Laparoscopic donor nephrectomy

Laparoscopic donor nephrectomy refers to a minimally invasive procedure to remove a kidney from the donor. I have observed 2 living donor kidney donations in which laparoscopic donor nephrectomy was performed concomitantly with the actual kidney transplant. The laparoscopic part was actually very cool 1) because of its semi-r0botic nature and 2) it is projected on the screen so I didn't have to strain to see it.

This procedure is performed through two or three 1/2 - inch puncture sites. With the patient under general anesthesia during the procedure, the surgeons make 1/2 - inch incisions. Laparoscope containing a video camera is introduced through one port, with its image projected onto a monitor so that the surgeons can see and control activity through the abdomen. Carbon dioxide is introduced to inflate the abdominal cavity(insufflation) to provide working space. The other 2 ports accommodate devices to perform the actual procedure such as staple gun. Once the organ(kidney) has been excised, a 2 -inch incision under the bellybutton is made to provide a path for extraction of the donated kidney. It is really neat to watch. Somehow the surgeon manages to slide in a plastic bag onto which the kidney is placed before it is taken out through the 2-inch incision. This is whole procedure is done by observing projected images on the monitor.


a) Excision of renal vein from www.laparoscopic.com

This state-of-art procedure, as compared to open kidney donation, has several advantages. First and most importantly, the smaller incision shortens postoperative hospital stay (usually two days), minimizes post-op discomfort, has less risk of hernia and scar formation, is more cosmetic and speeds up the patient's complete return to normal activity (2 wks compared to 6 for open surgery). Second, this procedure is much quicker than the old 12-inch long muscle splitting incision; it is a 2-hr operation. Lastly, the procedure doesn't require the detachment of the diaphragm, and therefore minimizes the risks of infectious disease such as pneumonia.

I thought this procedure was a textbook example of how technology has revolutionalized medicine. Watching the surgeon maneuver around several organs( intestines and and the spleen) to reach the kidney was not only astounding but also gave me a great appreciation of Anatomy and its mastery. All that said, it nonetheless left with me one lasting distaste. When the scope is inserted into the belly, the stomach and the organs become vividly visible including the yellow, disgusting fatty adipose around the stomach lining.. It is GROSS!

Dickson!

Again, With Feeling

"I hate this."

These are the words of Dr. Weinsaft as he describes the particularly "tedious," "eye numbing" job of evaluating basic cardiac function via cineMRI and phase contrast MR techniques. After observing him perform a few of these measurements, I'm not sure if I disagree. Perhaps I should explain...

A cineMRI is a variation of magnetic resonance imaging (MRI) that sacrifices spatial resolution for temporal resolution. Traditionally, MRI focuses heavily on spatial resolution, producing highly detailed images through scan times of several seconds or even minutes. In cineMRI, images are rapidly acquired at a relatively low resolution and are assembled into an image sequence resembling a smooth flip book movie. A cinema, perhaps? The resulting movie clearly shows heart motion and, when properly positioned, can provide insight into the operation and function of the rapidly moving bodies, such as the heart.

A typical cineMRI sequence (obtained from www.isi.uu.nl)

The above is a "short axis" view of the heart, a perspective that clearly shows the right and left ventricles. Given the movie-like qualities of the image sequence, it is then possible to evaluate the volume of the ventricles through an entire cardiac cycle and from this, we can obtain mountains of useful measures. End Diastolic Volume (EDV), End Systolic Volume (ESV), Stroke Volume (SV), Ejection Fraction (EF), Cardiac Output (CO), the wealth of information is endless. But first....how?

Manual labor.

"Sigh," says Dr. Weinsaft.

This is done by meticulously tracing each of the frames manually, separating structures of interest by dropping hundreds of points via a steady hand and a trusty mouse. Such an exercise takes an experienced cardiologist over ten minutes. For me? Coupled with a finicky software package that heartlessly punishes mistakes by totally erasing existing work? Better section off an afternoon.

