title: Accuracy in obtaining 100 μg from 10 mg of morphine for spinal anesthesia.
abstract: OBJECTIVE
  Dilution is often required to obtain appropriate concentrations of intrathecal morphine for analgesia. We compared techniques of diluting by measuring the quantity of morphine actually obtained in the final solution.
  
  
  METHODS
  This is an experimental study by 3 experienced anesthesiologists.
  
  
  METHODS
  The setting is at a university teaching hospital.
  
  
  METHODS
  There are no patients.
  
  
  METHODS
  There are no interventions.
  
  
  METHODS
  Five techniques for obtaining 100 μg from 10 mg/mL were compared: technique 1 (T1) = extraction up to 0.1 graduation on a 1-mL syringe, followed by simple dilution (SD). Technique 2 (T2) = As for T1 but syringe was shaken to mix solution. Technique 3 (T3): SD with 10-mL syringe. Technique 4 (T4): Double dilution with 10-mL syringe. Technique 5 (T5): Extraction up to the 0.1 graduation of a 1-mL syringe, then SD, then shake solution by hand. Three tests using high-performance liquid chromatography with ultraviolet were performed on each syringe prepared 3 consecutive times, namely, at the first (beginning, B), fifth (middle, M) and last (end, E) milliliter or 0.1 mL (depending on syringe type).
  
  
  RESULTS
  Average overall concentrations were 208 ±19, 199 ±24, 120 ±13, 136 ±9, and 119 ±16 μg/0.1 mL, T1-T5, respectively. By Kruskal-Wallis test, we classified the techniques according to the magnitude of the difference between the observed concentration of morphine and the desired (theoretical) concentration of 100 μg/0.1 mL. In ascending order, techniques ranked as follows: T5 (smallest difference), T3, T4, T2, and T1 (greatest difference) (P = .0001).
  
  
  CONCLUSIONS
  There is significant variability in the concentration of morphine actually contained in final solutions after dilution. Morphine presented in different premixed concentrations increases the risk of error. We advocate technique 5 as described above, whereas technique 1 should be prohibited.
authors.affiliation: University Hospital le Bocage, Dijon, France. Electronic address: mehdi.benkhadra@gmail.com.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Benkhadra
authors.affiliation: University Hospital le Bocage, Dijon, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Rivory
authors.affiliation: University Hospital le Bocage, Dijon, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Wessels
authors.affiliation: University Hospital le Bocage, Dijon, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Guerard
authors.affiliation: University Hospital le Bocage, Dijon, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Vadot
authors.affiliation: University Hospital le Bocage, Dijon, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Astruc
authors.affiliation: University Hospital le Bocage, Dijon, France.
authors.forename: Monique
authors.initials: M
authors.lastname: Dumas
authors.affiliation: University Hospital le Bocage, Dijon, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Girard
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000737:chemistry; D000775:Anesthesia, Spinal / Q000379:methods*; D000776:Anesthesiology / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004339:Drug Compounding / Q000379:methods*; D006785:Hospitals, University; D006801:Humans; D007278:Injections, Spinal; D009020:Morphine / Q000008:administration & dosage* / Q000737:chemistry; D013594:Syringes
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine
keywords: Analgesia; Anesthesia; Morphine