Liver Transplant IV

The liver synthesizes most of the proteins involved in coagulation or blood clotting. While we think of most cirrhotic patients as coagulopathic - unable to form clot - they are also paradoxically hypercoagulable. The liver also synthesizes proteins that break down clots so sometimes the balance tips towards formation of thrombi and emboli. We further perturb the system during surgery with local inflammatory mediators triggered by trauma, the transplant of a liver which has been synthesizing pro- and anti-coagulant proteins, transfusions of plasma to help reduce surgical bleeding.

This was most prominent in one of my liver transplants where after reperfusion of the new liver, clots were noted by transesophageal echocardiogram in the heart. There was a period of time when the heart was stunned during reperfusion, and I wonder if these low flow states in combination with procoagulants released from the liver lead to clot formation. Furthermore, the focus of the clot seemed to start from a central line tip sitting in the atria. However, when we checked coagulation tests, the patient's INR was 8 and PTT was over 300, both suggestive that the patient's blood was too thin.

This is the paradox of coagulation in liver disease. The patient was bleeding and clotting at the same time; somehow, the normal system of checks and balances had failed. This is disseminated intravascular coagulation, and in the middle of surgery, this is life-threatening. Even though it doesn't make much physiologic sense, we gave a small bolus of heparin to dissolve the clot while transfusing products to decrease the bleeding. Over the course of the surgery, the clot melted away. We didn't see any changes in our pulmonary artery pressures or oxygenation so we didn't think the clot emobolized from the heart to the lungs. Such situations show me the complexity of managing coagulopathy especially in the setting of a major surgery with vascular components in a cirrhotic patient.

Liver Transplant III

A gentleman with hepatitis C cirrhosis is scheduled for an orthotopic liver transplant. Though he has no other major medical conditions, his liver disease is fairly severe; his MELD score, a measure initially used to estimate 3 month mortality and now used to determine liver transplant priority, is 36, suggesting over 50% mortality in the next 90 days. He has significant ascites, leg swelling, esophageal varices, coagulopathy, portal hypertension, and hepatic encephalopathy. He needed a new liver.

We waited to induce anesthesia until the donor organ arrived. Until the transplant surgeon examines the organ fully, there is always the possibility that the surgeon may cancel the procedure. Though this was highly unlikely, we also did not want to put the patient at risk unnecessarily. Once we got the green light, we induced anesthesia, struggling with hypotension as liver disease severely impairs normal cardiovascular responses. We placed multiple lines including single lumen central line placeholders that could be converted to bypass cannulae if necessary. The transesophageal echocardiogram showed a hyperdynamic heart, commonly seen in patients with liver disease. We began reversing the patient's coagulopathy as his INR was five times normal. We began the patient on octreotide and some vasopressin, and the surgeons began.

To expose all the abdominal organs, major vessels, and the cirrhotic liver, the surgeons make a large "Chevron" incision below the ribcage about two feet long. He also makes an incision from the bottom of the breastbone down to the bellybutton. When he does so, several liters of ascites, fluid that accumulates in the abdomen as a result of liver dysfunction, spilled out. The dissection is meticulous, especially since the patient had gallbladder surgery in the past and had some scarring and adhesions. Through this time, we struggled with the blood pressure; cirrhotics are in a chronically vasodilated state, and general anesthesia doesn't help. This was a rare surgery in which we ran a very light anesthetic with heavy paralysis. With the level of liver dysfunction, the patient was confused and disoriented to start and would not be able to metabolize anesthetics easily. Thus, we expected our midazolam to linger longer than normal and provide adequate amnesia.

As the surgeons prepared to remove the old liver and connect the new one, they placed vascular clamps along the inferior vena cava. The clamp time was less than half an hour, but during this time, the normal blood return from the intestines and lower legs was impaired and portal venous pressures began to increase. The old liver came out, scarred, battle-ridden, even with the remnant of a TIPS catheter. The surgeons worked furiously to reconnect the inferior vena cava "cuff" of the new liver to the severed vena cava of the patient. Similarly, they reconnected the hepatic artery and portal vein. Meanwhile, we began optimizing the patient to the tenuous moment that the cross-clamps would be removed. We replaced electrolytes, warmed the patient, and decreased the anesthetic to almost nothing. Since the patient is anhepatic - liverless - the circulating medications were not being metabolized.

