Overview of Anesthesia for Transplant Surgery
According to the Organ Procurement and Transplantation Network registry, as of May 19, 2021, there are 107,485 people waiting for an organ transplant. The United Network for Organ Sharing, a non-profit group, works with local organizations to help find the best match between organ donors and patients who need transplants.
Given the high number of people on the waiting list, it’s very important for patients in need of a transplant to get registered as soon as possible. The medical team then assesses and helps improve the patient’s health condition while they wait. This way, when a suitable organ becomes available, the patient is ready to undergo the transplant surgery.
Why do People Need Anesthesia for Transplant Surgery
An organ transplant is usually required when an organ has completely failed or can no longer work effectively. This might be due to a disease affecting the organ itself or an illness that affects the entire body. While a patient waits for an organ transplant, they might undergo certain treatments to keep the organ functioning as effectively as possible.
For a kidney transplant, a patient will become suitable to receive a new organ when their kidney function, assessed by “glomerular filtration rate,” falls below a certain level. Glomerular filtration rate (GFR) measures how well the kidneys are cleaning the blood. Several conditions can cause kidney failure, including diseases affecting the kidney structure, genetic diseases, blood vessel diseases, cancer, or diabetes.
When it comes to kidney transplants from living donors, these can happen even before the patient reaches the worst stage of kidney disease (known as “end-stage renal disease” or ESRD), and might not have started treatment with dialysis (a machine that helps do the kidneys’ job when they can’t). Getting a kidney from a living donor offers the best outcomes for the patient.
A pancreas transplant might be needed if a patient has type 1 or 2 diabetes, chronic pancreatitis (a long-term inflammation), pancreatic cancer, or a previous failed transplant of the pancreas. This transplant can be performed alone or together with a kidney transplant.
A liver transplant is typically required when someone has severe liver disease or liver failure. Liver disease can be due to many factors such as alcohol abuse, viral hepatitis, or various metabolic disorders the body that cause damage to the liver. Depending on the severity of the disease, tumors and acute liver damage due to drug toxicity are other reasons for liver transplantation.
To determine who gets a liver transplant, a score called MELD (model for end-stage liver disease) score is used. This score prioritizes transplant based on how severely ill patients are. The higher the MELD score, the more urgent the need for transplant. There are a few exceptions to this scoring system, including liver cancer, a certain type of lung disease related to liver disease, a genetic disorder, and acute liver failure. For liver cancer, other criteria are used such as the size and number of tumors.
When a Person Should Avoid Anesthesia for Transplant Surgery
There are a few key reasons why someone may not be able to get an organ transplant:
1. If they currently have an infection,
2. If they have an active cancer,
3. If they are presently abusing drugs,
4. If their organ failure could potentially be reversed,
5. If they have a mental health condition that can’t be controlled,
6. If they’re not following treatment plans properly,
7. Or if they have a serious, overall health condition that could lead to poor outcomes with the new organ or a risk to their life.
Before getting an organ transplant, the patient should first receive treatment for any existing infection or cancer.
For the organ transplant to be successful, it is crucial that the patient continues with regular check-ins with their transplant team, pays consistent visits to the clinic, does regular blood tests, and takes their transplant medicines as instructed.
Therefore, only patients who are most likely to follow these instructions and benefit from an organ transplant should be chosen for this treatment.
Equipment used for Anesthesia for Transplant Surgery
When a patient is undergoing surgery, anesthesiologists use a set of standard tools to monitor their health. This includes a 5-lead electrocardiogram to monitor heart activity, a pulse oximeter to measure oxygen levels in the blood, non-invasive blood pressure monitoring, and temperature checks. Additionally, there may be other monitoring devices used depending on the type of surgery being performed.
Surgeries such as transplants can lead to major changes in blood flow (called hemodynamic variations), so constant monitoring is crucial. For instance, for patients getting a liver transplant, invasive arterial blood pressure monitoring is used to show real-time blood pressure readings.
The stroke volume variation and pulse pressure variation are key metrics used to help gauge the patient’s fluid balance. Based on the hospital’s procedures, the patient may have one or two arterial lines inserted (in the wrist and either the arm or leg). A central line is also put in to monitor central venous pressure, a crucial metric reflecting the amount of blood returning to the heart. It also allows for easy administration of medications like vasopressors and inotropes that help regulate blood pressure and heart function.
In some cases, when a patient has severe lung-related conditions, a pulmonary artery catheter may be used for monitoring pulmonary blood pressure. Also, a special imaging test called a transesophageal echocardiogram (TEE) might be used during liver transplant operations. This helps monitor the heart’s functioning, gives an understanding of the patient’s fluid balance, helps detect cardiac clots early, and assists with the placement of the PA catheter. However, this isn’t used in patients with severe esophageal varices, a condition involving enlarged veins in the esophagus.
During the surgery, surgeons often take advantage of an arterial blood gas analysis and thromboelastographic studies (TEG). The former provides essential insights into the patient’s acid-base balance and electrolyte levels, while TEG studies help understand blood clotting and identify possible deficiencies. This helps guide the doctors in treatment decisions. Monitoring of muscle relaxants is also done through a method called train-of-four studies. This assists with the safe removal of breathing tubes after surgery, which is crucial in transplants where organ function is suppressed, making drug metabolism slower.
