Should supraclavicular brachial plexus block be avoided in pregnancy?

Unilateral phrenic nerve block is common after supraclavicular brachial plexus block techniques, although it is rarely symptomatic in patients without respiratory disease. A 24-weeks-pregnant woman was scheduled for a carpal tunnel release because of intractable pain. After a perivascular subclavian brachial plexus block with 30 ml of 0.33% plain bupivacaine was performed, the patient developed a right phrenic nerve block manifested by acute dyspnea and cough. No deleterious consequences followed, but surgery was canceled. Respiratory changes produced by pregnancy might compromise ventilatory reserve. Thus, we suggest avoiding supraclavicular approaches to brachial plexus block in pregnant women, since they may be as prone to developing respiratory embarrassment, secondary to phrenic block, as patients with pulmonary pathology.