With the removal of the vascular clamp, blood flow began circulating through the new liver. However, this meant that all the toxins that built up while the donor liver was out of the body and being prepared are now released into the body. Cold potassium, preservation solution, cytokines, inflammatory mediators, and cellular debris floods into the heart. This is then followed by the venous blood draining from the intestines and lower extremities that could not be cleared during the cross-clamp. This blood is no better for the heart. To prepare for this hit, we gave calcium, glucose, insulin, and bicarbonate. Nevertheless, the patient's heart rate plummeted to 30 and the blood pressure halved, then halved again.The surgeons could not palpate the carotid or femoral pulses. This is the rollercoaster of the liver transplant. Fortunately, we anticipated this. I bolused atropine, escalating doses of epinephrine, and additional calcium chloride with appropriate responses. We shot a cardiac output with our pulmonary artery catheter and it showed a markedly stunned heart and a completely vasoplegic vascular system.

The anesthesia is challenging. We sent off blood gases every 20 minutes, adjusted our drips, fixed electrolytes, and gave blood products. The patient bled and bled and bled, and we found ourselves spiking bag after bag of blood, plasma, platelets, and cryoprecipitate. Eventually, we were able to achieve hemostasis and as the new liver began to work, we weaned the patient completely off drips. The heart began to squeeze vigorously, and we knew we had weathered the patient through.

Liver Transplant II

Our set-up for a liver transplant is pretty involved and can take me up to an hour. Although we use one of the large cardiac rooms, with all the equipment, it feels pretty crowded. We even have a floor plan to detail where everything goes. After we induce anesthesia and intubate the patient, we still have at least half an hour's worth of preparation. We place multiple lines including a femoral arterial line (believing that especially in cirrhosis, central pressures are more accurate than peripheral pressures). Sometimes, we'll also place a radial arterial line just for blood draws as we can be sending off a lot of blood gases, blood counts, and coagulation samples during the procedure. We then place two large 9 French introducers into the left internal jugular vein. We place a pulmonary artery catheter through one of these introducers. We hook them up to a Level 1 rapid transfuser and a Belmont rapid transfuser. We also have a backup Level 1 in the room in case one of the transfusers fails. Then depending on the surgeon, we may place additional 16 gauge central lines in the femoral and right internal jugular veins which allow the surgeons to rewire into a bypass cannula. We hook up our drips; routinely, I make phenylephrine, epinephrine, vasopressin, and octreotide. Lastly, we place a transesophageal echocardiogram probe. This can be a little tricky as patients often have esophageal varices that can hemorrhage, but the TEE allows us to visualize the cardiac contractility and volume status. By the time all this is done, I'm pretty spent, and we haven't even made incision.

Liver Transplant I

Liver Transplants are complicated for many reasons. Not only is the liver an incredibly vascular organ, but it also filters blood returning from the abdominal organs through the splanchnic circulation. In patients with end-stage cirrhosis, the pressures in the splanchnic circulation is very high as the blood cannot be drained through the scarred liver. This portal hypertension greatly increases the bleeding risk. So how do you replace a liver when you have to detach all the vessels, which are under high pressure, and reattach them to a new liver? During this whole process, the surgeons have to clamp the vessels to work on them. Where do they clamp and how does that affect the body under anesthesia?

In the most standard version, the surgeons will clamp the inferior vena cava, which receives all the blood draining from the liver. However, doing so means that venous drainage from the lower extremities and abdomen ceases since the blood cannot get back to the heart. The patient may tolerate this temporarily, but as time goes on, that venous pooling starts accumulating evil humors, and when the clamps are released, the accumulated toxins flood the body. To ameliorate this, surgeons often do liver transplants with veno-veno bypass. They bypass blood from the femoral and hepatic vessels to the jugular or axillary vein where it can return to the heart by the superior vena cava. This tends to smooth the clinical course when the inferior vena cava clamps come off, but comes with its attendant risks.

