University of Illinois at Chicago
This was the final week of the program, and my time in interventional radiology has been amazing. Our group had a great mentor, Dr. Bui. Today he showed us the basics on how to use/interpret an ultrasound. An ultrasound works by transmitting sound waves (generating by piezoelectric crystals in a transducer) that bounce off of tissues and bones at different frequencies. This allows the user to visualize distinct anatomy and physiology.
In summary, interventional radiology is a highly innovative field. From my experience, there is a company representative who proposes new devices or new applications for devices every week. However, there could be some improvements with devices. Stents are static, not dynamic; they do not respond to changes in flow or pressure, which is a potential area for further research. There are also challenges with deploying stents. For example, in some procedures, stents will spring forward unexpectedly. Generally, improvements could be made upon increasing the elasticity of devices (especially catheters) and increasing the efficacy of devices, such as inferior vena cava filters. Improving feedback and regulatory mechanisms in devices is an opportunity for innovation. For example, a kyphoplasty is performed to treat vertebral compression fractures by injecting cement into the bone to maintain shape and rigidity. The physician injects the cement until adequate pressure is felt. There could be improvements regarding changing the subjective nature of injecting the cement to a more quantitative, objective one.
Presently, two-dimensional (planar) imaging systems are used to navigate three-dimensional tissue and vasculature. This leads to limitations in depth perception when placing catheters/wires in vasculature and stents in certain procedures. Visualization in imaging is critical, so improving visualization should lead to better patient care. However, it is still important to keep the patient comfortable while obtaining images. In an angiogram, the patient must be apneic to obtain the best image; if not, the image must be taken again. The time spent for each procedure could be minimized, which leads to better patient care. Improvements in imaging may also refer to imaging techniques used for specific procedures. The transarterial chemoembolization (TACE) procedure is used to deliver chemotherapy to hepatocellular carcinoma. It works by restricting the tumor’s blood supply (embolization) while delivering chemotherapy via drug-eluting beads. It can be difficult to visualize the arteries leading to the tumor. Currently, there is a technology called the EmboGuide manufactured by Phillips, and it provides better visualization for the arterial feeders leading to the tumor.
From this program, I was able to better appreciate the the interdisciplinary nature of bioengineering and medicine; engineering feats are all over the clinic! From systems processes, such as keeping up with the flow of patient care, to device and imaging modalities, the opportunities for innovation in interventional radiology are endless.
Note: image taken from radiology.ucsf.edu
I was able to see a nephrolithotomy from the beginning with IR to the end with urology. The last time IR participated in a nephrolithotomy case, the nephroscope was missing, so I wasn’t able to fully see the procedure. It was really amazing to see how the kidney stones were removed, both manually and with the laser. The urologist used the pathways set up by the interventional radiologist, which made the procedure minimally invasive. One problem is that the fluoroscein machines are not as advanced in the operating rooms when compared to the IR department. This can sometimes cause the machines to overheat because of overuse.
In general, the interventional radiology department works efficiently with respect to patient management and flow. However, areas for improvement include communication and equipment/waste management. Some patients require an anesthesiologist to be present during the procedure because of higher operative risks or underlying medical problems. The IR team and the anesthesiologist may not always communicate effectively, leading to lost time. Equipment may sometimes be on back order, so it may not always be available. With respect to waste management, distinctions are not made between regular waste and biohazard waste in the IR rooms. This leads to increased costs in treating regular waste as hazardous waste, that could be reduced.
Note: image taken from www.svuhradiology.ie
This past week, I was able to observe in even more procedures and gain a better understanding of interventional radiology as a whole. One experience that was particularly memorable was observing a percutaneous nephrolithotomy, which is performed to remove a kidney stnoe. The interventional radiologists prepared the patient by setting up a catheter and guide wire directing the position of the kidney stone. The urologists would then perform the nephrolithotomy in the operating room.
In the middle of the nephrolithotomy procedure, the urologists were forced to stop because the nephroscope was broken. The other available scope was being sterilized which could take up to 2 hours. It is problem to have missing/nonfunctional equipment that is necessary for the surgery because it impedes patient care. Eventually the surgery was performed and the kidney stone was removed. However, there were post-operative complications. The interventional radiologists went back in to determine whether the patient was bleeding, which the patient was. After doing a renal angiogram, it was determined that the patient had several sources of bleeding in the renal calyx, so the kidney was embolized.
