title: Plasma concentrations of bupivacaine after spinal anesthesia with single shot femoral nerve block and periarticular injection in total knee arthroplasty.
abstract: OBJECTIVE
  To determine the plasma concentrations of bupivacaine and toxicity after periarticular injection (PAI) combined with spinal anesthesia and femoral nerve block (FNB).
  
  
  METHODS
  Forty-three patients scheduled for unilateral total knee arthroplasty (TKA) were enrolled in the prospective observational study. The dose of bupivacaine for spinal anesthesia was adjusted by the attending anesthesiologist. The single-shot femoral nerve block (FNB) and periarticular injection (PAI) were performed with 20 ml of 0.5% bupivacaine and 20 ml of 0.25% bupivacaine respectively. Venous blood samples from antecubital vein were collected at 60 minutes after femoral nerve block and at the time before periarticular injection, then at 15, 30, 45, and 60 minutes afterwards. Plasma bupivacaine concentrations were analyzed, using a high performance liquid chromatography with tandem mass spectrometry.
  
  
  RESULTS
  Ten males and 32 females, ASA I-II were included. The highest median plasma concentration was 586.22 ng/ml (min = 245.39, max = 1,614.36) at 45 minutes after periarticular injection. The maximum plasma bupivacaine concentration was 1,709.71 ng/ml at 60 minutes after periarticular injection. No clinical toxicity was encountered
  
  
  CONCLUSIONS
  The plasma concentration of bupivacaine in patients performed periarticular injection with 20 ml of 0.25% bupivacaine after spinal anesthesia and single-shot femoral nerve block with 20 ml of 0.5% bupivacaine is below the plasma toxic level.
authors.forename: Saowaphak
authors.initials: S
authors.lastname: Lapmahapaisan
authors.forename: Thitima
authors.initials: T
authors.lastname: Chinachoti
authors.forename: Wiriya
authors.initials: W
authors.lastname: Maisat
authors.forename: Natthawat
authors.initials: N
authors.lastname: Kleebchan
authors.forename: Somruedee
authors.initials: S
authors.lastname: Chatsiricharoenkul
authors.forename: Keerati
authors.initials: K
authors.lastname: Charoencholvanich
authors.forename: Paweenus
authors.initials: P
authors.lastname: Rungwattanakij
authors.forename: Nuchanat
authors.initials: N
authors.lastname: Sakulpacharoen
authors.forename: Jureeporn
authors.initials: J
authors.lastname: Sri-In
mesh_terms: D000368:Aged; D000775:Anesthesia, Spinal / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D002045:Bupivacaine / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D005260:Female; D005267:Femoral Nerve; D006801:Humans; D007270:Injections, Intra-Articular; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D010149:Postoperative Pain / Q000188:drug therapy; D011446:Prospective Studies
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine