Assessing quality and resources during campus-wide simulation integration.

INTRODUCTION: Our simulation center, supported by four departments (Surgery, OB/GYN, Urology, and Anesthesiology), is accredited as a comprehensive Accredited Educational Institute (AEI) and is now expanding to accommodate all departments on campus. METHODS: A 61-point questionnaire was administered to 44 stakeholders, representing all of UME and GME. Data were compared for AEI vs. non-AEI activities. RESULTS: Responses were collected from all 44 groups (100% response rate). Overall, 43 simulation activities were hosted within the AEI and 40 were hosted by non-AEI stakeholders. AEI activities were more likely to be mandatory (93% vs. 75%, p = 0.02), have written learning objectives (79% vs 43%, p < 0.001), and use validated assessment metrics (33% vs. 13%, p = 0.03). CONCLUSION: These data suggest that the AEI courses are more robust in terms of structured learning and assessment compared to non-AEI courses. Campus-wide application of uniform quality standards is anticipated to require significant faculty, course, and program development.

Proficiency-based preparation significantly improves FES certification performance.

BACKGROUND: The Fundamentals of Endoscopic Surgery (FES) certification has recently been mandated by the American Board of Surgery but best methods for preparing for the exam are lacking. Our previous work demonstrated a 40% pass rate for PGY5 residents in our program. The purpose of this study was to determine the effectiveness of a proficiency-based skills and cognitive curriculum for FES certification. METHODS: Residents who agreed to participate (n = 15) underwent an orientation session, followed by skills pre-testing using three previously described models (Trus, Operation targeting task, and Kyoto) as well as the actual FES skills exam (vouchers provided by the FES committee). Participants then trained to proficiency on all three models for the skills curriculum and completed the FES online didactic material for the cognitive curriculum. Finally, participants post-tested on the models and took the actual FES certification exam. Values are mean ± SD; p < 0.05 was considered significant. RESULTS: Of 15 residents who participated, 8 (53%) passed the FES skills exam at baseline. Participants required 2.7 ± 1.3 h to achieve proficiency on the models and approximately 3 h to complete the cognitive curriculum. At post-test, 14 (93%, vs. pre-test 53%, p = 0.041) passed the FES skills exam. 14 (93%) passed the FES cognitive exam and 13/15 (87%) passed both the skills and cognitive exam and achieved FES certification. CONCLUSIONS: Our traditional clinical endoscopy curricula were not sufficient for senior residents to pass the FES exam. Implementation of a proficiency-based flexible endoscopy curriculum using bench-top models and the FES online materials was feasible and effective for the majority of learners. Importantly, with a modest amount of additional training, 87% of our trainees were able to pass the FES examination, which represents a significant improvement for our program. We expect that additional refinements of this curriculum may yield even better results for preparing future residents for the FES examination.

Development, validation, and implementation of a cost-effective intermediate-level proficiency-based knot-tying and suturing curriculum for surgery residents.

BACKGROUND: The purpose of this study was to develop an intermediate-level proficiency-based knot-tying and suturing curriculum, evaluate construct validity, determine feasibility, document educational benefit, and quantify cost-effectiveness of implementation within a surgery residency program. METHODS: Six tasks with standardized metrics were developed using commercially available bench models; 39 PGY-1 surgery residents were enrolled in a 2-month curriculum (orientation/pre-test, self-practice, and a proctored post-test). Baseline trainee and expert performance were compared to assess construct validity. RESULTS: Baseline trainee and expert performance were significantly different (451 ± 83 vs 644 ± 10, p < 0.001), supporting construct validity. All trainees achieved proficiency during self-practice, completing 30 ± 17 repetitions over 3.4 ± 3.8 hours. Significant differences were detected between baseline and final trainee composite scores (451 ± 83 vs 607 ± 34, p < 0.001). CONCLUSIONS: Implementation of this curriculum was feasible and cost-effective. Construct validity and educational benefit in terms of skill acquisition were demonstrated. The purpose of this study was to develop an intermediate-level proficiency-based knot-tying and suturing curriculum, evaluate construct validity, determine feasibility, document educational benefit, and quantify cost-effectiveness of implementation within a robust surgery residency training program.

