Overview of Perioperative Management of Pheochromocytoma
Pheochromocytoma, also known as PCC, is a rare type of tumor that comes from a certain kind of tissue in your body called chromaffin tissue. This type of tissue produces a type of hormone known as catecholamines. The name “pheochromocytoma” comes from the Greek words for “dusky color tumor,” because these tumors turn a certain color when exposed to a type of salt.
PCC is not common, but it is diagnosed in 1 or 2 out of every 1,000 people each year. It is also responsible for causing high blood pressure in 1 out of every 500 adults. Most people are diagnosed with PCC in their 40s or 50s, and it affects men and women equally. However, if PCC is passed down in families (hereditary), it tends to show up at a younger age.
Anatomy and Physiology of Perioperative Management of Pheochromocytoma
The chromaffin tissue in our bodies contains cells that produce and store certain hormones, namely norepinephrine and epinephrine. Some tumors can also produce another hormone called dopamine. Pheochromocytoma, or PCC for short, is a type of tumor that causes these cells to produce an excessive amount of these hormones. This leads to various symptoms.
Normally, the adrenal medulla, a part of our body near the kidneys, secretes about 85% epinephrine and 15% norepinephrine, but in cases of PCC, norepinephrine is the primary hormone being produced.
Most PCC tumors are found in the adrenal gland and are solitary, meaning there’s usually just one. There’s an old saying in medicine that “10% of pheochromocytomas are familial (inherited), 10% are malignant (cancerous), 10% are extra-adrenal (located outside of the adrenal gland), and 10% are in children.” However, it’s a bit outdated and oversimplified. In fact, up to 20% of these tumors can be found outside the adrenal gland and about 20 to 30% are inherited.
The inherited forms of PCC are often associated with other conditions, including multiple endocrine neoplasias type 2A and 2B, neurofibromatosis (also known as Von Recklinghausen disease), and Von Hippel-Lindau syndrome.
Why do People Need Perioperative Management of Pheochromocytoma
Pheochromocytoma, often referred to as PCC, is a rare condition that mostly causes headaches, excessive sweating, and fast heart rate. PCC is a result of a tumor in the adrenal glands, which are small organs sitting on top of your kidneys, that overproduces adrenaline and noradrenaline hormones. This condition can also lead to high blood pressure, however, in some cases (10-20%), patients might have a normal blood pressure. When these hormones are in excess, they can cause your blood pressure to rise, contributing either to consistent or occasional hypertension.
It’s also possible for approximately 10 to 20% of PCC patients to not show clear symptoms, thus sometimes the tumor is discovered unintentionally during medical examinations for other health issues. Frequency of this condition in people with hypertension is less than 0.2%. Some PCC patients may also experience high blood sugar, increased urination and thirst, shaking, low blood pressure on standing up, blurry vision, and weight loss.
If a doctor suspects PCC based on these symptoms, they then confirm it by conducting tests to measure the levels of adrenaline, noradrenaline, and their byproducts, either in the urine or blood. The most reliable way to diagnose PCC is to analyze the levels of certain substances (metanephrines and catecholamines) in a urine sample collected over 24 hours. However, if it’s hard to collect a full day’s urine sample, especially in children, or there is a strong suspicion of a PCC, the doctor may choose to test a blood sample instead.
If the results from this test are positive, an imaging test such as a computed tomography (CT) scan or magnetic resonance imaging (MRI) may be done to confirm the presence of a tumor and find out its location. MRI and CT scans are commonly used because they are widely available. While MRI involves no radiation, takes a bit more time, and is more expensive, it is better in differentiating PCC from other adrenal gland masses. A variant of the CT scan that uses a radioactive compound (iodine 131-labelled meta-iodobenzylguanidine or MIBG) is also highly accurate for diagnosing and locating the tumor.
Previously, a test involving a substance called glucagon was used to confirm or exclude PCC, but it’s no longer favored because it is not consistently reliable and it could lead to severe high blood pressure. Some doctors also use specialized tests like clonidine or phentolamine suppression tests for diagnosis. Clonidine is a medication that stops the release of these hormones, but it does not affect the hormones released by PCC.
Preparing for Perioperative Management of Pheochromocytoma
Before going into the operating room for pheochromocytoma treatment (a rare tumor that usually starts in the cells of one of the adrenal glands), several steps are taken to make sure a patient is in the best possible health. This preparation lowers the chances of complications during and after the procedure. Doctors use a checklist called the Roizen criteria to confirm everything is good to go. The Roizen criteria includes:
* Your blood pressure hasn’t gone over 160/90 mmHg in the last 24 hours.
* You don’t have orthostatic hypotension, meaning your blood pressure hasn’t dropped to less than 80/45 mmHg when you stand up.
* There have been no changes in your heart’s EKG patterns for a week leading up to the surgery.
* Your heart hasn’t experienced more than five premature ventricular contractions (extra, abnormal heartbeats) per minute.
This checklist helps ensure that your blood pressure and heart rhythms are stable before the surgery because pheochromocytoma can make them erratic.
Hormones called catecholamines, especially one called noradrenaline, can make blood vessels squeeze down or constrict, which can lead to dangerously high blood pressure. So if you have pheochromocytoma, you’ll typically be given a medication that blocks these hormones’ effect, starting about 10 to 14 days before your surgery. The goal is to stabilize your blood pressure and your body’s fluid balance. The most common medication used for this purpose is phenoxybenzamine.
