Overview of Sonography Endobronchial Assessment, Protocols, and Interpretation
Endobronchial ultrasound (EBUS) is a high-level technique which makes use of a special ultrasound machine attached to a fiber optic camera, often called a bronchoscope. This is used for looking at and collecting samples from lymph nodes (part of the body’s immune system) close to the bronchial tubes (airways), around the hilum (part of the lungs where various structures like blood vessels enter and leave), and around the anterosuperior mediastinum (the front upper part of the space in the chest between the lungs). It also allows for observation and collection of samples from both masses located inside the bronchial tubes and those closely surrounding them.
The endobronchial ultrasound scope can provide live ultrasound guidance to a needle, which is especially helpful during biopsy procedures. Newer types of scopes, for instance the radial-EBUS, give a full 360-degree view, allowing for a more thorough examination of the peripheral parts of the bronchial tubes.
Since its development in the 1990s, the EBUS technique has become widely used over the past two decades. Specifically, the use of an EBUS with transbronchial needle aspiration (EBUS-TBNA), essentially using a needle to collect tissue samples via the bronchoscope, has become the best standard method for both determining the stage of non-small cell lung cancer and diagnosing mediastinal lymphadenopathy (a condition where the lymph nodes in the mediastinum become enlarged).
EBUS technologies are also increasingly being used to guide less invasive therapeutic procedures involving the bronchial tubes. Compared to other techniques such as mediastinoscopy (a surgical procedure that allows for the look around the mediastinal area), video-assisted thoracic surgery (VATS), and traditional open chest surgery, EBUS is minimally invasive. This means it involves smaller incisions and often leads to less pain and a quicker recovery. Plus, it has favorable results with less complications, and has high sensitivity and specificity, meaning it is very good at detecting diseases and avoiding false positives.
Anatomy and Physiology of Sonography Endobronchial Assessment, Protocols, and Interpretation
The EBUS method involves passing a scope through the mouth and upper throat. This allows it to pass through voice box to reach the windpipe (trachea). The carina, which is a structure inside the windpipe where it splits into two, and the bronchial tree, which are the air passages inside the lungs, are visualized via a fibreoptic bronchoscope.
It’s important for the operators to know the thoracic (chest) and mediastinal (area between the lungs) anatomy properly to safely locate and sample areas in this region. The anatomical stations or nodes, numbered from 1 to 14, are identified based on their position as defined by the International Association for the Study of Lung Cancer (IASLC). Each node is denoted either as ‘L’ for left or ‘R’ for right depending on which side of the body it’s on.
The EBUS technique can access certain nodal stations like the upper part of the windpipe (upper paratracheal), the area behind the trachea (retrotracheal), the lower part of the windpipe (lower paratracheal), subcarinal (below the point where the trachea splits into two), and the areas between the lobes of the lung (interlobar and hilar). But not all nodal stations can be accessed like this. Some other methods such as ultrasound fine-needle aspiration or endoscopic ultrasound are used for certain stations.
EBUS is often used to diagnose and stage lung cancer to help guide the nodal staging in combination with a type of imaging test called PET-CT. By looking at the nodal stations involved and their position, the EBUS technique can help identify the stage of lung cancer as described in IASLC’s 8 TNM staging document.
Some specific landmarks can be identified using the ultrasound tool. These include the aorta (the main blood vessel), pulmonary arteries (blood vessels in the lung), aortopulmonary window (space located between these arteries), and lymph nodes (small glands that filter lymph, the fluid that circulates through the lymphatic system). These identified areas are compared with endobronchial landmarks, which include the trachealis muscle and carina.
A side-viewing ultrasound probe is used to help in sampling. This provides a view across the layers of the bronchial wall and into the surrounding space as well as the mediastinum.
Why do People Need Sonography Endobronchial Assessment, Protocols, and Interpretation
EBUS, short for endobronchial ultrasound, is a procedure used in several situations, including:
- When it’s used as the primary test for diagnosing and evaluating the extent of lung cancer. This variation known as EBUS-TBNA is where a needle passes through a bronchoscope to collect cell samples from the lungs.
- When doctors need to figure out the cause of enlarged lymph nodes located in the middle of the chest (this condition is often a disease known as sarcoidosis but can occasionally be other inflammatory lung diseases, including a form of tuberculosis that affects the lymph nodes. The ability of EBUS-TBNA to detect these conditions depends on several factors, and this can vary quite a bit, especially depending on the doctor’s expertise.
In the United States, it’s recommended to use EBUS-TBNA as the first step for diagnosing a type of cancer called lymphoma, although this practice isn’t globally adopted or currently recommended in the United Kingdom. Also, EBUS can assist other methods for treating primary lung cancer, especially those aimed at relieving symptoms. These methods include applying heat or cold to reduce the tumor size, placing bronchial stents to keep the airways open, and guiding particularly targeted radiation treatment.
Another version of EBUS, known as Radial EBUS, helps in diagnosing disease processes located on the periphery of the lung fields. It uses a 360-degree probe to accomplish this, but unlike EBUS-TBNA, this form can’t show real-time visualization of the tissue-sampling needle.