I found this case to be very interesting because it highlights the collaborative nature of medicine. The interventional radiologists made the procedure minimally invasive, and the urologists are the ones who actually degraded and removed the stone. The interventional radiologists went back and treated any complications.
Some observations that I have made from my past two weeks in interventional radiology span from devices to processes/flow/communication. One device that I found interesting is the inferior vena cava (IVC) filter using for patients with severe embolisms and thrombosis. The filters work by mechanically acting like a barrier to break down the clot as it passes through. One problem is that for some patients, multiple IVC filters need to be placed in to be effective. Perhaps there is a better way.
Note: the picture is taken from http://www.pedesorangecounty.com/venous-treatments/
This past week was great so far! I was able to observe in some more procedures, including a transjugular interhepatic portal shunt system. It involves placing a stent between the portal and hepatic veins to correct for portal hypertension. The stent is a covered and contains a open-ended cage that is placed in the portal vein. The other end of the stent (covered) is placed at the very end of the hepatic vein. The stent is deployed using an inflatable balloon. Once again, the procedure is done “over a wire,” highlighting the finesse in the field. One of the problems I had noticed with this procedure is that it requires a blind puncture between the hepatic and portal veins. The physician had mentioned that it takes skill and practice to have a better understanding of how to navigate from the two veins, but there is still a lack of visualization. Another observation I noted was that the stents are static, not dynamic. They do not change according to the patient’s needs; for example, the stent is unable to accommodate for increased or decreased blood flow. If there were a way for the stent to regulate flow, it would definitely be an improvement and provide better, more personalized care for the patient.
I was also able to observe in on a hemodialysis reliable outflow (HeRO) device procedure, which was done in the operating room on the third floor. This procedure is novel, and it is used for patients who need an alternative form of hemodialysis. The HeRO device is an arterial graft connected to a central venous catheter. Overall, from my observations in the last 1.5 weeks, I have noticed that better visualization for the physician and more immediate and quantitative feedback about the device are potential problems.
The image was taken from wikipedia.org.
Interventional radiology is constantly being updated with new technologies and devices. For example, the AngioVac Cannula is a device manufactured by AngioDynamics. It is used to remove emboli, or clots, in veins. It works by using suction and vaccuuming up clots in large veins, like the superior and inferior vena cava. The tip is a balloon that can be expanded in a petal formation, which prevents the cannula from clotting from the emboli. One problem with this device is that it is fairly large, so it can only be used for large veins (IVC, for example). Perhaps the device could be made a bit smaller to allow it to perform more elegantly, which will also help the physician maneuver the cannula better.
I was also able to learn a little bit about the history of interventional radiology. One of the major advancements within the field is known as the Seldinger Technique, which was developed by Dr. Ivan Seldinger in 1953. It is used to obtain access to vasculature through a wire. A cannula/catheter/other device can be passed “over the wire” and the wire is removed. It can be used for angiographies, chest drain, or other procedures. Throughout the week, our group was able to observe in many procedures in the IR rooms.
Vascular access procedures are typically used when IV is not enough. In the cases I observed in, the physician placed a chest port to provide chemotherapy as a method of targeted drug delivery using image-guided techniques. The ports are devices that contain a reservoir attached to a catheter. It is subcutaneously inserted into the chest (in some cases, the arm as well) and the physician then guides the catheter into a vein. This procedure is used to deliver systemic chemotherapy, unlike transcatheter arterial chemoembolization.
This week has been truly amazing and the technology/innovation in this field is easy to see. I can’t wait to learn more!
Note: the image was taken from http://www.angiodynamics.com/products/angiovac
The first week of interventional radiology has been going great so far! I am excited to learn more about this upcoming field with my new group as well. During the week, we were able to observe procedures in the IR rooms. Some of the equipment/devices that are commonly used are wires, catheters, imaging techniques (of course), stents, filters, sheaths, etc. Catheters can come in many sizes with different functionalities, but they all serve the purpose of either drainage or administration of drugs and fluids.
