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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.

Learning Points:

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 [2]. 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).