The phrenic nerve infiltration for ipsilateral shoulder pain

We read with great interest the manuscript by Martinez-Barenys et al. [1] in which they compared phrenic nerve infiltration and suprascapular nerve block for ipsilateral shoulder pain following thoracic surgery. We have used similar technique of infiltration of the periphrenic fat pad in our practice for last 5 years, and we have been able to cut down the use of additional analgesia for the ipsilateral shoulder pain following our lung resections. The technique we use evolved in time and it is different in some aspects. We agree with the authors that shoulder pain is related most likely to the irritation of pericardium, mediastinal, and diaphragmatic pleural surfaces; therefore, we inject the periphrenic fat pad prior to resection and handling of the hilum. We believe that introducing the local anaesthetic at this stage provides a greater reduction in postoperative shoulder pain. We use 20 ml of 0.5% levobupivacaine as our anaesthetic agent and infiltrate the periphrenic fat pad above and below the hilum. We have also considered the use of indwelling catheter with infusion of a local anaesthetic to the periphrenic fat pad; however, we have found that isolated infiltration provided adequate pain relief within first 24 h. We did not observe reduction of the shoulder pain in patients were procedures involved the diaphragm. We think that this may be related to nerve fibres crossing from contra lateral phrenic nerve; however, further studies are required to fully understand the pathophysiology of the shoulder pain following the thoracic surgery.