Week 3

This week I continued to work on my two research projects, as well as shadow both clinicians I am working with.

Early in the week I mainly focused on my research with Dr. Hartl's group. I have been helping on data analysis for a paper they are writing. It has to do with the incidence of recurrent spine surgeries for people with a certain type of procedure. For example, when doing a fusion surgery, they secure that level of the spine and it loses natural movement. This puts extra stress on the levels above and below where the fusion is, so after time, some patients need additional surgery to correct new problems above or below the original level of surgery. Or what happens is patients don't have a fusion, but eventually the dysfunction returns so they then elect to have a fusion. I'm learning how to navigate the Epic Pro system that houses all patient information, which can be somewhat overwhelming with the amount of scans and files for each patient. Some of the things that we care about beyond surgical data is general patient data - like DOB, BMI, M/F - and more specific patient data - like family history of certain diseases, osteoporosis. We are also tracking patient scores for pain and body function pre-surgery and post-surgery.

I was able to shadow Dr. Hartl some more, this time in the hospital, not the Spine Center on 59th street. One patient was very interesting because there was clear leg pain and weakness, as well as trouble walking, but the scans did not show anything that would normally cause it. There was no nerve compression at L4 or L5, so it wasn't obvious what was causing the pain and weakness. I spoke with Dr. Hartl afterwards about options for this patient and he said that surgery is not possible without a clear target. It doesn't make sense to put someone through a multiple hour procedure just in hopes that you find something when in the OR.

I also shadowed Dr. Ana Krieger at the Center for Sleep Medicine. The patients here were very different from those at the Spine Center. Some patients were only sleeping less than five hours per night due to work life, while some patients were falling asleep throughout the day due to narcolepsy. Some patients had trouble falling asleep, while some patients had trouble staying asleep. Interestingly, many patients had problems with horrible nightmares making them feel exhausted even after 7 hours of sleep. I also noticed that weight has a huge correlation with sleep disorders, meaning that patients who were tired often ate food to stay awake, which lead to increased weight. This would lead to worsened sleep at night and more tiredness during the day, continuing the cycle of weight gain. And some patients noted that late at night when they couldn't sleep was another time when they would just snack on junk food for hours.

I have noticed that many patients in both the Spine Center and the Sleep Center are overweight, so I'm going to watch my pizza intake for the next few weeks while still in Manhattan.

Week 3: A Pig Heart and an Open Heart

The last time I had seen an actual heart was probably in high school… until this week!

This week, I started my research project at the DALIO Institute at Rockefeller University on a part of the heart that I didn’t even know existed:  the Left Atrial Appendage (LAA). The LAA is a small sac-like chamber on the left atrium that is useless after development (essentially the appendix of the heart). However, in patients with atrial fibrillation (abnormal rhythm of the atrium), clots can form in the LAA and be discharged into the bloodstream to cause a stroke. A device called a Watchman can be inserted into the LAA to occlude the opening and prevent clots from being thrown into the bloodstream, but (1) it is not the ideal geometry to fit the LAA and (2) no in vitro test system for LAA occlusion devices has been developed so far. For the next 5 weeks, I will be working with a Cornell BME undergrad to develop a 3D printable tissue-like model of the LAA for testing occlusion devices, with possible future applications of making a customizable printed occlusion device to fit the space more appropriately. This week, we started to get on our feet using the 3D printer and dissected a pig heart to examine the tissue properties that we will recapitulate with our model.

Earlier this week, I got to see what I was most excited for during Immersion:  an open heart surgery! The surgery was to replace an aortic valve and part of the aorta, and to repair the tricuspid valve. This was my first time in an OR and to see a real human heart, and I absolutely loved it! The OR team (especially the technicians and anesthesiology) were extremely nice and helpful before and during the surgery, and explained all of the different machines that they use during the procedure. For example, while repairing the heart, the blood must be pumped through a perfusion machine to oxygenate the blood for the body, while the heart and vasculature directly around it are bypassed. I found it fascinating to see how all of the blood was coming out of the body and passing through the machine, although WOW is it a lot of blood! Through some of the procedure, I was able to stand on a stool right over the patient’s head to get an incredible view of what the surgeons were doing, but was a little bit shocked at the smell of an open patient. I was a little bit worried about being able to handle the smell and the sight of so much blood, but it was not nearly as bad as I was expecting! On the one hand, though, it did make me grateful that I do research for a living instead of surgeries. 😊

Scrubbing in for my first surgery!