When the surgery is this tricky, the anesthesia has to be delicate and careful. The liver transplant is a great example of how complex surgery affects what we do on the other side of the curtain. We have to plan for potential large bleeding if those portal vessels are injured, aid in the preparation for and management of veno-veno bypass, and prepare for arrhythmias, hypotension, hypothermia, and cardiovascular collapse when that all-important inferior vena cava clamp comes off.

Book Review: Snow Crash

I read Neal Stephenson's Snow Crash right after Lexicon and there are some remarkable similarities. It, too, has an undercurrent of neurolinguistics, the idea that words can affect the brain. Set in a very different world, Snow Crash takes place in an amazingly constructed dystopic future that was so much fun to read. Like Ready Player One, characters interact in both a real and virtual world. The characters of this plot driven thriller are captivating, from a teenage heroine who skateboards highways by harpooning trucks to a ninja hacker who researches ancient civilizations to a mafia boss who guarantees 30 minute pizza deliveries. It was one great vacation read.

Image shown under Fair Use, from Wikipedia.

Book Review: Lexicon

Max Barry's Lexicon reminds me of Lev Grossman's The Magicians. Set in more-or-less the modern day in the modern world, it is about a secret fantastical group of people with semi-magical powers involving words. If the idea that words could have real power and influence is interesting, this is the book to read. Action-packed and fast paced, it moves quickly. The writing is easy, not too sophisticated, but appropriate to the novel. I loved the structure of the book which lends itself to liking two very polar characters and puzzling out the intrigue. It's a great light science fiction read which I managed surprisingly between my thoracic and liver calls.

Image shown under Fair Use, from maxbarry.com.

Liver Resection

A man with cholangiocarcinoma - cancer of the gallbladder - presents for a large resection of the liver. The liver is divided into eight segments based on its anatomy and our goal was to remove two-thirds of it. This was going to be a large, potentially bloody surgery because the tumor was fairly close to the inferior vena cava. We planned accordingly, placing an introducer sheath into one of the large neck veins and setting up a rapid transfuser. The surgeons worked carefully; I could see the concentration in their movements as they delicately dissected the cancer from the largest vein in the body. We watched closely, as any errant move could cause massive blood loss requiring clamping of the inferior vena cava. But our surgeons' precise movements allowed them to peel the cancer away, an amazing technical feat of precision. The tension relaxed as the rest of the liver segments were resected, the hepatic vessels clipped, the bile duct system reconstructed, and the lymph nodes sampled. The patient never had problems with low blood pressure or excessive bleeding, we were quite satisfied as we finished the ten hour procedure, removed the breathing tube, and brought him to the recovery unit.

I began another anesthetic when the resident in the recovery unit called me. "I wanted to make sure he was never hypotensive," she said, "because he's dropping him blood pressure right now. The surgeons think he's dry and we're giving him some albumin and fluids." This was an appropriate initial response; we keep patients dehydrated for liver resections because liver congestion can cause a lot of problems, and most patients require rehydration after the operation. But when I checked in again, he was even more hypotensive, requiring pushes of vasopressors to keep his blood pressure in the normal range. His oxygen requirement went up and he was becoming more confused again.

I knew something was very wrong. When I got to the bedside, I called for blood and told the surgeons we needed to go back. There was unresolved bleeding somewhere, even though the drains were empty and the belly was soft. When I drew a blood gas, the blood didn't look like blood; it was too dilute. The only way to find and stop the source of bleeding was to go back in and find the bleeder. We crashed the patient back into the operating room, four anesthesiologists, working seemlessly as a team. We re-induced anesthesia, a tricky but necessary affair for a patient in hemorrhagic shock. We got a rapid transfuser set up and called a massive transfusion protocol, giving a total of eight units of blood, seven units of FFP, and some platelets. Such a resuscitation requires a lot of work, and we were occupied the entire time. But we managed to titrate the pressors off, improve the acidosis, replenish electrolytes, and stabilize the patient. The surgeons found a bleeding arterial vessel whose clip had been dislodged. If we had waited much longer, the patient would have had a cardiac arrest. But we managed to get him to the ICU in stable condition. The problem is that his liver, which has already suffered a large resection, had further injury during the period of low blood pressure. It will be slow to clear the acidosis, make clotting factors, clear waste products, and function again. But we hope that we can tide him through this critical period.

