Our articles often mention the traumatic injuries that we will be at risk for in a collapse situation; when our physical workload is increased and modern medical care is no longer available. When a person is injured and a wound must be sutured, the area will be sensitive and difficult to repair without causing significant discomfort to a person already in pain.
Therefore, I am often asked about the use of Lidocaine (brand name Xylocaine), and other injectable local anesthetics for the purpose of preparing an injured area for suturing. Lidocaine may be placed around the actual wound superficially (local infiltration) or may be directed to “block” a specific nerve that serves the area to be repaired. This procedure is known as a nerve block. Each nerve block is intended to numb a portion of the course of a nerve as it travels through the body, in an effort to numb the injured area.
Relatively small and superficial lacerations are best anesthetized with local infiltration. In other circumstances, nerve blocks are more appropriate. As each area of the body and wound is different, the corresponding nerve block is different as well; let’s take the example of a hand injury. In this case, these situations would include:
· Multiple lacerations to the hand or fingers
· Injuries with multiple embedded foreign objects and debris
· Large lacerations
· Burns where extensive removal of dead tissue (debridement) is required
· Poisonous bites that involve the removal of significant foreign material, such as a stingray spine
· Areas that are sensitive or calloused (e.g., the palm of the hand)
There are various injectable local anesthetics on the market, such as Procaine (Novocain), Bupivacaine (Marcaine), and Mepivacaine (Carbocaine). Lidocaine (Xylocaine) is, however, the most widely used these days, due to the rapidity and effectiveness of its anesthetic action. Lidocaine also comes in the form of an ointment, jelly, patch, and aerosol spray. Injecting the drug gives, of course, a much stronger effect. You can obtain 1% or 2% Lidocaine; the more concentrated dosage is useful for longer procedures.
You can expect full effect about 10 minutes after administration, and the effect should last 1-2 hours. Epinephrine 1.200,000-1,000,000 has been used in conjunction with lidocaine to help decrease bleeding and prolong the effect further. This combo should not be used in areas with limited circulation, such as the fingers or earlobes. The epinephrine could constrict the blood vessels excessively and cause lack of blood flow to the tissues (also called “ischemia”).
Before you consider the use of local anesthetic, you should be aware of your patient’s medical history. Some, such as those with liver disease, cardiac disease, or the elderly, should receive less quantities of the drug.
Of course, you’ll need some equipment: Sterile towels and gauze to create a sterile field in which to work,an antiseptic such as Betadine, at least one 6cc or 10cc syringe, and a thin gauge needle (25 or 27 gauge will do fine). You can decrease the “sting” of the injection by warming the local anesthetic somewhat and/or adding 1cc of sodium bicarbonate solution to 10cc of medication.
Performing a local infiltration with injectable Lidocaine is relatively simple. Position your needle at one end of each side of the laceration and insert superficially at a 45 degree angle to the skin. Pull back on the syringe (“aspirate”) to make sure you haven’t entered a blood vessel by mistake (Intravenous or intra-arterial injection of Lidocaine can cause seizures or cardiac arrhythmias). Then, inject the drug slowly as you withdraw the syringe. A swelling should form (called a “wheal”).
Repeat until each side appears slightly swollen. You can decrease the discomfort of multiple injections by entering in an area already anesthetized by a previous injection. To see this procedure in real time, check out my YouTube video “How to Suture with Dr. Bones”.
To describe every type of nerve block would take an entire medical textbook, so let’s pick a specific one and go through the procedure. We’ll use the example of a laceration on the back of hand.
The nerve we want to block is the radial nerve, as it supplies sensation to that area. It’s helpful to have a book on anatomy in your medical library, so you can see where the nerve travels in that area. For now, see the image below:
You’ll start with the patient’s hand in the palm-up position. Clean the entire wrist and back of the hand with Betadine. Feel the radial artery pulse; this is the one that the doctor takes your pulse with when you have a physical exam. Then feel the radial styloid, this is the part of the wrist that protrudes slightly below the thumb area (see image below).
Insert your needle between the radial artery and the styloid near the crease of the palm, and inject 2-3cc of the anesthetic (aspirate first).
Next, you will turn the hand over and, using the same insertion site, inject another 5cc or so of Lidocaine along the back of the wrist to about the midpoint area. Use a longer needle than the one in the images if you can; this will decrease the numbers of injections you’ll have to do.
Finally,wait 10 minutes and then test the area for anesthetic effect by lightly touching the area to be sutured with a needle.
Complications of injecting local anesthesia include:
· Nerve injury – a sign of this is severe pain during the injection
· Vascular injury – usually with Lidocaine in combination with epinephrine
· Hematoma – blood accumulating under the skin due to puncture of a blood vessel
· Lidocaine toxicity – accidental injection of anesthetic into a blood vessel
Lidocaine toxicity presents with lightheadedness, visual changes, numbness (often in the tongue), metallic taste, and ringing in the ears. Severe cases can progress to unconsciousness and convulsions. In rare instances, a patient could develop heart arrhythmias, respiratory arrest, and even go into a coma.
Finally, it’s important to remember that, while we have the luxury of modern medical care, injuries and wounds should be treated by medical professionals. There are doctors with a lot of experience performing nerve blocks; take advantage of their expertise while they’re still there for you.
For more info on nerves blocks, a good site to check out is emprocedures.com
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