The intercostal nerve block is a peripheral nervous block in the thorax encompassed within the pharmacological procedure performed on the terminal branches for relief of pain in the thorax and the techniques on terminal branches for the relief of abdomen pain. In this procedure, nervous block is achieved after administering the analgesic drugs in the intercostal space.
The intercostal nerves can be blocked at any point of their path through the intercostal space, being preferable at the angle of the rib, the posterior track. With a linear probe placed perpendicular to the longitudinal axis of a costal arch, the sonogram will show two hyperechogenic lines that correspond to two adjacent costal arches. Between the two arches is a less hyperechogenic line that is pleura and below it will be a nonhomogeneous image that corresponds to the pulmonary parenchyma. To perform the intercostal nerve blocks, the needle is inserted into the long axis and the tip of the needle is advanced to the inner lower edge of the rib.
The most important difference with paravertebral thoracic block is its mechanism of action. Thus, the intercostal nerve block affect only the anterior branch of the spinal roots and the gray and white communicating branches. However, paravertebral block also affects the sympathetic chain.
Progression of Intercostal Nerve Blocks
- Intercostal nerve block is an old technique of peripheral nerve block. Braun described it briefly for the first time in 1907 in the second edition of the German book Die Lokalanastesie.
- It has been used for surgical anesthesia and postoperative analgesia since 1940. A few years later, Braun gave an extensive description of how to use intercostal blockin addition to the paravertebral block for multiple thoracic and spinal surgery.
- In 1940s, indications of intercostal nerve blocks were extended to the management of postoperative pain. Multiple investigators, including Zollinger and McCleery, reported a lower incidence of pulmonary complications and a significant reduction in the use of narcotics in the postoperative period of high abdominal surgery due to this blockade. Later, it would also be used in the control of pain, intercostal distribution, both acute and chronic.
- In 1960s, thanks to the discovery of long-term local anesthetics, it was found that it was a technique that provided periods of postoperative analgesia from 12 to 24 hours after thoracic and upper abdominal incisions. The technique was used for abdominal surgeries in combination with blockage of the celiac plexus, with or without sedation. Occasionally, with intercostal nerve blocks, minor abdominal surgeries and mastectomies were performed on the chest wall.
- In 1981 O’Kelly and Garry found the method of solving the problem of intercostal blockade in series. They placed in the extradural space at the level of intercostal space, a catheter, for control of pain in a patient with multiple unilateral costal fractures. In this way, the technique was more practical for both the patient and the anesthesiologist.
- Currently, intercostal nerve block is used primarily for the postoperative control of thoracotomies and cholecystectomies. It is also used successfully in pain relief associated with chest injuries. More often, an extradural catheter is usually used in intercostal space with a continuous infusion of local anesthetic.
- Despite being an easy-to-use technique and with a demonstrated therapeutic efficacy in the control of pain located in the thoracoabdominal wall, it has not been widely diffused, mainly due to fear of pneumothorax andatrogen.
Merits of Intercostal Nerve Blocks
- First of all, it is a simple procedure.
- It brings improvement of respiratory function in the postoperative period. Although the practice of bilateral intercostal nerve block in healthy subjects is associated with an alteration in respiratory mechanics, there is 7% decrease in vital capacity, 8% in functional residual capacity and 20% of maximum expiratory pressure in the airways. Its performance in thoracoabdominal surgeries leads to improvement in expiratory peak-flow and arterial blood gas due to optimal analgesia.
- It does not produce blockage in lower limbs which allows an early ambulation.
Demerits of Intercostal Nerve Blocks
- It has short analgesic duration unless catheter is used.
- There is partial efficacy of the technique as it does not control the pain generated by irritation of drainage tubes on pleura or the section of muscles of the shoulder girdle.
- It may cause complications such as pneumothorax and systemic toxicity.