A randomized comparison of laparoscopic, flexible endoscopic, and wired and wireless magnetic cameras on ex vivo and in vivo NOTES surgical performance.

BACKGROUND: The influence of endoscopic video camera (VC) image quality on surgical performance has not been studied. Flexible endoscopes are used as substitutes for laparoscopes in natural orifice translumenal endoscopic surgery (NOTES), but their optics are originally designed for intralumenal use. Manipulable wired or wireless independent VCs might offer advantages for NOTES but are still under development. OBJECTIVE: To measure the optical characteristics of 4 VC systems and to compare their impact on the performance of surgical suturing tasks. METHODS: VC systems included a laparoscope (Storz 10 mm), a flexible endoscope (Olympus GIF 160), and 2 prototype deployable cameras (magnetic anchoring and guidance system [MAGS] Camera and PillCam). In a randomized fashion, the 4 systems were evaluated regarding standardized optical characteristics and surgical manipulations of previously validated ex vivo (fundamentals of laparoscopic surgery model) and in vivo (live porcine Nissen model) tasks; objective metrics (time and errors/precision) and combined surgeon (n = 2) performance were recorded. RESULTS: Subtle differences were detected for color tests, and field of view was variable (65°-115°). Suitable resolution was detected up to 10 cm for the laparoscope and MAGS camera but only at closer distances for the endoscope and PillCam. Compared with the laparoscope, surgical suturing performances were modestly lower for the MAGS camera and significantly lower for the endoscope (ex vivo) and PillCam (ex vivo and in vivo). CONCLUSIONS: This study documented distinct differences in VC systems that may be used for NOTES in terms of both optical characteristics and surgical performance. Additional work is warranted to optimize cameras for NOTES. Deployable systems may be especially well suited for this purpose.

Developing a comprehensive, proficiency-based training program for robotic surgery.

INTRODUCTION: Robotically assisted surgery has become very popular for numerous surgical disciplines, yet training practices remain variable with little to no validation. The purpose of this study was to develop a comprehensive, proficiency-based robotic training program. METHODS: A skill deconstruction list was generated by observation of robotic operations and interviews with experts. Available resources were used, and other components were developed as needed to develop a comprehensive, proficiency-based curriculum to teach all deconstructed skills. Preliminary construct and content validity and curriculum feasibility were evaluated. RESULTS: The skill deconstruction list contained 23 items. Curricular components included an online tutorial, a half-day interactive session, and 9 inanimate exercises with objective metrics. Novice (546 ± 26) and expert (923 ± 60) inanimate composite scores were different (P < .001), supporting construct validity, and substantial pre-test to post-test improvement was noted after successful training completion. All 23 deconstructed skills were rated as highly relevant (4.9 ± 0.5; 5-point scale), and no skills were absent from the curriculum, supporting content validity. CONCLUSION: These data suggest that this proficiency-based training curriculum comprehensively addresses the skills necessary to perform robotic operations with early construct and content validity and feasibility demonstrated. Further validation is encouraged.

Magnetically anchored cautery dissector improves triangulation, depth perception, and workload during single-site laparoscopic cholecystectomy.

