title: Opioid-sparing effect of preemptive bolus low-dose ketamine for moderate sedation in opioid abusers undergoing extracorporeal shock wave lithotripsy: a randomized clinical trial.
abstract: BACKGROUND
  Ketamine has been used as part of a multimodal analgesia regime in opioid abusers undergoing general anesthesia. We studied the opioid-sparing effect of a very low-dose bolus of ketamine as part of moderate sedation for opioid abuse patients undergoing extracorporeal shock wave lithotripsy.
  
  
  METHODS
  In this randomized, placebo-controlled clinical trial, 190 opioid abusers were enrolled. They were stratified into 2 blocks based on their daily opioid consumption. Both blocks were then randomized to receive 0.1 mg/kg IV ketamine (group K) or placebo (group P). Lithotripsy was performed under moderate sedation with intermittent bolus doses of remifentanil (0.2 µg/kg) to alleviate pain. The total remifentanil dose (primary outcome) and respiratory adverse events (secondary outcome) were compared in the 2 groups.
  
  
  RESULTS
  Remifentanil administration in the group with low-opioid consumers was 1.6 ± 0.4 µg/kg (group P) compared with 1.0 ± 0.2 µg/kg in group K (confidence interval [CI](of difference) 95%, 0.4-0.7; P < 0.001). Patients who had high-opioid consumption received 2.0 ± 0.5 µg/kg (group P) vs 1.5 ± 0.3 µg/kg (group K) remifentanil (CI(of difference) 95%, 0.40-0.75; P < 0.001). Ready to discharge time was statistically longer in high-consumption opioid abusers who received placebo compared with group K (55 ± 13 minutes vs 44 ± 8 minutes, CI(of difference) 95%, 6-15; P < 0.001). The incidences of bradypnea, apnea, nausea, vomiting, and hemodynamic changes were not statistically different between the ketamine and placebo groups.
  
  
  CONCLUSIONS
  Preemptive low-dose ketamine (0.1 mg/kg) as a bolus has opioid-sparing effects in opioid abusers undergoing moderate sedation.
authors.affiliation: Anesthesiology Research Center, Labbafinejad Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Babak
authors.initials: B
authors.lastname: Gharaei
authors.forename: Alireza
authors.initials: A
authors.lastname: Jafari
authors.forename: Homayoun
authors.initials: H
authors.lastname: Aghamohammadi
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Kamranmanesh
authors.forename: Mahtab
authors.initials: M
authors.lastname: Poorzamani
authors.forename: Hedayatollah
authors.initials: H
authors.lastname: Elyassi
authors.forename: Baharak
authors.initials: B
authors.lastname: Rostamian
authors.forename: Alireza
authors.initials: A
authors.lastname: Salimi
mesh_terms: D000293:Adolescent; D000328:Adult; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use; D000778:Anesthetics, Dissociative / Q000627:therapeutic use*; D016292:Procedural Sedation / Q000379:methods*; D004311:Double-Blind Method; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D007649:Ketamine / Q000627:therapeutic use*; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009293:Opioid-Related Disorders / Q000150:complications*; D010147:Pain Measurement; D010865:Pilot Projects; D010880:Piperidines / Q000008:administration & dosage / Q000627:therapeutic use; D011183:Postoperative Complications / Q000453:epidemiology; D020250:Postoperative Nausea and Vomiting / Q000453:epidemiology; D000077208:Remifentanil; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D000778:Anesthetics, Dissociative; D010880:Piperidines; D007649:Ketamine; D000077208:Remifentanil