Lastly, the anesthesiologist uses a tool called the bispectral index to help prevent awareness during anesthesia and adjust medication dosages. They also monitor the oxygen saturation in the jugular vein to measure brain blood flow and oxygen use, particularly during phases of liver transplantation known as the anhepatic and neohepatic phases, where there are significant changes in cardiac output which can adversely affect blood flow to the brain.
Preparing for Anesthesia for Transplant Surgery
When someone is considered for organ transplant, a thorough health check-up is immediately conducted to ensure the person is a good match for the transplant and to reduce any chances of complications during or after the procedure. Part of these check-ups includes testing for illnesses like cancer, infectious diseases, and other viral conditions such as HIV, hepatitis, Epstein-Barr virus, and cytomegalovirus. Health conditions like heart disease, blockages in the arteries, and stroke are also taken into account.
Doctors also check for allergies, past organ transplants, blood transfusions, and pregnancies, which help them decide the amount of antibodies (proteins that help the body fight off harmful substances like bacteria and viruses) in the person’s body. This information is crucial to guide the immunosuppression treatment, which is medication given to prevent the body’s immune system from rejecting the new organ. The occurrence of a rabbit allergy is particularly important since one of the treatments is made from rabbit blood.
In some cases, when the patient needs a medical procedure to improve their heart’s blood flow, a team of different sorts of doctors work together to decide the best time and method for this procedure. For instance, treatments like balloon angioplasty (a procedure that widens blocked or narrow arteries) and stenting (inserting a small tube into an artery to keep it open) involve a certain regimen (schedule) of drug treatment that helps prevent blood clots. Patients with lung diseases that are hard to control should not have an organ transplant.
Younger patients who need a pancreas transplant might be at a higher risk of getting complications relating to blood vessels since such patients usually have diabetes.
Even after being deemed suitable for a transplant, the doctors will still do a thorough examination, especially focusing on the patient’s airways, before the surgery takes place. They will also ask about any history of bleeding or blood clotting issues, past anesthetics given, any previous issues with anesthetics, and a family history of anesthetics. Doctors will also inquire about any drug allergies to avoid potential reactions during the operation.
Also, if a patient has a medical device like a pacemaker or defibrillator implanted in their body, it needs to be checked by a device company representative before the surgery.
On the day of the transplant surgery itself, several tests are conducted. These include a complete blood count, a metabolic panel (a blood test that checks for different substances in your blood), a coagulation panel to check how well your blood clots, an echocardiogram (a procedure that lets your doctor see the size and shape of your heart), chest X-ray, COVID testing, and a thorough examination of the airways. All these steps ensure that the operation goes as smoothly as possible and helps reduce any chance of complications.
How is Anesthesia for Transplant Surgery performed
In general, doctors will administer antibiotics and immunosuppressants, which lower body’s ability to reject a transplant, based on individual care plan on the surgery day. The surgeon will also prepare the organ from the donor for implantation.
Kidney Transplant
If the patient is dependent on dialysis (a process to clean the blood when kidneys can’t), it needs to be managed properly. Previously, patients were kept away from dialysis for 24 hours prior to the transplant to lower the amount of heparin (a blood-thinning medication) in their system. But now, with enhanced medical protocols and testing, this is no longer necessary.
During surgery, the patient’s body temperature is maintained and secured. Various medications are used to keep the patient unconscious (induction) and muscles relaxed to allow the operation to take place smoothly. Certain medications that could harm the kidneys are avoided, as they can accumulate and cause complications. Generally, a combination of oxygen and air, or oxygen and nitrous oxide are used along with an inhaled anesthetic during surgery.
Maintaining the right amount of fluid in the patient’s body before, during, and after the surgery is crucial. Too much or too little fluid can cause complications. The aim is to ensure a good blood flow to the new kidney as it does not have the in-built capacity to adjust its blood flow.
Before surgery, the patient is given medications like Mycophenolate and methyl-prednisolone that reduce the chances of the body rejecting the new organ.
Pancreatic Transplant
For a pancreatic transplant, patients with diabetes need a thorough check of their airway as they may have an increased risk of stiffness in the neck joint. The surgical procedure is conducted under general anesthesia and requires careful dispensation of medications and monitoring of blood glucose levels – particularly since the transplanted pancreas starts working within minutes of the operation.
Liver Transplant
During a liver transplant, medications are carefully selected and administered as the liver plays a key role in metabolizing drugs. Some medications might negatively affect blood flow to the liver, which is not desirable during a transplant. Similar to other transplants, right amount of fluids are administered. The need for medications to maintain or elevate the blood pressure levels should be anticipated, especially after the re-establishment of the blood flow to the transplanted liver. Medications like Albumin could be used to manage the patient’s volume status, as it is often decreased in end-stage liver disease. This way, the risk of complications after a liver transplant can be reduced.
Possible Complications of Anesthesia for Transplant Surgery
During organ transplant procedures, there can be some complications. These issues could be caused by various factors including the anaesthetic drugs used during surgery, the body’s lowered immune response, issues with the transplanted organ itself, imbalances in the levels of acids, bases, and electrolytes in the body, problems with blood clotting, and loss of blood. Each of these problems might come up differently depending on the type of organ being transplanted.
What Else Should I Know About Anesthesia for Transplant Surgery?
Transplant surgeries like those for the kidney, pancreas, and liver can be highly complex, presenting a unique set of challenges before, during, and after the operation. By carefully preparing beforehand and being ready for any unexpected issues that may arise during the surgery, we can significantly improve the chances of success in these intricate procedures.
