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The intercostal nerves (ICNs) innervate the major parts of the skin and musculature of the chest and abdominal wall. The block of these nerves was first described by Braun in 1907, in the textbook Die Lokalanästesie.1 In the 1940s, clinicians noticed that intercostal nerve blocks (ICNBs) could favorably effect a reduction in pulmonary complications and in narcotic requirements after upper abdominal surgery.1 In 1981, continuous ICNB was introduced to overcome the problems associated with repeated multiple injections.1 Today, ICNB is used in a great variety of acute and chronic pain conditions affecting the thorax and upper abdomen. Less commonly, it is also used for breast and minor chest wall surgery and, in combination with celiac plexus blockade, abdominal operations, usually with light sedation or general anesthesia. As with many other regional techniques, the advantages of ICNBs include superior analgesia, opioid-sparing effect, improved pulmonary mechanics, reduced central nervous system depression, and avoidance of urinary retention. It should be noted, however, that supplemental systemic analgesia is also almost always needed. The disadvantages of the technique include the requirement for technical expertise, risks of pneumothorax, and local anesthetic toxicity with multiple levels of blockade.

ICNB provides excellent analgesia for chest trauma such as rib fractures2,3 and for postsurgical pain after chest and upper abdominal surgery such as thoracotomy, thoracostomy, mastectomy, gastrostomy, and cholecystectomy.4 Respiratory parameters typically improve with relief of pain.2,3 Blockade of the two dermatomes above and the two below the level of surgical incision is required. ICNB does not block visceral abdominal pain, for which a celiac plexus block is required. It is inadequate for renal surgery since a block from T5 to L3 is required. In itself, ICNB alone does not provide adequate intraoperative anesthesia, and supplemental analgesics or sedatives are usually required except for minor body surface surgery. Neurolytic ICNB may be used to manage chronic pain conditions such as postmastectomy pain (T2) and postthoracotomy pain.

  1. 1. When pneumothorax would be a disaster. ICNBs may help a patient tethering on the brink of respiratory decompensation, but if an unintended pneumothorax could have serious consequences, an alternative block should be considered unless a chest tube is in place.

  2. 2. Coagulation abormalities. This contraindication is not as strong as in central neuraxial blocks but may become absolute if severe.

  3. 3. Local infection, lack of expertise and resuscitating equipment, and lack of any short-term plan to wean from the ventilator should also discourage the use of this block.

As thoracic nerves T1 to T12 emerge from their respective intervertebral foramina, they divide into the following rami (Figure 44–1):

  1. 1. The paired gray and white anterior rami communicantes, which pass anteriorly to the sympathetic ganglion and chain

  2. 2. The posterior cutaneous ramus, supplying skin and muscle in the paravertebral region

  3. 3. The ventral ramus (ICN, the main focus of this chapter)

Fig. ...

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