This case taught me that even if a field looks bloodless, an unexpected post-operative course must include unseen and unexpected hemorrhage. Sometimes a re-operation is necessary and sometimes the anesthesiologist who knows the patient's physiology best and identifies that something is direly wrong needs to speak up and make it happen. Access was central here, and the fact that we had an introducer to give blood as fast as a unit a minute saved this patient's life. The case taught me to prioritize and manage a rapidly changing clinical situation. This is what physician anesthesiologists train to do.

Liver Rotation

On a two week liver anesthesia rotation, we get assigned to some of the more complex liver surgeries and take call for all liver transplants that come in. It's a busy two weeks as the weekday surgeries tend to be busy, involved cases and liver transplants are some of the biggest cases we do, requiring a great deal of set-up time and lasting from eight to twelve hours. Patients with liver disease have important relevant medical issues, as well. As the liver produces all the clotting factors, these patients can bleed a lot if they have liver dysfunction or undergo a large resection; this can limit our ability to put in epidural catheters for post-operative pain. Liver disease can cause altered mental status with hepatic encephalopathy, involve the lungs with hepatopulmonary syndrome, and precipitate kidney failure with hepatorenal syndrome. While the heart is usually uninvolved, if patients develop liver disease because of alcohol or drugs, we have to rule out cardiac consequences. We depend a lot on the skill of our surgeons as well since the liver is next to important structures and receives a large blood supply. Bleeding can be brisk and catastrophic, and these cases are one of the few that I request a rapid transfuser such as a Level-1 or Belmont. Nevertheless, at this stage of my training, such cases are exciting, challenging, and educational, and I look forward to it.

1800

This is the 1800th post! Perhaps I've done close to that number of anesthetics, which is a little mindboggling. Reflecting on this reminds of the real privilege of being a physician and an anesthesiologist. Even though things feel a little more routine and straightforward in my third year of anesthesia, I've also developed a real respect for what we do. General anesthesia has become so safe in the last few decades that it is easy to underestimate what it involves. Although we often use the metaphor of "sleep," it's really not a state of sleep. When we induce anesthesia, we render someone unconscious, devoid of their normal physiologic protective reflexes. In doing so, we take responsibility for their body, confident that we can weather them through a surgeon taking a scalpel and traumatizing the patient. With each anesthetic, there is the risk that we cause irreparable, irreversible harm. And each time I induce that state - a state dramatically affecting the patient's neurologic, cardiovascular, and pulmonary systems, I know that I am risking a patient's health with the confidence that my knowledge, skills, and medicine will be enough.

Thoracic

I thoroughly enjoyed my month on thoracic anesthesia. I found the cases challenging and diverse, really pushing my technical skills with lung isolation and thoracic epidural catheters and engaging my medical knowledge with complex and ill patients. I've always enjoyed longer tougher cases than many short simple ones. And in thoracic, there isn't much downtime; the surgery itself affects the anesthetic management intimately and so we are always anticipating and responding. Thoracic anesthesia cases are tiring but very satisfying at the end of the day. In practice, there isn't a huge volume of thoracic surgery so anesthesiologists can choose to eschew it from their practice if they choose. And unfortunately, these skills get rusty if they aren't continually honed. I definitely want to keep thoracic anesthesia in my armamentarium as I start looking into what kind of practice I'd like to eventually join.

Variations in Practice

Talking to one of my surgeon friends in the last post reminded me that there's a wide variation in practice. Some surgeries that are routinely done in an open fashion here are done laparoscopically or robotically elsewhere. We are experts in certain procedures that aren't performed at outside hospitals. From a pre-operative standpoint, we don't routinely check pregnancy tests for women in their childbearing years before surgery whereas it is always performed at other places. Our anesthetics differ as well; in Europe, anesthesiologists use laryngeal mask airways for cases that we would normally intubate. There is a wide variation in how to maintain anesthesia, what post-operative pain management entails, which antiemetics are routine. Even in other specialties, there are many approaches to the same clinical scenario, and much of it is institution, culture, or training based.

