European Journal of Vascular & Endovascular Surgery
Volume 34, Issue 4 , Pages 405-410, October 2007

Vascular Anastomosis Model: Relation Between Competency in a Laboratory-based Model and Surgical Competency

  • C. Wilasrusmee

      Affiliations

    • Department of Surgery, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Thailand
    • Corresponding Author InformationCorresponding author. C. Wilasrusmee, MD, Department of Surgery, Ramathibodi Hospital, 270 Rama VI Road, Bangkok 10400, Thailand.
    • ,
  • P. Lertsithichai

      Affiliations

    • Department of Surgery, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Thailand
    • ,
  • D.S. Kittur

      Affiliations

    • Department of Surgery, SUNY Upstate Medical University, Syracuse, New York, USA

Accepted 27 May 2007. published online 07 August 2007.

Article Outline

Background

Previously, we presented a new, laboratory-based, vascular anastomosis model as a tool to objectively quantify surgical skill. The purpose of the present study was to determine the relation between the outcomes of vascular anastomosis in the laboratory and technical competency, when performing similar vascular anastomoses, in the operating room.

Materials and methods

Twenty-nine resident surgeons-in-training participated in the present study. All residents had at least one previous laboratory training session using the vascular anastomosis model. Then residents had to create a forearm arterio-venous bridge graft in the operating room (OR). Three measures were used to assess technical competency in the OR: completion time of the graft to vein anatomosis, leakage grade across the anastomosis, and the mini-objective structured assessment of technical skills (MOSAT) score. Similar outcomes obtained in the laboratory were used as predictors of OR outcomes. Significant predictors were identified using multiple linear regression and multiple ordinal logistic regression modelling.

Results

Worse leakage in the laboratory predicted worse leakage in the OR, longer completion time and worse MOSAT score in the OR. Longer completion time in the laboratory was associated with longer OR completion time, but less leakage. Higher year of training and greater laboratory exposure were related to higher MOSAT score and shorter completion time in the OR, respectively.

Conclusions

Completion time and grade of anastomosis leakage measured in the laboratory were predictive of technical competency in the OR. The vascular anastomosis model may be useful for training in clinical surgery.

Keywords: Surgical education, Anastomosis leakage, Arterio-venous bridge graft, MOSAT score

 

Back to Article Outline

Introduction 

The impact of increasing surgical experience on surgical skills has been confirmed in many studies.1, 2, 3, 4, 5, 6 Laboratory-based vascular surgery training models have been used to improve the technical skill of surgical residents in training. This modality has better teaching-learning environment when compared to traditional apprenticeship training system in the operating room. Trainees can practice repeatedly surgical techniques and re-use materials. The cost of training is low due to the elimination of patients and animals. The most important asset is related directly to patient safety.7, 8, 9 Laboratory-based training eliminates or reduces errors and complications that may otherwise occur to patients.4

Previously we have reported and validated the development of a new vascular anastomosis training model to help improve technical skill.10 The completion time of the anastomosis, leakage grade, diameter of the anastomosis as measured in the vascular anastomosis laboratory significantly related to the year of residency training. The aim of the present study was to determine the relationship between certain aspects of surgical technical competency as measured in the vascular anastomosis laboratory and the technical competency as measured in the operating room (OR).

Back to Article Outline

Materials and Methods 

Twenty-nine resident general surgeons-in-training participated in the present study. These consisted of 14 second-year, 9 third-year, and 6 fourth-year residents. All residents had previous training using the new vascular anastomosis model at least once during a vascular anastomosis workshop held annually at the institute. The latest workshop experience for all participants were held 6 months before the present study, and a few (10 residents: 3 second-year, 4 third-year, and 3 fourth year) had further experience one year before the latest workshop. The trainees had never performed vascular anastomosis in operating room by themselves. All participating residents were required to create a forearm arterio-venous bridge graft11 (Fig. 1) in chronic renal failure patients under the supervision of one instructor, who assessed the residents' performance using the MOSAT methodology.12 The forearm arterio-venous bridge graft was created between brachial artery and cephalic or basilic vein by suturing a 6mm polytetrafluoroethylene (PTFE) graft in an end to side fashion to the native vessels. Patients who had small-diameter veins (less than 3mm) and/or severe arterial calcification were excluded.

