Chapter 10: Pain assessment and management
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Source: Adapted from Schug et al. [166].
Anatomy, physiology and related theory
Regional analgesia blocks transmission of pain impulses through a nerve by depositing an analgesic drug (usually local anaesthetic with or without an opioid) close to the nerve, cutting off sensory innervation to the region it supplies. This can target either peripheral or central (spinal) nerves. Pain impulses are inhibited but some sensations of touch and muscle functions are intact. Regional analgesia gives relief of pain on movement. This facilitates early post‐operative mobilization of patients, even after major surgery in frail patients. Infiltration of the wound with local anaesthetics followed by optimally dosed non‐opioid and opioid analgesics is a good alternative for some types of surgery.
Specific regional analgesia nerve blocks
Specific types of regional analgesia nerve blocks can be used for different types of acute or chronic pain. Table 10.4 lists examples of different regional nerve blocks and the procedures they can be used for.
Table 10.4 Examples of regional analgesia blocks
| Type of block | Remarks |
|---|---|
| Brachial plexus block | The brachial plexus is the major nerve bundle going to the shoulder and arm. This block can be used to manage pre‐operative pain in shoulder injuries and intractable cancer pain from tumours invading the brachial plexus, such as those involving the breast and chest wall. Depending on the level of surgery, the anaesthetist will decide at what level to block the brachial plexus – e.g. for surgery at the shoulder, an interscalene or cervical paravertebral block performed at a location above the clavicle may be used. For surgeries below the shoulder joint or clavicle, an intraclavicular or axillary block may be used. |
| Paravertebral block | Paravertebral blocks can be used to numb a specific area in one part of the body, depending on where the block is performed. For example, paravertebral blocks at the level of the neck can be used for thyroid gland or carotid artery surgery; blocks at the level of the chest and abdomen can be used for many types of breast, thoracic and abdominal surgery; and blocks at the level of the hip can be used for surgeries involving the hip, the knee and the front of the thigh. |
| Femoral nerve block | The femoral nerve provides sensation and motor function to the front of the thigh and knee. This block is commonly used for procedures that cover this area (such as surgery of the knee). It can also be used to provide analgesia for patients with hip fractures pre‐operatively while they are waiting to go to theatre. |
| Sciatic and popliteal nerve block | The sciatic nerve provides sensation and motor function to the back of the thigh and most of the leg below the knee. This block is commonly used for surgery on the knee, calf, Achilles tendon, ankle or foot. |
| Lumbar plexus block | The lumbar nerves join to form the lumbar plexus. An anterior or posterior approach can be used. This block is commonly used for lower limb surgery such as hip and knee surgery, and for femoral shaft and neck fractures. |
| Spinal (intrathecal) central nerve blocks | Spinal blocks are forms of anaesthesia that temporarily interrupt sensation from the chest, abdomen and legs by injection of local anaesthetic medication in the vertebral canal, which contains the spinal cord, spinal nerves and cerebrospinal fluid. They can be used as a form of anaesthesia and are typically given as a single injection that will last for 2–6 hours, depending on the type and volume of local anaesthetic given. If an opioid is given, such as morphine, this can produce analgesia lasting 12 hours ( Schug et al. [166]). |
| Intercostal and interpleural block | This block is used to provide somatosensory and motor blockade to the chest and abdominal wall. It is often used in thoracotomy, mastectomy and rib fractures. Continuous local anaesthetic infusion analgesia can be achieved using a subpleural catheter placed in the space posterior to the parietal pleura alongside the paravertebral area, or more laterally in the intercostal region ( Schug et al. [166]). |
