title: Pain on injection of propofol: propofol LCT vs propofol MCT/LCT with or without lidocaine pretreatment.
abstract: BACKGROUND
  Pain on injection was a disadvantage of propofol long-chain triglyceride (LCT) and reduces patient satisfaction. Based on a systematic review, the recommended method to attenuate this pain was a previous administration of lidocaine under tourniquet for 30-120 seconds before injection of propofol (pretreatment of lidocaine). Recently, propofol medium-chain triglyceride/long-chain triglyceride (MCT/LCT) emulsion was proposed for its ability to decrease pain on injection. The authors conducted a double-blind randomized controlled trial to compare the incidence and severity of pain on injection between the new propofol MCT/LCT and the propofol LCT with and without lidocaine pretreatment.
  
  
  METHODS
  360 adult patients with ASA physical status I-III who underwent general anesthesia were assigned into 4 groups by computer-generated randomization; Group I - pretreatment of lidocaine 1% and propofol LCT Group I - pretreatment oflidocaine 1% and propofol MCT/LCT Group III - pretreatment of saline and propofol MCT/LCT and Group IV- pretreatment of saline and propofol LCT mixed with lidocaine 1%. All groups received pretreatment under tourniquet for 60 seconds. Evaluators who were blinded to the injected drugs recorded pain intensity (none, mild, moderate and severe) after the first 30% of total induction dose ofpropofol was injected at a rate of 1 ml/s by questioning patients. Data was analyzed by using Kruskal-Wallis testfor ordinal data. Post hoc analysis was performed by using the Mann-Whitney U-test with Bonferroni's correction on pairwise comparisons and was considered significant with p value of less than 0.05.
  
  
  RESULTS
  Patients in an individual group had insignificant differences in their demographic data. The incidences of pain in Group I, II, III and IV were 61.1%, 46.7%, 62.2% and 55.6% respectively with an average incidence of 56% (p = 0.006). There were 15.6%, 5.6%, 23.3% and 24.4% of patients in Group I, II, III and IV who rated pain intensity as severe. Pain on injection of propofol MCT/LCT with lidocaine pretreatment was less than propofol MCT/LCT alone (p = 0.001).
  
  
  CONCLUSIONS
  The incidence of pain on injection of propofol MCT/LCT was not different from that caused by propofol LCT with pretreatment of lidocaine and the intensity of pain on propofol MCT/LCT injection decreased significantly when using lidocaine pretreatment. Therefore, the authors could conclude that an injection of new propofol MCT/LCT solution was an alternative in reducing pain sensation to propofol LCT with pretreatment of lidocaine. Additionally, pain of propofol MCT/LCT injection could be alleviated by pretreatment of lidocaine with a 60 seconds tourniquet time before the injection ofpropofol.
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Chulalongkorn University, Bankok, Thailand.
authors.forename: Rattanaporn
authors.initials: R
authors.lastname: Burimsittichai
authors.forename: Kanya
authors.initials: K
authors.lastname: Kumwilaisuk
authors.forename: Somrat
authors.initials: S
authors.lastname: Charuluxananan
authors.forename: Wipada
authors.initials: W
authors.lastname: Tingthanathikul
authors.forename: Porntep
authors.initials: P
authors.lastname: Premsamran
authors.forename: Nutthawooth
authors.initials: N
authors.lastname: Sathapanawath
mesh_terms: D000704:Analysis of Variance; D018686:Anesthetics, Intravenous / Q000008:administration & dosage* / Q000009:adverse effects; D000779:Anesthetics, Local / Q000008:administration & dosage; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007275:Injections, Intravenous / Q000009:adverse effects*; D008012:Lidocaine / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology*; D010147:Pain Measurement; D015742:Propofol / Q000008:administration & dosage* / Q000009:adverse effects; D018709:Statistics, Nonparametric; D014280:Triglycerides / Q000737:chemistry
chemical_list: D018686:Anesthetics, Intravenous; D000779:Anesthetics, Local; D014280:Triglycerides; D008012:Lidocaine; D015742:Propofol