A middle aged female presents with progressively worsening shortness of breath and pleuritic chest pain several hours after outpatient surgery for a right rotator cuff repair. She has a dry cough, hoarse voice and mild epigastric pain. Her right arm is in a sling, and she has an infusion pump with her. The insertion site is clean. She is tachycardic with oxygen sats of 92% on room air. An upright Chest X-ray is performed.
Concerned for pulmonary embolism, a PE-protocol CT is ordered. While awaiting the radiology read, you pull up the study and see the scout radiograph:
What is on your differential diagnosis? What would you do next?
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Final Diagnosis: Diaphragm Paralysis secondary to scalene block for shoulder surgery
Case Conclusion: The patient’s pain pump was providing a continuous interscalene block for her rotator cuff repair. A CT PE protocol was performed which was negative for a pulmonary embolism. It did reveal a right hemidiaphragm paralysis, which appeared much more subtle on the initial Chest X-ray. Anesthesia was contacted and they decreased the infusion of the interscalene block. The patient’s symptoms improved enough for discharge.
Interscalene brachial plexus block is used for shoulder, arm, and elbow surgery. Local anesthetic is injected at the interscalene groove to provide anesthesia to the brachial plexus at C5-C7 [1, Figure 1]. The procedure can be done by a landmark technique or an ultrasound can be used to visualize the brachial plexus [Figure 2]. An interscalene block results in an ipsilateral phrenic nerve block in 100% of cases. Diaphragmatic paralysis can be confirmed by ultrasound within 5 minutes of injection. The block can last for 3 to 4 hours after placement . Therefore, this block should be avoided in anyone with respiratory insufficiency or contralateral diaphragmatic nerve palsy. It is estimated that this block reduces forced vital capacity by up to 40%, and decreases FEV and peak expiratory flow rates. As seen in this patient, diaphragmatic paralysis becomes more obvious on imaging when the patient lies down, as the abdominal contents shift into the chest, reducing vital capacity by up to 50% (3,4).
Other side effects include a block of the recurrent laryngeal nerve, resulting in a hoarse voice and a mild Horner’s syndrome . Fortunately, more serious complications including pneumothorax or accidental vertebral artery injection are rare.
Case Conclusion by Alicia Oberle
1. Interscalne Brachial Plexus Block. The New York School of Regional Anesthesia. 9/26/13. http://www.nysora.com/techniques/nerve-stimulator-and-surface-based-ra-techniques/upper-extremitya/3346-interscalene-brachial-plexus-block.html
2. Uremy W, Talts K, Sharrock N. One hundred percent incidence of hemidiaphragmatic paresis associated with interscalene brachial plexus anesthesia as diagnosed by ultrasonography. Anesthesia Analgesia. 1991 Apr; 72 (4): 498-503.
3. Fujimura N, Namba H, Tsunoda K, et al. Effect of hemidiaphragmatic paresis caused by interscalene brachial plexus block on breathing pattern, chest wall mechanics, and arterial blood gases. Anesthesia Analgesia. 1995 Nov; 81(5):962-6.
4. Pere P, Pitkanen M, Rosenberg PH, et al. Effect of continuous interscalene brachial plexus block on diaphragm motion and ventilator function. Acta Anaestheiology Scandinavia. 1992 Jan; 36(1): 53-7.
5. Madison SJ, Ilfeld BM. Chapter 46. Peripheral Nerve Blocks. In: Butterworth JF, IV, Mackey DC, Wasnick JD. eds. Morgan & Mikhail's Clinical Anesthesiology, 5e. New York, NY: McGraw-Hill; 2013. http://accessmedicine.mhmedical.com.beckerproxy.wustl.edu/content.aspx?bookid=564&Sectionid=42800579. Accessed November 27, 2015.