Keywords
microsurgery - surgical simulation - surgical education - autologous reconstruction
Consistent, frequent, and intensive practice is essential in the refinement and mastery
of microsurgical skills.[1] In an effort to meet the educational needs of surgical residents, microsurgical
training models—which allow the novice surgical trainee to practice microsurgical
skills in a laboratory setting that is both low stakes and realistic—have been developed.[2] Studies have shown that repetitious practice on such models over a long period of
time is a highly effective means by which surgical residents may overcome the steep
learning curve associated with microsurgery.[1]
[3] It is no surprise, then, that laboratory simulations have become an indispensable
component of microsurgical training.[1]
[2]
[4]
Live animal models are considered the gold standard for simulated microsurgical training;
however, their use is limited by high costs and associated ethical concerns.[5] The use of cadaveric animal tissue—most commonly chicken, rat, and porcine—presents
an alternative that is cost-effective, acceptably realistic, and shown to improve
resident's competence.[6]
[7]
[8]
[9]
[10] However, without investigation, it is difficult to discern a microsurgical training
model's ability to contribute positively toward resident's education. Consequently,
it is essential to evaluate a given model for fidelity and impact prior to its incorporation
into a training curriculum.[11]
We recently described the creation of the Blue-Blood porcine chest wall as a realistic
and affordable means of simulating internal mammary artery (IMA) and internal mammary
vein (IMV) preparation and anastomosis.[12] This procedure is extremely important for residents in plastic and reconstructive
surgery to learn as it is a key step in autologous breast reconstruction. This operation
(e.g., deep inferior epigastric perforator [DIEP] flaps) typically relies on the use
of the IMA and IMV as the recipient vessels.[13]
[14]
[15]
[16] The preparation of the IMA and IMV is a crucial step in autologous breast reconstruction,
as failure to perform it correctly may result in patient injury,[17] complication, or flap failure.[18]
[19] Thus, the Blue-Blood porcine chest wall model was developed with the intention of
improving resident's comfort and expertise in this critical surgical procedure prior
to performing the operation on humans.
The aim of the present study was to assess the effect of training with the Blue-Blood
porcine chest wall on trainee confidence in performing dissection and anastomosis
of the IMA and IMV, as well as obtain resident's and faculty's perspectives on the
realism and utility of this model.
Methods
This study was reviewed by the University of Wisconsin Institutional Review Board
(IRB) and determined to be exempt. As such, a formal information sheet approved by
the University of Wisconsin IRB was provided to all individuals invited to participate,
who then had the option to accept or decline participation. Participants could withdraw
at any point during the study.
Setting and Study Population
Postgraduate year (PGY)3, PGY4, PGY5, and PGY6 plastic surgery residents and microsurgery
faculty from the Division of Plastic Surgery at the University of Wisconsin were invited
to participate. PGY1 and PGY2 residents were excluded as use of the simulator is most
beneficial to residents with a strong grasp of basic microsurgery techniques and some
experience in the operating room (OR) during cases of breast reconstruction via microvascular
free tissue transfer.
Level of training was recorded for each participant. Subjective, anchored experience
with this procedure in humans was additionally documented for each participant and
categorized as follows: none, minimal, some, moderate, considerable, or extensive.
The Blue-Blood porcine chest wall model was assembled as previously described, as
demonstrated in [Fig. 1].[12] All training sessions were conducted at the University of Wisconsin Microsurgical
Training Center housed in the laboratory of the senior author (S.O.P.). One expert
microsurgeon (W.Z.) led individual training sessions and performed as the microsurgical
assistant. During training sessions, participants were guided through dissection of
the chest wall, preparation of the internal mammary vessels, and vessel anastomoses,
as demonstrated in [Video 1].
Video 1 Blue-Blood pig thorax simulator for internal mammary vessel dissection. Narrated
video captured through a surgical microscope showing a resident's training session
on the novel Blue-Blood pig thorax simulator. (Reprinted with permission from Zeng
W, Gunderson KA, Sanchez RJ, et al. The Blue-Blood porcine chest wall: a novel microsurgery
training simulator for internal mammary vessel dissection and anastomosis. J Reconstr
Microsurg 2020.)