Predictors of surgical technical competency used in the present study included outcome measures defined in the previous vascular anastomosis training model study.10 These predictors were the completion time of the end to side graft anastomosis measured using the model, the grade of anastomotic leakage and number of leaks. In addition, measures of training experience also were included as potential predictors. These included the year of residency training and a previous laboratory-based model training one year before the workshop (the “latest workshop”) in which the predictors were recorded.

Three outcome measures were used to assess surgical technical competency in the operating room: completion time of PTFE graft to vein anatomosis, leakage across the anastomosis, and the mini-objective structured assessment of technical skills (MOSAT) score.12 A single examiner evaluated the technical performance, both in the laboratory and in the operating room.

Completion time of anastomosis 

After dissection and control of the cephalic or basilic vein and its branches, the PTFE graft was prepared for the anastomosis between graft and vein. Completion time was defined from the beginning of venotomy and ended when the suture was cut after the final knot.

Leakage across the anastomosis 

After completion of the arterial anastomosis, vascular clamps were released and direct compression was applied over the anastomosis for three minutes. The grading of leakage was defined as: 0 – no leakage; 1 – blood dripping from the anastomosis (Fig. 2); 2 – blood ejecting from the anastomosis (Fig. 3); 3 – blood bursting from the anastomosis (Fig. 4).

Mini objective structured assessment of technical skills (MOSAT) 

The technical performance of vascular anastomosis was assessed using MOSAT score (Table 1). The detailed checklist is operation-specific for separate actions that are necessary in performing vascular anastomosis.12, 13, 14 The reliability of this method has been reported to be high (reliability coefficient = 0.781).

Table 1. Mini objective structured assessment of technical skill (MOSAT) for vascular anastomosis
TaskDone Incorrectly or Not doneDone correctly
Control of vessel
1. Appropriate clamp(s) (DeBakey(s) available for the exam)01
2. Clamp(s) placed entirely across artery; may occlude side-to-side or anterior-posterior01

Arteriotomy
3. Anterior wall, in midline: longitudinal01
4. Uses appropriate blade (#11) to start01
5. Extends with Potts scissors or blade01
6. Appropriate size: 1.5-2 times the circumference of the artery01
7. Avoids trauma to posterior wall of artery01

Preparing graft
8. Ensures graft oriented, not twisted01
9. Cuts graft to appropriate length and contour (“cobra-head”)01

Anastomosis
10. Selects appropriate suture (4-0 available for exam)01
11. Selects vascular needle driver and forceps01
12. Starts appropriately: box stitch in heel or parachutes starting few bites from apex01
13. Bites consistently spaced 2-3mm from one another01
14. Instructs assistant to follow; appropriate tension and direction01
15. Avoids excessive trauma/handling of artery with instruments01
16. Guides suture down to desired position following bites01
17. Ensures that graft lays as patch (on outside) over the arteriotomy01
18. Flushes prior to last few bites01
19. Ties final suture appropriate tension, no air knot01
20. Minimum of 6 throws on all knots01
21. Needle loaded 1/2 to 2/3 > 80% of the time01
22. Uses correct needle, needle angle > 80% of the time01
23. Bites through artery and graft started at 90° > 80% of the time01
24. Follows curve of needle on entrance/exit > 80% of the time01

Maximum total score 24

Total score given

Back to Article Outline

Statistical Analysis 

Continuous variables were summarized as mean (standard deviation) or median (range) as appropriate. Categorical variables were summarized as counts and percentages. Predictors significantly associated with the completion time of the end-to-side vascular anastomosis in the operating room or with the MOSAT score, and those associated with grade of clinical leakage or with the number of leaks, were identified using multiple linear regression and multiple ordinal logistic regression, respectively. Statistical significance was defined as a p-value of 0.05 or less. All statistical analyses were performed with STATA version 7 (Stata Corp, College Station, TX, USA).

