Here we present a protocol for the use of the pig superior epigastric artery perforator flap as a learning module for head and neck microvascular reconstruction.
Live models that resemble surgical conditions of humans are needed for training free-flap harvesting and anastomosis. Animal models for training purposes have been available for years in many surgical fields. We used the female (because they are easy to handle for the procedure) Yorkshire pigs for the head and neck reconstruction by harvesting the deep inferior epigastric artery perforator or the superior epigastric artery perforator flap. The anastomosis site (neck skin defect or tracheal wall defect) was prepared via the dissection of the common carotid artery and the internal jugular vein, in which 3.5× loupe magnification was used for anastomosis as we use on human cases in real life. This procedure demonstrates a new training method using a reliable learning model and provides a detailed anatomy in a live scenario. We focused on the ischemia time, harvesting, vessel anastomosis, and designing the flap to fit the defect site. This model improves tissue handling and with the use of proper instruments can be repeated many times so that the surgeon is fully confident before starting the surgery on humans.
Reconstruction following surgery for the head and neck malignant diseases is a difficult procedure associated with significant morbidity. Microvascular free-flap reconstruction has been well established as the standard approach to reconstruction for over 20 years1,2,3. Free-flap transfer plays a significant role in improving the head and neck management in cancer patients and in post-traumatic injuries thereby pushing the boundaries of surgical excision of disease beyond previous techniques, resulting in greater patient quality of life and longer survival rates1,2,3. The various flaps for reconstruction include rotational, graft, and free flaps.
The role of free flaps in the head and neck reconstruction has expanded. It is the most difficult flap to work with, requiring skilled and delicate handling. Flap failure is a catastrophic event, with significant morbidity4,5. Thus, considerable training time is required to develop the precision necessary for the successful surgical outcomes3,4,5,6,7,8,9. The steep learning curve associated with such a surgery can influence the outcome for patients and affect treatment management3,4,5,6,7,8,9. To reduce the training time and learning curve for new surgeons, a training model is needed that mimics human biology and provides similar surgical field conditions8.
The goal of this study is to show the visibility of Porcine as a good training module for the head and neck microvascular reconstruction resembling the human case with improved skills in the active fashion.
This study investigated the use of a porcine model for training new colleagues in the head and neck microvascular reconstruction for free-flap transfer to provide a cost-effective and less stressful supplement to the clinical field training with reliably similar features for free-flap procedures. Pigs have been used for many studies and as teaching models for various surgical reconstructions, e.g., breast reconstruction;5 however, pigs have never been used for head and neck reconstruction except in our study for tracheal reconstruction due to tracheal stenosis10.
The idea was started after Frederic Bodin7, who describe the similar flap for breast reconstruction. The main advantage for the study over the other module of microvascular training is the active livening module with a real immediate result of the procedure.
This study was guided and approved by the Department of Laboratory Animal Resources, Yonsei Biomedical Research Institute, Yonsei University College of Medicine, accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International. This study followed the guidelines for the Care and Use of Laboratory Animals of the Institute of Laboratory Animal Resources Commission on Life Sciences National Research Council. All Pigs were acclimated for One week before the operation.
1. Preparation
2. Procedure: Reception Site
3. Procedure: Flap Site
Note: The superior epigastric artery perforator (SEAP) flap harvest can be performed, according to the method described by Frederic Bodin7.
4. Anastomosis and Closure
5. Post-operative Care
6. Euthanasia
We performed the procedure on six pigs: cervical skin defect reconstruction on two pigs, tracheal reconstruction on two pigs, and free flap to test vascular anastomosis device in two pigs. The pigs were monitored for 3 months and there was no clinical sign of neurological deficit.
The mean time for ischemia was 50 min (range, 35-80 min); the time decreased as the procedure was repeated. The mean harvest time of the six pigs was 55 min. There is no morbidity happen at the donor site in our module. The mean pedicle size of the flaps was 10 cm, which is similar to most that in the human head and neck. The mean artery diameter was 4.5 mm quite larger than human 2 mm, and the mean vein diameter was 5.84 mm also quite larger than human 2 mm although it simulates the real-life experience. The Skin paddle size ranging from 25 cm2 to 40 cm2 without significant effect in Flap failure (Table 1).
With practice, repeated confidence, skill and time of surgery was improved. Unfortunately, the case number 5 was getting longer time in harvesting and anastomosis. The flap in this case end with the total loss plus the diameter of the artery was the smallest one which represents one of challenges in the reconstruction surgery and it was a good lesson for judging the pedicle selection with great impact in our surgeon success in real life.
Animal | Purpose for free flap | Harvest time (min.) | Ischemia time (min.) | Flap result | Donor site morbidity | Pedicle length (cm) | Recipient site | Artery diameter (mm) | Vein diameter (mm) | Skin paddle size of flap (cm2) |
1 | Cervical skin defect reconstruction | 45 | 55 | Survived | None | 10 | Neck | 4 | 6.5 | 32 |
2 | Cervical skin defect reconstruction | 50 | 50 | Survived | None | 10 | Neck | 6 | 5 | 25 |
Mean | 47.5 | 52.5 | 10 | 5 | 5.75 | 28.5 | ||||
3 | Tracheal defect reconstruction | 55 | 40 | Survived | None | 9 | Neck | 5 | 7 | 35 |
4 | Tracheal defect reconstruction | 62 | 45 | Survived | Seroma | 15 | Neck | 4 | 6 | 40 |
Mean | 58.5 | 42.5 | 12 | 4.5 | 6.5 | 37.5 | ||||
5 | Test of device for vascular anastomosis | 70 | 80 | Total loss | N/A | 8 | Neck | 3.5 | 5 | 28 |
6 | Test of device for vascular anastomosis | 49 | 35 | Survived | Seroma | 8 | Neck | 4 | 5 | 32 |
54.625 | 50 | 50.8333 | 10.25 | 10.25 | 4.5 | 5.84375 | 32.25 | 32 |
Table 1. Porcine Reconstruction Flap Model Measurement
Figure 1. A porcine model SEAP flap harvesting and head and neck reconstruction. (A) The upper abdomen flapdrawing for the superior epigastric artery perforator (SEAP). (B) SEAP intramuscular dissection. (C) The flap contained the skin, subcutaneous tissue, muscle with fascia, and the superior epigastric artery with venae comitantes. (D) The carotid artery and internal jugular vein post anastomosis. Please click here to view a larger version of this figure.