INTRODUCTION: This study evaluated operative outcomes and workload during single-site laparoscopy (SSL) using a magnetically anchored cautery dissector (MAGS) compared with a conventional laparoscopic hook cautery (LAP). METHODS: Each cautery was used to perform six SSL porcine cholecystectomies. For MAGS, the cautery device was inserted through the umbilical incision, magnetically coupled, and deployed; two graspers and a laparoscope were used. For LAP, two percutaneous retraction sutures, one grasper, a hook cautery dissector, and a laparoscope were used. Operative outcomes, surgeon ratings (scale, 1-5; 1 = superior), and workload (scale, 1-10; 1 = superior) were evaluated. RESULTS: No significant differences were detected for operative outcomes and surgeon ratings, however, trends were detected favoring MAGS. Surgeon workload ratings were significantly better for MAGS (2.6 ± 0.2) vs. LAP (5.6 ± 1.1; p < 0.05). For MAGS, depth perception and triangulation were excellent and the safe handling protocol was followed with no complications. For LAP, the parallelism of instruments and lack of triangulation hindered depth perception, caused instrument conflicts, and resulted in two minor complications (one superficial liver laceration and one inadvertent burn to the diaphragm). CONCLUSION: These data suggest that using the MAGS device for SSL cholecystectomy results in equivalent (or better) operative outcomes and less workload compared with LAP.

Magnetically anchored camera and percutaneous instruments maintain triangulation and improve cosmesis compared with single-site and conventional laparoscopic cholecystectomy.

BACKGROUND: This study evaluated operative outcomes and ergonomics for a magnetic camera (MAGS) used in conjunction with percutaneous instruments [percutaneous surgical set (PSS)] compared with single-site laparoscopic (SSL) and conventional laparoscopic (LAP) cholecystectomy techniques. METHODS: Four surgical trainees each performed three porcine cholecystectomies using three randomized techniques including MAGS/PSS, SSL, and LAP. The operative outcomes, procedure-specific ratings (1-5 scale; 1 = superior), workload (1-10 scale; 1 = superior), and global impressions (1-10 scale; 10 = superior) were recorded. Comparisons used analysis of variance (ANOVA) on ranks (Kruskal-Wallis), and p values lower than 0.05 were considered significant. RESULTS: The operative outcomes were similar except for significantly higher blood loss with SSL (16.3 ± 10.3) versus LAP (2.8 ± 1.5; p < 0.05) but not with MAGS/PSS (4.8 ± 3.8). Several inadvertent tissue-damaging events occurred with SSL but not with MAGS/PSS or LAP. The incision was significantly shorter with MAGS/PSS (29.3 ± 2.8 mm) and SSL (29.3 ± 2.5 mm) than with LAP (48.0 ± 3.6 mm; p < 0.05). Compared with SSL (3.6 ± 0.5), the procedure-specific ratings significantly favored MAGS/PSS (2.8 ± 0.4) and LAP (1.7 ± 0.2; p < 0.05). Ergonomics and technical challenges both were rated significantly inferior with SSL (4.3 ± 1.0 and 3.8 ± 0.5, respectively) versus LAP (1.5 ± 0.6 and 2.0 ± 0.8, respectively; p < 0.05) but not with MAGS/PSS (2.5 ± 1.0 and 3.0 ± 0.8, respectively). Both MAGS/PSS (4.5 ± 0.5) and SSL (4.8 ± 1.0) were associated with a significantly greater workload than LAP (2.5 ± 0.6; p < 0.05). Global impression ratings were significantly higher for LAP (8.7 ± 1.3) versus SSL (5.8 ± 2.0; p < 0.05) but not for MAGS/PSS (7.1 ± 1.8). Cosmesis was significantly better with MAGS/PSS (9.5 ± 0.6) versus LAP (6.5 ± 2.4; p < 0.05) but not with SSL (8.8 ± 1.3). CONCLUSION: The MAGS/PSS technique allows better triangulation and fewer technical difficulties than SSL and better cosmesis than LAP. Further development of these devices is warranted.

Comprehensive proficiency-based inanimate training for robotic surgery: reliability, feasibility, and educational benefit.