Back to Article Outline

Results 

Baseline data for all resident surgeons who participated in the present study are presented in Table 2. The outcomes of the study are presented in Table 3. Laboratory-based technical ability and training experience were associated significantly with the outcomes of interest are presented in Table 4, Table 5, Table 6, Table 7 for the outcomes completion time of the end-to-side anastomosis in the operating room (OR), leakage grade seen in the OR, number of leaks seen in the OR and MOSAT score, respectively. Significant predictors identified on multivariable analysis included completion time of the end-to-side anastomosis as measured in the laboratory, leakage grade measured in the laboratory, current year of residency training and previous laboratory-based experience one year prior to the latest workshop.

Table 2. Baseline and laboratory data
VariablesYear 2 (N=14)Year 3 (N=9)Year 4 (N=6)Overall (N=29)
Age (years): mean (SD)26.9 (1.3)27.6 (1.1)29.8 (3.3)27.7 (2.1)
Gender (male:female): number (%)13:1 (93:7)8:1 (89:11)6:0 (100:0)27:2 (93:7)

Previous laboratory experience (yes):
Number (%)3 (21)4 (44)3 (50)10 (34)

Completion time of ES in laboratory (minutes):
Mean (sd)23.8 (8.6)20.6 (3.0)15.8 (4.1)21.2 (7.1)

Number of leaks in the laboratory: number (%)
16 (43)3 (33)3 (50)12 (41)
24 (29)4 (44)3 (50)11 (38)
33 (21)1 (11)04 (14)
42 (7)1 (11)02 (7)

Leakage grade in the laboratory: number (%)
18 (57)7 (78)5 (83)20 (69)
23 (21)1 (11)04 (14)
33 (21)1 (11)1 (17)5 (17)

“Year” refers to year of residency training; ES is end-to-side anastomosis; percentages may not add to 100 due to rounding.

Table 3. Clinical results in the operating room
VariablesYear 2 (N=14)Year 3 (N=9)Year 4 (N=6)Overall (N=29)
MOSAT score:
Mean (SD);18.9 (1.7)20.3 (2.1)21.2 (1.3)19.8 (1.9)
Median (range)19.5 (15 to 20)21 (16 to 22)22 (19 to 22)20 (15 to 22)

Completion time of ES in OR (minutes):
Mean (SD)21.9 (3.2)20.6 (2.1)19.3 (4.1)20.9 (3.2)

Number of leaks in OR: number (%)
112 (86)4 (44)1 (17)17 (59)
22 (14)4 (44)4 (67)10 (34)
301 (11)1 (17)2 (7)

Leakage grade in OR: number (%)
19 (64)7 (78)2 (33)18 (62)
24 (29)2 (22)4 (67)10 (34)
31 (7)001 (4)

“Year” refers to year of residency training; ES is end-to-side anastomosis; percentages may not add to 100 due to rounding.

Table 4. Significant predictors of completion time of end-to-side anastomosis in OR
VariableEffect95% CIp-value
Leakage grade in laboratory2.40 per grade increase1.54 to 3.26<0.001
Completion time in laboratory0.18 per minute increase0.8 to 0.270.001
Previous laboratory experience (yes)−1.54−2.86 to −0.220.024
Table 5. Significant predictors of leakage grade in OR
VariableOdds Ratio95% CIp-value
Leakage grade in laboratory18.8 per grade increase1.5 to 236.40.040
Completion time in laboratory0.83 per minute increase0.69 to 0.990.023
Table 6. Significant predictors of number of leaks in OR
VariableOdds Ratio95% CIp-value
Year of training10.7 per higher year2.5 to 46.80.002
Previous laboratory experience (yes)0.070.01 to 0.840.036
Table 7. Significant predictors of MOSAT score
VariableEffect95% CIp-value
Year of training0.91 per year increase0.34 to 1.480.003
Leakage grade in laboratory−1.64 per grade increase−1.06 to −2.22<0.001

