 

 

“Stress impairs psychomotor performance in novice laparoscopic surgeons.”

Arora, S., N. Sevdalis, et al. (2010).

Surgical Endoscopy and Other Interventional Techniques 24(10): 2588-2593.

 

Background: Little is known about acute stress in surgery although it is recognized to impair human performance in safety-critical industries. This study aimed to establish a direct empirical link between stress and psychomotor performance of novice surgeons. Methods: Eighteen participants completed this cross-sectional study. Participants carried out laparoscopic tasks on a MIST-VR simulator. Validated dexterity parameters were obtained from MIST-VR (path length, time taken, number of errors). Stress was assessed using the validated Imperial Stress Assessment Tool (ISAT). This captured stress subjectively using the State Trait Anxiety Inventory (STAI) questionnaire and objectively using salivary cortisol and mean and maximum heart rate. Results: Regarding technical performance, median values obtained were 55.12 s (range = 22.9-99.8) for time taken, 4.83 (range = 3-7) for economy of motion, and 88.0 (range = 35-175) for number of errors made. Subjective stress (STAI) correlated with economy of motion (r = 0.53, p = 0.042) and number of errors (r = 0.51, p = 0.034). Objective stress (mean and maximum heart rate) correlated with time taken (r = 0.62, p = 0.004), economy of motion (r = 0.55, p = 0.048), and number of errors (r = 0.67, p = 0.012). Conclusion: This is the first study to demonstrate through direct correlation that stress impairs surgical performance on a simulator. Training in managing stress may be required to minimize these deleterious consequences and improve patient care. © 2010 Springer Science+Business Media, LLC.

 

 

 

“Intracorporeal knot-tying for the thoracoscopic surgeon: A novel and simplified technique.”

Gopaldas, R. R. and R. M. Reul (2010).

Texas Heart Institute Journal 37(4): 435-438.

 

Thoracoscopic surgery has usually been limited by 2-dimensional vision and the limited space between ribs-problems that have been only partially overcome by the use of robotics. One of the technical challenges of any minimally invasive surgical approach is tying an intracorporeal knot. For the thoracoscopic surgeon, we describe an easier technique of knot-tying that involves using a right-angled dissector. The technique enables ambidextrous performance and is particularly useful for ligating major pulmonary vessels that might be too small to be stapled or too confined for the admission and maneuvering of a stapling device. Rotating the thumb-dials accordingly enables one to vary the configuration of the knots to create slip or reef knots. The technique is easy to learn and does not require any complicated devices. It is easily adapted to create even more complex constructs, such as a double surgeon’s knot. This technique has special advantages in areas of limited domain and in situations that require very narrow angles of instrument manipulation, particularly in thoracoscopic-assisted procedures. © 2010 by the Texas Heart® Institute, Houston.

 

 

 

“Complications in 2200 consecutive laparoscopic radical prostatectomies: Standardised evaluation and analysis of learning curves.”

Hruza, M., H. O. Weiß, et al. (2010).

European Urology 58(5): 733-741.

 

Background: Laparoscopic radical prostatectomy (LRP) represents an established treatment modality for localised prostate cancer. Objective: To report standardised complication rates for LRP, evaluate the development of complication rates over time, and show changes within the learning curves of laparoscopic surgeons. Design, setting, and participants: We conducted a standardised analysis of 2200 consecutive patients who underwent LRP between 1999 and 2008 at a single institution. Intervention: LRP was performed using a transperitoneal (n = 871) or extraperitoneal (n = 1329) retrograde Heilbronn technique. Five surgeons operated on 96% of the patients. Measurements: Complications were classified according to the modified Clavien system. Total complication rates and changes over time were analysed. Three generations of surgeons were defined for evaluation of learning curves. Results and limitations: Minor complications occurred in 21.7% of patients (Clavien 1: 6.8%; Clavien 2: 14.9%); anaemia requiring transfusion (10.4%) dominated. Early reinterventions were necessary in 6.7% of patients (Clavien 3a: 3.6%; Clavien 3b: 1.5%; Clavien 4a: 1.5%; Clavien 4b: 0.1%). Late Clavien 3b complications occurred in 4.7% of patients – most of them anastomotic strictures. Mortality was 0.1% (Clavien 5). There was a significant decrease in overall complication rates over time, resulting predominantly from decreasing Clavien 1-2 events. Learning curves of third-generation surgeons plateaued earlier compared to the first generation (250 vs 700 cases). The limitation of this study is that data concerning comorbidity were not included. Conclusions: LRP is a safe procedure characterised by an acceptable profile of complications. Specifically, few major complications are reported. According to the complication rates, the learning curve of third-generation surgeons is significantly shorter compared to first- and second-generation surgeons. © 2010 European Association of Urology. Published by Elsevier B.V. All rights reserved.