BACKGROUND: We previously developed a comprehensive proficiency-based robotic training curriculum demonstrating construct, content, and face validity. This study aimed to assess reliability, feasibility, and educational benefit associated with curricular implementation. METHODS: Over an 11-month period, 55 residents, fellows, and faculty (robotic novices) from general surgery, urology, and gynecology were enrolled in a 2-month curriculum: online didactics, half-day hands-on tutorial, and self-practice using nine inanimate exercises. Each trainee completed a questionnaire and performed a single proctored repetition of each task before (pretest) and after (post-test) training. Tasks were scored for time and errors using modified FLS metrics. For inter-rater reliability (IRR), three trainees were scored by two raters and analyzed using intraclass correlation coefficients (ICC). Data from eight experts were analyzed using ICC and Cronbach's α to determine test-retest reliability and internal consistency, respectively. Educational benefit was assessed by comparing baseline (pretest) and final (post-test) trainee performance; comparisons used Wilcoxon signed-rank test. RESULTS: Of the 55 trainees that pretested, 53 (96 %) completed all curricular components in 9-17 h and reached proficiency after completing an average of 72 ± 28 repetitions over 5 ± 1 h. Trainees indicated minimal prior robotic experience and "poor comfort" with robotic skills at baseline (1.8 ± 0.9) compared to final testing (3.1 ± 0.8, p < 0.001). IRR data for the composite score revealed an ICC of 0.96 (p < 0.001). Test-retest reliability was 0.91 (p < 0.001) and internal consistency was 0.81. Performance improved significantly after training for all nine tasks and according to composite scores (548 ± 176 vs. 914 ± 81, p < 0.001), demonstrating educational benefit. CONCLUSION: This curriculum is associated with high reliability measures, demonstrated feasibility for a large cohort of trainees, and yielded significant educational benefit. Further studies and adoption of this curriculum are encouraged.

Proficiency-based training for robotic surgery: construct validity, workload, and expert levels for nine inanimate exercises.

BACKGROUND: We previously developed nine inanimate training exercises as part of a comprehensive, proficiency-based robotic training curriculum that addressed 23 unique skills identified via task deconstruction of robotic operations. The purpose of this study was to evaluate construct validity, workload, and expert levels for the nine exercises. METHODS: Expert robotic surgeons (n = 8, fellows and faculty) and novice trainees (n = 4, medical students) each performed three to five consecutive repetitions of nine previously reported exercises (five FLS models with or without modifications and four custom-made models). Each task was scored for time and accuracy using modified FLS metrics; task scores were normalized to a previously established (preliminary) proficiency level and a composite score equaled the sum of the nine normalized task scores. Questionnaires were administered regarding prior experience. After each exercise, participants completed a validated NASA-TLX Workload Scale to rate the mental, physical, temporal, performance, effort, and frustration levels of each task. RESULTS: Experts had performed 119 (range = 15-600) robotic operations; novices had observed ≤ 1 robotic operation. For all nine tasks and the composite score, experts achieved significantly better performance than novices (932 ± 67 vs. 618 ± 111, respectively; P < 0.001). No significant differences in workload between experts and novices were detected (32.9 ± 3.5 vs. 32.0 ± 9.1, respectively; n.s.). Importantly, frustration ratings were relatively low for both groups (4.0 ± 0.7 vs. 3.8 ± 1.6, n.s.). The mean performance of the eight experts was deemed suitable as a revised proficiency level for each task. CONCLUSION: Using objective performance metrics, all nine exercises demonstrated construct validity. Workload was similar between experts and novices and frustration was low for both groups. These data suggest that the nine structured exercises are suitable for proficiency-based robotic training.

Content and face validity of a comprehensive robotic skills training program for general surgery, urology, and gynecology.