On the fun side of NYC, adventuring this week took me to a few museums (the Whitney Museum, Houdini Museum, and American Museum of Natural History), and the highlight foods of the week were S’MAC (different flavors of Mac n’ Cheese) and Hotel Tortuga (giant and delicious burritos for a great price).

Left:  Spinach and goat cheese from S'MAC

Center:  Dinosaurs were the highlight of the Natural History Museum

Right:  A coffin that Houdini escaped from at the Houdini Museum

Week 2: What does it mean to have a brain tumor?

It may not be trivial for us to understand what it will be like to have a brain tumor. I had many misconceptions about a brain tumor, not until I was in the clinic with Dr. Schwartz.

I always assume that patients with a brain tumor will have severe headaches, abnormal behaviors, irreversible brain damage and etc. However, the symptoms of a brain tumor or brain disease are way beyond my imagination.

There is a 70-80-year-old patient with extra fluid surrounding his brain, exerting excessive pressure on his brain but he appeared fully functionally and planning for a cruise trip. There is a girl with a tumor on her pituitary gland, instead of impeding her limb function, it makes her body to accumulate excess fat and stopped her mensuration. There is a lady with a perfect lifestyle that exercises and monitor her nutrient carefully, an unexpected brain tumor leads to an excess amount of growth hormone into her body, leading to the thickening of fingers.

I am always amazed by how complicated our brain is. It is the only organ in our body that distinguished us out from other animals. It is what gives us intelligibility and communicability. At the same time, it is what affects us the most when things went wrong in our brain. And of utmost importance, the mystery of the brain is still unexplored.

Looking at the patients that suffer from all kinds of symptoms that are caused by the brain tumor that causes unpredictable symptoms, I hope I can give them a hand as a biomedical engineering in the field of neuroscience, to uncover the mystery of the brain.

The Meaning of Informed Consent

“Something is voluntary, which is done neither through force nor through ignorance.”

Saint John of Damascene in Orthodox Faith

The Meaning of  Informed Consent

The Belmont Report (1979), echoing the Nuremberg Code (1947) and the Declaration of Helsinki (1964), underlines the need of informed consent in research involving human subjects. Federal Regulations on the Protection of Human Subjects require that an investigator obtain informed consent of any human being, or their legally authorized representative, before engaging them as subjects in research (45 CFR §46.116). Specific requirements are listed therein for a legally effective consent. These measures are taken to ensure that participation in research is voluntary.

What makes an action voluntary?

The classic definition of voluntary is given by Aristotle. In his words: 
τὸ ἑκούσιον δόξειεν ἂν εἶναι οὗ ἡ ἀρχὴ ἐν αὐτῷεἰδότι τὰ καθ᾽ ἕκαστα ἐν οἷς ἡ πρᾶξις. "A willing act would seem to be one of which the source is in oneself, when one knows the particular circumstances in which the action takes place.” (Joe Sachs translation, 2002). This is a complete definition, by genus and specific difference. Let me explain.

Voluntary activity is classified in the broader category of natural activity (this is the genus), the characteristic of which is to proceed from an internal principle. To natural activity is opposed violent activity, which proceeds from an external principle. The very tangible example that is given by medieval commentators is that of a stone which is thrown up in the air. For the stone, going up is violent motion, but coming down is its natural motion: left to itself, the stone falls.

What differentiates voluntary activity from other forms of natural activity, and sets it apart as of a specific kind, is that it is accompanied by a knowledge of the end pursued and its circumstances (this is the specific difference). Most properly, this kind of activity is that of a human being, who having the use of reason, can know goals as goals, the means to get there in the circumstances, and understand the relationship between the means and the end sought. 

Involuntary is the opposite of voluntary. We can identify three basic kinds of involuntary.

(1)   Negative involuntary. This describes activities which are of such a kind that they are incapable of being voluntary, as is the case of the motion of bodies which do not possess knowledge. An example is the movement of the stars.