 

 

 

“Artificial tactile feedback can significantly improve tissue examination through remote palpation.”

Schostek, S., M. J. Binser, et al. (2010).

Surgical Endoscopy and Other Interventional Techniques 24(9): 2299-2307.

 

Background: In laparoscopy, impaired feedback information from the operation site and reduced instrument dexterity lead to high demands on surgeons’ skill and experience. Pre-clinical studies have shown that artificial tactile feedback (ATF) could significantly improve the quality of tactile feedback information. Additional information about interaction effects of tissue features when using ATF as well as related detection thresholds would be valuable for drawing conclusions on possible clinical application scenarios. Objective: To identify surgical procedures in laparoscopy that could benefit from ATF in tissue examination through remote palpation. Methods: We have developed a laparoscopic grasper capable of providing ATF by measuring the pressure distribution on one forceps jaw with a tactile sensor array. The data was presented graphically on the endoscopic screen. We conducted a study among surgeons and non-surgeons, comparing the capability to detect hidden objects through remote palpation with and without ATF. The data were analyzed using repeated-measures multiple analysis of variance (MANOVA) in two designs. Results: ATF could enhance feedback information with significant positive effects on accuracy, speed, the reduction of the number of grasps, and user confidence. The positive effect of ATF turned out to be especially strong if hidden objects were either hard and too small or large and too soft to be recognized by remote palpation without ATF. Conclusions: Our study contributes to the discussion on promising application scenarios of ATF-enhanced instrumentation in laparoscopic surgery. Based on our study results, such instrumentation may be valuable for detection and examination of hidden bodies or structures through remote palpation. © 2010 Springer Science+Business Media, LLC.

 

 

 

“The Learning Curve for Laparoscopic Radical Prostatectomy: An International Multicenter Study.”

Secin, F. P., C. Savage, et al. (2010).

Journal of Urology.

 

Purpose: It is not yet possible to estimate the number of cases required for a beginner to become expert in laparoscopic radical prostatectomy. We estimated the learning curve of laparoscopic radical prostatectomy for positive surgical margins compared to a published learning curve for open radical prostatectomy. Materials and Methods: We reviewed records from 8,544 consecutive patients with prostate cancer treated laparoscopically by 51 surgeons at 14 academic institutions in Europe and the United States. The probability of a positive surgical margin was calculated as a function of surgeon experience with adjustment for pathological stage, Gleason score and prostate specific antigen. A second model incorporated prior experience with open radical prostatectomy and surgeon generation. Results: Positive surgical margins occurred in 1,862 patients (22%). There was an apparent improvement in surgical margin rates up to a plateau at 200 to 250 surgeries. Changes in margin rates once this plateau was reached were relatively minimal relative to the CIs. The absolute risk difference for 10 vs 250 prior surgeries was 4.8% (95% CI 1.5, 8.5). Neither surgeon generation nor prior open radical prostatectomy experience was statistically significant when added to the model. The rate of decrease in positive surgical margins was more rapid in the open vs laparoscopic learning curve. Conclusions: The learning curve for surgical margins after laparoscopic radical prostatectomy plateaus at approximately 200 to 250 cases. Prior open experience and surgeon generation do not improve the margin rate, suggesting that the rate is primarily a function of specifically laparoscopic training and experience. © 2010 American Urological Association Education and Research, Inc.

 

 

 

“A survey of image-guided radiation therapy use in the United States.”

Simpson, D. R., J. D. Lawson, et al. (2010).

