University of Florida Nasal Cavity Model to Aid Fight Against Serious Nose Bleeds

Like the cure for the common cold, effectively stopping a serious nosebleed has been a seemingly insurmountable challenge.

Doctors use a variety of packing materials or inflatable balloons in the nose to stop serious bleeding. While packing materials have come a long way since their invention, they still have some significant problems. They don’t always stop the bleeding and they can be very uncomfortable for the patient – both while the materials are in the nose, and as they are being removed. Many balloons designed for the nasal cavity are out-of-date, yet are still used, sometimes with little success.

Dr. Jeremy Melker, a resident physician at the University of Florida, is taking the first steps toward objectively evaluating packing materials and balloons used to stop bleeding from the nose. Melker used Geomagic Studio software from Geomagic (www.geomagic.com) to help him create an anatomically accurate model of the human nasal cavity. Geomagic Studio enables 3D photography, the process of capturing a physical object and automatically processing it as an accurate digital model.

“Although a prior cadaver study had been performed to determine how balloons expand inside the human nose, I wanted to take the research a step further and measure the amount of pressure delivered to different areas inside the nasal cavity,” says Melker. “When balloons and other packing materials are placed inside the nose, there are certain points where pressure is necessary to stop the bleeding, and other points where too much pressure can cause discomfort and even complications such as pressure ulcers.”

Creating the Virtual Nose

The anatomy of the nose and sinus cavities is extremely complex. Melker’s first step in creating a physical model of a human nose was to analyze the static 2D images from 50 CT scans. He took 30 measurements of each side of the nose to do a statistical analysis and find the “average” nose. From this analysis, Melker identified one scan that was very close to the average values.

CT data from the scan was then imported into sliceOmatic image-processing software from TomoVision (www.tomovision.com), where a 3D STL model was created by stacking the 2D images. The rough files generated by sliceOmatic were then brought into Geomagic Studio for further refinement and to test whether the model was anatomically correct with respect to the original data sets.

“Geomagic Studio was essential in ensuring anatomically accurate smooth models from the CT data,” says Melker.

Melker used Geomagic to split the model in half and created 16 tunnels from the outside of the model to the inner surface of the nasal cavity. These will be used in the physical model to allow placement of pressure transducers on the inner surface of the nose. Geomagic Studio automatically created a boundary cycle that defines the depth and creates the walls of a hole. A second boundary cycle can also be selected to create a connection between the two surface holes.

A Model for Testing

Once the virtual model was completed, it was sent to Product Development Services (Durham, N.C.) to produce an accurate physical model using stereolithography (STL). During the STL, or solid imaging process, the virtual model is again mathematically sliced into thin axial layers, typically 0.001 to 0.0006 of an inch thick. A laser then traces the geometry of each layer on the surface of a liquid photopolymer resin. A chemical reaction is initiated wherever laser energy strikes the photopolymer resin, transforming the resin from its liquid state into a solid plastic form.

“Without Geomagic, I would not have had the time or the money to create this model,” says Melker. “Geomagic enabled me to build the virtual dataset myself rather than paying a private consulting firm to do it for me. Given the number of hours invested in this project, the cost savings is easily in excess of five to ten thousand dollars.”

Melker also stresses the importance of using the virtual model to ensure the accuracy of his data early on. “Geomagic allowed me to ensure that the model was anatomically correct early on – before I ever sent anything out to a rapid prototyping company for a physical model. The measurements I input from Geomagic matched the fittings perfectly in the final physical model.”

With an accurate physical model in place, Dr. Melker has an essential tool by which he can conduct research that could eventually comfort the millions threatened by serious nosebleeds.