Doctors experienced in performing EBUS should select patients for this procedure, keeping in mind the patient’s medical history and other relevant factors. Images from a computed tomography (CT) scan or a PET-CT scan can significantly assist in this decision-making process, as it can indicate whether alternate diagnostic tests might be more appropriate. Alternatives may include different kinds of needle aspiration, ultrasound, procedures to inspect the chest cavity, or a minimally invasive surgical procedure known as VATS.
When a Person Should Avoid Sonography Endobronchial Assessment, Protocols, and Interpretation
This test might not be suitable for everyone as it can sometimes cause complications. The doctor performing the procedure needs to consider each patient individually, taking into account their overall health, other health conditions, and ability to withstand an invasive procedure. The test can be risky for people with specific health problems. By carefully selecting patients for the test, we can reduce the risk of complications and improve the outcomes for our patients.
Things that can make this test unsuitable include:
- If you’ve had a heart attack in the last four weeks. If you already have severe heart disease, you might need to talk to a heart specialist first.
- If you have issues with your general physical conditions like low oxygen levels, low blood pressure, a fast or slow heartbeat. The test involves introduction of a scope and medications that can sometimes make these issues worse.
- If you have a condition that affects your ability to stop bleeding, i.e., coagulopathy or bleeding diathesis. The accepted parameters for this can be a bit variable, but usually a certain blood test (international normalized ratio) being less than 1.5 or a platelet count (blood cells that help stop bleeding) of more than 50,000 per ml is considered safe.
- If you can’t give informed consent, are allergic to anesthetics, or have dental or spinal issues that prevent safe passage of the scope.
The doctor will consider these factors before deciding to perform the test.
Equipment used for Sonography Endobronchial Assessment, Protocols, and Interpretation
The tools needed to conduct convex EBUS (a procedure to examine the lungs) and EBUS-TBNA (a specific type of biopsy procedure using a bronchoscope – a thin, lighted tube passed through the mouth or nose and into the lungs) are listed below:
- A mouth guard: This is used to protect your teeth and keep the bronchoscope stable in your mouth.
- Oxygen delivery system: This can be supplied through a nasal tube or mask. Equipment to measure blood oxygen levels and blood pressure is also used.
- Fibreoptic bronchoscope: This piece of equipment comes with a light and is used to get a detailed look at your bronchial tubes, which are the passages that allow air in and out of your lungs. This is usually done before the EBUS procedure.
- Topical anesthesia: A local numbing medicine is sprayed on the throat area and injected through the bronchoscope to numb the vocal cords, windpipe, and main airways in your lungs. The laughing gas ‘1% lidocaine’ is commonly used.
The EBUS instrument (also known as Convex Endobronchial Ultrasound Scope) is a special type of bronchoscope that has a small ultrasound equipment on the side. The ultrasound on this scope produces images that are about 35 degrees off from the direction the scope is pointing, making it easier to see the areas being examined. This scope is usually bigger than a standard bronchoscope and is connected to a system that powers the light, displays images, and stores the images for future reference. A special balloon is attached to the ultrasound portion of the scope and is inflated to better fit against the bronchial wall, improving the quality of the images. This balloon is inflated with sterile water during the procedure.
The EBUS-TBNA sampling system is another part of the procedure. This system uses a thin needle to collect tissue samples for testing. The needle size varies, typically between 19-22G. It’s helpful to have a wall suction unit to help clear any secretions and make the patient more comfortable during the procedure. The suction syringe is used to collect the sample material. Often, staff will quickly prepare and examine the sample under a microscope on-site to ensure they’ve collected enough material for testing. The necessary equipment for slide preparation and staining, sample containers, slides, and transport solutions, including something called RPMI solution, is also needed.
Who is needed to perform Sonography Endobronchial Assessment, Protocols, and Interpretation?
The EBUS, which stands for Endobronchial Ultrasound, is a specialized procedure done by one or two doctors who are experts in lung diseases. These doctors have been trained in advanced lung procedures and regularly do EBUS. Some countries provide special training and competency checks for these doctors.
Nurses will be there during the procedure to help keep you comfortable. They will also provide a mild sedation, help with technical aspects, and ensure that everything goes smoothly. Afterward, they will also care for you in a recovery area. Sometimes, an additional procedure called ROSE (Rapid On-Site Evaluation) of EBUS-TBNA (Transbronchial Needle Aspiration) is done, for which a specially trained laboratory staff will be present.
If the EBUS is done under general anesthesia, which means you’ll be completely asleep, there will be trained anesthesia staff on hand. These professionals are responsible for administering the anesthesia that keeps you comfortable during the procedure and for providing any support you might need for your breathing.
Preparing for Sonography Endobronchial Assessment, Protocols, and Interpretation
Before starting the EBUS (Endobronchial Ultrasound), a procedure used to diagnose lung diseases, it’s essential to provide the patient with all necessary information. This includes the possible risks and benefits of the procedure, which helps the patient make an informed decision. It’s crucial to make sure the patient isn’t allergic to any of the medications that may be used during the procedure, and that the patient’s blood clotting function is normal.
