Use of Three-Dimensional Imaging Reconstruction Software as a Training Tool for Cranial Vena Cava Venipuncture in the Ferret

Summary

We propose that a three-dimensional virtual anatomy reconstructive software tool adds beneficial adjunctive training in teaching ferret cranial vena cava venipuncture to laboratory animal medicine trainees.

Abstract

At the University of Georgia College of Veterinary Medicine, three-dimensional (3D) virtual anatomy reconstructive software has been incorporated into the veterinary anatomy curriculum. With this teaching platform, students are exposed to learning opportunities beyond cadaver dissection and textbook resources. We propose that this 3D anatomy tool can serve as a beneficial adjunctive training aid in teaching laboratory animal personnel technical skills, specifically cranial vena cava (CVC) venipuncture in ferrets. The CVC is one of the preferred sites for a large blood volume collection in the ferret. Though an overall relatively safe technique for collecting blood, the risks of this blind approach include limited ability to hold off the vein after venipuncture and accidental damage to surrounding structures. In this pilot project, 5 lab animal staff trainees were exposed to 3D reconstructed ferret thoracic images and videos in conjunction with verbal instruction to perform cranial vena cava venipuncture in the ferret. The success of the approach was evaluated based on the trainees' ability to correctly angle the needle and syringe, insert the needle at the appropriate location, and collect blood from the site. Of the 5 trainees, 5 (100%) mastered the vertical angle of the needle, 4 (80%) mastered the horizontal angle of the needle, 5 (100%) correctly identified the manubrium as a landmark for insertion, and 2 (40%) successfully collected blood within two attempts of using this approach. As trainees were able to accomplish many key criteria for success, we conclude that the training was successful in providing key anatomic landmarks and spatial awareness necessary for CVC blood collection in the ferret. Beyond the scope of ferret venipuncture, 3D reconstructed images have a potential role in demonstrating surgical techniques and approaches for various clinical skills in veterinary medicine.

Introduction

We proposed that adding 3D reconstructed cervical and thoracic images and videos of a ferret to our standard training procedures would aid lab animal personnel in visualizing the relevant anatomy to help them master the positioning and landmarks necessary to perform cranial vena cava (CVC) venipuncture in the ferret. To that end, we conducted routine training with five laboratory animal staff members who work with ferrets. During this training, we piloted the addition of the 3D reconstruction images, observing staff success after training in the areas of positioning the syringe and needle in the vertical and horizontal planes, identifying a major anatomic landmark, and collecting blood. All staff viewed the 3D images and videos since there were too few trainees to conduct a quantitative, comparative trial contrasting traditional training with the addition of 3D tools.

Venipuncture is a mainstay practice in laboratory animal medicine for blood collection in research studies and provision of clinical veterinary care. Various techniques are used across species due to anatomical differences, level of technical expertise, and the purpose of blood collection. Venipuncture can be challenging, especially if the phlebotomist is not familiar with the approach or relevant anatomy of the area.

The CVC in an adult ferret has an approximate diameter of 3.0-3.5 mm. It is the main vessel located cranial to the heart, and it is formed by the confluence of the left and right subclavian veins with the external jugular veins. The CVC drains into the right atrium of the heart. Other important structures in the area include the heart, aorta, carotid artery, esophagus, trachea, vagus nerve, and phrenic nerve¹. The relatively long thorax of the ferret minimizes the risk of puncturing other major structures, making this a safer approach in this species compared to other small mammals due to the substantial distance from the most cranial portion of the CVC to the base of the heart. With that said, the technique can be technically challenging and poses a risk for puncturing neighboring intrathoracic structures, including the carotid artery and trachea (Figure 1)². The CVC and external jugular vein are the preferred sites for the collection of large blood volumes (up to 2 mL) in the ferret^2,3. Large volumes of blood are often necessary for routine health screening and collection for research studies. Ferrets are commonly used in laboratory animal medicine as translational models for research in influenza and other airway diseases due to the resemblance of their respiratory tract to that of humans^4,5. Sites for more limited blood collection include the lateral saphenous and cephalic veins². Other common lab animal species for which the cranial vena cava is a suitable venipuncture site include rats, hamsters, and guinea pigs³.

