Ultrasound-guided parasternal blocks: techniques, clinical indications and future prospects

Fascial plane blocks represent anesthetic procedures performed to manage perioperative and chronic pain. Recently, many fascial blocks techniques have been described increasing their field of applications. They offer anesthetic and analgesic efficacy, easy of execution and low risk of complications. The newest techniques recently described are the ultrasound parasternal blocks (US-PSB) which provide analgesia to the antero-medial chest wall. In particular, the antero-medial chest wall blocks are performed to provide analgesia and anesthesia in several and different surgeries such as median sternotomy, breast surgery, implantable cardioverter-defibrillator implantation and in the management of acute and chronic pain. The nervous target for these blocks is represented by the anterior branches of the intercostal nerves which enter the intercostal (ICM) and pectoralis major (PMM) muscles innervating the antero-medial region of chest wall, the main cause of poststernotomy pain. Local anesthetic is injected deep to PMM and superficial to the ICM or between the internal thoracic muscle (IIM) and transversus thoracis muscle (TTM). So, essentially these blocks may be described as superficial or deep parasternal-intercostal plane blocks, based on where the target nerves are hunted. Even if they all provide analgesia to the antero-medial chest wall, the anatomical injection site represents the main peculiarity that differentiates these techniques. To date, a common nomenclature for antero-medial chest wall blocks or parasternal-intercostal plane blocks is not yet well defined and a standardized nomenclature is needed to ensure an adequate communication among anesthesiologists.