(2)   Privative involuntary. This describes an activity which has the aptitude of being fully voluntary, but lacks the specific element while still having the generic element. This is the case of someone who pursues a goal but is ignorant of key circumstances. For example, a student buys a cheap car that happens to be a lemon. He freely chose to buy the car but did not know it was a lemon. He wanted a car, but not a lemon!

(3)   Contradictive involuntary. This describes an activity which lacks the generic element of the voluntary, namely, proceeding from an internal principle. Contradictive involuntary connotates the action of an external principle which acts despite a positive repugnance. An example is a kidnapping. 

This division of the involuntary indicate its various causes. Negative involuntary is of no concern to the ethicist. The causes of privative and contradictive involuntary, however, deserve all of his attention, since they can interfere in what should be a voluntary activity (for example in human subjects research). Ignorance causes privative involuntary, while coercion causes contradictive involuntary. This is the meaning of the phrase quoted at the beginning from Saint John of Damascene in Orthodox Faith, “something is voluntary, which is done neither through force nor through ignorance.”

The Belmont Report addresses both of these causes and firstly, that human participants in research should be duly informed:

“It may be that a standard of "the reasonable volunteer" should be proposed: the extent and nature of information should be such that persons, knowing that the procedure is neither necessary for their care nor perhaps fully understood, can decide whether they wish to participate in the furthering of knowledge. Even when some direct benefit to them is anticipated, the subjects should understand clearly the range of risk and the voluntary nature of participation.” (Belmont Report, C. Applications, 1. Informed Consent, PP: Information)

It is also the duty of the researcher to make sure that this information is presented at an appropriate level and adequately understood by the potential subject. 

Secondly, the Report makes clear that the future participant must act free of external coercion or even undue influences:

“An agreement to participate in research constitutes a valid consent only if voluntarily given. This element of informed consent requires conditions free of coercion and undue influence. Coercion occurs when an overt threat of harm is intentionally presented by one person to another in order to obtain compliance. Undue influence, by contrast, occurs through an offer of an excessive, unwarranted, inappropriate or improper reward or other overture in order to obtain compliance.” (Belmont Report, C. Applications, 1. Informed Consent, PP: voluntariness)

If consent were given in the presence of coercion or undue influence, we would not have a “valid” consent, one which is given freely, coming from the participant himself.

Week Two

This week was began with more clinical work at Dr. Kennedy's office in HSS. At this point I feel much more comfortable talking to patients, trying to figure out what their issue is, and what a proper course of treatment would be. When I first began I was very hesitant to talk to the patients and I didn't have enough confidence in my knowledge to come up with a solution. However, Dr. Kennedy's explained to me that there are two major components to the issues that a patient present, a biological and mechanical component. Being that my background is in biomedical engineering I feel that it is much more natural for me to identify mechanical problems, such as improper bone alignment, and possible solutions. The biological component is a bit more difficult for me to understand since many treatments to biological issues, like PRP, are treatments that I've only heard of after beginning my time at HSS.

There were fewer surgeries that took place this week, however one of these surgeries was particularly hard for me to watch since I had never seen a case of osteomyelitis before. This infection had unfortunately caused the deterioration of two bones in her foot to the point that the bone had become completely soft. When the surgeries began the patient had swelling on her foot comparable to the size of a baseball, which turned out to be necrosed tissue. After all of the tissue had been removed there was a large hole in the foot that was filled with PMMA in order to prevent the infection from occupying the space. Since I have never actually seen PMMA in real life before I was surprised to learn that its hardening process was exothermic and caused it to heat up very noticeably. 

The last day of the week involved working at NYDG once again and observing PRP and shockwave therapy treatments. I was very excited since I was actually able to experience shockwave therapy firsthand. Back in December I injured my wrist boxing and while it healed to the point that it stopped causing me pain, it began to creak very loudly until I received this treatment. While I found shockwave to be very uncomfortable, I noticed that I received immediate relief from discomfort in my wrist. To be honest, I was very skeptical about the efficacy of the treatment but I'm happy to say that the treatment presents so many benefits with little to no risk. I would certainly encourage more doctors in the future to use this treatment since its applications go far beyond only orthopedic purposes. 

Week 2: I didn't pass out!