This is not to say that one practice is better than another. There are certainly standards and guidelines, but most variation in clinical medicine falls within perfectly acceptable norms. This, then, becomes the art of medicine. We tailor our practice to the strengths of our physicians, the expectations of our patients, the review of complex and often conflicting research data and evidence. We make conscious choices in creating the culture and norm at our institution, then tailor specific decision-making to each individual patient. As a result, patients may get different diagnostic tests or treatments at different places, and we understand this can be distressing, especially if patients think there's one right answer or approach. Unfortunately, such variation in practice comes with the uncertainty, complexity, unknowns, and challenges of clinical medicine.

Ivor-Lewis

One of the bigger cases we have is the Ivor-Lewis esophagectomy for cancers of the lower esophagus. We begin by placing a thoracic epidural for post-operative pain control because the incision is quite large. Then after inducing anesthesia, we place a single lumen endotracheal tube and additional lines and monitors; we always have arterial access, and sometimes opt for central venous access as well. The general surgeons start with an upper endoscopy to look at the esophageal cancer and then perform a large abdominal laparotomy to mobilize the stomach and nearby structures. After they are done, we switch out the single lumen endotracheal tube to a double lumen tube. The thoracic surgeons then cut open the chest cavity. After resecting the cancer, they have to take the stomach, freed from its moorings, and pull it up into the chest to reform the gastrointestinal tract. Because all of this happens deep within the chest, we have to deflate a lung to give the surgeons space to work. They are quite close to critical vascular and nerve structures, making it a high risk surgery. The challenges for the anesthestic management include balancing fluid goals. An open abdomen and chest causes an enormous loss of insensible evaporation, but we try to keep patients dry in thoracic surgery because wet lungs can be hard to manage. Post-operative pain control is tricky because the incision extends all the way from the ribcage down to the bellybutton; a well-placed epidural will catch the area, but a poorly placed one will be patchy. Nevertheless, for some patients, this surgery is worth it if it means that the cancer is cured.

Watching the Surgery

One of the fun and unique privileges of being an anesthesiologist is being able to watch the surgery. Because we work with many surgeons in different fields, we get to see everything, from lithotripsy of a kidney stone to a hip replacement to delivery of a baby by C-section to biopsy of a brain tumor. In some procedures, I can't really follow what the surgeons are doing; despite watching multiple sinus surgeries, I'm never sure where we are. But many times it is imperative that we follow what the surgeons are doing. In my thoracic rotation, for example, I follow the manipulation of the lung carefully. Not only is it fascinating to see an organ so central to anesthesia practice, but what they are doing matters. When the surgeons are close to large blood vessels, I make sure they don't injure any of them, and if they do, I am ready to respond to a rapid massive blood loss. When the surgeons enter the thoracic cavity, I watch to make sure the lung is isolated and deflated so they don't accidentally injure it. When they are finishing the lung surgery, I watch as I inflate the lung to make sure that everything inflates appropriately. The same principles applied when I was on my cardiac anesthesia rotation where manipulation of the heart and great vessels had many direct anesthetic implications.

LD50

The LD50 is a pharmacokinetic term that describes the lethal dose of a drug for 50% of the study population. We talk about similar concepts all the time in anesthesia (for example, the dose of a drug for 50% of patients to fall asleep) so I loved this comic.

Image is from xkcd, drawn by Randall Munroe, shown under Creative Commons Attribution License.

Why I Put IVs in the Hands

This great observation shown under Fair Use, from http://thisisindexed.com/. I've learned over the years not to catch too much arm-hair when putting the tourniquet on and to go for hairless real-estate when taping IVs in place.

Living Related Kidney Transplants II

Equally important is the psychological aspect of living related kidney transplants. Donors and recipients meet with social workers not only to examine their social support structures, but also to assess the psychological impact of such an operation. What is it like to ask a sibling to risk her life (albeit an extremely small risk) and give up an organ for you? Does living with a chronic disease (often since childhood) change someone's coping abilities and interdependence on others? What is the power dynamic like if one sibling has always been healthy and the other always sick? How will the relationship change after the transplant? Even if one has the best intentions and true altruism, what is it like to go through an operation and its attendant pain, discomfort, rehabilitation, and complications purely for someone else's health? What if the sibling, other family members, or friends put pressure on the donor to undergo the procedure? These questions can get pretty complex, and I think understanding them is essential to keeping living related transplants ethical.