Emergency medicine trainees prefer using homemade gelatin and tofu models over commercial phantom models for learning ultrasound-guided peripheral intravenous (IV) placement, according to research published March 9 in the Journal of Emergency Medicine.
A team led by Dr. Karima Sajadi from Drexel University in Philadelphia wrote that using such do-it-yourself (DIY) models could help with training in settings with limited resources.
"If these results were to be replicated, training programs in resource-limited settings could offer appropriate ultrasound-guided peripheral IV catheter placement training to a larger number of students using life-like DIY models at minimal cost with perhaps similar learning outcomes," Sajadi and colleagues wrote.
Bedside ultrasound is used in emergency medicine situations to help guide practitioners in obtaining IV access for patients with peculiarities of their anatomy or comorbidities that make such access challenging.
In training scenarios, human patients, commercially available arm models, or various DIY models are used. Researchers pointed to commercially available arm simulators being costly -- hundreds of dollars per model -- and unusable after a certain number of times. On the other hand, DIY models are inexpensive, easy to make before a teaching session, and then can be immediately disposed of.
However, it's not known how well either DIY or commercial models resemble the human body in practices where IV placement is needed. Sajadi et al wanted to find this out from sonographic and tangible points of view.
The team used three models:
- A DIY model made of gelatin that cost about $10
- A DIY tofu model that cost about $5
- A commercial model (Blue Phantom, CAE Healthcare) that had been used for two years prior to the experiment.
Trainees used point-of-care ultrasound (POCUS) and a linear probe to help guide IV placement into the models.
After their experience, 25 trainees filled out a survey on which model they favored. Questions on their preference of model were on a scale of 1 to 7, with 7 considered "almost perfect." Sonographic and tangibility scores were combined to make up the overall score for each respective model.
| Preference of ultrasound-guided I.V. model for emergency medicine trainees | ||||
| Commercial model | Tofu model | Gelatin model | p-value | |
| Overall score | 8.29 | 9.96 | 10.6 | 0.0005 |
| Sonographic closeness to human models | 4.33 | 5.12 | 5.24 | 0.0212 |
| Tangible closeness to human models | 3.96 | 4.84 | 5.36 | 0.0023 |
The researchers wrote that the preference for gelatin may be due to its thick, wide-target artificial veins being able to withstand multiple attempts by novice learners. The tofu model, which used balloon veins, was considered "more delicate" by researchers.
"Although almost one-quarter of participants preferred tofu as the optimal teaching medium, one critique of the model, per respondent commentary, was that the tofu artificial flesh was too soft and visualization was obscured by air artifact," they added.
The team also wrote that the commercial model's lower scores may be attributed to expected deterioration and shadowing from its prior use. Comments from trainees pointed to the model's artificial flesh being too firm and having too much resistance to allow for proper IV placement.
However, they added that comparing DIY models to new commercial models may not be possible for emergency medicine departments due to the costliness of the commercial models.
Although researchers wrote that larger study populations could yield more significant scores, they touted DIY models as being suitable, cost-effective substitutes for commercial models in learning environments.
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