Fig. 1 Fully assembled Blue-Blood internal mammary artery training model. (Reprinted with
permission from Zeng W, Gunderson KA, Sanchez RJ, et al. The Blue-Blood porcine chest
wall: a novel microsurgery training simulator for internal mammary vessel dissection
and anastomosis. J Reconstr Microsurg 2021;37(04):353–356.)
Data Sources
Participants anonymously completed a survey immediately prior to and immediately following
the training session to assess change in participant confidence, model fidelity, and
perceived model utility. We utilized an eight-question survey with a five-point rating
scale to assess change in resident's confidence in performing seven key procedural
steps in humans, as well as the procedure as a whole ([Table 1]), with a response of 1 corresponding to “not at all confident” and 5 corresponding
to “extremely confident.” The post-training survey also assessed model fidelity with
regard to the anatomy of the model ([Table 2]) and performing each surgical step on the model as compared with humans ([Table 3]).
Table 1
Participant's confidence survey
Surgical steps
|
Not at all
|
Slightly
|
Moderately
|
Very
|
Extremely
|
Dissection down to rib
|
◯
|
◯
|
◯
|
◯
|
◯
|
Incision and elevation of the perichondrium
|
◯
|
◯
|
◯
|
◯
|
◯
|
Excision of rib
|
◯
|
◯
|
◯
|
◯
|
◯
|
Identification of vessels
|
◯
|
◯
|
◯
|
◯
|
◯
|
End-to-end anastomosis
|
◯
|
◯
|
◯
|
◯
|
◯
|
Use of venous coupler
|
◯
|
◯
|
◯
|
◯
|
◯
|
Evaluation of anastomosis
|
◯
|
◯
|
◯
|
◯
|
◯
|
Overall surgical procedure
|
◯
|
◯
|
◯
|
◯
|
◯
|
Note: Participants were asked to rate how confident they are performing each part
of the procedure in humans independently both before and after their training session.
Table 2
Anatomic fidelity survey
Anatomic feature
|
Not at all
|
Slightly
|
Moderately
|
Very
|
Extremely
|
Overall anatomy
|
◯
|
◯
|
◯
|
◯
|
◯
|
Vessel depth
|
◯
|
◯
|
◯
|
◯
|
◯
|
Vessel thickness
|
◯
|
◯
|
◯
|
◯
|
◯
|
Vessel consistency/behavior
|
◯
|
◯
|
◯
|
◯
|
◯
|
Rib anatomy
|
◯
|
◯
|
◯
|
◯
|
◯
|
Perichondrium anatomy
|
◯
|
◯
|
◯
|
◯
|
◯
|
Note: Participants were asked to mark how realistic they felt the anatomy was in this
model compared with humans.
Table 3
Surgical fidelity survey
Surgical step
|
Not at all
|
Slightly
|
Moderately
|
Very
|
Extremely
|
Dissection down to rib
|
◯
|
◯
|
◯
|
◯
|
◯
|
Incision and elevation of the perichondrium
|
◯
|
◯
|
◯
|
◯
|
◯
|
Excision of rib
|
◯
|
◯
|
◯
|
◯
|
◯
|
Identification of vessels
|
◯
|
◯
|
◯
|
◯
|
◯
|
End-to-end anastomosis
|
◯
|
◯
|
◯
|
◯
|
◯
|
Use of venous coupler
|
◯
|
◯
|
◯
|
◯
|
◯
|
Evaluation of anastomosis
|
◯
|
◯
|
◯
|
◯
|
◯
|
Overall surgical procedure
|
◯
|
◯
|
◯
|
◯
|
◯
|
Note: Participants were asked to mark how realistic they felt each surgical step was
in this model compared with humans.
Finally, participants were asked questions regarding model utility. Participants were
asked if they believe practice with this model would improve residents' ability to
perform this operation in the OR, if they would recommend that this model be incorporated
into the plastic surgery residency microsurgical training curriculum and, if so, at
what training level they felt it would be most beneficial. A free text section was
provided for additional comments regarding the model and training experience. Time
to completion of each training session was also documented.
