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- Open Access
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Ultrasound-guided regional anesthesia simulation: use of meat glue in inexpensive and realistic nerve block models
© The Author(s). 2019
- Received: 14 January 2019
- Accepted: 2 May 2019
- Published: 15 May 2019
Ultrasound-guided regional anesthesia (UGRA) is increasingly used by emergency physicians to provide safe and effective pain relief for patients. However, one of the factors limiting its widespread use is the lack of realistic models available for learners to train on. There are currently no inexpensive nerve block models available that are injectable and that closely mimic nerves, fascial planes, muscles, and other landmarks. Our aim is to create inexpensive, injectable nerve block models that can be used as effective medical training tools for UGRA.
By using a lean cut of pork such as pork loin, yarn soaked in ultrasound gel to simulate peripheral nerves, and drinking straws filled with gel to represent vascular structures, we created various nerve block models. Meat glue applied between sections of meat appears hyperechoic under ultrasound, thereby mimicking fascial planes and has the added benefit of helping to secure the components of the model together. Using these elements, we were able to create realistic peripheral nerve, fascia iliaca compartment, serratus anterior plane, and interscalene brachial plexus models.
One of the necessary skills in performing UGRA involves placing the needle tip along a fascial plane and visualizing hydrodissection of this plane with the local anesthetic. When meat glue (transglutaminase) is applied between layers of meat such as pork loin, the meat binds together and creates a hyperechoic line that mimics a fascial plane. When meat glue is applied to two apposing fascial layers naturally occurring on the meat, the fascial plane can be injected, and fluid can be seen hydrodissecting in this space. We created several nerve block models using meat glue and other components to mimic normal landmarks.
We have developed inexpensive and easily reproducible models that create the realistic appearance of tissues, nerves, and fascial planes under ultrasound. They can also accurately simulate hydrodissection of fluid in fascial planes. We hope these nerve block models will allow for the education in UGRA to be more widespread and accessible to learners from all specialties.
- Regional anesthesia
- Meat glue
- Nerve block model
Ultrasound Guided Regional Anesthesia (UGRA) is increasingly used by emergency physicians as a safe and effective method of pain control in patients with various musculoskeletal injuries [1–4]. Regional anesthesia has been shown to reduce the utilization of systemic analgesics and their subsequent side effects [1, 2, 5]. Examples of commonly used UGRA in the emergency department include fascia iliaca compartment blocks in patients with hip and proximal femur fractures [1, 2, 5–8], interscalene brachial plexus blocks in patients with shoulder dislocations , serratus anterior plane blocks in patients with rib fractures , and forearm nerve blocks in patients with hand injuries [10–13]. Studies have shown that medical training on simulation models is an effective way to learn new procedures and ultrasound techniques [14–16]. However, there are currently no inexpensive nerve block models available that are injectable and that closely mimic nerves, fascial planes, muscles, and other anatomical landmarks.
We used readily available and inexpensive material to create various training models that closely mimic the normal sonographic landmarks and on which needle insertion can be practiced under sonographic guidance. We also introduce the novel use of meat glue (transglutaminase) as a way to bind components of the model together and to create fascial planes that can be hydrodissected with fluid injected through a needle. These realistic models offer learners the ability to test and practice techniques that are not possible in other UGRA models. Two of these models, the serratus anterior plane and fascia iliaca compartment model were incorporated into a nerve block workshop for emergency medicine attending staff. After the workshop, attending physicians were surveyed regarding the fidelity and effectiveness of these models in their education.
Approximately 2–3 lbs. of boneless pork tenderloin ($5.50/lb.)
Pork tenderloins was bought from local meat market. There was no permission necessary to buy and use the Pork tenderloins.
Straws (regular $0.01ea, wide $0.07ea)
Ultrasound gel ($4.00/bottle)
Chewing gum ($1.50/pack)
Meat glue ($12.00/6 oz. bag)
Pork tenderloin: Meat is cut into shape of desired muscle groups. Meat with an overlying layer of fascia is preferred for optimal ability to hydrodissect along fascial planes.
Nerve: Yarn is soaked in ultrasound gel and any air trapped between the fibers is squeezed out. We find that using thicker “chunky” yarn yields better results. Several strands of yarn can be braided or twisted together to form thicker nerves.
Fascia: Meat glue is sprinkled between meat layers to simulate fascia and bind pieces of meat together.
Large Vessels: Large size straws are filled with ultrasound gel and occluded on both ends with already chewed chewing gum.
Interscalene Brachial Plexus: Regular thin size straws are filled with ultrasound gel and occluded on both ends with already chewed chewing gum to simulate the hypoechoic appearance of these nerves.