On the first day, I observed a renal angiogram for a hypertensive patient (see picture above for what a renal angiogram looks like). An angiogram is used to visualize arteries. In this case, the hypertension caused narrowing of blood vessels (also known as stenosis) in the kidney. For the procedure, the IR physicians used a balloon to open up and dilate the blood vessels. Contrast dye was used to better visualize the vasculature in the x-ray. The physician can then literally see where the stenosis is and where the balloon needs to be placed, which is known as balloon angioplasty. A balloon catheter is passed “over the wire” and then inflated once its target site is reached. The inflation causes the vessel to expand, and the balloon is then deflated and removed. One problem associated with balloon dilation is that there should be a way for the physician to know how much the vessel has been dilated. Yes, imaging is available, but if there were a more immediate way to deliver that information to the user, it could potentially lead to better patient care.
Another interesting procedure I observed was a transcatheter arterial chemoembolization (TACE). It is used to restrict a tumor’s blood supply by embolizing the vessels leading to the tumor, and it can also deliver targeted chemotherapy to the tumor, leading to atrophy. Generally, this procedure is only done in the liver because the liver is supplied by the proper hepatic artery and portal vein. The chemotherapy medication is bound to a drug-eluting bead, or microsphere, which then can deliver targeted drug therapy of high doses to the tumor. It has been used for hepatocellular carcinomas (HCCs). The catheter is passed through the abdominal aorta, and then through the celiac trunk and common hepatic artery, and then reaches the proper hepatic artery. Then the physician uses angiography to determine which smaller arterial branches are supplying the tumor and embolizes them.
From a bioengineering perspective, TACE is an interesting procedure because it involves targeted drug-delivery. This topic is growing in the bioengineering field as new research is constantly coming out. Some aspects of TACE that can be improved upon are including the use of biodegradable particles because technically, the particles never leave the body after infusion, loading multiple drugs onto one sphere, and increasing the specificity of the beads to ensure that the tumor is targeted appropriately.
Note: the images were taken from openi.nlm.nih.gov
Several bioengineering technologies are commonly used throughout the ophthalmology clinics, namely the slit lamp, indirect ophthalmoscope, visual field exams, and imaging scans. These devices and technologies can be updated to improve patient care. For example, the slit lamp is used for an ocular examination with every patient. Yet there is still a high rate of cervical stenosis and scoliosis for ophthalmologists. This technology can definitely be improved to make both the physician and the patient more comfortable. The portable slit lamp serves as an excellent first step towards improving the slit lamp technology. With respect to user-centered design, medical devices or products can be personalized for the patient, such as for contact lenses. A possible research development is that contact lenses could be customized via 3D printing to address multiple ocular problems for patients.
A commonly noted problem in the ophthalmology clinics is patient wait times. The technician begins the examination by measuring visual acuity and visual fields. Many patients must also get an Optical Coherence Tomography which is a light-based imaging test that takes pictures of the retina before being examined by the physician. Research in ophthalmic imaging techniques also show options for high resolution imaging, which can be utilized to improve patient care as well. The current imaging instrument, known as the Optos, combines imaging techniques, such as ophthalmoscopy, fundus, fluorescein angiography, and indocyanine green angiography. The instrument can be improved upon with respect to speed of examination and ease of use.
After interviewing patients, physicians, technicians, and administrators throughout our three weeks, our team noted that the most common issue in the clinic was patient wait times and patient flow. The clinic would like to move completely to electronic medical records (EMR), but the financial costs involved are slowing the transformation.
In conclusion, my three weeks in the ophthalmology clinic has been absolutely amazing! I learned a lot about medical devices and technologies, and I am looking forward to my next rotation.
This past week I was given the opportunity to observe in more retina and pediatric surgeries. The majority of the retina surgeries we observed were pars plana vitrectomies, which is a procedure that removes the vitreous humor from the vitreous chamber (located in the back of the eye). A vitrectomy is performed to remove the vitreous humor; this may occur for retinal detachments or vitreous hemorrhages. It can also be performed when the vitreous humor becomes clouded or contaminated with blood. The image above shows how there are infusion “ports” through which the surgeon gain access to the vitreous chamber with the necessary devices. The ophthalmologist suctions the vitreous gel out. After (if indicated), the surgeon uses laser to treat any holes or tears in the retina via photocoagulation. Then, silicone oil or gas is injected to ensure that the retina remains attached to the back of the eye and does not collapse. If silicone oil is used, it must be removed after the retina has healed. There are, however, some complications with using the silicone oil. The oil can enter into the anterior chamber, causing an increase in intraocular pressure (IOP), which may lead to open-angle or close-angle glaucoma. Increased IOP has also been shown as a complication for intravitreal gas vitrectomies. The gas can alter scleral rigidity as well. There needs to be definite improvements on how the silicone oil is removed from the eye, preventing further complications.
