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BLOCK AT A GLANCE

Injection of the local anesthetic into the intercostal space within the planes through which the intercostal nerves travel.

  • Indications: Analgesia for rib fractures, postsurgical analgesia for chest and upper abdominal surgery (i.e., thoracotomy, thoracostomy, mastectomy, gastrostomy, and cholecystectomy), herpes zoster, or post-herpetic neuralgia

  • Goal: Local anesthetic spread in the intermuscular plane around the intercostal nerve

  • Local anesthetic volume: 3 to 5 mL at each level

GENERAL CONSIDERATIONS

The intercostal nerve block is a well-established nerve block technique to provide analgesia to the thoracic wall. The landmark-based technique was considered an “advanced” technique with a relatively high risk of complications. Expert use of ultrasound (US) helps to decrease the risk of pneumothorax as the pleura is readily identified and can be avoided. Intercostal blocks can be performed with small gauge needles and are a good alternative in patients needing analgesia following chest surgery, particularly when epidural analgesia is not indicated (e.g., anticoagulation enhanced recovery protocols).

Limitations and Specific Risks

For most indications, multiple-level intercostal nerve blocks are required to cover the area of interest, which increases the discomfort and the risk of adverse events. Reported complications of intercostal nerve blocks include pneumothorax (1%), injury to the peritoneum and abdominal viscera, local anesthetic systemic toxicity (LAST), hematoma due to injury to the intercostal artery, and inadvertent spinal anesthesia. It is widely known to be a nerve block procedure with one of the most rapid local anesthetic (LA) systemic uptake rates as the nerve runs in close contact with the corresponding artery and vein.

ANATOMY

The spinal nerves T2-T12 innervate the thoracic wall and upper abdomen. After emerging from their respective intervertebral foramina, thoracic nerve roots divide into dorsal and ventral rami. The dorsal rami provide innervation to the skin and muscles of the paravertebral region. The ventral rami continue laterally as the intercostal nerves (Figure 33-1). Each intercostal nerve then pierces the posterior intercostal membrane approximately 3 cm lateral to the intervertebral foramen and enters the subcostal groove of the rib. Initially, the nerves travel between the parietal pleura and the intercostal membrane. However, just lateral to the angle of the rib, they enter the space between the innermost and internal intercostal muscles, where they continue for much of the remainder of their course along with the intercostal arteries and veins (Figure 33-2). Small collateral nerves cross the space and travel along the upper border of the rib below. At the midaxillary line, the intercostal nerve gives rise to the lateral cutaneous branch, which pierces the internal and external intercostal muscles. This branch provides innervation to the muscles and skin of the lateral chest and upper abdominal wall (Figure 33-1). The continuation of the intercostal nerve terminates as the anterior cutaneous branch, giving innervation to the skin and muscles of the anterior chest and abdominal ...

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