UGRA model construction
Peripheral nerve model
Fascia Iliaca compartment model
Interscalene brachial plexus model
Serratus anterior plane model
UGRA model workshop
Forty board certified emergency medicine physicians participated in a workshop that consisted of a lecture on the serratus anterior plane block (SAPB) and fascia iliaca compartment block (FICB), followed by a one-hour hands-on session with both a live human model and ultrasound-guided injection of the UGRA meat model. Participants were emailed an anonymous online survey after the workshop that asked if they felt the SAPB and FICB meat model helped them practice the following four techniques: 1) visualizing the entire needle using the in-plane technique, 2) knowing where to deposit the anesthetic fluid, 3) hydrodissection, and 4) differentiating when the needle tip was in the muscle belly (incorrect place) versus the fascial plane (correct place).
Peripheral nerve model
Fascia Iliaca compartment model
Interscalene brachial plexus model
Serratus anterior plane model
UGRA model workshop survey results
Out of forty attending physician participants, fourteen participants responded to an anonymous online survey after the workshop. All 14 respondents either agreed (6 out of 14, 43%) or strongly agreed (8 out of 14, 57%) that the SAPB meat model helped them practice each of the following four techniques: 1) visualizing the entire needle using the in-plane technique, 2) knowing where to deposit the anesthetic fluid, 3) hydrodissection, and 4) differentiating when the needle tip was incorrectly placed in the muscle belly (Additional file 5: Video S5) versus correctly placed in the fascial plane (Additional file 4: Video S4). When asked about the FICB meat model, all 14 respondents either agreed (7 out of 14, 50%) or strongly agreed (7 out of 14, 50%) that the FICB meat model helped them practice all four techniques.
It is essential that a UGRA meat model provide as close to a real-life training experience as possible. Our model accomplishes this with its realistic sonographic appearance of tissues, nerves, muscles, fascial planes, and blood vessels. There are several skills necessary in successfully performing UGRA. Performing in-plane technique and visualizing the needle tip on a meat model will mimic the appearance and feel of inserting the needle through muscle in a live UGRA. Another important skill involves placing the needle tip in the space either adjacent to the nerve or along a fascial plane. We found that when two layers of naturally occurring fascia were apposed together with meat glue, it will create a plane that can be hydrodissected mimicking the deposition of local anesthetic in real patients. Fluid injected into the space disrupts the fascia locally without disseminating to other areas along the fascial plane due to the binding ability of the meat glue. This helps differentiate correct injection into the fascial plane as opposed to incorrect injection into the muscle belly. The model can therefore be injected repeatedly by several learners along different sections of the fascia.
Our experience incorporating the UGRA meat models in teaching workshops has shown that learners are able to practice the aforementioned techniques using these models. A survey of emergency medicine attendings after use of the SAPB and FICB in a UGRA workshop found that 100% of respondents either agreed or strongly agreed that the models helped them practice in-plane technique, visualization of the needle tip, hydrodissection, and differentiation of the needle tip in the muscle belly versus the fascial plane.
The model is inexpensive and uses easily obtainable materials. The authors were able to create all four models described here for under 40 US Dollars. We found that the model can be frozen after initial use, thawed and used again for a second time. The ability to hydrodissect is retained even on second use. However, the model needs to be completely thawed or else the ice in the meat will cause acoustic shadowing that will diminish visibility.
The main limitation of these UGRA meat models is its perishability. We found that the models can be used no more than two separate workshops. However, each meat model can be injected repeatedly by several learners. These meat models also lack the external anatomy needed to help the trainee learn where to place the probe on a real person, therefore we recommend complementing these models with demonstration of external landmarks on a live model.
We have developed inexpensive, easily reproducible, injectable models that can be customized to mimic the nerves, fascial planes, muscle, and blood vessels seen in a variety of nerve blocks. The use of meat glue allows trainees to learn ultrasound-guided nerve block techniques including the ability to hydrodissect fluid along a fascial plane. The authors are not aware of any other nerve block model construction techniques that offer the ability to visualize the injection of local anesthetic along a fascial plane. We believe that these models can help make UGRA education more effective, widespread and accessible for learners of all specialties. Further studies would need to be conducted to test the efficacy of these models when used as a medical training tool in teaching UGRA.
No funding was obtained for this study.
Availability of data and materials
Not Applicable. We have provided detailed instructions in methods to build the simulation models.
All authors (LN, JL, KO, SB, LH and ED) contributed equally in building the simulation models and writing the manuscript. All authors read and approved the final manuscript.
Ethics approval and consent to participate
Not Applicable. This manuscript describes the method of building high-fidelity low-cost models to be used in training of physicians. No human or live animal model was involved and per national guidelines there were no need for institutional board review . Pork tenderloins were bought from local meat market. There was no permission necessary to buy and use the pork tenderloins. Ethics approval and consent to participate is not applicable to this manuscript.
Consent for publication
The authors declare that they have no competing interests.
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