Peripheral Nerve Block Techniques to Administer

Introduction:

Peripheral nerve blocks are widely used in surgical and post-surgical analgesia. They have advantages over general anesthesia. Many different peripheral nerve blocks depend on the area to anesthetize. Some of the peripheral nerve blocks are supraclavicular block, radial nerve block, femoral nerve block, and sciatic nerve block.

What Is the Peripheral Nerve Block?

Peripheral nerve blocks are a type of regional anesthesia. They are used to anesthetize the areas in the body's periphery, like arms, shoulders, legs, feet, etc. According to surgical requirements, nerve blocks related to the peripheral body parts are given. There are many peripheral nerve blocks related to specific body areas. Some are interscalene block, supraclavicular block, femoral nerve block, and sciatic nerve block. Usually, we use Lidocaine and Bupivacaine as anesthetics in this block.

What Are the Indications for Peripheral Nerve Block?

They are indicated to inhibit the effects or complications of general anesthesia. The following are the indications where peripheral nerve blocks are required:

• Patients at high risk of respiratory depression, using general anesthesia.

• Patients who avoid systemic medications.

• Patients who cannot go for oral medications.

What Are the Tools Required for Peripheral Nerve Block?

The tools or equipment required for nerve blocks depends on the technique used to anesthetize. However, nerve stimulator guidance, ultrasound guidance, and continuous catheter are essential tools most peripheral nerve blocks require.

• Nerve Stimulator Guidance - A nerve stimulator transmits an electrical current through the tip of a needle. The needle is used for aspiration and then injecting the local anesthesia. A wire between the hand and the electrode allows an electrical circuit to form and generate an electrical pulse to stimulate the nerve.

• Ultrasound Guidance - It is a portable machine having a probe along with it. It visualizes the superficial and deeper nerves and their surrounding structures. It is used to access the proper needle tip position, visualize the spread of local anesthesia, and even identify the anatomy and pathology.

• Continuous Catheter - It is available with a needle-like epidural kit having a needle and a catheter.

What Are the Preoperative Aspects Before Going for the Peripheral Nerve Block?

Preoperative aspects before injecting anesthesia into peripheral nerve blocks are:

• A detailed history of the patients.

• Physical examination of the patients.

• Acknowledging the patients about the risks and postoperative care required for recovery.

• The patient should follow the fasting guidelines if going for surgery.

What Are the Techniques for Peripheral Nerve Blocks?

The techniques for peripheral nerve block are based on the block types, assigned according to the body parts. Peripheral nerve blocks are different in different body parts. The upper extremities have interscalene block, supraclavicular block, infraclavicular block, and axillary block. The lower extremities have a femoral nerve block, lumbar plexus block, obturator nerve block, sciatic nerve block, and popliteal nerve block. Some blocks with brief techniques:

1. Interscalene Block - It anesthetizes the nerve from the shoulder and the cervical region (brachial plexus). The technique makes the patient lie with the head turned opposite the block's side. The landmarks are marked on the cervical part of the neck. Ultrasound guidance is used to identify the blood vessels (carotid artery, internal jugular vein, and subclavian artery). Nerves are traced. When the sixth cervical nerve (C6 nerve) in the cervical region is identified, the needle is directed toward the nerve. The needle tip is next to the nerve root, and local anesthesia is injected.

2. Supraclavicular Block - It is used to block the lateral side of the neck region where the supraclavicular muscle is present. Positioning the patient in a supine (lying on back) position with arm sideways and head away from the block. The ultrasound guidance is taken to locate the surrounding blood vessels (the carotid artery and internal jugular vein). The needle is inserted, and local anesthesia is given by ensuring the needle tip touches the first rib. But the anesthesia is injected only after aspiration.

