Bilateral phrenic-nerve block in man: technical problems and respiratory effects.

Abstract

Attempts were made to produce bilateral phrenic nerve blocks in 11 normal volunteers in order to evaluate the respiratory effects. The study demonstrated that selective bilateral block of the phrenic nerves is difficult to achieve, even with the use of a nerve stimulator, because the sympathetic, vagus, and recurrent laryngeal nerves may be blocked inadvertently. The results in three subjects with evidence of pure bilateral phrenic nerve blocks indicated that in the sitting position ventilation is not impared, inspirtory capacity is reduced 25 per cent, and there is an altered sensation in breathing as well as breath holding. The subjects became acutely aware of their breathing, which was deeper and slower. The feeling of discomfort during breath-holding was less intense, and thus more tolerable, during phrenic-nerve block.