A single "segmented" frame (obtained from www.isi.uu.nl)

Upon repeating the process 30 or more times for each short axis slice, we obtain something like this:

A fully segmented image sequence (obtained from www.isi.uu.nl)

From here, the software package takes over, automatically calculating the relevant statistics from the segments. After copying down this information, Dr. Weinsaft begins his clinical reading.

The problem? Segmenting the heart manually is a time-consuming, monotonous affair that can often take more time than the reading itself. If only there was an automated method...

Fortunately, there is. An algorithm, developed by Noel Codella, of Cornell University, is capable of segmenting the inner region of the left ventricle, with future development aimed towards fully segmenting all regions of interest in the heart. In addition to being far more consistent in segmentation decisions (an admittedly subjective judgement call at times when done manually), Noel's algorithm is fast. The time required for evaluating a single case is 1/20th that of a manual evaluation by an experienced observer.

Unfortunately, the algorithm is still being fully evaluated and its results cannot be fully relied on as of now. My job, for the remainder of the summer, is to segment as many cases as possible, using both the automatic algorithm and manual segmentation. By quantifying the agreement between the two methods and by measuring useful statistics such as the amount of time saved using automation, it is hoped that we'll provide compelling evidence as to the accuracy and speed of computer-assisted evaluations.

This convergence between computerized automation and "traditional" human evaluation is one of the aspects of engineering that interest me the most. A cardiologist shouldn't have to spend more time connecting-the-dots than than he does in rendering a diagnosis. An experienced clinician with decades of schooling and experienced shouldn't be limited by how quickly they can perform an activity we learned in pre-school. And with a little more work from engineers, hopefully they won't have to.

My Research

Since my doctor was out on vacation this week, I was mainly able to research on my projection –a five decade review on esophageal atresia with and without trachioesophageal fistula.

Esophageal atresia (EA)/trachioesophageal fistula (TEF) is a congenital disease that involves a failure of the development of the esophagus. Normally the esophagus (connects the mouth to the stomach) and trachea (connects the mouth to the lungs) are separate pipes; but in EA/TEF these pipes are underdeveloped and/or connecting. The failure in separating is pinpointed to the fourth fetal week when the trachea and esophagus should start to divide.

About 85% of all EA/TEF cases have an esophagus that ends in a blind pouch and a trachea that connects to the proximal portion of the esophagus. This part is called esophageal atresia. Trachioesophageal fistula is defined when the distal esophagus (one coming from the stomach) connects to the distal trachea. There are many other types of EA/TEF, some with only EA and no fistulas. Some cases involve EA with both proximal and distal TEFs -meaning the lower esophagus connects to both the upper and lower trachea. Other cases may involve an EA with proximal TEF but no distal TEF.

aafp.org


The first reported case was reported in 1670 but a successful intervention did not occur until 1941. After the successful operation, the mortality rate for EA/TEF decreased exponentially. The risk factors for survival previous to 1995 and after 1941 were mainly weight and other complications. Now, after 1995, weight is no longer an issue as ICU, surgical and anesthetic techniques have advanced greatly. Cardiac and other complications remain an issue as it sometimes prevents emergency surgical intervention; cardiac complications arise in 30% of all cases.

My project involves statistical analysis on all the cases of EA/TEF in the New York Presbyterian hospital during five decades. The decades are divided into three eras -1960 to 1974, 1975 to 1995 and 1995 to 2007. We are interested in seeing if there is a statistical difference in mortality, morbidity, and other complication rates between eras. We also plan to perform follow up calls to patients from different eras to see what post operative care is still needed many years later.

From what I’ve calculated, there is no statistical significance in terms of mortality, morbidity, complication between eras despite improvement in patient care, neonatal intensive care advances and surgical advances. The data set could possibly be bias and I’m looking into this factor in the upcoming weeks.

Modern Medicine

Vascular Surgery
Week 3

This week I’ll outline two procedures I saw that bookend modern medicine: the guillotine amputation and the arteriovenous fistula.