BACKGROUND: The authors previously developed a comprehensive, proficiency-based robotic training curriculum that aimed to address 23 unique skills identified via task deconstruction of robotic operations. The purpose of this study was to determine the content and face validity of this curriculum. METHODS: Expert robotic surgeons (n = 12) rated each deconstructed skill regarding relevance to robotic operations, were oriented to the curricular components, performed 3 to 5 repetitions on the 9 exercises, and rated each exercise. RESULTS: In terms of content validity, experts rated all 23 deconstructed skills as highly relevant (4.5 on a 5-point scale). Ratings for the 9 inanimate exercises indicated moderate to thorough measurement of designated skills. For face validity, experts indicated that each exercise effectively measured relevant skills (100% agreement) and was highly effective for training and assessment (4.5 on a 5-point scale). CONCLUSIONS: These data indicate that the 23 deconstructed skills accurately represent the appropriate content for robotic skills training and strongly support content and face validity for this curriculum.

A randomized comparison of laparoscopic, magnetically anchored, and flexible endoscopic cameras in performance and workload between laparoscopic and single-incision surgery.

BACKGROUND: This study aimed to evaluate the surgeon performance and workload of a next-generation magnetically anchored camera compared with laparoscopic and flexible endoscopic imaging systems for laparoscopic and single-site laparoscopy (SSL) settings. METHODS: The cameras included a 5-mm 30° laparoscope (LAP), a magnetically anchored (MAGS) camera, and a flexible endoscope (ENDO). The three camera systems were evaluated using standardized optical characteristic tests. Each system was used in random order for visualization during performance of a standardized suturing task by four surgeons. Each participant performed three to five consecutive repetitions as a surgeon and also served as a camera driver for other surgeons. Ex vivo testing was conducted in a laparoscopic multiport and SSL layout using a box trainer. In vivo testing was performed only in the multiport configuration and used a previously validated live porcine Nissen model. RESULTS: Optical testing showed superior resolution for MAGS at 5 and 10 cm compared with LAP or ENDO. The field of view ranged from 39 to 99°. The depth of focus was almost three times greater for MAGS (6-270 mm) than for LAP (2-88 mm) or ENDO (1-93 mm). Both ex vivo and in vivo multiport combined surgeon performance was significantly better for LAP than for ENDO, but no significant differences were detected for MAGS. For multiport testing, workload ratings were significantly less ex vivo for LAP and MAGS than for ENDO and less in vivo for LAP than for MAGS or ENDO. For ex vivo SSL, no significant performance differences were detected, but camera drivers rated the workload significantly less for MAGS than for LAP or ENDO. CONCLUSION: The data suggest that the improved imaging element of the next-generation MAGS camera has optical and performance characteristics that meet or exceed those of the LAP or ENDO systems and that the MAGS camera may be especially useful for SSL. Further refinements of the MAGS camera are encouraged.

Construct and face validity of the American College of Surgeons/Association of Program Directors in Surgery laparoscopic troubleshooting team training exercise.

BACKGROUND: Our aim was to develop an objective scoring system and evaluate construct and face validity for a laparoscopic troubleshooting team training exercise. METHODS: Surgery and gynecology novices (n = 14) and experts (n = 10) participated. Assessments included the following: time-out, scenario decision making (SDM) score (based on essential treatments rendered and completion time), operating room communication assessment (investigator developed), line operations safety audits (teamwork), and National Aeronautics and Space Administration-Task Load Index (workload). RESULTS: Significant differences were detected for SDM scores for scenarios 1 (192 vs 278; P = .01) and 3 (129 vs 225; P = .004), operating room communication assessment (67 vs 91; P = .002), and line operations safety audits (58 vs 87; P = .001), but not for time-out (46 vs 51) or scenario 2 SDM score (301 vs 322). Workload was similar for both groups and face validity (8.8 on a 10-point scale) was strongly supported. CONCLUSIONS: Objective decision-making scoring for 2 of 3 scenarios and communication and teamwork ratings showed construct validity. Face validity and participant feedback were excellent.

Tissue compression analysis for magnetically anchored cautery dissector during single-site laparoscopic cholecystectomy.