Each increase in the leakage grade measured in the laboratory adds 2.4 minutes to the completion time in the OR and each minute increase in the completion time in the laboratory adds 0.18 minutes to the completion time in the OR (Table 4). Previous laboratory-based experience decreases the completion time in the OR by 1.54 minutes (hence the negative number “−1.54” in Table 4). The findings in Table 4, Table 7 can be summarised: worse leakage noted in the laboratory predicts longer completion time and worse MOSAT score in the OR; longer completion time in the laboratory is associated with longer completion time in the OR. Increased clinical experience and more laboratory exposure can improve the MOSAT score and decrease completion time in the OR, respectively.

The coefficients in Table 5 can be interpreted as follows. The chance of an increase in the grade of leakage in the OR for one higher grade of leakage in the laboratory is 18.8 times that of one lower leakage grade in the laboratory. The chance of an increase in the grade of leakage in the OR is 0.83 times (17% decrease in the odds) for each minute increase in the completion time in the laboratory. The worse the leakage in the laboratory the worse it was in the OR, but taking more time in completing an anastomosis in the laboratory predicted less leakage in the OR. The coefficients in Table 6 can be interpreted in a similar manner, with the number of leaks increasing with year of training, but decreases with prior experience in the laboratory.

The MOSAT score was a good univariate predictor of surgical technical competency in the present study (data not shown). However, there was no significant association between the MOSAT score and the number of leaks, although there was a tendency for fewer leaks to occur with higher score. In the multivariate analysis the MOSAT score was dropped from the list of significant predictors in Table 4, Table 5, Table 6.

The number of leaks was not significantly associated with any other OR measure such as completion time, leakage grade or MOSAT score, although there was a slight tendency for more leaks if completion time was shorter in the OR, if grading of leakage was more severe and if the MOSAT score was higher. The latter finding (with the MOSAT score) probably was confounded by the fact that higher year residents had higher MOSAT score and tended to produce more leaks in the OR.

Back to Article Outline

Discussion 

Technical ability or competency is an important part of overall surgical competency.15, 16 Our results (Table 4, Table 5, Table 6, Table 7) indicate that the most important predictors of surgical technical competency in the OR consisted of technical competency measured in the vascular anastomosis laboratory as well as the year of residency training. This was true regardless of the outcomes considered, i.e. in terms of the end points of technical performance (completion time of the end-to-side anastomosis, number of leaks and grading of leakage), or in terms of the process of technical performance (the MOSAT score). Higher year of residency training and previous experience of attending the same laboratory-based workshop contributed significantly to faster completion of vascular anastomosis in the OR, lower grade of leakage and better process performance according to the MOSAT methodology. The only important predictors of surgical technical competency were leakage grade and completion time of anastomosis as measured in the laboratory-workshop. That is, lower grades of leakage and shorter completion time noted in the laboratory were significantly associated with higher level of technical competence in the OR. In our general surgical resident training program, trainees have never performed vascular anastomosis by themselves. Practice using the laboratory-based model provided the trainees with a chance to use the instruments, understand the techniques and gain some technical competency.

Curiously, the number of leaks detected in the operating room was not significantly associated with other technical outcomes, i.e. with the completion time of anastomosis, leakage grade in the OR and MOSAT score. Contrary to expectations, higher year of training was associated with more leaks in the OR, even after adjusting for previous laboratory-based experience. This non-significant finding (higher year of training with more leaks in OR) was not seen in the laboratory (Table 1). Although there is no clear explanation for this, it is suspected that in the operating room the residents may have been under the pressure to operate faster and hence produced more anastomotic leaks, which may reflect the fact that the laboratory environment cannot duplicate the atmosphere of the operating room.