Statistical Analysis
Descriptive statistics were calculated to characterize the participants' responses
to the general survey information (i.e., PGY level and amount of experience). Next,
microsurgical competency survey results were analyzed. The Shapiro–Wilk normality
test was utilized to confirm that the data were not normally distributed. Subsequently,
a paired two-sample Wilcoxon's tests were conducted to assess if microsurgical competency
survey results demonstrated a statistically significant change in confidence among
participants prior to and after completing the IMA activity. These survey results
were then visualized via generation of paired data point boxplots.
To assess how level of surgical training influenced participants' confidence, one-way
ANOVA tests were used to determine if there was a relationship between level of surgical
training (resident vs. attending) and difference in survey responses prior to and
after the IMA activity. The one-way ANOVA test was again utilized to quantify the
association between level of surgical training and time used to complete the IMA training
activity. Finally, descriptive statistics were conducted to evaluate participants'
perception of realism of the IMA training model.
Results
A total of 17 participants, including 12 residents and 5 faculty members, participated
in this study, with previous experience preparing the IMA in humans ranging from “none”
to “extensive.” Breakdown of participant training level and previous experience can
be visualized in [Figs. 2] and [3], respectively.
Fig. 2 Number of participants in study by level of surgical training.
Fig. 3 Number of participants in study by level of experience performing procedure in humans.
None = no experience. Minimal = observation only. Some = acting as first assist. Moderate = acting
as primary surgeon with minimal supervision. Considerable = comfortable with all aspects
of the procedure, not regularly performed in my practice. Extensive = perform this
operation regularly in my practice.
Self-Assessed Confidence
After training with the Blue-Blood IMA model, participants had significantly increased
comfort and confidence in performing six of the seven key procedural steps identified
([Table 4]). Additionally, participants were significantly more confident in their ability
to perform the procedure as a whole after the training session, with a pretraining
average confidence rating of 2.94 out of 5 and a posttraining average confidence rating
of 3.47 out of 5 (p = 0.008). Change in confidence performing the procedure can be visualized in [Fig. 4]. Notably, every participant reported improvement in confidence in at least one of
the seven key procedural steps identified. When stratified by trainee type (resident
vs. faculty), there was a significant difference in the amount of change in confidence
following the training session, with residents reporting a significantly greater change
in confidence in four of the seven procedural steps and the procedure as a whole ([Table 5]).
Fig. 4 Boxplot of participant's confidence in performing overall procedure pre- versus posttraining
with the Blue-Blood chest wall model. Gray lines show individual participant change
in responses.
Table 4
Participant's confidence pre- versus posttraining with model
Procedural step
|
Pre-survey
Mean ± SD
(range)
|
Post-survey
Mean ± SD
(range)
|
p-Value
|
Dissection to rib
|
3.24 ± 1.62
(1–5)
|
3.82 ± 1.13
(1–5)
|
0.03125a
|
Elevation of perichondrium
|
3.35 ± 1.54
(1–5)
|
3.76 ± 1.25
(1–5)
|
0.02627a
|
Excision of rib
|
3.00 ± 1.70
(1–5)
|
3.59 ± 1.28
(1–5)
|
0.06789
|
Identify vessels
|
3.12 ± 1.50
(1–5)
|
3.71 ± 1.10
(1–5)
|
0.01922a
|
End-to-end anastomosis
|
3.29 ± 1.31
(1–5)
|
3.76 ± 1.20
(1–5)
|
0.005962a
|
Venous coupler
|
3.24 ± 1.39
(1–5)
|
3.75 ± 1.24
(1–5)
|
0.03054a
|
Evaluation of anastomosis
|
3.29 ± 1.40
(1–5)
|
3.76 ± 1.20
(1–5)
|
0.01471a
|
Overall surgical procedure
|
2.94 ± 1.52
(1–5)
|
3.47 ± 1.23
(1–5)
|
0.008334a
|
Notes: Participant's perceptions of confidence levels of performing each surgical
step in humans before versus after training session. 1 = not at all, 2 = slightly,
3 = moderately, 4 = very, 5 = extremely. Significance indicated by superscript “a.”