Cancer 116(16): 3953-3960.

 

BACKGROUND: Image-guided radiation therapy (IGRT) is a novel array of in-room imaging modalities that are used for tumor localization and patient setup in radiation oncology. The prevalence of IGRT use among US radiation oncologists is unknown. METHODS: A random sample of 1600 radiation oncologists was surveyed by Internet, e-mail and fax regarding the frequency of IGRT use, clinical applications, and future plans for use. The definition of IGRT included imaging technologies that are used for setup verification or tumor localization during treatment. RESULTS: Of 1089 evaluable respondents, 393 responses (36.1%) were received. The proportion of radiation oncologists using IGRT was 93.5%. When the use of megavoltage (MV) portal imaging was excluded from the definition of IGRT, the proportion using IGRT was 82.3%. The majority used IGRT rarely (in <25% of their patients; 28.9%) or infrequently (in 25%-50% of their patients; 33.1%). The percentages using ultrasound, video, MV-planar, kilovoltage (kV)-planar, and volumetric technologies were 22.3%, 3.2%, 62.7%, 57.7%, and 58.8%, respectively. Among IGRT users, the most common disease sites treated were genitourinary (91.1%), head and neck (74.2%), central nervous system (71.9%), and lung (66.9%). Overall, 59.1% of IGRT users planned to increase use, and 71.4% of nonusers planned to adopt IGRT in the future. CONCLUSIONS: IGRT is widely used among radiation oncologists. On the basis of prospective plans of responders, its use is expected to increase. Further research will be required to determine the safety, cost efficacy, and optimal applications of these technologies. © 2010 American Cancer Society.

 

 

 

“A comparison of early learning curves for complex bimanual coordination with open, laparoscopic, and flexible endoscopic instrumentation.”

Spaun, G. O., B. Zheng, et al. (2010).

Surgical Endoscopy and Other Interventional Techniques 24(9): 2145-2155.

 

Background: This study takes an initial step towards understanding the learning process of flexible endoscopic surgery. Bimanual coordination learning curves were contrasted between three different surgical paradigms. We hypothesized that use of an open or laparoscopic paradigm would result in better performance and a shorter learning process (reaching a learning plateau earlier) than an endoscopic paradigm. Methods: Our model required seven subjects to perform identical bimanual coordination tasks with three different tools (a dual-channel endoscope with graspers, laparoscopic Maryland graspers, and straight hemostats for open surgery). The task required subjects to coordinate two instruments in order to perform a series of standardized maneuvers. Performance was measured by movement speed and accuracy. The learning process was broken down into three distinct phases: the practice phase, the short-term retention phase, and the long-term retention phase. The learning curves of four surgical novices for 33 tasks with each device were compared with the performance of three surgeons. Results: Overall performance speed was significantly faster using open or laparoscopic tools than endoscopy for all groups (open 13 ± 1 s; lap 28 ± 3 s; endo 202 ± 82 s; P < 0.001). The difference between open and laparoscopy was not significant (P = 0.149). There was no significant difference (P = 0.434) in accuracy (number of ring drops) between any of the devices. Novices performed significantly slower than the expert in the endoscopy task (P = 0.010). Their performance improved with practice (P = 0.005) but they failed to reach the level of the expert after the practice phase (novices: 202.3 ± 23.4 s versus expert: 89.0 ± 34 s, P = 0.009). Conclusions: Bimanual coordination tasks have shortest performance time and are easiest to learn using an open surgery paradigm. Performance times and the learning process take longer for the laparoscopic paradigm and significantly longer for the endoscopic paradigm. © 2010 Springer Science+Business Media, LLC.

 

 

 

“Decreasing strain on the surgeon in gynecologic minimally invasive surgery by using semi-active robotics.”

Tchartchian, G., J. Dietzel, et al. (2010).

International Journal of Gynaecology and Obstetrics.

