Konstantatos et al., J Pain Relief 2012, 1:3 DOI: 10.4172/2167-0846.1000104 Research Article Open Access Volume 1 • Issue 3 • 1000104 J Pain Relief ISSN: 2167-0846 JPAR, an open access journal A Randomized, Double-Blind, Placebo-Controlled Study of the Analgesic Efficacy of Intravenous Acetaminophen in Ambulatory Surgery Alex Konstantatos 1,2 *, Julian Smith 1 and Margaret Angliss 1 1 Department of Anaesthesia and Perioperative Medicine, Alfred Hospital, Melbourne, Australia 2 Senior Lecturer, Department of Medicine, Monash University, Australia Abstract Purpose: We investigated whether intraoperative intravenous acetaminophen has the potential to reduce pain after ambulatory surgery and reduce time to discharge from the post anaesthesia care unit and hospital. Methods: We tested this hypothesis by conducting a prospective randomized, double-blind clinical trial in patients undergoing ambulatory surgery. A total of 145 patients were randomized to pre and postoperative placebo (50), intravenous (IV) operative and postoperative oral acetaminophen (49), and pre and postoperative oral acetaminophen (48). Results: The primary end point; visual analogue scale mean pain intensity over 24 hours after completion of surgery, was not signifcantly different between the 3 groups, control group 2.0 (1.6), mean (SD), (IV) acetaminophen group 2.1 (1.9) and oral acetaminophen group 2.1 (1.6); (p=0.93). Time to ftness for discharge from the postoperative care unit (p=0.77) and time to ftness for discharge from hospital (p=0.27) also did not vary signifcantly between the three groups. Conclusion: The addition of intraoperative IV acetaminophen to a standard analgesia regimen in patients undergoing ambulatory surgery did not signifcantly improve pain control or discharge times after surgery compared with pre and postoperative oral acetaminophen or placebo. *Corresponding author: Alex Konstantatos, Department of Anaesthesia and Perioperative Medicine, Alfred Hospital, Monash University, Melbourne, Australia, Fax: 0390762813; E-mail: A.konstantatos@alfred.org.au Received January 10, 2012; Accepted February 09, 2012; Published February 15, 2012 Citation: Konstantatos A, Smith J, Angliss M (2012) A Randomized, Double-Blind, Placebo-Controlled Study of the Analgesic Effcacy of Intravenous Acetaminophen in Ambulatory Surgery. J Pain Relief 1:104. doi:10.4172/2167-0846.1000104 Copyright: © 2012 Konstantatos A, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Keywords: Acetaminophen; Intravenous; Ambulatory anesthesia; Acute pain Introduction Recent advances in anaesthesia and surgery, along with eforts to optimize healthcare cost-efciency have led to an ever increasing number of surgical procedures being performed on an ambulatory basis. Estimates in the US [1] place the proportion of ambulatory surgery at 70-80% of all surgeries performed. Opioids are among the most widely used analgesics. Opioids have known adverse efects, most notably nausea, vomiting, respiratory depression, pruritis and urinary retention. Tese may limit recovery and ftness for discharge afer ambulatory surgery. Consequently, multimodal, opioid sparing analgesic regimens are widely used. Oral Acetaminophen is frequently used for mild to moderate pain. IV acetaminophen has the potential to reduce mild to moderate pain associated with ambulatory surgery and reduce time to discharge from the post anaesthesia care unit and hospital. Analgesic efcacy of acetaminophen is said to best equate [2] with peak cerebrospinal fuid levels which are reliably achieved approximately 15 minutes afer completion of IV infusion. We conducted a prospective randomized, double-blind clinical trial in patients undergoing ambulatory surgery. Eligible consenting patients were randomly allocated to one of three groups. In addition to usual analgesia, patients received pre and postoperative placebo, or pre and postoperative oral acetaminophen. Mean pain intensity by visual analogue scale (VAS) measured over 24 hours was the primary outcome measure. Methods Study population Te study protocol was approved by the Ethics and Research Committee of Te Alfred Hospital on 6 th December 2005. All patients gave written informed consent which described the nature of the trial procedure and hypothesis in detail. Patients were enrolled between February 2006 and July 2007. Subjects were eligible if they provided informed consent and were aged 18-60 years, underwent surgery under general anaesthesia with an expectation of discharge within 24 hours, and agreed to an analgesia plan comprising any one or a combination of opioids and local anaesthetic infltration of wound as well as the study medication (acetaminophen or placebo). Exclusion criteria included a past or current history of persistent pain syndrome greater than 3 months, signifcant liver or renal disease, drug or alcohol abuse, continuing requirement for post operative nonsteroidal anti-infammatory medication, concurrent treatment with anti-epileptic or antidepressant medication including gabapentin or pregabalin allergy to acetaminophen or mannitol, history more than one week of continuous opioid therapy up to the time of surgery. Patients were excluded postoperatively if there was a need for reoperation within 24 hours of initial surgery. Procedures Te study was a prospective, randomized, double-blind clinical trial. Patients were randomly assigned by computer generated randomization to receive one of three treatments: (i) pre and postoperative oral placebo and intraoperative intravenous placebo (ii) Journal of Pain & Relief J o u r n a l o f P a i n & R e l i e f ISSN: 2167-0846