INTRODUCTION: The purpose of this study was to evaluate the histological effects of dynamic abdominal wall compression using the magnetic anchoring and guidance system (MAGS) platform. METHODS: Cholecystectomy was performed in two nonsurvival and two survival pigs using a single-site laparoscopic (SSL) approach. A deployable MAGS cautery dissector was used to perform the entire dissection in conjunction with a laparoscope and other instruments. The abdominal wall areas corresponding to the region occupied by the MAGS platform were examined grossly and microscopically for signs of tissue damage. Gallbladder dissection time was 36 min with no complications. Compressed abdominal wall thickness was 1.4 cm. RESULTS: In all four animals, a very mild skin erythema was noted immediately postprocedure but was nonvisible within 20 min. Mild peritoneal blanching was noted in two animals, and one animal exhibited a 5-mm area of petechiae. Necropsy demonstrated no adhesions. Light microscopy documented no evidence of tissue injury for all specimens. DISCUSSION: This study demonstrated that the use of the MAGS cautery dissector for a SSL cholecystectomy was advantageous in providing triangulation and did not result in any significant gross or microscopic tissue damage despite the thin abdominal wall of the porcine model.

Two-year skill retention and certification exam performance after fundamentals of laparoscopic skills training and proficiency maintenance.

BACKGROUND: The purpose of this study was to determine 2-year performance retention and certification exam pass rate after completion of a proficiency-based fundamental laparoscopic skills (FLS) curriculum and subsequent interval training. METHODS: Surgery residents (postgraduate year [PGY]1-5, n = 91) were enrolled in an Institutional Review Board approved protocol. All participants initially underwent proficiency-based training on all 5 FLS tasks. Subsequently, available residents were enrolled every 6 months in an ongoing training curriculum that included retention tests on tasks 4 and 5, with mandatory retraining to proficiency if the proficiency levels were not achieved. The final retention test included the actual FLS certification examination for PGY4-5 trainees. RESULTS: A 96% participation rate was achieved for all curricular components during the 2-year study period (PGY3-5, n = 33). Skill retention at retention 1-4 was 83%, 94%, 98%, and 91% for task 4 and 85%, 95%, 96%, and 100% for task 5, respectively. All PGY4-5 (n = 20) residents passed the FLS certification examination, achieving 413 +/- 28 total score on the skills portion (passing score > or =270) and demonstrating 92% retention for all 5 tasks. CONCLUSION: Proficiency-based training with subsequent ongoing practice results in a very high level of skill retention after 2 years and uniformly allows trainees to pass the FLS certification examination.

Maintaining proficiency after fundamentals of laparoscopic surgery training: a 1-year analysis of skill retention for surgery residents.

BACKGROUND: The purpose of this study was to determine performance retention after initial and ongoing Fundamentals of Laparoscopic Surgery (FLS) skills training. METHODS: Surgery residents (postgraduate year [PGY] 1-5; n = 91) initially underwent proficiency-based training during a 2-month period for all 5 FLS tasks. Subsequently, available residents (PGY 2-5; n = 44) were enrolled in a follow-up curriculum for Tasks 4 and 5, with retention testing at 6.5 +/- 1.0 months (Retention 1) and 12.5 +/- 1.3 months (Retention 2), followed by mandatory retraining if needed. RESULTS: Forty-two residents participated in the follow-up curriculum. For Task 4, retraining was required for 55% of trainees after Retention 1 and for 40% after Retention 2 testing. For Task 5, retraining was required for 86% of trainees after Retention 1 and for 48% after Retention 2 testing. Compared with posttest performance, skill retention was 86% and 96% for Task 4 and 87% and 96% for Task 5 at Retentions 1 and 2, respectively. CONCLUSION: A modest decrement in performance was detected at 6.5 months, but a small amount of additional structured practice reinforced skill acquisition and minimized skill loss at 12.5 months. In addition to clinical experience, trainees may benefit from ongoing FLS simulator training to optimally maintain proficiency.

Postpneumonectomy lung expansion elicits hypoxia-inducible factor-1alpha signaling.