Although I didn’t think it was possible, week two was even better than week one. I got to learn more about the project I will be working on, which is about analyzing the pattern in MRI and PET prostate images using texture analysis to identify tumor development and patient outcome. I learned how to use different biomedical image processing software to analyze the texture in the images. The differences in the image analyzing software made me wonder whether different software could produce different outputs of the same image.

I went to a few cancer seminars hosted in the Memorial Sloan Kettering Building and in the Belfer Building. The first seminar was about how different proteins and molecules in the cytoplasm have are in various liquid phases which allows them to separate and aggregate naturally in the cell. One of the future implications of this research might be to be explain how proteins aggregate in the brain causes Alzheimer disease.

I was also able to shadow a plastic surgeon, Dr. Jason Spector, and a neurosurgeon, Dr. Ted Schwartz during their surgeries. The plastic surgery cases were diverse and weren’t just cosmetically related as I had expected. The first surgery was for placing natural skin graft onto the patient’s heel and the second surgery was for removing a lesion on the cheek. The third was an eyebrow lift and upper eyelid gold-weight insertion for treating facial paralysis and lagopthalmos (inability to close eyelids completely due to facial nerve damage).  The first neurosurgery was a lumbar spine surgery, I think, since the surgeons were working near the lower back region.

One of the things that amazed me most about the operating room was how everyone was able to work together as if they were an ant colony. Some of the nurses would hold out the instruments before the doctor asked for them, or the doctors would work together in a crowded area. I am even more excited about the next few weeks!

Week 2

Week 2

06-22-2018

We were blessed with wonderful weather when we visited the Status of Liberty last weekend. Even though we couldn’t reserve the tickets to go up to the crown, looking down from the top of the pedestal was enough to make my heart rate go up because of the height (so much for going up to the Empire State Building, haha!).

I have yet to visit the clinic or observe in the OR due to scheduling issues and Dr. Rodeo’s travel plan. However, the paperwork should be down by next week.

Things have been moving smoothly in the lab. I practiced the ACL transection on rat cadavers as planned. Anterior 

cruciate ligament (ACL) originates from the lateral posterior side of the femur, cross the posterior cruciate ligament (PCL), and link the medial anterior side of the tibia. It is one of the several very important ligament in mammalian knees. Its rapture is the most common of the ligaments in knee injuries and a major cause of post traumatic osteoarthritis (PTOA). As a result, the open surgical method of ACL transection has been used as a standard to study PTOA. Anteriorly to the knee is the meniscus, a transvers thin fibrous cartilage. Flanking the knee are the lateral and medial collateral ligaments, the later is also used in some PTOA models. In the open surgical ACLT model, it is important to not damage the surrounding ligaments and tissues, especially the MCL and PCL. The open surgical ACLT procedure is relatively easier in rats than in mice because the ACL can be exposed and is visible thus avoiding the bind operation that could possibly damage other ligaments and structures.

For the closed POTA model development, I have designed a simple crankshaft apparatus to produce a controlled linear motion. The parts should be printing in the 3D printer as I type these words. I will assemble them and conduct some preliminary testing next week.   

Week 2

 Since Dr. Gauthier was in Paris for ISMRM conference this week, mostly of the time I read papers she sent to me or I found interesting and related to my immersion project topic. One of the most interesting paper I read from these paper stack was called "QSMnet". Our lab has pioneered the development and application of Quantitative Susceptibility Mapping (QSM) which solves the dipole inversion problem to get the magnetic susceptibility distribution around the tissue. In our method, we incorporated regularization term to penalize the striking artifacts caused by the ill-posedness of the dipole kernel, and used iterative optimization algorithm like Conjugate Gradient (CG) descent to minimize the objective function. QSM was firstly used to detect the susceptibility distribution around the brain, and has been extended to other applications like cardiac imaging, combination with PET imaging and so on. Recently, deep learning, or Convolutional Neural Network (CNN) specifically speaking, has become extremely popular when dealing with image related computational problems, and image reconstruction problem like QSM is one important case of them. In this QSMnet paper, the authors delicately designed a network structure to mimic the dipole inversion process appeared in QSM problem. They trained the network based on thousands of high quality subjects and applied the state of art deep learning techniques to get optimal results. Surprisingly, they obtained the results which were obviously better than ours. I think I should discuss this paper with the guys in the lab when they are back and possibly come up with other deep learning based method to improve our existing method.