The Guillotine Amputation

http://www.steinergraphics.com/

This is a guillotine amputation. Like its name implies, this type of amputation is performed by cutting linearly through, and perpendicular to, the long axis of a limb. It’s used in emergency situations for quick removal of malignant infection. It’s also called a “flapless” amputation because no tissue is left to cover the stump. The wound is dressed but left open to avoid new infection until a proper amputation can be performed when the patient is more stable. This picture shows a transtibial amputation with the distal tibia and fibula in the stump end.

I got a first-hand view of this amputation as I held the patient’s stump while the surgeon wrapped the wound. Needless to say, this condition is as painful as it looks. This procedure is the same one that was used on the battlefields of the American Civil War nearly 150 years ago.

The Arteriovenous Fistula

http://www.vascularweb.org/

As I mentioned previously, the AV fistula is the joining of an artery to a vein. This has the effect of increasing blood flow to the vein and can be felt as a vibration or “thrill” when the anastamosis under the skin is palpated (think of a cat purring). In response to the increased blood flow, the vein stretches and remodels to become stronger. This is called maturing, and after 3-6 months the vein will increase in size and look like a cord under the skin. This is an important procedure for dialysis patients—once mature, the fistula is strong enough to facilitate the insertion of the large needles needed for dialysis. This was a fantastic procedure to see—the surgeon opens the arm and literally sews an artery to a vein.

The guillotine amputation is crude and primitive and the AV fistula is complex and requires significant technological advancement, but both techniques currently classify as modern medicine.

or maybe scary statisticians?!

So last time I wrote about three large scale lung cancer screening trials that concluded unanimously x-ray screening for lung cancer does not decrease disease specific mortality. Now, the question becomes what would be the right parameters in making conclusions from a diagnostic clinical trial and what factors shall be taken into account when evaluating the results of these studies?
An article published in 1999 by Dr. Henschke concluded that CT screening for lung cancer is more efficient than chest x-ray since in a small observational study she observed that 85% for cancers are missed using CXR. This motivated the NCI to put together what is considered to be the most expensive RCT, the National Lung Screening Trial (NLST) where they've screened nearly 50,000 people in two arms (CT vs. x-ray) for three years and then they follow up patients for 7-8 years. The final measure of screening successfulness is the mortality rate and the final results are supposed to come out in 2008-2009.
One of the issues associated with setting up an RCT is that it costs so much. You need to have a large population in order to avoid statistical biases and population heterogeneity. So far it is estimated that the NLST has cost $250,000,000, and it seems this figure could be doubled (or maybe it is already doubled). Because the study is really costly, screening takes place in 2-3 years because the lengthier the screening, the more costly the study will be. An important question here is that will a 2-3 year screening necessarily decrease the "mortality"? An answer to this involves complicated statistical modeling, but it has been estimated that if NLST or previous RCTs screened for 18 years, then the decrease in mortality would have been significant between the control and screened arm. Now, no one in the right mind will screen 50,000 people for 18 years because the country may very well go bankrupt. So instead these trials cut on the number of years of screening and no wonder they do not detect a significant decrease in mortality. After you initiate screening, you have to take into account how long it takes for effects to be observable, specially since in the first few years the mortality would not be different because when you start the screening there are already a lot of patients with late stage lung cancer that will die.
More on the other issues later....

Plastic Surgery - Breast Reconstructions

So my second week has been spent doing much of the same as the previous week - rounds first thing in the morning and OR cases for the remainder of the day. Rounds are starting to get less hectic and more fun because I actually know what’s going on now and can interact with the actual doctors…and the patients for that matter. The patients actually trust me and ask my opinion on medical matters, which is always interesting…

As for the OR, breast reconstructive surgery is by far the most common procedure for plastics…or at least from what I have experienced. There are probably 2-3 procedures every single day, without fail…it’s actually pretty humanizing when you step back for a second and reflect on it – for example, by writing this blog entry. I guess what I’m trying to say, is that the OR cases are the fun and exciting parts of our day (or at least mine) and we (or I) view them as just another fun spectacle; however, being in a hospital, most, if not all of these patients are here because they are really sick. Yet, as mere observers, it’s our entertainment. So, in my case, these 2-3 patients a day…yeah, they all have cancer. It really is an eye-opener. According to the American Cancer Society women in the United States have a 1 in 8 lifetime chance of developing invasive breast cancer… that is also expected to take almost 41,000 lives and much more worldwide…somehow, those numbers just seem so much more real now that I look it in the face every single day.