At the University of Georgia College of Veterinary Medicine (UGA CVM), we have incorporated software for three-dimensional (3D) image reconstruction (Table of Materials) into the small and large animal anatomy courses for teaching first-year veterinary students. The 3D virtual anatomy software can be used to reconstruct images from computed tomography (CT) and magnetic resonance imaging (MRI) studies⁶. Students at the UGA CVM are exposed to this technology in the anatomy curriculum in conjunction with gross cadaver dissection. The goal of incorporating this software into the course is twofold: to expose students to diagnostic imaging and to allow students to interact with 3D anatomical structures beyond the scope of cadaver dissection. This novel resource enhances the students' learning experiences and helps better prepare them to master clinical skills, as they have an opportunity to visualize the relationship of anatomical structures in a different light. The software was originally designed for education in human medicine, with studies showing that 3D virtual anatomy platforms are beneficial resources for human medical students as they provide a comprehensive modality that allows users to explore images in a unique approach that can be tailored for specific learning goals^7,8,9.

Protocol

The protocol for the use of ferrets in this study was approved by the UGA Institutional Animal Care and Use Committee. The UGA animal care and use program holds an Animal Welfare Assurance with the NIH Office of Laboratory Animal Welfare, has a research registration with the USDA, and is fully accredited by AAALAC International.

The ferrets were housed in designated animal quarters in open caging with ad libitum access to a high-density ferret diet (Table of Materials) and auto-watering (tap water). Lights were maintained on an automated 12:12 light:dark cycle, temperature set-point at 68 +/- 4 ^oF, and relative humidity of 30-70%. The ferrets were socially housed with other ferrets and provided with enrichment toys.

1. Obtaining 3D reconstruction images for training

NOTE: The 3D reconstructed scan used for training was that of a de-identified, anesthetized adult male ferret positioned in dorsal recumbency for a CT scan. The scan was acquired from the UGA Veterinary Teaching Hospital archive and was reconstructed in the software program by the authors.

1. Open the 3D reconstruction software program and use the computer mouse to click on File then Open and double click to select the desired uploaded scan.
2. Using the mouse, click on any location of the scan. Hold down the mouse button while simultaneously dragging the mouse to position the scan so that the ferret is in dorsal recumbency with the head towards the top of the computer screen and the tail towards the bottom of the screen. Repeat as needed to manipulate certain body parts.
3. Using the mouse, click on the Add a plane feature in the program. The plane will appear as a red, transparent rectangle.
4. Using the mouse, click on the left and right arrows associated with the Add a plane feature to move through the options for plane location. Click the arrow until the plane lies parallel with the ventral aspect of the animal.
5. Using the scroll wheel on the mouse, scroll from down to up to advance the plane from ventral to dorsal (or superficial to deep). Advance the plane with the mouse scroll wheel until there is a clear image of the cranial vena cava vessel.
6. Screenshot the image and save it in a desired location. These steps can also be screen-recorded and saved as a video. This step varies depending on which computer hardware the user has.

2. Training for venipuncture

NOTE: Five staff members were included in the training, all of whom provided consent to be involved. All five staff members, who had varying levels of knowledge of ferret anatomy, were shown the 3D reconstructed images and videos prior to their venipuncture attempts. Three were animal care technicians, and two were veterinary technicians. Three of the participants had prior experience handling syringes and needles, while two did not.