During the most of the time this week, I stayed in the lab working on my thesis project, which focuses on medical image reconstruction problem. I also tried to figure out how to combine the image reconstruction techniques I've utilized to Dr. Gauthier's project, MS lesion related work. My first thought was to use the same network architecture as I'm using for reconstruction now to handle with MS lesion segmentation problem. I believe this should work as long as we have enough data to fit the model. I should talk about this direction with Dr. Gauthier when she is back too.

I really enjoy my PhD thesis topic and also the immersion project, hopefully some useful outcomes could be come out at the end of the immersion.

2

Radiation therapy (RT) is far less barbaric than it sounds. Yes, at its core, it is zapping a patient’s body with high-energy photons, electrons, protons or other modalities, but the delivery is extremely precise and the dosage is carefully determined based on the target area, organs at risk (OARs), and the tolerance of the tissues therein. The precision of the equipment is such that it can deliver radiation to the target area ±~1 mm and 1^o of rotation. Compared to other methods of disease treatment, namely surgical resection and chemotherapy, which can affect substantial amounts of proximal healthy tissue and have widespread systemic effects respectively, this seems like the best example of precision medicine in an oncologist’s toolbox.

This week I have seen numerous patient consults, follow-ups, and planning sessions, largely for patients with low and high grade gliomas, brain- or bone-metastatic cancers, or benign brain tumors. For patients with benign tumors like meningiomas and schwannomas, RT is used either alone or in conjunction with surgical resection, and is meant as a definitive, curative treatment whose purpose is to ameliorate any existing neurological symptoms caused by compression of brain tissue. It is also meant to prevent future neurological symptoms from developing. These tumors tend to be very slow growing, on the order of 1 mm per year, so treatment is not urgent if the patient does not present with symptoms. Generally, for patients with metastatic disease or gliomas, the treatment is palliative – intended to slow or stop growth of existing lesions and limit any associated pain or neurological symptoms. Radiation therapy does a good job at palliation.

In a tumor board this week, a patient was presented with an arachnoid cyst, a cerebrospinal fluid filled cyst formed in one of the three meningeal layers near the brain stem. The cyst was surgically resected and sent to pathology where a parasitic flat worm was found. Additionally, neoplastic cells were identified, but the cells did not appear to come from a brain cell lineage. The patient did not have any other tumors, so this could not be a metastasis. A google search led the pathologist to a paper published several years ago in which a patient with advanced HIV presented with multiple neoplasms that, when genotyped, had no human DNA in them. Indeed, in our case, when the sample was stained for human cellular markers, it came back negative. The cancerous lesion identified in this patient’s brain was actually an arachnoid cyst caused by a parasitic flat worm that had cancer.

The worm’s next of kin have been instructed to seek genetic screening.  

Week 2

Prior to the start of our immersion term in New York City, I had only ever in the same room as 2 surgeries (both on myself). The past two weeks that number has increased ten-fold, as the majority of my time this week was spent in the operating rooms of interventional radiology.

Granted, these surgeries are generally quick and routine: biopsies among the most common of what I’ve now witnessed. As an observer of the technique required, I feel as though that routine seems mundane to me now; anesthetize, image, incise, insert probe, collect biopsy, deliver to in-room pathologist for confirmation as to correct samples collected (I’m sure the patients are thankful for this: I can’t imagine being called back to find out the initial biopsy was insufficient and needing to be called back for a second biopsy), and either collect more samples or close up. I’ve seen patients move in and out of the operating room in less than 30 minutes, and the numbers I’ve been told bear this out – apparently the department performs ~3 lung biopsies a day! In addition to these biopsies, I saw quite a few procedures adjusting inlet/outlets from specific organs: be it lines for bile removal or intake feeds for chemotherapeutics.

One of these procedures gave me the opportunity to learn about an interesting condition: a Morel-Lavallée lesion, wherein the skin and fascia covering the muscle separate, forming a gap susceptible to fluid accumulation and infection. In my head the layers are so compact, that frankly the idea that something like this could occur in response to physical trauma left me queasier than anything else I’ve seen so far.

