Pain Control for the Critically Ill Patient: Ultrasound for the Win!

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The Pre-brief

Today’s topic equips Resuscitationists with another tool for pain control in the critically ill: the serratus anterior plane block (SABP).

3 Cases to Consider

Case 1: 92-year-old male with a history of CHF, atrial fibrillation not on anticoagulation presents to the ED in respiratory distress.  


HR: 102

RR: 32

O2 Saturation: 94%

BP: 144/86

Exam: Chronically ill appearing male with decreased bibasilar breath sounds, decreased aeration.


BNP: 1180

CXR: moderate bilateral uncomplicated pleural effusions


BIPAP without improvement. 

Your next step(s): Pt is in moderate to severe respiratory distress. Counsel the family on intubation…


Case 2:

85-year-old female with history of CHF, COPD, atrial fibrillation on aspirin presents to the ED after being found on the floor by family with right-sided chest wall pain. 


HR: 112

RR: 25

O2 Saturation: 92%

BP: 162/94

Exam: Chronically ill appearing female with right-sided chest wall tenderness. 


BNP: 230

VBG: pH= 7.25 with PCO2 of 75

CXR: no pneumonia, no pneumothorax, right sided rib fractures 5-9 with trace pleural effusions

Interventions: Tylenol, Toradol, low dose fentanyl

Your next step(s): Patient is in respiratory distress. Counsel the family on intubation…


Case 3:

21-year-old man, status post transthoracic esophagectomy for corrosive stricture, on mechanical ventilation for 2 days post-op. Was on mechanical ventilation for 2 days post-op. Throughout t ICU course, the patient had postoperative pain especially around the thoracotomy incision site inferior to the anterior axillary nipple line but due to hemodynamic instability was not a candidate for epidural infusion. 


The role of ultrasound guided serratus anterior plane block in the critically ill is an important topic

Some Potential Indications in the Critically Ill:

  • Multiple traumatic rib fractures
  • Herpes zoster pain
  • Tube thoracostomy
  • Post-thoracotomy pain

Anatomy and Positioning for Block:

Patient can be in either lateral decubitus (preferred) or supine position. They should be placed on continuous cardiac monitoring, blood pressure monitoring, and pulse ox.

Supplies needed:

  • Linear probe
  • Sterile probe cover and sterile gel?
  • Cleaning solution
  • Anesthetic: Please consider the use of a longer-acting and less concentrated agent as the volume will need to be across the fascial plane. In patients,>40kg can consider 15ml of 0.5% bupivacaine with 15ml of normal saline in a 30ml syringe.
  • Needles: 20-22g blunt needle or spinal needle, 25-30g needle for superficial skin wheal
  • Lipid Emulsion Therapy in close proximity in case of local anesthetic systemic toxicity (LAST)


  1. Position your patient.
  2. Place the probe at approximately the level of the 5th rib in the mid axillary line to locate the Serratus Anterior Muscle. It will lie superficial to the ribs.
  3. Make a superifical wheal with local anesthetic 
  4. Clean the area. 
  5. Place probe back at the site of interest and insert the needle tip in an in-plane approach. Once you believe you are in the correct position inject 1-2ml of anesthetic solution. If you are correctly hydrodissecting you will see the fluid spread away from the needle and open up the fascial plane.
  6. Anticipate approximately 20 minutes prior to the onset of block given that it is a planar block.

The intended effect of this block is to anesthetize the lateral cutaneous branches of the thoracic intercostal nerves. 

How can we now apply this to the cases presented?

Case 1- The patient’s family does not want intubation, you proceed with the SAPB to place a chest tube for the effusion. Pt does not require any more pain medications in the Emergency Department.

Case 2- The patient’s family does not want intubation, you proceed with SAPB. After the administration, the patient reports complete relief of pain and discharge a few days later without any opioids.

Case 3- Since the patient did not receive an epidural infusion, consider bilateral SAPB for continued pain management. The patient is weaned off the ventilator with the use of fewer opioids. 

SAPB can also be used for multi-modal analgesia in the critically ill without altering sensorium or respiratory drive. The distribution of anesthetic along a plane allows for a large area to be anesthetized effectively. This can be applied for a variety of presentations and in the right setting can decrease the need for the use of opioids.


  1. Lin J, Hoffman T, Badashova K, Motov S, Haines L. Serratus Anterior Plane Block in the Emergency Department: A Case Series. Clin Pract Cases Emerg Med. 2020;4(1):21-25. Published 2020 Jan 21. doi:10.5811/cpcem.2019.11.44946
  2. Madabushi R, Tewari S, Gautam SK, Agarwal A, Agarwal A. Serratus anterior plane block: a new analgesic technique for post-thoracotomy pain. Pain Physician. 2015 May-Jun;18(3):E421-4. PMID: 26000690.
  3. Tekşen Ş, Öksüz G, Öksüz H, Sayan M, Arslan M, Urfalıoğlu A, Gişi G, Bilal B. Analgesic efficacy of the serratus anterior plane block in rib fractures pain: A randomized controlled trial. Am J Emerg Med. 2020 Dec 23;41:16-20. doi: 10.1016/j.ajem.2020.12.041. Epub ahead of print. PMID: 33383266.
  4. Nagdev, A, Mantuani, D, Durant, E, Herring, A “Ultrasound-Guided Serratus Anterior Plane Block Can Help Avoid Opioid Use for Patients with Rib Fractures.” ACEP Now. 05 Apr. 2019. Web.


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