Figure 2. A porcine model after surgery and 3 months later. (A) Skin paddle of the SEAP flap after exteriorized and sutured to the cervical midline skin incision. (B) The abdominal skin incision after closure. (C) The Neck reconstruction site 3 months later. (D) The abdominal donor site after 3 months. Please click here to view a larger version of this figure.
Significant morbidity and defects can occur in head and neck malignancy patients during surgical management. Microvascular free tissue transfer has become essential for reconstruction in most cases. The viability of the flap is a critical issue, requiring steadiness, precise handling of the pedicle, tactile sensation, visuospatial ability, and excellent operative flow from the surgeon8. To develop these skills, one needs extensive practice with a training model3,4,5,6,7,8,9.
Several studies have discussed methods for learning these skills, including vascular anastomosis, which has been the focus of most studies and for which a 'microvascular practice card' was developed;9 chickens6,7 and rats have been used for this purpose. Human cadavers have also been used for many training courses and for estimating clinical status; e.g., reperfused human cadavers7 were used in one study with good results. To our knowledge, there is no published study using a SEAP or DIEP flap porcine model for head and neck defects, except our study on tracheal defects, which modeled respiratory mucosa and function. The research group in France5 used the DIEP flap, the transverse musculocutaneous gracilis flap, and the superior gluteal artery perforator flap for the breast reconstruction. To build on our previous study, we used the same flap for a cervical skin defect to test the procedure for vascular anastomosis and tracheal defects.
The pedicle diameter and length in the porcine model are similar to those in humans, and the overall biological similarity is sufficient to mimic clinical field conditions in humans. This exercise should improve the timing and skills necessary to accomplish the delicate harvesting and dissection of the pedicle and proper anastomosis3,4,5,6,7,8,9. Unfortunately, the DIEP flap, which is usually used in humans, was not applicable to this model due to its small caliber. We did not consider this a major issue because our goal was to develop skills and to recreate realistic physiological conditions with real and immediate feedback. The common carotid artery and internal jugular vein are sometimes used for microvascular anastomosis in humans, especially the internal jugular vein, which can be used for side-to-end or end-to-end anastomosis. Although the common carotid is not commonly used, the external carotid can be used in cases when other branches are injured.
Our porcine model is a living animal that, despite some anatomical differences, can reliably approximate clinical conditions in an actual surgical procedure at a lower cost than a human cadaver, and gives real feedback for microvascular reconstruction, harvesting, and anastomosis performed in the same location. Additionally, the model can help develop the dexterity, visuospatial ability, and the judgment required for these procedures.
The authors have nothing to disclose.
This work was funded and supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (2015R1C1A1A01051907). This work was also supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2016M3A9E9941746).
Pigs XP Bio, Seoul, South Korea | |||
Surgical Hair Removal shaver | 3M | ||
22 gage catheter | B.BRAUN | ||
syring with needle size 18 | Jung Rim Medical | ||
Intramuscular alfaxan | Careside | 10ml/VAL | |
Intramuscularxylazine | Bayer | ||
Intramuscular azaperone | Sigma-aldrich | 34223 | |
Intramuscular atropine | Daewon | 0.5mg/A | |
Intramuscular cefazolin | Yuhan | 1g | |
intravenous Ketorolac | Hana Pharm | 30mg | |
Swine ansthesia mask | DRE | 1392 | |
endotracheal cuff tube 6.5 mm | SMITH medical | 100/150/065 | |
ansthesia Machine | Dräger | PRIMUS IE | |
2% lidocaine topical solution | Taejoon | ||
vet ointment | Pfizer | terramycin | |
eye cover patch | Innomed | S-universal010S | |
betadine solution 1%. | Korea Pharma | ||
gauze 4*4 | First Medical | 22*30CM 320S | |
blade No. 23 | Paragon | 23 | |
lahey retractor | V.Mueller | SU3960 | |
kelly tissue scissors | SOLCO | 05-1990 | |
blade No. 11 | Paragon | 11 | |
surgical marking pen | Aspen Surgical | Regular #2750 | |
allis | V.Mueller | SU4055 | |
tie suture | Covidein | non-needle | |
3.5× surgical loupe | zeiss | eyemag smart | |
double clamp without frame | V.Mueller | CH7155 | |
microscissors | AESCULAP | FD038R | |
Ringer's lactate | Daehan | 500ml/1bag | |
amoxicillin–clavulanate | Ilsung | 0.6g/V | |
Meloxicam | Samil | 7.5mg | |
propofol | Dong Kook | 120mg/V | |
intravenous KCl solution | Daehan | 20ml/50P | |
mosquito curved | SOLCO | 013-0111 | |
mosquito straight | SOLCO | 05-1050 | |
ethilone 10-0 suture | ethicone | 10/0W1756 | |
Vicryl 3-0. | ethicone | 3/0W9890 | |
buprenorphine | Hanlim | 0.3mg |