By far the most notable procedure I was able to observe this week was a Transjugular Intrahepatic Portosystemic Shunt (TIPS). This procedure is done in response to hypertension in the portal vein, a frequent side effect of long term liver damage, which can lead to renormalization of blood flow through alternatives paths, and thus long term engorgement and possible hemorrhage of the alternative vessels not used to the additional flow demand. A shunt is placed between the portal vein and hepatic vein by piercing a path between the two with a wire, after which the shunt is inserted. This was the longest procedure I’ve had the chance to witness (all in all the preparation to completion time was six and a half hours), and I don’t know how the surgeons can remain so focused during that entire period as they guide the angioscope through the blood vessels.

All in all, this week represented the last bit of full time clinical exposure here at the hospital. I’ve now got a desk and a project started on some rather large-scale data analysis concerning lung biopsies (which, frankly, makes me happy that I got to see so many of them!), so I’m excited to see where that goes.

Week 2: First time watching brain surgery

This week Dr. Prince was in Paris during ISRMM. I had a couple of images I needed to analyze - calculate the volume of chest that is being pushed inside by the tissue expander- this is easy to do with a program called Volume Viewer (General Electric). I manually segment the volume of chest from MRI images and compare it to the other side of the chest (left or right). I was able to analyze 12 patients and other 16 patients with breast implants. I also had to do some phantom experiments on the MRI, and I must confess, I was pretty scared to handle that machine by myself. Is quite overwhelming and it has thousands of parameters that need to be modified in order to acquire a specific type of image.
Since the machine was busy with patients during the whole day, I was only able to access it around 6pm. I would put the tissue expander phantom on the machine and play with the acquisition parameters in order to reduce the artifact caused by the magnet inside the expander. I honestly was very confused of what I was doing (in term of the parameters) and even though I acquired some data and tried to explore by myself how the machine works, I still need another session with Dr. Prince to  feel confident.
Besides of that, I was able to shadow Dr. Schwartz on brain surgery on Wednesday. I'm very interested in this type of surgery since I do it all the time back in Ithaca (on mice, obviously) so I was very curious to find out how it was in human. That day, Dr. Schwartz was operating a lady that had brain tumor near the pituitary gland, so he needed to extract the tumor through the nose. That was pretty impressive! But definitely a very good experience, I'm glad I had the chance. Hopefully I can shadow other type of surgeries from my friends from now on.
On the fun side, I have kept exploring NYC and went to a jazz bar on Thursday night (Smalls bar) definitely recommended for those jazz lovers.

Week 2: Cardiac Clinic and My Own MRI

This week I have become more involved in one of the research projects that the lab is working on. I am helping to add to the patient population for a manuscript that was in progress when I arrived. I have had to interpret variables that were generated by the lab software from both nuclear stress tests and echocardiograms. This has been a useful endeavor as I have had to learn terminology and useful calculations for cardiac stress measurements. We are using these to get an overall picture of the patients cardiac reaction to the stress test. I have helped to add more than 1000 patients to the original 2500.

I have also had the chance this week to shadow a cardiac fellow in the cardiac clinic. This has been my first direct interaction with patients in terms of diagnosis and general checkups. It is very interesting to see the range of reasons that patients are referred to the clinic. It is also very good to be able to learn what it is like to get a patient's information directly from them, rather than another doctor. There were also a lot of patients that didn't show up to their appointments. More than half of the patients did not come, and apparently that is fairly common. I find that very concerning since most of these patients are coming in with concerns of cardiac health and their diagnosis could be time sensitive.

I have continued to view MRIs for both patients and volunteers this week. I was even able to volunteer myself for one of the cardiac MRI studies that the lab has ongoing. It was a very long and boring process; I even fell asleep briefly for a few minutes. The only interesting thing that happened to me while I was being scanned was that towards the end I began to get really hot since I had a blanket and some other equipment on my chest. So I came out of the MRI sweating, but cooled down almost immediately after getting out of the bore. It was really cool to see the images of my heart. It's a weird feeling to see that much detail of the inside of your body. It's very different to be looking at patient images rather than your own. Overall, it's been a good week with a variety of experiences.

Outside of the hospital I've been able to go around the city some more and continue running new routes around the UES and central park. One of the more memorable things is going to Times Square and getting some of the best tacos I've ever had in an unexpected place.

