title: Effects of flow rate modifications on reported analgesia and quality of life in chronic pain patients treated with continuous intrathecal drug therapy.
abstract: OBJECTIVE
  We compared the analgesia and the quality of life of a constant daily dose of intrathecal drug administered at different flow rates in patients treated for chronic pain. We postulate that the quality of the analgesia, at the same daily dose, will show an infusion rate dependent pattern with decreased pain at higher flow rates.
  
  
  METHODS
  Twenty consecutive patients on stable intrathecal treatment were included in a double-blind three-period crossover study where the same daily dose was administered at single, double, and quadruple flow rates in a randomized sequence.
  
  
  METHODS
  The mean daily pain score and the quality of life (EuroQol measure of health outcome [EQ-5D]) were measured following each flow rate change, after 1 week of stabilization. Results.  Visual analog scale (VAS) scores remained unchanged with all flow rates. Compared with the lowest flow rate, the EQ-5D index decreased with double and even more with quadruple flow rate, suggesting a clinically relevant worsening of the health state with higher flow rates. Adverse events were equally distributed in all groups.
  
  
  CONCLUSIONS
  Pain VAS did not significantly change with flow rate. This is consistent with preclinical data showing very limited increase in drug distribution in the cerebrospinal fluid with much larger flow rate augmentation. However, the quality of life decreased consistently as the flow rate increased. This was entirely due to a worsening of the pain and anxiety dimension of the EQ-5D questionnaire, caused presumably by a slight increase in pain rather than adverse events. We suggest that at higher flow rates increased drug dilution results in a decreased effect at the receptor site.
authors.affiliation: Department of Anesthesiology and Pain Management, Hospital of Morges, Morges, Switzerland. christophe.perruchoud@chuv.ch
authors.forename: Christophe
authors.initials: C
authors.lastname: Perruchoud
authors.forename: Sam
authors.initials: S
authors.lastname: Eldabe
authors.forename: Anne
authors.initials: A
authors.lastname: Durrer
authors.forename: Michèle
authors.initials: M
authors.lastname: Bovy
authors.forename: Morag
authors.initials: M
authors.lastname: Brookes
authors.forename: Grace
authors.initials: G
authors.lastname: Madzinga
authors.forename: Fay
authors.initials: F
authors.lastname: Garner
authors.forename: Alan M
authors.initials: AM
authors.lastname: Batterham
authors.forename: Carole
authors.initials: C
authors.lastname: Menoud
authors.forename: Myriam
authors.initials: M
authors.lastname: Jacobs
authors.forename: Ash
authors.initials: A
authors.lastname: Gulve
authors.forename: Eric
authors.initials: E
authors.lastname: Buchser
mesh_terms: D000698:Analgesia / Q000379:methods*; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000627:therapeutic use*; D002908:Chronic Disease; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007278:Injections, Spinal; D008297:Male; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement; D011788:Quality of Life; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid