Paravertebral blocks in breast cancer surgery: is there a difference in postoperative pain, nausea, and vomiting?

BACKGROUND: The purpose of this study was to evaluate postoperative pain and postoperative nausea and vomiting (PONV) in patients with paravertebral blocks (PVB) undergoing breast cancer surgery with or without axillary staging.
METHODS: An Institutional Review Board approved, retrospective chart review from January 2007 to December 2009 was performed at a single institution. Charts were reviewed for type of breast cancer surgery, axillary staging, PVB, PONV, postoperative pain score, dosages of pain medication and antiemetic medication given in the Post Anesthesia Care Unit (PACU), and during the postoperative days (POD). The study population consisted of females with a diagnosis of breast cancer undergoing breast cancer surgery, with or without axillary staging. Patients were excluded if they: had simultaneous myocutaneous tissue flap breast reconstruction, had additional surgical procedures, used continuous delivery postoperative pain medications, had a history of chronic pain, or had a history of chronic antiemetics prior to surgery. All patients received standard perioperative medications per the anesthesia department.
RESULTS: A total of 419 patients underwent breast cancer surgery during the given time period of which 337 patients were able to be included in the study. Of these patients, 241 of the 337 patients had PVB and 96 patients did not have PVB. The mean age was 59.5 years. The mean BMI was 28.7 kg/m(2). Also, 45.5% of the patients who had PVB (110) had a mastectomy, while 41.1% of patients in the non-PVB cohort (39) had a mastectomy. In addition, 45 patients with PVB had immediate tissue expander reconstruction and only 14 patients in the non-PVB group. Of patients with PVB, 53.3% (129) had a sentinel lymph node biopsy (SLN) and 33.5% (81) had full axillary dissections. Of patients in the non-PVB, 35.8% (34) had no axillary staging and 44.2% (42) underwent SLN. Also, 229 patients with PVB and 78 patients without PVB had a general anesthetic. Only 3.3% of patients with PVB and 4.2% of patients without PVB had postoperative nausea (P = 0.746). One patient with PVB and no patients without PVB reported emesis in the PACU (P = 1). There was no difference in morphine equivalents (P = 0.234) or in pain scores (P = 0.521) between the 2 groups in the PACU. There was no difference in amount of morphine equivalents given on POD0 (P = 0.8) or POD1 (P = 0.079). The reconstruction patients with PVB used less opioid analgesic on POD1 compared with the non-PVB reconstruction group (P = 0.02).
CONCLUSIONS: Patients undergoing breast cancer surgery who have paravertebral blocks have similar postoperative nausea and vomiting and similar postoperative pain scores compared with patients without paravertebral blocks. PVB may have an important role in decreasing postoperative pain and opioid analgesic usage in patients electing to have immediate breast reconstruction with tissue expanders.