Week 2: Moving Skin Around

This week I experienced full days in the clinic, OR, and lab with each presenting a unique opportunity to learn. In the clinic, I saw patients coming in for consultation, post-op, and follow up appointments spanning the whole spectrum of surgery planning, recovery, and healing. It was interesting to see patients in the OR that I had met last week in clinic for per-operative appointments. One of the most interesting parts of this week was observing a skin graft procedure. I have learned so much in a short time in the OR and here is what I learned from watching a skin graft operation! 

        This procedure affects 2 part of the patients body: the donor site and the graft site. This operation involved moving a thin healthy section of skin from the thigh to a wounded area.  In this case the patient had already undergone one surgery in preparation for a skin graft because they had a open wound and a poor wound healing response due to other co-morbidities. The first surgery was the addition of a biomaterial layer to the wound. Integra, a collagen hydrogel, is a material that the body can infiltrate and vascularize. This layer is placed on to the wound days before the skin graft operation to allow any underlying healthy tissue and vessels to grow up and into the layer. The addition of integra creates a thinker layer of tissue and increases the chance the skin graft will take. 

          Skin grafts must be placed on highly vascualrized regions to keep the transplanted skin alive. The grafts come in two varieties: split thickness or full thickness. Split thickness grafts include the epidermis and a thin section of dermis whereas full thickness grafts include the epidermis and the entire dermis. In this procedure a split thickness graft was used that was  1/100 of an inch think or about 250 μm.  The properties of the skin graft are determined by the amount of collagen and elastin which control the contractile behavior. The grafts contract in two ways after they are removed from the donor site.  Primary contracture occurs immediately when the skin graft is removed from the donor site while secondary contracture occurs after the graft is put in its new place. In this case with a split thickness skin graft, there is little primary contracture but greater secondary contracture. 

Before the skin is taken from the donor site, epinephrine is injected to cause vaso-contraction and limit the bleeding. Next the surgeon uses a tool called a dermatome to remove the skin graft of the desired thickness.  Click here to see an schematic of the dermatome as it shaves off a thin layer of skin.  This leaves the donor site in a state similar to what to you would experience with a brush burn except that instead of pieces of skin being left in the carpet, sidewalk, or basketball court, the scraped off piece of skin is collected.

        After the skin graft is removed, it is flattened out and rolled through a mesher which is a device that pokes holes into the graft. Meshing the graft allows for fluid drainage, increased flexibility and potential to cover a larger area. The top reason skin grafts fail is because they collect fluid under the surface. To combat this the skin is meshed and force or suction is applied by a wound vac to draw off the excess fluid. I have seen several cases of wound vacuums and they consist of foam placed over the wound followed by the suctioning components, tubes, and dressings. The vacuum suction can be applied continuously or intermittently. Intermittently is slightly better for the wound and graft but this causes more pain because every time the vacuum is turned on, the increase in pressure tugs on the wound. Therefore it is more common to use continuous vacuum pressure to increase patient comfort. The forces applied by the vacuum also promote healing by stimulating angiogenesis, myofibroblast action, collagen production, granulation tissue formation. The skin graft can start to re-vascualrize in 24 hours. Angiogenesis can occur from both sides; vessels can sprout from both the wound bed and the skin graft. When the new vessels meet each other it is called inosculation (derived from the latin word for kissing). The healing process can proceed when the graft is vascularized and connected to the vasculature of the wound.

This week in lab I started working with my first tissue samples from the OR. Back in Ithaca I study obesity and its relationship to breast cancer so here it is great to have the opportunity to access and test human adipose samples making my studies more clinically relevant.  It is a completely different experience isolating samples form tissues composed of human skin and fat discarded during surgery then it is in mice. I dissected the samples, saved them, and am working on adapting protocols for decellularization of the adipose tissue. 

Figure 1: Adipose Tissue I am using for my research project

Meanwhile,  for my adventures in NYC I went to MOMA and got to see works of art such as Van Gogh's Starry Night and Monet's Water Lilies.  I had the chance to see the Statue of Liberty and Ellis Island which were beautiful as well. Weeknight activities include walks to Central Park and stops for ice cream!