1. Show the 3D reconstructed images and videos to a group of five laboratory animal staff trainees, incorporating anatomy instruction from an experienced lab animal veterinarian or technician familiar with the anatomy and blood collection procedure. Provide supplemental reading materials as needed for the knowledge of the trainee.
2. Listen carefully to questions from the trainees, and answer those before live animal training.
3. Describe the procedure again during steps 3 and 4 of the protocol as the technique is demonstrated to the trainees before they attempt it for the first time, regularly referring to the 3D reconstructed images.
   NOTE: A total of seven ferrets were used in training. Three trainees were assigned one ferret each, and they had one blood collection attempt with their ferret. The other two trainees were assigned two ferrets each; one was used for their first blood collection attempt and the other was used for their second attempt.

3. Positioning for venipuncture

1. For the CVC approach, use awake, sedated, or anesthetized ferrets.
2. Sedate the animal with an intramuscular injection of butorphanol 0.1-0.3 mg/kg, midazolam 0.1-0.3 mg/kg, and, only if needed, ketamine 1-3 mg/kg.
3. Place the animal in dorsal recumbency with the head and neck extended.
4. Firmly and symmetrically restrain the ferret to allow the best opportunity to enter the vessel with the needle. At least one assistant is required to restrain the animal while the phlebotomist makes the approach (Figure 2). The restrainer can put pressure upward between the shoulder blades to lift the thoracic inlet and cranial thorax toward the phlebotomist.

4. Approach and blood collection

1. Disinfect the skin of the cranial thorax over the manubrium with alcohol.
2. Palpate the sternum (Figure 3).
3. Insert the needle at the notch between the manubrium and first rib on the animal's right side of the sternum.
4. Angle the needle 30-45° and direct it towards the opposite (left) hip. Insert it at the site of the notch, and aspirate to draw blood (Figure 4).
5. Observe the trainees as they attempt the venipuncture approach. Record their success in mastering the ability to vertically angle the needle and horizontally angle the needle. Identify the manubrium as a landmark for insertion and collect blood from the site. Document how much blood was obtained with each successful attempt.
   NOTE: Depth of sedation was based on response to physical and audible stimuli, palpebral reflex, and righting reflex. After blood collection, flumazenil 0.2 mg/kg was administered intramuscularly for sedation reversal, if needed. The ferrets were returned to the colony after the procedure.
6. Use a 5/8-inch, 25 G needle with a 1- or 3-mL syringe to draw blood with this technique.
   NOTE: As a rule of thumb, no more than 10% of an animal's blood volume should be collected in one collection. The blood volume of the ferret is estimated to be 5-6% of the total body weight¹. Both a lab animal veterinarian and an experienced lab animal veterinary training technician were present to ensure that blood collection was performed appropriately and any troubleshooting for the technique (i.e., subtle movements in needle angling or direction, depth of needle insertion) was done in real time according to their instruction.

5. Measurement of success

1. Evaluate the trainees' ability to correctly angle the needle and syringe, insert the needle at the appropriate location, and collect blood from the site.
2. Record how many trainees correctly accomplished the vertical angle of the needle, the horizontal angle of the needle, and palpation of the manubrium.
3. Document how many trainees successfully collected blood, along with the volume of blood collected.

Results

The 3D reconstructed ferret CT videos and images depict the anatomical structures that are associated with the CVC at various planes and provide a comprehensive understanding of the anatomical layout of the cranial thorax. The associated structures, such as the manubrium, sternum, ribs, muscles of the thoracic wall, heart, external jugular vein, subclavian vein, and CVC, are clearly labeled in Figure 1. The location for needle insertion is depicted in Figure 5. ...

Discussion

This pilot study was designed to determine if adding 3D images and videos to our routine training procedures held promise for future use. This initial trial was designed to qualitatively observe and report our findings if future use and study appeared warranted. The focus of determining success was based on teaching the relevant anatomy landmarks for the CVC blood collection technique in the ferret to staff members familiar with ferrets and whose job assignments were likely to need this skill. In the highly regulated env...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
BodyViz	BodyViz, Clive, IA	N/A	Easy-to-Use 3D Anatamy Learning Platform
LabDiet 5L14	University of Georgia, Athens, GA	N/A	Ferret Diet