 

OBJECTIVE: To assess the advantages of a surgeon-controlled robotic endoscope holder in gynecologic minimally invasive solo-surgery as compared with conventional assistance with a second surgeon. METHODS: One hundred gynecologic laparoscopies were consecutively allocated to surgery with either a robot as the surgical assistant or a conventional assistant surgeon. Total operation time, image stability, and frequency of corrective maneuvers of the camera, in addition to the surgeon’s satisfaction regarding the ergonomics of the intervention, were recorded. All interventions were performed by the same surgeon. All laparoscopic surgery was classified as either easy or advanced surgery. RESULTS: The image stability score was significantly higher (10 vs 7; P<0.001) and fewer corrective maneuvers of the robotic endoscope were necessary (1 vs 5; P<0.001) with the robotic laparoscope holder; in addition, the surgeon recorded a significantly higher satisfaction score for the ergonomics of the semi-active robot (10 vs 7; P<0.001). CONCLUSION: The robot does not prolong total operation time and increases the surgeon’s comfort by improving image stability and laparoscope handling. It could provide major benefit, especially in complex gynecologic laparoscopic surgery.

 

 

“Pelvic exenterative surgery for palliation of malignant disease in the robotic era.”

Boustead, G. B. and M. R. Feneley (2010).

Clinical Oncology (Royal College of Radiologists) 22(9): 740-746.

 

A Medline-based literature review was carried out of the surgical management of advanced pelvic cancers and the effect of minimally invasive technology in this setting to review the current status of exenterative surgery for advanced pelvic malignancies. Palliation and/or resection of advanced pelvic cancer affecting one or more pelvic compartments offers benefit and improved quality of life in carefully selected patients. This complex surgery is best carried out by experienced multidisciplinary teams after meticulous preoperative staging and assessment. Survival rates at 5 years are between 25 and 40% in the absence of metastatic disease and between 18 and 24 months in the palliative setting. Open surgery remains the gold standard approach, but emerging reports of laparoscopic and robotically assisted laparoscopic techniques may be feasible in highly selected individuals.

 

 

 

“Telemedicine in 2010: robotic caveats.”

Freeman, W. D., K. A. Vatz, et al. (2010).

Lancet Neurology 9(11): 1046.

 

 

           

“Purposeful design in surgical robotics.”

Nelson, C. A. and D. Oleynikov (2010).

Surgical Endoscopy: 1-2.

 

 

           

“Robotic instrumentation: Evolution and microsurgical applications.”

Parekattil, S. J. and M. E. Moran (2010).

Indian Journal of Urology 26(3): 395-403.

 

This article presents a review of the history and evolution of robotic instrumentation and its applications in urology. A timeline for the evolution of robotic instrumentation is presented to better facilitate an understanding of our current-day applications. Some new directions including robotic microsurgical applications (robotic assisted denervation of the spermatic cord for chronic orchialgia and robotic assisted vasectomy reversal) are presented. There is a paucity of prospective comparative effectiveness studies for a number of robotic applications. However, right or wrong, human nature has always led to our infatuation with the concept of using tools to meet our needs. This chapter is a brief tribute to where we have come from and where we may be potentially heading in the field of robotic assisted urologic surgery.

 

 

 

“Role of laparoscopy in reconstructive surgery.”

Rassweiler, J., G. Pini, et al. (2010).

Current Opinion in Urology.

 

PURPOSE OF REVIEW: Despite increasing laparoscopic expertise in reconstructive surgery, open procedures still represent the gold standard. Robot-assisted techniques increasingly replace laparoscopy. However, laparoscopy is also developing: by improvement of ergonomics, new instruments, and techniques further reducing access trauma. We evaluated the actual role of laparoscopy focusing on main indications of urologic reconstructive surgery. RECENT FINDINGS: We analysed the current literature (PubMed/Medline) concerning indications, perioperative results, complications, and long-term outcome of laparoscopy for pyeloplasty, ureteral reimplantation, stone surgery, management of vesico-vaginal fistula, sacrocolpopexy (including evidence level). For all indications, laparoscopy provides the advantages of less postoperative pain, blood loss, shorter convalescence, and minimal disfigurement. However, it requires expertise with endoscopic suturing. Most experience (N > 1000) exists with laparoscopic pyeloplasty and sacrocolpopexy which can be considered as valuable options (IIB). Concerning ureteral reimplantation and repair of vesico-vaginal fistula, only a limited number of cases were reported (N < 150) (III). Laparoscopic stone surgery may gain importance particularly in developing countries. Robot-assistance will definitively increase the application of laparoscopic techniques providing optimal ergonomics, whereas the role of single-port surgery will be limited. SUMMARY: Laparoscopy will increasingly be used for reconstructive urologic surgery. This trend will be supported by the widespread use of the DaVinci device.