For pediatric ophthalmology, the main surgeries performed are strabismus surgeries, which corrects the extraocular muscles for improved ocular alignment. Strabismus is when the eyes are not aligned; it is also know as cross-eyes or wall-eyes. One or both eyes can move in different directions, which often causes double vision. There are generally two types of strabismus surgeries: recession (muscle is cut and reattached further back on the eye) and resection (muscle is cut from extraocular portion and reattached closer to the front of the eye).
Note: the image was taken from www.allaboutvision.com
During my experiences in the oculoplastics rotation, I was able to get a more wholistic perspective of ophthalmology as oculoplastics mainly deals with external ocular issues, such as eyelid, tear duct, and orbit problems. Some of the patients in the clinic were in for follow-ups after surgery to ensure that the complications are minimized and the targeted area is healing. I noticed that the time spent with each patient depended on the reason for the patient coming to the clinic. For example, if a patient is having trouble with their tears, such as excessive tearing or dry eyes, the physician can inject a saline-based solution into the lacrimal (tear) ducts to see how well the tears flow. If the tears begin to overflow by coming out of the eye, it means that there is either a partial or full blockage with one of the tear ducts.
One device that is commonly used in the oculoplastics clinic is the exophthalmometer; there are two types of exophthalmometers, the Hertel and Luedde rulers. I saw the Hertel ruler in the clinic. This device is used to measure how much far the eyeball is displaced out. It is commonly used for patients with thyroid eye disease, but it can also be used to measure the retraction of the eyeball inside the eye (known as enophthalmos). The device works by measuring the distance from the orbital rim and the corneal apex. One problem with this device is that it requires the ophthalmologist to hold the ruler up to the patient’s eyes and manually measure the distances. The measurements can be different depending on the physician, so the variability of measurement associated with this device can affect readings, which can then affect patient care. Another problem I had noticed in the clinic is that there is a need for better imaging to photograph the eyelids in a standardized way. Different health care providers measuring eyelid distances should get the same values.
I was also able to observe an exenteration surgery, which is one of three types of eye socket removal surgeries. It involves removing the entire eye socket, including external ocular muscles, tear gland system, and cutting the optic nerve. This is the worst possible scenario, and is generally performed to prevent cancer metastasis. An enucleation surgery removes the eyeball, but leaves the external muscles and the rest of the orbit. An evisceration surgery is when the contents of the eye are removed but the outside of the sclera (the white of the eye) is left. In the exenteration surgery, the patient was placed under general anesthesia, and the attending worked efficiently to balance teaching the residents and completing the surgery in a timely manner. After the entire eye is removed, a partial-thickness skin graft is removed from the thigh using a surgical tool called the dermatome. The skin graft is then cranked through a mesh, which expands the graft to its maximum size and removes any excess blood. The graft is then placed into the lining of socket.
I had noticed that the surgery generally went very smoothly. The attending was able to teach and let the residents/fellows perform the surgery as well. There was some time lost because the dermatome was not getting the right thickness of skin, so it took a couple tries for it to work. The skin would also dry up quickly so oil had to be reapplied to the skin graft every couple of minutes in case there was a delay in placing the skin graft into the eye.
Note: the images were taken from integralife.com and https://en.wikipedia.org/wiki/Exophthalmometer
This week we switched rotations to the cornea service and contact lens service. In the cornea service, the ophthalmologist examines the integrity of the cornea and follow-up on post-operative surgeries. Some patients have had cataracts, while others have had corneal transplants. In the cataract surgery, patient’s lens that is cloudy and hazy due to age-related causes is replaced with an artificial acrylic intraocular lens (IOL). During the cataract surgery, the cataract is broken apart via phacoemulsification using a high-frequency ultrasound device. Suction is then used to remove all of the cataract pieces.The ophthalmologist then places one of several intraocular lenses. There are several types of IOLs, namely aspheric, toric, accommodating, and multifocal. Aspheric IOLs differ from conventional (spherical) lenses because the aspheric lens can incorporate changes in lens shape, providing better vision. Toric IOLs are used for astigmatism because they have scale markers for the ophthalmologist to adjust accordingly during surgery. Accommodating IOLs combine aspheric IOLs and haptics; haptics are the “legs” that protrude from the IOL and are used for support. Lastly, multifocal IOLs are used to correct for presbyopia because they magnify the lens (the patient may not need reading glasses after cataract surgery with a multifocal lens). When I spent time in the contact lens service, I noticed that some patients had a combination of ocular issues, so one contact lens could not solve all ocular issues; it usually only addressed a couple of problems. Patients did not feel comfortable with their contact lenses, which led to multiple extra visits with the optometrist.
