3. Skin wheal.
After cleaning the area under and around the transducer, place an anesthetic skin wheal (3–5 mL lidocaine with epinephrine) posterior to the transducer with the patient in a lateral decubitus position and anterior to the transducer with the patient in supine position. Clean the area and apply a transparent dressing over the transducer.
4. Needle entry.
Inject the skin wheal with an in-plane approach, always noting the needle tip. Once the visualized needle tip is located just above the serratus anterior muscle, aspirate to confirm lack of inadvertent vascular puncture and slowly inject 1–2 mL of anesthetic solution. Fluid placed in the fascial plane will immediately spread away from the needle tip and open the fascial plane. Anesthesia placed incorrectly in the serratus anterior muscle will not separate the fascial plane. Once the fascial plane is clearly opened, aspirate, then gently inject 2–3 mL of dilute anesthetic solution in a sequential manner until all 30 mL of dilute anesthetic is injected (see Figure 6). Ensure clear needle-tip visualization and lack of inadvertent vascular puncture during deposition of the entire dilute anesthetic volume. Clinicians should be aware that onset of analgesia is often longer for planar blocks; expect 15–30 minutes before onset of the block.
Unlike other nerve blocks that are classically thought to target a single nerve, the goal of the ultrasound-guided SAPB is to deposit a large volume of dilute anesthetic in a fascial plane. Anechoic anesthetic fluid will slowly spread with patient respirations and anesthetize the interconnected lateral cutaneous branches of the thoracic intercostal nerves.
Acute pain control in the emergency department for patients with multiple rib fractures can be a conundrum. A multimodal pain strategy that centers around the ultrasound-guided SAPB could offer significant pain relief without altering sensorium or respiratory drive. This ultrasound-guided planar block could alter the classic, and often ineffective, algorithm for the treatment of patients with acute rib fractures in the emergency department while maintaining vital pulmonary function.
Dr. Nagdev is director of emergency ultrasound at Highland Hospital, Alameda Health System, in Oakland, California
Dr. Mantuani is assistant director of emergency ultrasound at Highland Hospital.
Dr. Durant is an ultrasound fellow at Oregon Health & Science University in Portland.
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