 

 

 

“Considering robotics? Plan for a program, not just procedures.”

Saver, C. (2010).

OR Manager 26(8).

 

 

           

“The advancement of robotic surgery a Successes, failures, challenges.”

Tamás, H. (2010).

A robotsebészet hódítása – Sikerek, kudarcok, kihívások 151(41): 1690-1696.

 

Computer-integrated robotic surgery systems appeared more than twenty years ago and since then hundreds of different prototypes have been developed. Only a fraction of them have been commercialized, mostly to support neurosurgical and orthopaedic procedures.Unquestionably, the most successful one is the da Vinci surgical system, primarily deployed in urology and general laparoscopic surgery. It is developed and marketed by Intuitive Surgical Inc. (Sunnyvale, CA, USA), the only profitable company of the segment. The da Vinci made robotic surgery is known and acknowledged throughout the world, and the great results delivered convinced most of the former critics of the technology. Success derived from the well chosen business development strategy, proficiency of the developers, appropriate timing and a huge pot of luck. This article presents the most important features of the da Vinci system, the history of development along with its medical, economical and financial aspects, and seeks the answer why this particular system became successful.

 

 

 

“Robot-assisted airway support: a simulated case.”

Tighe, P. J., S. J. Badiyan, et al. (2010).

Anesthesia and Analgesia 111(4): 929-931.

 

Recent advances in telemedicine and robotically assisted telesurgery may offer advanced surgical care for the geographically remote patient. Similar advances in tele-anesthesia will be necessary to optimize perioperative care for these patients. Although many preliminary investigations into tele-anesthesia are underway, none involves remote performance of anesthesia-related procedures. Here we describe simulated robotically assisted fiberoptic intubations using an airway simulation mannequin. Both oral and nasal approaches to fiberoptic intubation were successful, but presented unique opportunities and challenges inherent to the robot’s design. Robotically assisted airway management is feasible using multipurpose surgical robotic systems.

 

 

 

“”State of art” of robotic surgery.” ”State of art robotické chirurgie ”

Veverková, L., I. Čapov, et al. (2010).

19(1): 17-20.

 

The following article outlines the history and technical parametres of the Da Vinci robotic system. It explains the advantages as well as disadvantages of the system. The indication and number of robotic operations conducted in the Czech Republic are also included and that since the first operation in 2005 till now. Between 1 October 2005 and 19 March 2010 there were 3,086 such operations conducted in CR. The authors also discuss their 4-year experience of working with the system.

 

“Clinical requirements and possible applications of robot assisted endoscopy in skull base and sinus surgery.”

Eichhorn, K. W. and F. Bootz (2011).

Acta Neurochir Suppl 109: 237-240.

 

Functional Endoscopic Surgery of Paranasal sinuses (FESS) and Skull Base surgery is one of the most frequent surgeries performed at the ENT department of the Bonn University, Germany. Beside of surgical Navigation Robotic is one of the upcoming fields of Computer assisted Surgery developments. This work presents novel research and concepts for Robot Assisted Endoscopic Sinus Surgery (RASS) of the Paranasal sinuses and the anterior Skull Base containing the analysis of surgical workflows, the segmentation and modelling of the Paranasal sinuses and the anterior Skull Base and the development of the robotic path planning. An interdisciplinary group of software engineers and surgeons in Braunschweig and Bonn, Germany are approximate to solutions by a clinical and technical research program financed through the DFG (Deutsche Forschungsgemeinschaft, German research Community).

 

 

 

“Robot-assisted surgery – Point of view of the vascular surgean.”

Štádler, P., L. Dvořáček, et al. (2010).

Pohled cévního chirurga na roboticky asistované operace 19(1): 14-16.