The image was taken from the Laboratory of Ocular Biomechanics at the University of Pittsburgh.
This past week in ophthalmology has been great. I was able to observe in the glaucoma and retina clinics, which were both extremely busy. In the glaucoma clinic, I learned about the Ahmed shunt, the Baerveldt shunt, and Express Mini Shunt, which are all options for to lower the intraocular pressure (IOP). Typically, these shunts are inserted after IOP lowering medications and trabeculectomies are not enough. In glaucoma, IOP and cup-to-disc ratio are two quantitative values to measure the degree of the disease. Generally, two tests are conducted consistently for patients with glaucoma: the Humphrey Visual Field test and the Optical Coherence Tomography test. The Humphrey Visual Field measures vision loss, especially peripherally for glaucoma patients. The visual field test works by briefly shining light of different intensities. Patients must press a buzzer when they detect light. The instrument then provides a map of where the retina is able to detect a light stimulus, which provides the physician with information regarding peripheral vision loss. The Optical Coherence Tomography test is an imaging technique that is generally used to measure glaucoma progression and the layers of the retina.
The retina clinic was just as busy; I was only able to ask questions between patients. OCT was used again, but instead to quantitatively visualize the retinal layers. This would provide the physician with information about how healthy the retina, the ganglion cells, and bipolar cells are. In a condition known as age-related macular degeneration (AMD), the macula (an area on the center of the retina) is damaged due to age-related causes. In order to diagnose a patient with AMD, visual acuity and OCT are measured. Another procedure known as fluorescein angiogram is performed by injecting fluorescent dye into the patient’s vein and letting the dye run through the blood vessels in the eye. The ophthalmologist can now visually identify leaking blood vessels. With most patients in the glaucoma and retina clinics, the eyes are dilated. The ophthalmologist can now use a magnifying lens to examine the retina and optic nerve.
The image was adapted from wikipedia.org
Bioengineering (and engineering in general) has evolved to focus on user -centered design. In the case of medical devices/approaches in a hospital setting, the user can include nurses, physicians, technicians, and possible even patients. Regardless of how advanced the medical engineering equipment is in the exam room, the physician is still treating the patient, which is why it is absolutely crucial to remember that bioengineering devices should not distract from healthcare delivery, but rather enhance it.
In healthcare, quality, access, and cost are the three main factors that affect outcomes. When I observed the physicians this past week, I noticed that several instruments were used consistently with every patient, namely the slit lamp, the indirect ophthalmoscope, and the head lamp. Can the instruments be modified upon in order improve quality? Perhaps. But at what cost? And cost doesn’t necessarily have to refer to monetary value; it could more possibly refer to time. How long will it take for the physician to re learn techniques and procedures with different equipment? How inconvenient will that be for the patient? These are questions that the designer must keep in mind.
My first rotation is in the ophthalmology clinic. I was a little apprehensive on the first day in the cornea clinic, but I was more excited than anything. Dr. Sugar was giving a lecture to the first year residents on how to use the slit lamp. It is definitely a bulky, yet graceful instrument, and I was able to learn about how to give a comprehensive eye exam. One of the biggest problems with the slit lamp is that neither the patient nor the physician is often comfortable. Physicians are usually bending their necks to reach the scope and patients are not comfortable leaning over the chin and head rests. Dr. Sugar had mentioned that ophthalmologists who have been working for over 30-40 years get cervical stenosis and scoliosis, bending of the cervical spine. The slit lamp has been around since the 1910s, so the technology is fairly old. I wonder if there is a better way to improve physician and patient comfort while using the slit lamp. But again, at what cost?
The ophthalmology rotation has been great so far, and I am excited to see how the rest of the program goes.