Table 5
Resident versus faculty change in confidence after training session
|
Difference in pre-survey and post-survey responses
Mean ± SD
(range)
|
|
Procedural step
|
Resident
(
n
= 12)
|
Faculty
(
n
= 5)
|
p
-Value
|
Dissection to rib
|
0.917 ± 0.900
(0–2)
|
−0.2 ± 0.447
(−1 to 0)
|
0.004196a
|
Elevation of perichondrium
|
0.583 ± 0.669
(0–2)
|
0 ± 0
(0–0)
|
0.0116a
|
Excision of rib
|
0.833 ± 1.19
(−2 to 2)
|
0 ± 0
(0–0)
|
0.03407a
|
Identify vessels
|
0.833 ± 0.835
(0–2)
|
0 ± 0
(0–0)
|
0.005354a
|
End to end anastomosis
|
0.583 ± 0.515
(0–1)
|
0.2 ± 0.447
(0–1)
|
0.1596
|
Venous coupler
|
0.636 ± 0.809
(0–2)
|
0.2 ± 0.447
(0–1)
|
0.1896
|
Evaluation of anastomosis
|
0.583 ± 0.669
(0–2)
|
0.2 ± 0.447
(0–1)
|
0.1944
|
Overall surgical procedure
|
0.75 ± 0.622
(0–2)
|
0 ± 0
(0–0)
|
0.001537a
|
Notes: Comparison of change in confidence before and after training session between
residents and faculty. Significance indicated by superscript “a.”
Model Fidelity
Overall model fidelity, with regard to the anatomy of the model and performance of
each surgical step, was evaluated by each participant. On average, participants felt
the surgical steps and anatomy were “moderately” to “extremely” realistic ([Table 6]). Of participants with at least “moderate” experience with this procedure in humans
(13 participants), the majority (10 participants) rated model anatomy and performance
of key procedural steps as “very” or “extremely” realistic as compared with humans.
In the category of anatomic fidelity, vessel depth and performance of anastomoses
were perceived as the model's strongest features; however, participants noticed differences
in rib and perichondrium anatomy, describing these structures as wider and flatter
in comparison to human anatomy.
Table 6
Model fidelity evaluation
Fidelity category
|
Answer (scale: 1–5)
Mean ± SD (range)
|
Anatomic fidelity
|
Overall anatomy
|
3.65 ± 0.61 (3–5)
|
Vessel depth
|
3.94 ± 0.83 (2–5)
|
Vessel thickness
|
3.76 ± 0.66 (3–5)
|
Vessel consistency
|
3.88 ± 0.86 (2–5)
|
Rib anatomy
|
3.06 ± 0.77 (2–4)
|
Perichondria anatomy
|
3.56 ± 1.03 (1–5)
|
Surgical fidelity
|
Dissection of rib
|
3.47 ± 0.51 (3–4)
|
Perichondrium
|
3.41 ± 0.87 (2–5)
|
Excision of rib
|
3.76 ± 0.75 (2–5)
|
Identify vessels
|
4.11 ± 0.93 (2–5)
|
End to end anastomosis
|
4.24 ± 0.75 (3–5)
|
Venous coupler
|
4.09 ± 0.94 (2–5)
|
Evaluation of anastomosis
|
4.29 ± 0.69 (3–5)
|
Overall surgical procedure
|
3.88 ± 0.60 (3–5)
|
Notes: Descriptive statistics to evaluate participants' survey responses pertaining
to how realistic the IMA training model is. 1 = not at all, 2 = slightly, 3 = moderately,
4 = very, 5 = extremely.
Model Utility
Perception of model utility was remarkably positive. One hundred percent of participants
believed practice with this model would improve residents' ability to perform this
procedure in the OR. One hundred percent of participants also stated they would recommend
this model be incorporated into the existing microsurgical training curriculum. Most
participants believed that utilization of this model in the training curriculum would
be most beneficial during the PGY3 and PGY4 years ([Table 7]).
