Overview of Interpleural Analgesia
The method of pain relief known as interpleural analgesia was first highlighted by Reiestad and his team as a way to manage intense pain after surgery. This method works by injecting medicine into the space between the ribs, known as the interpleural space. This allows the medicine to reach many nerves across different ribs from just one injection point.
Stromskag and his team believe that the medication moves backwards to reach these nerves once it is injected. Because of how this process works, it’s considered an ideal approach for relieving pain in the chest and stomach areas.
When used correctly, this form of pain relief can help to better manage pain, lessen the need for potent painkillers like opioids, and in some cases it may even help to enhance lung function.
Anatomy and Physiology of Interpleural Analgesia
Interpleural analgesia is a form of pain relief where a doctor injects medication into a space in your body called the pleural cavity. The pleural cavity is found around the lungs, where two membranes, called the parietal and visceral pleura, are located. The parietal pleura lines the inside of your chest wall, whereas the visceral pleura covers the lungs and other structures inside the chest, like blood vessels and bronchi – which are small tubes that carry air to your lungs.
Before the doctor can reach the pleural cavity, they must first navigate a needle through an area called the intercostal space, which is located on the back or side of your chest wall. This space between the ribs contains three layers of muscles and a bundle of nerves, veins, and arteries, referred to as the neurovascular bundle.
The three muscle layers in this space are the external intercostal muscles—closest to the surface, the internal intercostal muscles— a layer in the middle, and the innermost intercostal muscles— the deepest layer. The intercostal nerve, which is part of the neurovascular bundle, comes from the front branches of the spinal nerves in your chest. These chest spinal nerves come out of openings in your spine and initially rest just under your parietal pleura.
As these nerves move further away from the spine, they start to sit more towards the outside, near the angle of your ribs. From that point, they’ll continue moving further away between the internal and innermost intercostal muscles. These nerves, along with the rest of the components in the neurovascular bundle, tend to be located just under each rib as they move through the intercostal space.
Why do People Need Interpleural Analgesia
Interpleural analgesia is a type of pain relief method which can be used following certain surgeries, such as chest or upper abdominal surgeries. This method involves administering pain relief medication directly into the space between the layers of the pleura, the thin membranes that line the lungs. Using this technique has been proven very effective for managing pain after procedures like gallbladder removal surgeries.
A study by a group of researchers, including VadeBoncouer, showed that this method not only reduces the use of opioid painkillers but also helps improve lung function. Also, it’s worth noting that this method can be used to treat the pain caused by a range of conditions like broken ribs, shingles (a painful skin rash caused by the chickenpox virus), or pain caused by reduced blood flow to the upper extremities.
While this type of pain relief can be used to manage acute (short-term) pain, it’s also beneficial for managing chronic (long-term) conditions or pain crisis such as cancer, shingles-related nerve pain, chronic pancreatitis (inflammation of the pancreas), or complex regional pain syndrome, a condition that causes severe and often chronic pain, usually after an injury to a limb.
Remember, this method is quite specific and should be carried out only by medical professionals who understand the anatomy of the chest and can correctly administer the pain relief medication.
When a Person Should Avoid Interpleural Analgesia
There are certain circumstances where a medical procedure might not be suitable:
Absolute Restrictions
This could be when a patient does not give their permission, is allergic to the local anesthesia (the medication used to numb a specific area of the body), or if there’s an ongoing infection at the exact spot where treatment would be inserted.
Possible Restrictions
There are also some situations where a procedure might be risky, but not entirely ruled out. These include if a patient has a blood clotting disorder, if they’ve suffered paralysis of the phrenic nerve (a nerve that controls the diaphragm, our main breathing muscle), on the opposite side of where the procedure will take place, or if they’re suffering from lung problems. These lung problems could include:
- Bullous lung disease, where air pockets form in the lungs.
- A recent lung infection.
- Chronic obstructive pulmonary disease, a long-term condition that makes it hard to breathe.
- Pleural adhesions, where the two layers of tissue that cover the lungs stick together.
- Hemothorax, when blood collects between the chest wall and the lung.
Equipment used for Interpleural Analgesia
Here is a list of necessary tools doctors use when performing injection or catheter placement in the space between the lungs (interpleural):
- A machine that uses sound waves to create images (Ultrasound machine), but only if the procedure is guided by the ultrasound
- Skin cleaner (topical antiseptic)
- Sterile gloves, clean cloths and sheets
- A special type of needle (16- to 18-gauge Tuohy needle), used to guide the catheter (a small, flexible tube)
- A catheter with multiple holes
- Small needle (25-gauge needle) to numb the spot where the procedure will be done for the patient who’s awake during the procedure
- A syringe made of glass or plastic that indicates when the needle has gone beyond the lung space (loss-of-resistance syringe)
- Devices that monitor oxygen level in the blood (pulse oximetry), a continuously monitored blood pressure device and a device that tracks the heart’s electrical activity (continuous electrocardiogram)
- A bag filled with a solution that resembles the body’s own fluid (bag of crystalloid solution)
- A tube for delivering this fluid into a vein, which has a three-way connector (intravenous tubing)
- A local anesthetic for numbing the pain; if the anesthesiologist chooses bupivacaine, the optimal strength recommended is between 0.25% to 0.5%, with a volume between 10 to 30 mL.
