The serratus anterior plane block (SAPB) is a field block that provides analgesia from T2 to T9 dermatomes of the hemithorax by anesthetizing the lateral cutaneous branches of the intercostal nerves in that area. It was first described in a 2013 study demonstrating long-lasting thoracic-wall anesthesia with no significant adverse effects (1). It has since been utilized by anesthesia for prophylactic treatment of post-thoracotomy and post-mastectomy pain (2-4) and has demonstrated utility for treatment of rib fracture pain in the acute setting (5).
This case series describes its use in the Emergency Department (ED) for patients with thoracic wall pain from rib fractures, herpes zoster and chest tube placement.
Is the SAPB feasible, safe and efficacious when used for a variety of thoracic wall pain syndromes in the ED?
Methods & Study Design
Case series in which six patients (age 60-94) underwent SAPB for treatment of thoracic pain. Exclusion criteria were not specified; however, patients were included regardless of pre-procedural, multimodal analgesic use. The authors recorded extent of injury and indication for SAPB. Outcomes of interest included efficacy of the nerve block and adverse events due to SABP during hospital stay.
SAPB was performed as follows: 25-30 mL of anesthetic (0.25% bupivacaine) was injected under ultrasound-guidance into the serratus anterior plane, either superficial (n=4) or deep (n=2) to the serratus anterior muscle. Sonographic landmarks for identification of the injection site included the lateral borders of the latissimus dorsi muscle and pectoralis muscle.
SAPB was most commonly performed for pain related to anterior or posterior rib fractures (n=4), that was inadequately controlled with parenteral opioids. SAPB provided complete or near-complete pain relief in these patients. Additionally, SAPB resulted in significant pain relief for acute herpes zoster pain (n=1) and pre-procedural analgesia prior to tube thoracostomy (n=1). Both superficial and deep injection locations resulted in effective analgesia. No adverse events were noted.
Strength & Limitations
This is the first study to demonstrate efficacy of the SAPB for acute herpes zoster pain and procedural pain, and it adds to the growing body of literature supporting the use of SAPB for rib fracture pain.
Limitations of this study include small sample size and lack of systematic data collection. The authors note there is a possibility that physicians may not have documented all side effects. Additionally, patients received non-standardized dosing of parenteral pain medication prior to SABP, therefore underdosing may have exaggerated the impact of the nerve block on pain relief. Generalizability is limited as nerve blocks were performed by ultrasound fellowship-trained emergency physicians.
“SAPB can be an effective analgesic modality for thoracic diseases and injuries including rib fractures, herpes zoster, and thoracostomy placement.”
SAPB was an effective adjunct to parenteral opioids in this case series. Though limited, early data suggests that this is a safe and effective procedure. Additional prospective studies are needed to compare SAPB to traditional techniques for the treatment of pain related to acute herpes zoster, thoracostomy, and rib fracture.
The Bottom Line
Serratus anterior plane block, when performed by appropriately-trained physicians, is an effective and safe alternative to parenteral opioids and can provide significant, long-lasting analgesia for a variety of painful thoracic conditions.
For more on the serratus anterior plane block see here:
This post was written by Greta Davis, MS4 at UCSD School of Medicine. Review and further commentary were provided by Charles Murchison, MD and Amir Aminlari, MD.
Lin J, Hoffman T, Badashova K, Motov S, Haines L. Serratus Anterior Plane Block in the Emergency Department: A Case Series. Clin Prac Cases Emerg Med. 2020 Feb;4(1):21-25.
1. Blanco R, Parras T, McDonnell JG, et al. Serratus plane block: a novel ultrasound-guided thoracic wall nerve block. Anaesthesia. 2013;68:1107-13.
2. Khalil AE, Abdallah NM, Bashandy GM, et al. Ultrasound-guided serratus anterior plane block versus thoracic epidural analgesia for thoracotomy pain. J Cardiothorac Vasc Anesth. 2017;31(1):152-8.
3. Rahimzadeh P, Imani F, Faiz SHR, et al. Impact of the ultrasound-guided serratus anterior plane block on post-mastectomy pain: a randomized clinical study. Turk J Anaesthesiol Reanim. 2018;46(5):388-92.
4. Madabushi R, Tewari S, Gautam SKS, et al. Serratus anterior plane block: a new analgesic technique for post-thoracotomy pain. Pain Physician. 2015;18(3):E421-4.
5. Durant E, Dixon B, Luftig J, et al. Ultrasound-guided serratus plane block for ED rib fracture pain control. Am J Emerg Med. 2017;35(1):197.e3-6.