title: Randomized double-blind comparison of phrenic nerve infiltration and suprascapular nerve block for ipsilateral shoulder pain after thoracic surgery.
abstract: OBJECTIVE
  Despite the use of thoracic epidural analgesia, a constant severe ache occurs in the ipsilateral shoulder of almost 75% of patients after thoracotomy. The aim of this prospective-randomized study was to investigate the effect of phrenic nerve infiltration (PNI) compared with suprascapular nerve block (SNB) on ipsilateral shoulder pain after thoracic surgery.
  
  
  METHODS
  After Local Research Ethics Committee approval, written informed consent was obtained from 90 adult patients undergoing thoracotomy for pulmonary resection. Patients were excluded if they had preexisting shoulder pain, were unable to understand the visual analog scale (VAS) scoring system or due to failure of epidural analgesia. The phrenic group (PNI) received 10 ml of 2% lidocaine infiltrated into the periphrenic fat pad, 1-2 cm close to the diaphragm, just before chest closure. The suprascapular group (SNB) received 10 ml of 0.5% plain bupivacaine injected into the suprascapular fossa once the surgery was finished. A blinded observer to the study group assessed the patient's shoulder and thoracotomy pain, using the VAS score and a five-point observer verbal rating score (OVRS), at 0.5, 1, 2, 3, 4, 5, 6, 12, 48, and 72 h after surgery and at discharge. The time and dose of any administered analgesic medication were recorded.
  
  
  RESULTS
  Finally, 74 patients were included (37 per group). Sixteen patients were excluded (unable to understand scoring system, failure of the epidural technique, and lost data). There were no significant differences in age, gender, body mass index, type/duration of operation, and pain scores at rest, between the two groups. Shoulder pain intensity was significantly lower in the PNI group compared with the SNB group (median value of VAS area under the curve for the PNI group: 8.1 (0-70.9)cm vs 114.3 (43.8-193.8)cm for the SNB group; p < 0.001). There were no significant differences between the two groups according to postoperative thoracotomy pain.
  
  
  CONCLUSIONS
  Phrenic nerve block with 2% lidocaine should be performed in all patients undergoing a major thoracic surgery procedure. These results strongly support the hypothesis that irritation of the pericardium and/or mediastinal-diaphragmatic pleural surfaces results in pain that is referred to the shoulder via the phrenic nerve.
authors.affiliation: Thoracic Surgery Department, University Hospital Germans Trias i Pujol, Badalona, Barcelona, Spain. cmartinezb.germanstrias@gencat.cat
authors.forename: Carlos
authors.initials: C
authors.lastname: Martinez-Barenys
authors.forename: Jordi
authors.initials: J
authors.lastname: Busquets
authors.forename: Pedro E Lopez
authors.initials: PE
authors.lastname: de Castro
authors.forename: Roser
authors.initials: R
authors.lastname: Garcia-Guasch
authors.forename: Javier
authors.initials: J
authors.lastname: Perez
authors.forename: Esther
authors.initials: E
authors.lastname: Fernandez
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Mesa
authors.forename: Julio
authors.initials: J
authors.lastname: Astudillo
mesh_terms: D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002045:Bupivacaine / Q000008:administration & dosage; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000175:diagnosis / Q000517:prevention & control*; D010791:Phrenic Nerve; D011013:Pneumonectomy / Q000009:adverse effects / Q000379:methods; D011446:Prospective Studies; D020069:Shoulder Pain / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D013908:Thoracotomy / Q000009:adverse effects*
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine; D002045:Bupivacaine