The patient’s vital signs, like blood pressure, heart rate, and the amount of oxygen in the blood, need to be checked. Also, a suitable vein should be identified and prepared for an intravenous line (or IV) that may be needed during or after the procedure.
Before the procedure can start, there’s a ‘sign-in’ process where all equipment is double-checked, the medical team introduces themselves to the patient, and everything about the patient’s health is confirmed. This is all done to make sure that the procedure will be safe to proceed. This sign-in process follows the World Health Organisation’s surgical safety checklist.
The last step before the procedure begins is giving the patient something called ‘conscious sedation’. This is a type of anesthesia which makes the patient relaxed and drowsy but still awake. The exact type and amount of sedation can vary depending on where the procedure is done. After all these steps, the procedure can begin.
How is Sonography Endobronchial Assessment, Protocols, and Interpretation performed
When your doctor needs to get a close look at your lungs, they might use a procedure called endobronchial ultrasound (EBUS). Here’s a simplified description of how the procedure is usually done.
First, they may use a special device called a fiberoptic bronchoscope to look at your bronchial tree, the part of your airway in your lungs. This also lets them deliver a local anesthetic to numb key parts of your airway, including your vocal cords, trachea (windpipe), and main branches of your bronchial tree. After that, they’re ready to introduce the EBUS scope – a special tool that uses sound waves to create images of your lungs.
The EBUS scope is usually larger than the bronchoscope so it has to be passed through your mouth. Once the device is in and they’ve seen your vocal cords, they navigate the scope to the specific area they want to study. They decided where to look based on images they took before the procedure.
Depending how they’re going to use this procedure, what they look for might change. If it’s for diagnosis, they’ll look at the node (or small tissue sample) that will most likely test positive. If the procedure is to help provide a complete picture of a certain disease (or staging), they will look at each nodal station – different locations in your lungs, and then focus on the location that could give the most serious diagnosis.
They often use the images from the ultrasound, along with familiar structures in the lungs, to help guide them. So that the ultrasound can give a clearer image, they inflate a balloon to make closer contact with the inner wall of the bronchial tubes.
Once they’ve located the right nodes, they get ready to take a sample in a process known as EBUS-TBNA. A sampling needle is attached to the scope and then guided to the right place in your lung tissue. This is done using live ultrasound images. The needle collects the sample by agitating the node, and then suction is used to collect the tissue. Usually, they’ll need to do this three times to ensure a good sample. These samples are then placed on a slide and sent off to be examined by scientists in a lab.
After they’ve got the samples, the EBUS scope is removed and they check all the samples are correctly labelled and ready to be sent to the lab.
Possible Complications of Sonography Endobronchial Assessment, Protocols, and Interpretation
The endobronchial ultrasound (EBUS) is a very safe procedure with very low risk, similar to a fibreoptic bronchoscopy. The most common side effects reported include cough, fever, shortness of breath, complications from anesthesia, and lung infection. Major complications from EBUS are rare.
Most difficulties occur during the EBUS-TBNA (transbronchial needle aspiration—a method of sampling tissue), including minor bleeding, collapsed lung, small tears in the airway, inflammation of the lining of the heart, and mediastinitis (infection of the chest cavity). Minor bleeding is typical, but significant bleeding can occur if a large blood vessel is hit. This is exceptionally uncommon, but if it happens, immediate emergency measures are taken.
In such serious situations, the medical team may insert the scope deeper and inflate a balloon to stop the bleeding. The patient would be moved to a side and ice-cold saline and adrenaline would be applied to the bleeding spot. In some cases, advanced procedures such as bronchial artery embolization (closing off the bleeding vessel) or surgery may be needed.
Studies suggest that the likelihood of complications from EBUS-TBNA are lower compared to taking a lung biopsy through the bronchi. The overall complication rate is less than 1% for EBUS-TBNA. Even when complications do happen, they usually don’t require additional treatments.
Before the procedure, the healthcare team will obtain consent from the patient after explaining both common and uncommon side effects, including the risk of pneumothorax (collapsed lung), bleeding, and infection such as mediastinitis. Most complications usually show up within the first 24 hours after the procedure. Patients are advised to watch out for signs like low oxygen levels, serious coughing up of blood, or continued fever, and seek urgent medical attention if these symptoms occur.
What Else Should I Know About Sonography Endobronchial Assessment, Protocols, and Interpretation?
EBUS-TBNA (Endobronchial Ultrasound with Transbronchial Needle Aspiration) is gaining reputation worldwide as the go-to test for diagnosing and identifying the stage of lung cancer. Alongside its growing use to help guide treatment procedures involving the airways in your lungs, it’s important for doctors to be well-versed in using this technique and aware of any possible complications. This knowledge and caution can help ensue better results for their patients. This technique involves using an ultrasound along with a special needle to take tissue samples from the lungs and assess their condition.