These “blocker” medications ease the tension in your blood vessels, but they can occasionally cause side effects like low blood pressure when you stand up (orthostatic hypotension) and an abnormally high heart rate (tachycardia). Still, these side effects are usually less common with the newer, more selective blockers.
It’s good to know that doctors will always make sure you’re on an alpha blocker before starting a beta blocker. If they did it the other way around, the alpha blocker wouldn’t work properly, and your blood pressure could get dangerously high.
There’s another medicine, alpha-methyl-para-tyrosine (metyrosine), that can help by slowing down the production of the hormones the tumor causes. This is particularly useful if the tumor can’t be removed entirely.
To round up the preparation, an experienced anesthetist will assess your cardiovascular health to make sure your heart can cope with the stress of surgery. They’ll also check on how well the blockers are working, whether you’re well-hydrated and consider any other health problems you might have.
How is Perioperative Management of Pheochromocytoma performed
When we talk about the surgical approach to treat pheochromocytoma, a tumor of the adrenal glands near your kidneys, there are generally two main strategies. Most commonly, specialists will use a minimally-invasive procedure. This technique can either gain access to the tumor from the back (retroperitoneal) or through the abdomen (transperitoneal). Minimally-invasive surgery is often chosen because patients usually experience less pain after surgery, recover quicker, and face less risk of blood clots. They also generally spend less time in the hospital, which makes the treatment cost-effective. However, in some cases, where the tumor is too large or not located in the adrenal glands, traditional open surgery might be necessary.
Regarding anesthesia preparation, patients are usually given an anti-anxiety medicine, like midazolam. It’s crucial to monitor the patient’s blood pressure during surgery, as potential changes could happen when anesthesia is induced. Therefore, an arterial line, a special kind of IV reserved for intensive care and surgeries, is used. There are various ways to use anesthesia. It can either be applied through breathing (general anesthesia) or injected near the nerves in your back (epidural anesthesia). This latter type is often considered if open surgery is scheduled as it gives better pain control after surgery. It’s important to have two IV lines for fluids and drugs. Special heart-monitoring methods like transesophageal echocardiogram (a type of ultrasound) or a pulmonary artery catheter (a device that measures pressures in the heart) may be used in patients with severe heart disease.
During and after surgery, managing your blood pressure and heart function is crucial, as manipulation of the tumor and the effects of medication can cause sudden changes. To ensure everything goes smoothly, anesthesiologists use various medications, like vasodilators (drugs that widen blood vessels) to control sudden increases in blood pressure. They may also use medications to control your heart rate. After the tumor’s main blood source is tied off, your blood pressure may drop suddenly. In this case, fluids and medications to constrict your blood vessels could be used. Depending on how stable the patient’s condition is after surgery, they may be either transferred back to the regular surgical unit to recover or taken to the intensive care unit for closer monitoring.
Possible Complications of Perioperative Management of Pheochromocytoma
After a tumor is removed, some people might experience low blood pressure. This can be caused by several factors such as changes in the body’s response to certain hormones, decrease in blood volume, or the lasting effects of powerful blood pressure medications like phenoxybenzamine. About half of the patients may have high blood pressure for several days after the tumor is removed.
Levels of norepinephrine, a hormone that helps regulate blood pressure, may not get back to normal for a few days after the surgery. High blood pressure can also indicate that some of the tumor might still be in the body. Low blood sugar is another potential issue after surgery; it’s important to check blood sugar levels regularly every 4 to 6 hours. This is because the sudden drop in the hormone catecholamine after removing the tumor can cause insulin, a hormone that regulates blood sugar, to suddenly increase.
What Else Should I Know About Perioperative Management of Pheochromocytoma?
Surgery to remove the tumor, known as surgical resection, is the best treatment for pheochromocytoma (PCC) – a rare, usually noncancerous tumor that grows in an adrenal gland. This is a successful treatment in over 90% of cases. However, it can be a very complex procedure for doctors due to the damage that this disease can cause to other organs and the sudden changes in catecholamines (a group of hormones) levels, which can affect your heart rate and blood pressure.
Because of these risks, patients must undergo thorough pre-surgery preparation to enhance safety during the operation and recovery. This involves a team of different medical specialists including a doctor who specializes in anesthesia, a surgeon, and an expert in hormone-related diseases, or an endocrinologist. They work together to assess the extent of damage caused to other organs by changes in the catecholamine levels. For instance, these hormones can affect the heart, leading to abnormal rhythms, reduced heart-pumping efficiency, and even heart disease.
To ensure safe surgery, medication to control blood pressure and balance the amount of blood in your blood vessels are generally given beforehand. Furthermore, the surgical approach can cause changes in your heart rate and blood pressure. Anesthesia, which puts you to sleep during surgery, is required for this procedure and needs to be given carefully. The depth of anesthesia (how asleep you are) must be smoothly managed to keep you comfortable and safe.
To ensure that any changes in your blood pressure can be detected and managed effectively, a small tube (arterial line) is inserted into one of your arteries before you are put to sleep, to constantly monitor the blood pressure.
Sudden changes in blood pressure are the most common complication during surgery. Blood pressure can usually rise during the start of the surgery and can drop after the tumor is removed. Therefore, clear communication between the anesthetist and the surgeon is crucial in order for them to anticipate and tackle any sudden changes in your heart rate or blood pressure during the surgery.