Table 7
Benefit of model based on level of training
Level of training
|
Number of responses
|
Medical student
|
0
|
PGY1
|
2
|
PGY2
|
4
|
PGY3
|
12
|
PGY4
|
12
|
PGY5
|
9
|
PGY6
|
5
|
PGY7
|
0
|
Faculty
|
1
|
Note: Level of training at which utilization of IMA model and training session is
perceived to be most beneficial.
Time to Completion
We found that differences in time to completion of the training session based on level
of surgical training did not reach significance ([Table 8]); however, a trend demonstrating a decrease in time to completion was noted as level
of surgical training increased ([Fig. 5]). On average, residents required more time to complete the training model than faculty
(40.5 ± 10.7 minutes vs. 31.5 ± 10.0 minutes).
Fig. 5 Line graph with error bars illustrating the mean time used to complete the IMA model
training session for each level of surgical training.
Table 8
Time to completion by level of training
|
n
|
Number of minutes used to complete anastomosis
Mean ± SD
(range)
|
p-Value
|
Level of training
|
|
|
0.0724
|
PGY3
|
3
|
45.0 ± 14.8
(30.4–60)
|
|
PGY4
|
4
|
40.9 ± 13.9
(22–52.6)
|
|
PGY5
|
4
|
37.8 ± 6.59
(31.9–47.1)
|
|
PGY6
|
1
|
36.9 ± NA
(NA)
|
|
Faculty
|
5
|
31.5 ± 10.0
(20.5–40.6)
|
|
Overall
|
|
Resident
(n = 12)
|
Faculty
(n = 5)
|
p-Value
|
Minutes used to complete IMA training activity
Mean ± SD
(range)
|
40.5 ± 10.7
(22.00–60.00)
|
31.5 ± 10.0
(20.5–40.6)
|
0.1345
|
Note: Amount of time required to complete the IMA model training session across discrete
levels of surgical training.
Discussion
Preparation of the IMA and IMV as recipient vessels is a critical step of breast reconstruction
via microsurgical free tissue transfer that plastic surgery residents must master.
In this study, we have demonstrated that not only is the Blue-Blood porcine chest
wall simulator highly realistic, but also that training with the model improves resident's
comfort and confidence in performing the steps of this procedure after just one session.
Expert faculty and residents alike agree integration of this model into existing microsurgical
training curriculum would be beneficial.
The traditional model for surgical training revolved around an apprenticeship model,
with the aim of providing trainees hands-on learning in a setting that fostered autonomy.[2]
[20]
[21] Many surgical training programs have transitioned from the apprenticeship model
to a paradigm that emphasizes core competencies and formalized assessments.[21] Resultantly, surgical training models have been popularized as they increase the
efficiency with which trainees may acquire critical surgical skills.[22]
[23]
[24] This finding underscores the potential of the Blue-Blood porcine chest wall simulator
to provide a highly productive learning experience for surgical trainees.
Ziolkowski et al recently published a pilot study of a novel, fully synthetic, DIEP
flap IMA anastomosis surgical simulator.[25] This model focused on providing authentic simulation of chest excursion that occurs
during natural breathing of a patient while completing the surgical anastomosis of
this procedure. The authors demonstrated residents had an increase in confidence performing
anastomoses after practice on the simulator, highlighting the importance of surgical
simulation in the acquisition of the specific skills of insetting a DIEP flap and
improving confidence prior to the operating theater. The Blue-Blood simulator similarly
identified increased resident's confidence in performing these skills. Our model also
carries the additional advantages of improved vessel fidelity by use of cadaveric
tissue, real-time feedback with the Blue-Blood perfusion system, and the ability to
improve acquisition of other steps involved in the preparation of the vessels in addition
to the anastomosis, all provided at a much lower cost—$55 versus >$13,000 for physical
materials.
The findings herein identify an increase in confidence on the part of the resident
trainees with use of this model. While there is no doubt the most realistic training
occurs in the OR, this can be a high stress environment for both the trainee and the
faculty surgeon when it comes to performing critical portions of procedures for the
first time, particularly with faculty–trainee pairing that may be new to each other.
