Phrenic nerve block after interscalene brachial plexus block. Case report

Phrenic nerve block is a common adverse event of brachial plexus block. However, in most cases it does not have any important clinical repercussion. The objective of this work was to report a case with phrenic nerve block with respiratory repercussions in a patient with chronic renal failure who had an extensive arteriovenous fistula created under perivascular interscalene brachial plexus block.

A 50-year old male patient, smoker, with chronic renal failure on hemodialysis, hypertension, hepatitis C, diabetes mellitus, and chronic obstructive pulmonary disease, was scheduled for creation of an arteriovenous fistula in the right upper limb under interscalene brachial plexus block. The brachial plexus was identified by a peripheral nerve stimulator. Thirty-five milliliter of a local anesthetic mixture containing equal parts of 2% lidocaine with epinephrine at 1:200.000 and 0.75% ropivacaine were injected. After the injection, the patient was alert and oriented, but developed dyspnea and predominance of intercostal respiration on the side of the blockade. Breath sounds were not present in the right base. SpO2 was maintained at 95% with oxygen through nasal cannula. Institution of invasive ventilatory support was not necessary. A chest X-ray showed the right hemidiaphragm on the 5th intecostal space. The patient returned to normal after three hours.

In this case, the patient developed complete paralysis of the phrenic nerve with respiratory symptoms. Although invasive treatment was not necessary, it is necessary to alert anesthesiologists to restrict the indication of this technique.