A board-certified anesthesiologist skilled in providing competent and safe ultrasound-guided regional anesthesia should be necessary to perform this peripheral nerve block, with a registered nurse or an anesthesiology resident to assist the procedure.

The equipment necessary to perform this regional blockade in a safe and standard monitored environment usually includes labeled premedication drugs, resuscitation supplies easily identifiable, and all the equipment to perform the block readily available ideally in an induction room. It is crucial a well-trained assistant present handle medications, help with the position of the patient, and during the injection of the local anesthetics. This figure should be properly familiar with CPR and resuscitation protocols if it becomes necessary in the block area. 

Different monitors are available to decrease the risk of complications related to regional anesthesia, such as intraneural injection or needle-nerve damage. One of them may be an expendable in-line pressure-monitoring mechanism for controlling the pressure while injecting the local anesthetic in the site of the regional block, and it can be documented. Documentation of every stage of this procedure is essential in every institution performing currently regional anesthesia for ensuring an effective and safe practice.[2][6]

Intercostal nerve blocks without US guidance are performed following the next steps: 

• The patient can be situated in the sitting, lateral, or prone position prior to performing the block. The sitting one should lean to some degree forward with a pillow between their arms to retract the scapulae, and some support is needed.
• After cleaning the skin with an antiseptic solution, it is important to identify the block sites (like the inferior borders of the targeted ribs) at around 6 to 8 cm from the midline, and they should be marked over the skin.
• Infiltration of the needle sites with the preferred local anesthetic.
• Introduction of the needle in the sagittal plane and advance it approaching the inferior edge of the correspondent rib ending in the subcostal groove.
• A little dose of local anesthetic should be injected to desensitize the periosteum.
• The needle is advanced at this point forward only 2 to 3 mm, and the clinician should feel a “pop” of the fascia close to the internal intercostal muscle, with or without the existence of paresthesia. What is anesthetized is usually helpful to ensure the correct position of the needle.
• The injection of 3 ml to 5 ml of local anesthetic is recommended, making sure their aspiration for blood is negative.
• The clinician should repeat the previous steps as needed to achieve the desired level of anesthesia.[5] 

ULTRASOUND TECHNIQUE 

• Place the high-frequency linear transducer in a transverse orientation in order to identify the external, internal, and innermost intercostal muscle layers between ribs (image 1).
• Power Doppler or B-mode is normally used to localize the blood vessels, keeping in mind that caudal to the arteries lie the intercostal nerve.
• After localizing the angle of the rib with a long-axis view, the clinician now should insert the needle in-plane aimed centrally and administer the local anesthetic 2 cm medial to that situation under the costal groove, always controlling needle tip as it is advanced. The local anesthetic should be deposited between the innermost intercostal muscle and internal intercostal muscle layers (image 1).
• It is crucial to aspirate for blood to ensure the needle is not intravascular.
• An indentation in the pleura is often shown in the sonogram after the intercostal block is performed.
• A single injection can spread centrally the drug of choice to anesthetize different intercostal spaces.
• Multiple levels should be often required to provide a better quality of analgesia.
• Detailed calculation of the doses of local anesthetic is necessary because the peak plasma levels after this block are pretty high and occur quickly.[2][6]

DOSING

It is considered that a dose of the local anesthetic agent of 0.1 to 0.15 ml/kg per intercostal space (maximum dose 2 to 3 ml per space) can be administered after making sure that the tip of the needle is in the proper tissue plane. Common medications used for this blockade are ropivacaine 0.2%, levobupivacaine 0.25%, or bupivacaine 0.25%.[7][8][9]

The fairly new liposomal bupivacaine is a safe option for the management of severe pain in patients undergoing a thoracotomy or mastectomy as well.[10][11][12]

• Arterial puncture (anterior thoracic artery injury) and hemothorax
• Local anesthetics systemic toxicity (LAST)
• Local infection
• Pain during procedure
• Pneumothorax
• Nerve damage
• Pleural injury
• Fail technique
• Catheter malposition or dislodgement
• Muscle laceration[13]

This single specific block commonly provides around 8 to 12 hours of analgesia with fewer complications compared with other different blocks or epidural injections, and even a shorter learning curve. Besides that, it is demonstrated up to 72 hours of pain relief when liposomal bupivacaine suspension is administered intraoperatively as part of this intercostal block.[10] With the consideration of not to exceed the maximum dose of 266 mg and combined with multimodal analgesia, it would require fewer doses of opioids given to the patient.[14]

Clinicians performing intercostal nerve block need to be well trained in recognizing the thoracic anatomy using the ultrasound and be familiar with anatomic variations as well. Besides that, to provide a safe technique, all the necessary equipment should be readily available, and good communication with the assistant during the procedure is crucial. Complications like hemopneumothorax, intravascular damage, or severe toxicity anesthetics-related should be minimized, and early recognition and urgent management by the providers of the regional block is mandatory. Multiple randomized trials found that a well organized interprofessional team of health workers from different specialties decreases the risk of severe adverse events while performing successful regional anesthesia. [Level 1]