The process variable (MOSAT score) was able to predict the endpoints of technical performance reasonably well, as would be expected, but was dropped from the multivariate models due to significant association with other, stronger, predictors.

Age and gender were not associated with technical competency 

Technical competency in terms of completion time and anastomotic leaks, measured in a vascular anastomosis laboratory-workshop environment, was able to predict surgical technical competency in the operating room 6 months later. Additional laboratory-workshop experience one year before the OR test added significantly to technical competency. This shows that our vascular anastomosis model is a valid and useful model for predicting surgical competency in operating room.

Back to Article Outline

Acknowledgement 

We thank Professor Amnuay Thithapandha for his help with the English editing of this manuscript.

Back to Article Outline

References 

  1. Jackson MJ, Pandey V, Wolfe JH. Training for infrainguinal bypass surgery. Eur J Vasc Endovasc Surg. 2003;26:457–466
  2. Pandey VA, Black SA, Lazaris AM, Allenberg JR, Eckstein HH, Hagmuller GW, et al. Do workshops improved the technical skill of vascular surgical trainees?. Eur J Vasc Endovasc Surg. 2005;30:441–447
  3. Datta V, Mandalia M, Mackay S, Chang A, Cheshire N, Darzi A. Relationship between skill and outcome in the laboratory-based model. Surgery. 2002;131:318–323
  4. Smith CD. Teaching surgical techniques and procedures using advanced educational tools and concepts. Asian J Surg. 2005;28:159–162
  5. Fanua SP, Kim J, Shaw Wilgis EF. Alternative model for teaching microsurgery. Microsurgery. 2001;21:379–382
  6. Hosnuter M, Tosun Z, Savaci N. A nonanimal model for microsurgical training with adventitial stripping. Plast Reconstr Surg. 2000;106:958–959
  7. Shine KI. Health care quality and how to achieve it. Acad Med. 2002;77:91–99
  8. Bagian JP. Patient safety: lessons learned. Pediatr Radiol. 2006;36:287–290
  9. Beard JD, Education and Training Committee of the Vascular Society of Great Britain and Ireland . Setting standards for the assessment of operative competence. Eur J Vasc Endovasc Surg. 2005;30:215–218
  10. Wilasrusmee C, Phromsopha N, Lertsitichai P, Kittur DS. A new vascular anastomosis model: relation between outcome and experience. Eur J Vasc Endovasc Surg. 2007;33:208–213
  11. D'Cunha PT, Besarab A. Vascular access for hemodialysis: 2004 and beyond. Curr Opin Nephrol Hypertens. 2004;13:623–629
  12. Martin JA, Regehr G, Reznick R, MacRae H, Murnaghan J, Hutchison C, et al. Objective structured assessment of technical skill (OSATS) for surgical residents. Br J Surg. 1997;84:273–278
  13. Backstein D, Agnidis Z, Sadhu R, MacRae H. Effectiveness of repeated video feedback in the acquisition of a surgical technical skill. Can J Surg. 2005;48:195–200
  14. Reznick R, Regehr G, MacRae H, Martin J, McCulloch W. Testing technical skill via an innovative “bench station” examination. Am J Surg. 1997;173:226–230
  15. Datta V, Chang A, Mackay S, Darzi A. The relationship between motion analysis and surgical technical assessments. Am J Surg. 2002;184:70–73
  16. Baldwin PJ, Paisley AM, Brown SP. Consultant surgeons' opinion of the skills required of basic surgical trainees. Br J Surg. 1999;86:1078–1082

PII: S1078-5884(07)00357-7

doi:10.1016/j.ejvs.2007.05.015

European Journal of Vascular & Endovascular Surgery
Volume 34, Issue 4 , Pages 405-410, October 2007

Article Tools

* Image Usage & Resolution