title: The characteristics of postoperative fentanyl effect-site concentration during intravenous fentanyl analgesia after posterior lumbar spine fusion.
abstract: OBJECTIVE
  To examine the characteristics of postoperative fentanyl effect-site concentrations during intravenous analgesia in patients requiring or not requiring a fentanyl bolus and in patients with or without postoperative nausea and vomiting (PONV).
  
  
  METHODS
  Retrospective observational study.
  
  
  METHODS
  University-affiliated general hospital.
  
  
  METHODS
  Sixty patients who underwent posterior lumbar spine fusion.
  
  
  METHODS
  The authors simulated the fentanyl effect-site concentration for 48 postoperative hours and compared it between patients who did and did not require a fentanyl bolus and between patients who did and did not experience PONV.
  
  
  RESULTS
  At the end of anesthesia, the fentanyl effect-site concentration was similar between 37 (61.7 percent) patients requiring and 23 (38.3 percent) patients not requiring a postoperative fentanyl bolus (p=0.97). Within the first 12 postoperative hours, the concentration decreased in both groups (p < 0.01). The fentanyl effect-site concentration was higher in patients requiring a postoperative fentanyl bolus (within 12 hours, 1.4 ± 0.32 ng/mL vs 0.89 ± 0.35 ng/mL; between 12 and 48 hours, 0.94 ± 0.19 ng/mL vs 0.57 ± 0.09 ng/mL) (p < 0.05). PONV occurred in 22 (36.6 percent) patients, but more so in women (68.2 percent; p < 0.01); PONV was similar between patients requiring and not requiring a fentanyl bolus (p=0.78). Between the 12th and 48th postoperative hours, fentanyl effect-site concentrations were higher in patients with PONV (0.61 ± 0.10 ng/mL vs 0.57 ± 0.10 ng/mL, p=0.03).
  
  
  CONCLUSIONS
  Patients needing a postoperative fentanyl bolus require a higher fentanyl effect-site concentration possibly because of individual variations, and PONV depends on the postoperative fentanyl effect-site concentration.
authors.affiliation: Staff Anesthesiologist, Department of Anesthesiology, Hamamatsu Rosai Hospital, Hamamatsu, Japan.
authors.forename: Tsunehisa
authors.initials: T
authors.lastname: Sato
authors.affiliation: Chief in Anesthesiology, Department of Anesthesiology, Hamamatsu Rosai Hospital, Hamamatsu, Japan.
authors.forename: Mutsuhito
authors.initials: M
authors.lastname: Kikura
authors.affiliation: Professor and Chairman, Department of Anesthesiology and Intensive Care, Hama-matsu University School of Medicine, Shizuoka, Japan.
authors.forename: Shigehito
authors.initials: S
authors.lastname: Sato
mesh_terms: D000368:Aged; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D006801:Humans; D007275:Injections, Intravenous; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000188:drug therapy*; D020250:Postoperative Nausea and Vomiting / Q000453:epidemiology / Q000517:prevention & control; D012189:Retrospective Studies; D013123:Spinal Fusion
chemical_list: D000701:Analgesics, Opioid; D005283:Fentanyl