 

Purpose of the study: Drawing on their experience, the authors reflect on the current options of robot-assisted vascular surgery. Applied methods: The robotic vascular surgery team has proposed surgical procedures for individual types of vascular reconstructions. The surgeons succeeded in finding both the most favourable port placement to allow comfortable use of the robotic system, and in modifying the currently used transperitoneal approach. Results: There has been no mortality in the presented group; in four cases (2.7 %) it was necessary to convert to classical surgery. Four patients (2.7 %) suffered post-operative complications. A technical fault of the robotic equipment occurred in one case (0.7 %), and in one case (0.7 %) it was necessary to withdraw from the intervention due to an inoperable finding on the aorta. Conclusion: From a practical point of view, the greatest benefit of robotics is the speed of performing a vascular anastomosis. The time intervals in vascular robotics are currently comparable with classical vascular surgery; moreover, vascular robotics offers all the advantages of mini-invasive surgery.

 

 

 

“Robotic technology in spine surgery: current applications and future developments.”

Stuer, C., F. Ringel, et al. (2011).

Acta Neurochir Suppl 109: 241-245.

 

Medical robotics incrementally appears compelling in nowadays surgical work. The research regarding an ideal interaction between physician and computer assistance has reached a first summit with the implementation of commercially available robots (Intuitive Surgical’s( (R) ) da Vinci ( (R) )). Moreover, neurosurgery – and herein spine surgery – seems an ideal candidate for computer assisted surgery. After the adoption of pure navigational support from brain surgery to spine surgery a meanwhile commercially available miniature robot (Mazor Surgical Technologies’ The Spine Assist((R))) assists in drilling thoracic and lumbar pedicle screws. Pilot studies on efficacy, implementation into neurosurgical operating room work flow proved the accuracy of the system and we shortly outline them. Current applications are promising, and future possible developments seem far beyond imagination. But still, medical robotics is in its infancy. Many of its advantages and disadvantages must be delicately sorted out as the patients safety is of highest priority. Medical robots may achieve a physician’s supplement but not substitute.

 

 

 

“Robot-Assisted Anterior Lumbar Interbody Fusion in a Swine Model In Vivo Test of the da Vinci Surgical-Assisted Spinal Surgery System.”

Yang, M. S., D. H. Yoon, et al. (2010).

Spine (Phila Pa 1976).

 

STUDY DESIGN.: The use of the da Vinci Surgical System to perform an anterior lumbar interbody fusion in a swine model to identify the technical properties, processes, merits, demerits, and limitations of a video-assisted robotic surgical system. OBJECTIVE.: This study was designed to demonstrate the feasibility of using a robotic surgical system to perform spinal surgery. SUMMARY OF BACKGROUND DATA.: Video-assisted laparoscopic anterior fusion was first reported in 1995 and afterward was spotlighted for several years. However, this technique has not become popular because of technical difficulties and complications associated with video-assisted procedures on the spine. As such, there is a demand for investigations to improve this technology. The da Vinci Surgical System provides 3-dimensional visualization as well as uniquely dexterous instruments that are remarkably similar to human hands. Video-assisted surgery with the da Vinci Surgical System robot has already provided great value to the fields of urology, cardiology, gynecology, and general surgery over the last decade. Preclinical studies for application of this system in spinal surgery have recently been conducted. METHODS.: A pig underwent anterior lumbar interbody fusion using da Vinci Surgical System assistance, with Tyche expandable cages used for preparation of endplates and cage placement. The setup time, operation time, amount of bleeding, and the number of complications associated with robotic manipulation were recorded. Before euthanasia, the animal underwent radiologic examination to confirm proper placement of cages. RESULTS.: The total duration of the procedure took 6 hours, with some complications related to frozen armsand robotic arm collision. Even so, there was neither any significant nerve or vessel injury nor peritoneal organ damage. Furthermore, radiologic assessment confirmed proper position of the cage in the center of the disc space. CONCLUSION.: Use of the da Vinci Surgical System to perform an anterior spinal procedure was shown to be safe and effective in a swine animal model. The utilization of this advanced technology shows promise to reduce the incidence of complications compared with other approaches. It requires further testing in animal models and cadavers, along with serial comparisons to current procedures.