We (42) previously reported differential regulation of hypoxia-inducible factors (HIF-1alpha, -2alpha, and -3alpha) mRNA in canine lungs during normal maturation and postpneumonectomy (PNX) compensatory growth in the absence of overt hypoxia. To test the hypothesis that lung expansion activates HIF signaling, we replaced the right lung of six adult foxhounds with inflated custom-shaped silicone prosthesis to keep the mediastinum in the midline and minimize lateral expansion of the remaining lung. After 3 wk of recovery and stabilization of perfusion, the prosthesis was acutely deflated in three animals, causing the remaining lung to expand by 114%. In three other animals, the prosthesis remained inflated. Three days following deflation, we observed significant elevation in the mRNA and nuclear protein levels of HIF-1alpha ( approximately 60%) as well as activation of its transcriptional regulator, the serine/threonine protein kinase B (phospho-Akt-to-total Akt ratio, 124%), and the mRNA and protein levels of its downstream targets, erythropoietin receptor (71-183%) as well as VEGF (33-58%) compared with the pre-PNX control lung from the same animal. The mRNA of HIF-2alpha, HIF-3alpha, and VEGF receptors did not change with acute deflation. We conclude that in vivo lung expansion by post-PNX deflation of space-occupying prosthesis elicits coordinated activation of HIF-1alpha signaling in adult lungs. This pathway could play an important role in mediating lung growth and remodeling during maturation and post-PNX compensation.

Splenectomy impairs diffusive oxygen transport in the lung of dogs.

The spleen acts as an erythrocyte reservoir in highly aerobic species such as the dog and horse. Sympathetic-mediated splenic contraction during exercise reversibly enhances convective O2 transport by increasing hematocrit, blood volume, and O2-carrying capacity. Based on theoretical interactions between erythrocytes and capillary membrane (Hsia CCW, Johnson RL Jr, and Shah D. J Appl Physiol 86: 1460-1467, 1999) and experimental findings in horses of a postsplenectomy reduction in peripheral O2-diffusing capacity (Wagner PD, Erickson BK, Kubo K, Hiraga A, Kai M, Yamaya Y, Richardson R, and Seaman J. Equine Vet J 18, Suppl: 82-89, 1995), we hypothesized that splenic contraction also augments diffusive O2 transport in the lung. Therefore, we have measured lung diffusing capacity (DL(CO)) and its components during exercise by a rebreathing technique in six adult foxhounds before and after splenectomy. Splenectomy eliminated exercise-induced polycythemia, associated with a 30% reduction in maximal O2 uptake. At any given pulmonary blood flow, DL(CO) was significantly lower after splenectomy owing to a lower membrane diffusing capacity, whereas pulmonary capillary blood volume changed variably; microvascular recruitment, indicated by the slope of the increase in DL(CO) with respect to pulmonary blood flow, was also reduced. We conclude that splenic contraction enhances both convective and diffusive O2 transport and provides another compensatory mechanism for maintaining alveolar O2 transport in the presence of restrictive lung disease or ambient hypoxia.

Ventilatory acclimatization in awake guinea pigs raised at high altitude.

To determine if laboratory strains of guinea pigs bred at sea level (SL) are "pre-adapted" to high altitude (HA), we raised litter-matched weanling Hartley guinea pigs for 4 months at SL, intermediate altitude (IA, 1250 m) or HA (3800 m) and exposed them acutely to 100, 21 and 12% inspired O2 at their respective altitude of residence. Control animals raised at SL were also exposed acutely to 10 and 8% inspired O2. In awake spontaneously breathing guinea pigs raised at SL, resting minute ventilation and tidal volume increased significantly when inspired O2 tension fell below about 60 mm Hg. In guinea pigs raised at IA or HA, ventilation was higher at any given inspired O2 tension in direct relationship to the altitude of residence. Resting hematocrit was also higher in animals raised at HA than at SL. We conclude that the pattern of ventilatory acclimatization to HA exposure in Hartley guinea pigs is similar to that in laboratory rats and human lowlanders; therefore laboratory guinea pigs are not pre-adapted and are suitable animals for the study of adaptation to high altitude.