3. Infraclavicular Block - It is used to block the area over the shoulders. The patient is placed in a supine position with their head away from the side of the block. The arm is grabbed with elbows flexed. Blood vessels (the axillary artery and the brachial plexus) are identified by ultrasound. The needle adjacent to the axillary arteries is inserted, and local anesthesia is injected. Injecting the anesthesia should be consistently done after aspiration.

4. Axillary Block - It is used to block the elbow, forearm, and hand. It blocks the axillary nerve. The patient is laid back with the arm at a 90-degree angle and elbow flexed. After the ultrasound, the needle is inserted perpendicular to the skin, making a tip next to each nerve.

5. Radial Nerve Block - The hand, thumb, and fingers get anesthetized. The needle is inserted in the wrist (proximal to the styloid process of radius), and local anesthesia is injected.

6. Medial Nerve Block - The medial nerve anesthetizes the palm surface and tip of the thumb, index, and ring fingers. The needle is inserted in the wrist between the tendons, and anesthesia is injected.

7. Ulnar Nerve Block - It anesthetized the medial side of the forearm and fifth finger with the ring finger. The ulnar nerve is between the ulnar artery and the flexor carpi ulnaris tendon. Under the tendon, the needle is placed in the wrist region, and local anesthesia is injected.

8. Lumbar Plexus Block - It anesthetizes the medial thigh, knee, and medial leg. The patient is lying in a lateral position with a leg made to flex at the hip and knee. After using the ultrasound guidance, the needle is inserted in the lower back, reaching the posterior third of the psoas major muscle.

9. Femoral Nerve Block - It anesthetizes the hip, medial thigh, knee, and ankles. The patient is in the supine position. Ultrasound guidance is used to identify the nerve. The needle is inserted in the pelvic region (in-plane or out-of-plane approach in fascia iliac). The tip of the needle is adjacent to the nerve, and anesthesia is injected.

10. Obturator Nerve Block - It anesthetizes the hip and all the medial thighs. The patient's position is supine. The ultrasound guidance identifies the muscles and vessels (the femoral vein, pectineus, and adductor muscles). The needle is inserted in the pelvic region near the fascia iliac, and anesthesia is injected.

11. Sciatic Nerve Block - It anesthetizes the hip, the muscles of the thigh, and the lower legs. The patient is placed in the lateral lying position with hips at 45 degrees and knees at 90 degrees. After using an ultrasound probe, the needle is inserted from lateral aspects in the buttock region. Aspiration checking is done. The anesthesia is deposited.

12. Popliteal Nerve Block - It anesthetizes the back of the leg. The patient's position is supine or prone (lying on the belly). The popliteal artery and tibial nerve are located by ultrasound guidance. Further, the needle is inserted at the back at the junction of the knee.

13. Saphenous Nerve Block - It also anesthetizes the back of the leg. Supine position of the patient with legs straight. An Ultrasound probe identifies the nerve adjacent to the femoral artery. In-plane approach is used to deposit the anesthesia near the knee.

14. Pericapsular Nerve Block - It is an inter-plane block that blocks the femoral artery and obturator artery. The patient is supine, and anesthesia is injected into the pelvic region (psoas tendon and pubic ramus) under ultrasound. This nerve block gives better results for analgesia of the hip.

15. iPack Block - It infiltrates local anesthetic in the popliteal artery and posterior capsule of the knee. The anesthesia is deposited in the femoral artery and capsule of the knee. This benefits by not letting the whole leg or foot function lose. It is used as a postoperative pain reliever in total knee arthroplasty.

What Are the Complications of the Peripheral Nerve Block?

Complications:

• Pneumothorax.

• Horner syndrome (disrupted pathway on one side from the brain to the face and eye).

• Paralysis.

• Local anesthesia toxicity.

Conclusion:

Peripheral nerve blocks are used in many surgeries or for postoperative analgesics. There are many techniques established to overcome complications and enhance patient outcomes. Some methods like iPack and pericapsular nerve block are used mainly postoperatively for pain. Different techniques have different ways of insertion, but aspiration before depositing the local anesthesia is very important.