ULTRASOUND ASSESSMENT OF CONTRALATERAL DIAPHRAGMATIC FUNCTION PRIOR TO INTERSCALENE BLOCK

INTRODUCTION:  The interscalene brachial plexus block (ISB) is a common regional anesthesia technique for procedures involving the shoulder and upper arm. A well described and likely unavoidable complication of this block is... [ view full abstract ]

INTRODUCTION:  The interscalene brachial plexus block (ISB) is a common regional anesthesia technique for procedures involving the shoulder and upper arm. A well described and likely unavoidable complication of this block is temporary paralysis of the ipsilateral phrenic nerve. The degree of which this may affect a given patient’s pulmonary function is variable and may often go unrecognized in otherwise healthy patients. However, patients with underlying pulmonary disease may be more likely to display symptoms of dyspnea, and in severe cases respiratory failure may ensue. Therefore, proper patient selection and preoperative evaluation is crucial. One particular preoperative finding that is viewed as a contraindication to ISB is preexisting contralateral phrenic nerve palsy. We report a case of successful left ISB performed after ultrasonographic assessment of diaphragmatic function, for a patient with radiographic evidence of contralateral hemidiaphragm elevation on preoperative chest radiograph   

CASE DESCRIPTION:  A 70 year old woman with chronic persistent asthma, chronic rhinosinusitis, hypertension, GERD, hypothyroidism and obesity was scheduled to undergo a left total shoulder arthroplasty. Preoperative evaluation noted a prior chest radiograph which revealed an elevated right hemidiaphragm with patchy basilar reticulation. Previous pulmonary function testing results were also reviewed and were unremarkable.  Further evaluation with a bedside ultrasound was performed prior to performing planned ISB for perioperative pain management.  This demonstrated appropriate right diaphragmatic excursion and pleural sliding. Subsequently a left ultrasound-guided ISB was performed and well tolerated, followed by general anesthesia and successful completion of the scheduled surgery. Post-operatively the patient had appropriate pain control and had no reports of subjective dyspnea or evidence of respiratory insufficiency.  

DISCUSSION:  In this case report, we suggest that point-of-care ultrasound may be used preoperatively to assess for hemidiaphragm dysfunction prior to performing ISB.  Such an approach may be useful for identifying or excluding pre-existing hemidiaphragm weakness, which may impact a patients’ ability to tolerate the unilateral phrenic nerve palsy that could accompany an ISB.