Development of a renal tumor mimic model for learning minimally invasive nephron sparing surgical techniques.

PURPOSE: New laparoscopic partial nephrectomy and tumor ablation techniques are continuously being developed and evaluated in large animal models. However, to our knowledge no reliable renal tumor model exists to evaluate procedure efficacy. We developed and assessed the reliability of a tumor mimic model to serve as a training tool for minimally invasive kidney surgery. MATERIALS AND METHODS: An agarose based model was created using a mixture of 3% agarose, 3% cellulose, 7% glycerol and 0.05% methylene blue. It is liquid when heated, but solidifies after cooling to physiological temperatures. The agar was injected (0.7 cc) into porcine renal parenchyma to make endophytic or completely intraparenchymal lesions. Three-dimensional ultrasound images of the lesions were obtained during initial development to ensure spherical lesions. A group of 20 lesions was initially placed in an ex vivo setting to assess size consistency and define baseline impedance characteristics. An additional 20 tumor mimics each were established in a laparoscopic model in a laparoscopic box trainer and an in vivo laparoscopic model. They were ablated with a temperature based radio frequency generator to assess impedance characteristics but the efficacy of ablation was not assessed. The in vivo model consisted of placing the agar lesion percutaneously under direct laparoscopic vision. RESULTS: The agarose mixture was easily injected and readily visible on ultrasound as hyperechoic distinct lesions. Lesions had a mean size of 10.8 +/- SD 1.3 mm on ultrasound and 10.9 +/- 1.2 mm grossly. The impedance of normal renal parenchyma and unablated lesions was similar. Mean lesion size in the ex vivo model after radio frequency ablation was 9.8 +/- 2.0 mm on ultrasound, which was similar to the gross mean lesion size of 9.7 +/- 1.0 mm. Similar results were obtained for the in vivo model with a mean size of 10.1 +/- 2.1 and 10.4 +/- 1.5 mm, respectively. The lesions were easily identified grossly as blue solid lesions that replaced renal parenchyma. CONCLUSIONS: The described renal tumor mimic model reproducibly creates ex vivo and in vivo porcine kidney lesions. Lesion size and impedance do not change with the application of radio frequency energy. This model should be a valuable adjunct in the development, assessment and teaching of novel, nephron sparing, minimally invasive surgical techniques.

Retinoic acid-induced alveolar cellular growth does not improve function after right pneumonectomy.

To determine whether all-trans retinoic acid (RA) treatment enhances lung function during compensatory lung growth in fully mature animals, adult male dogs (n = 4) received 2 mg x kg(-1) x day(-1) po RA 4 days/wk beginning the day after right pneumonectomy (R-PNX, 55-58% resection). Litter-matched male R-PNX controls (n = 4) received placebo. After 3 mo, transpulmonary pressure (TPP)-lung volume relationship, diffusing capacities for carbon monoxide and nitric oxide, cardiac output, and septal volume (V(tiss-RB)) were measured under anesthesia by a rebreathing technique at two lung volumes. Lung air and tissue volumes (V(air-CT) and V(tiss-CT)) were also measured from high-resolution computerized tomographic (CT) scans at a constant TPP. In RA-treated dogs compared with controls, TPP-lung volume relationships were similar. Diffusing capacities for carbon monoxide and nitric oxide were significantly impaired at a lower lung volume but similar at a high lung volume. Whereas V(tiss-RB) was significantly lower at both lung volumes in RA-treated animals, V(air-CT) and V(tiss-CT) were not different between groups; results suggest uneven distribution of ventilation consistent with distortion of alveolar geometry and/or altered small airway function induced by RA. We conclude that RA does not improve resting pulmonary function during the early months after R-PNX despite histological evidence of its action in enhancing alveolar cellular growth in the remaining lung.