Implementation of a surgical training model may provide a platform for the trainees
to refine their skills until deemed suitable for transition to the OR under preceptor
supervision.[2]
[26]
[27] Eventually, this simulation training has the potential to not only bring more opportunity
and autonomy for the residents but also improve the safety and health of patients
undergoing free flap breast reconstruction.
An additional benefit was identified in this study on the part of the faculty. In
discussion with participating attendings, multiple faculty members stated that existence
of the model made them more confident in residents' abilities to perform this portion
of the procedure in the OR. In turn, they stated that they would be more likely to
allow them to perform it in the OR in the future after having practiced with this
model, highlighting the value that this model can bring to a trainee's education.
Furthermore, the study herein highlighted the realism of the model with regard to
anatomy. Importantly, the similar anatomical configuration of the porcine chest wall
makes this a suitable model for multiple methods of IMA and IMV dissection. As our
institution employs the non–rib-sparing technique, in this study, the seven key procedural
steps evaluated were those of the non–rib-sparing technique. Though not evaluated
in this study, this model may easily be used for other methods of IMA and IMV dissection,
including rib-sparing techniques.[12]
[28]
[29] Rib-sparing techniques have become more popular recently, and some series have demonstrated
a decreased complication profile than non–rib-sparing techniques.[30] This technique is seen by some as more technically challenging, requiring creation
of anastomoses in a more confined area. Use of this model for practice of this technique
prior to the OR would likely be beneficial for residents, just as it was found to
be for the non–rib-sparing technique in this study.
Importantly, the focus of this study was to assess change in resident's confidence
in performing IMA and IMV dissection and anastomosis after training with the model,
with the goal of improving trainee's confidence and safety in performing this procedure
in the OR. The purpose of this study was not for the creation of a resident assessment
tool. As such, at its current level of evaluation, we recommend this model as an adjunct
training tool for a comprehensive microsurgical curriculum, and not as an assessment
tool for resident's competency. With the push toward competency-based education and
training in plastic and reconstructive surgery, valid, objective assessment of resident's
performance is necessary. Further investigation is required for this model to create
a formal assessment tool for microsurgical and plastic surgery education.
There are several limitations to this study. This study was conducted at a single
institution with a robust microsurgical curriculum; thus, the generalizability for
which level of trainee this model is most beneficial for may differ at other institutions.
Results may be different in our small cohort than across different institutions where
there is variation in clinical exposure, variation in clinical volume, and who may
have an entirely different surgical and microsurgical training curriculum. As we have
implemented our microsurgery curriculum earlier in resident's training over the years,
as is true for many programs across the nation, it is apparent residents are gaining
technical skills at earlier stages in their training. In the future, this model may
prove beneficial as part of a resident's microsurgical training curriculum even earlier
in residency than the PGY3 level, which was the cutoff utilized in this study. Additionally,
this study only assessed resident's confidence change immediately after one training
session with the simulator. Further research is necessary to determine the long-term
impact on resident's confidence and how repeated use of the model affects training
outcomes. Furthermore, as mentioned earlier, the present study utilized self-reported
participant's confidence to assess the validity of the Blue-Blood porcine chest wall
simulator, which has been used to assess previous surgical training models[31]
[32]
[33]; however, self-reported confidence is limited in its generalizability in that it
is not standardized. Future investigations into the validity of the Blue-Blood porcine
chest wall simulator might implement methods of evaluation that are more standardized
and objective. Finally, the low cost for the creation of this model ($55) accounts
for physical materials required for assembly only, as described previously.[12] The cost of this model is low in the setting of an institution with an existing
simulation laboratory with dedicated laboratory microscope and microsurgical training
staff, as well as donated cadaveric specimens. Cost of creating and maintaining a
space such as this would be much greater than $55. However, it is our belief that
this model in isolation would also be appropriate for training under loupe magnification
and would only require the additional purchase of a basic microsurgical instrument
set.
Conclusion
The Blue-Blood porcine chest wall model is a novel simulator for resident's training
of IMA and IMV preparation and anastomosis. Training with this simulator increases
trainee's confidence in performing key surgical steps of the procedure after one training
session. The model is perceived as highly authentic and valuable to resident's education
by both residents and faculty and will be formally integrated into our institutional
microsurgery training curriculum.