title: Influence of polyvinyl chloride infusion extension tube on propofol injection pain: a randomised controlled study.
abstract: BACKGROUND
  Propofol injection pain is a common and unsolved anaesthesia problem.
  
  
  OBJECTIVE
  The present study attempted to confirm that the plasticiser di(2-ethylhexyl) phthalate in polyvinyl chloride (PVC) infusion tubes may increase propofol injection pain by increasing the aqueous propofol concentration.
  
  
  METHODS
  A randomised controlled study.
  
  
  METHODS
  University teaching hospital, 1 April to 25 June 2013.
  
  
  METHODS
  One hundred patients scheduled for elective surgery were allocated randomly to the PVC or the control (C) group. The PVC group received a propofol (Diprivan) infusion via a 1-m PVC infusion extension tube, whereas group C received propofol injected directly through the port of the cannula.
  
  
  METHODS
  After the syringe was loaded with propofol, air was expelled from the tube and the syringe was left standing for 5 min; intravenous propofol 0.5 mg kg was then injected either through the PVC tube or directly into the cannula.
  
  
  METHODS
  A verbal rating scale was used to evaluate the propofol injection pain in both groups. Di(2-ethylhexyl) phthalate and aqueous propofol concentrations were also measured in samples of propofol after simulated injection. To investigate whether the increase in aqueous propofol concentration was caused by leached di(2-ethylhexyl) phthalate, the same amount of di(2-ethylhexyl) phthalate as that measured in the PVC group was added to the samples (group D).
  
  
  RESULTS
  The incidences of pain in groups PVC and C were 88 and 46%, respectively (P < 0.0001). The di(2-ethylhexyl) phthalate concentration in group PVC (1.01 ± 0.07 μg ml) was greater than that in group C (lower than the detection limit of 0.03 μg ml). No significant difference was found between the aqueous propofol concentrations in groups PVC (25.9 ± 1.8 μg ml) and D (24.4 ± 1.1 μg ml) (P = 0.22), which were significantly higher than that in group C (14.3 ± 1.0 μg ml) (P = 0.079).
  
  
  CONCLUSIONS
  Propofol injection pain is increased by contact with PVC infusion tubing as a result of an increase in aqueous propofol concentration caused by di(2-ethylhexyl) phthalate leaching into the lipid emulsion.
  
  
  BACKGROUND
  chictr.org identifier: ChiCTR-TRC-12003170.
authors.affiliation: From the Department of Anaesthesiology, Qilu Hospital of Shandong University (QW, NZ, WL), Shandong Quality Inspection Centre for Medical Devices, Jinan, China (YS, YJ).
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
authors.forename: Na
authors.initials: N
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Shen
authors.forename: Yufei
authors.initials: Y
authors.lastname: Jia
authors.forename: Weifu
authors.initials: W
authors.lastname: Lei
mesh_terms: D000328:Adult; D000368:Aged; D004051:Diethylhexyl Phthalate / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000139:chemically induced* / Q000175:diagnosis*; D010968:Plasticizers / Q000008:administration & dosage / Q000009:adverse effects*; D011143:Polyvinyl Chloride / Q000008:administration & dosage / Q000009:adverse effects*; D015742:Propofol / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D010968:Plasticizers; D011143:Polyvinyl Chloride; D004051:Diethylhexyl Phthalate; D015742:Propofol
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