On the other hand. Due to advances in medicine and science, many patients with breast cancer survive AND can have breasts surgerically created to resemble a natural breast in form and appearance. I’ve heard and seen many patients first-hand that are very pleased with the results of the surgery. Anyway, I have digressed from anything remotely science oriented. I suppose I should provide some details on this procedure since it is basically all I have written about today.

Bilateral Mastectomy with Breast Reconstruction

As the name suggests, breast reconstruction is simply the surgical rebuilding of a breast to create a natural looking one, typically involving reconstructing the areola and nipple as well.

Usually the procedure starts with the general surgery team making an incision around the nipple and continuing it laterally to form enough of a hole to remove the entire breast. The underlying breast tissue (including the nipple, but usually leaving the areola) is then separated and removed from the pectoralis major via a bovie (the electric knife). Before the plastics team arrives, the removed tissue and remaining margins are probed with essentially a Geiger counter. Honestly, I’m not really sure what is a high or low number, the thing seems to go crazy no matter what. However, the removed tissue is always much higher than the remainder (obviously). They use a Geiger counter probe because the patient is injected with a radioisotope before the procedure starts. This radioisotope translocates to the lymph nodes and is imaged to show the surgeons approximately what needs to be removed. The probe is used mostly as a double check.

When the plastics team arrives there are no breasts left…just an empty cavity. However, it is their job to recreate what was lost. Unfortunately, that involves multiple operations. So, they begin by separating the pectoralis major from the underlying fascia. Next, with the aid of some wonderfully engineered biomaterials, a temporary, partially saline-filled, tissue expander is placed under the pectoralis major muscle of the chest wall. In subsequent procedures, the tissue expander is incrementally filled with more saline to sketch out the overlying tissue. This in turn, allows for enough slack to eventually surgerically insert a real silicone or saline implant, all the while subjecting the tissue to minimal tension.

Notice that many subsequent operations are needed to complete this overall procedure… such as nipple and areola reconstruction. Also, keep in mind that once the implants are secured and the wounds perfectly healed the end of the road is still up ahead. It is a common misconception that implants will essentially last a lifetime (perhaps this would be a nice invention). However, the reality is that even after all of these procedures, each woman will most likely have at least one, if not more, additional maintenance follow-up surgeries due to any number of reasons from simple aging to a failed implant. Sad.

The ICU

Over the past few weeks, I have been mainly observing cases in the OR. Today, I had my first experience with making rounds in the ICU. I met Janet at 5:50AM and we made our way to the ICU in the neurology department. There we met with current medical students and residents. From what I can tell, there was one resident who was responsible for looking after the patients the previous night. As we walked from room to room, there were several students who were in charge of reading stats of the patient such as blood pressure, white and red blood cell count and any other pertinent information regarding the patient's status. There was a lot of jargon I did not understand. It seemed as though they were making sentences out of letters and numbers. However, I believe I was able to figure out that "output" referred to the amount of urine was excreted by the patient.

It was an interesting...I guess more shocking, experience. I was somewhat taken back by how loud they would talk to the patients. It's six in the morning and they're yelling at the patient to squeez their fingers, stick your toungue out and wiggle your toes. I couldn't help but think, "take it easy man...it's six in the morning." If it was me and I just had brain surgery, I would have asked them to come back around nine, when I would be a bit more awake and responsive. One patient said it was 1907, but I wasn't sure whether he was extremely tired or really thought it was 1907. I guess my point is that it doesn't seem like six in the morning is a good time to test a patient's cognitive function. But hey, I'm no doctor.

After the rounds, they got together and talked about their current cases and got advice from the head resident. All of them had little sheets, with all the patients names and status. They all fold their pieces of paper the same way and take notes the same way. I wonder who started it? I guess it would be cool to know that you were responsible for how all the medical students take notes. Overall, it was a good experience. I will continue to make rounds in hopes to understand their jargon and see how patient's treatments evolve.