The doctor will use these tools to ensure the procedure is safe and as painless as possible.
Preparing for Interpleural Analgesia
The patient is positioned either lying flat on their back (supine position) or on their side (lateral position) for the procedure. The area for the procedure is usually chosen between the 4th to 7th rib spaces from the top in the chest area (thorax). It is important to do the insertion just above the rib to prevent injury to the nerve and blood vessels (neurovascular bundle) which are located just beneath each rib.
If the patient is lying on their side, they should be positioned with the side that needs the operation facing down. In this case, the area for inserting the needle is identified by drawing a line along the back of the underarm (posterior axillary line), or about 3 to 4 inches away from the middle of the back. If the procedure is to be done with the patient lying on their back, the needle insertion point is determined by drawing a line either down the middle of the underarm (mid-axillary line) or along the front of the underarm (anterior axillary line).
Once the area is identified, it is cleaned with an antiseptic to kill germs and prevent infection. Then, sterile towels or a sterile drape is placed over the area to keep it clean throughout the procedure.
How is Interpleural Analgesia performed
This is a complicated procedure, so let’s break it down. A medical solution is prepared to connect to a three-way device which also attaches to a needle and empty glass syringe. All these instruments are filled with the solution before proceeding. Once the patient’s procedure site is numbed, the needle is gently pushed over the rib into a space between the ribs. This is done when the patient breathes out to safely avoid puncturing the lining that covers vital organs in the chest.
With constant soft pressure applied to the syringe, the needle is slowly moved onward until it has poked a hole in the layer lining the chest cavity. This precise spot is confirmed when resistance on the syringe lessens. Following this step, the procedure can continue in one of two ways: either a flexible thin tube (catheter) is inserted into the space for pain relief over an extended time or a single injection is given for instant but short-term relief.
If a catheter is inserted, the three-way device is adjusted so the medical solution can flow freely while any remaining solution in the syringe is expelled. When fluid starts to flow freely through the needle, it verifies that it is indeed in the right place inside the chest cavity. At this point, the syringe is disconnected and the solution is allowed to flow out from a port on the device. This prevents air from getting into the chest space.
Once all this is done, a catheter with multiple openings at its end is threaded into the chest cavity. The needle and the three-way device are then removed, leaving the catheter behind. Medication is then sent through this catheter in several doses or in a continuous flow for pain relief. It’s important to closely monitor the site of the catheter for any sign of bleeding or infection. When it’s time to remove the catheter, the medical professional applies gentle pressure and pulls it out, making sure the whole tip comes out without breaking.
Alternatively, in the case of just one injection, a local anesthetic is injected into the chest space. After this injection, all instruments are removed. This needs to be done keeping the whole system closed so air can’t get into the chest space.
Possible Complications of Interpleural Analgesia
The main issue that can occur with the interpleural block, a type of anesthesia that numbs a certain area, is a condition called pneumothorax. This is when air or gas collects in the space around the lungs, causing the lung to collapse. A review of 703 procedures showed that this lung collapse could happen in about 2% of the cases. However, using methods that prevent air from entering the space around the lungs can lower the chances of collapsing a lung when doing this type of anesthesia.
Like with any procedure that uses local anesthesia, doing an interpleural block can lead to local anesthetic toxicity. This is an adverse reaction to the anesthesia, and it can happen especially when a large amount or volume of it is needed for pain relief.
Also, because the phrenic nerve and upper thoracic sympathetic ganglia (groups of nerve cells) are close to the area of the interpleural block, doing this procedure may result in hemidiaphragm paralysis (when one side of the diaphragm can’t move) or Horner syndrome (a condition that affects one side of your face).
There are also other possible issues that can occur, including:
– Bleeding or hemothorax (blood collects in the space around the lungs, which can cause the lung to collapse)
– Local infection (an infection that starts in one part of the body)
– Misplacement, movement of the catheter (a thin tube), or the anesthesia block not working
– Pleural Effusion (extra fluid builds up in the space around the lungs)
– Injury to the bronchi (the large air passages that lead from the trachea, or windpipe, to the lungs) or a bronchopleural fistula, (an abnormal passage or hole that forms between a bronchus and the space around the lung) forming.
What Else Should I Know About Interpleural Analgesia?
Interpleural analgesia is a method used to manage and control pain. It is safe and effective, and could potentially be a good alternative to epidural analgesia, which is another pain relief method.
This technique works by injecting a pain reliever into the area between your lungs (pleural cavity). The medicine then spreads backwards to the nerves between your ribs (intercostal nerves), providing pain relief. This method is particularly helpful for managing pain in the chest and upper stomach area.
Interpleural analgesia is not only used to treat immediate, or acute, pain but is also a useful method for managing persistent, or chronic, pain. Given its safety, effectiveness, and the relative ease of carrying out the procedure, it can be seen as a practical choice for pain management.
