title: Relationship between body surface area and arterial concentrations of bupivacaine following lumbar epidural anesthesia.
abstract: OBJECTIVE
  Most prior studies have shown no relationship between body mass or body surface area (BSA) and maximum plasma concentration of local anesthetic agent (Cmax) following neural block.
  
  
  METHODS
  Forty-nine patients, aged 55 or older, undergoing elective total hip arthroplasty, had arterial plasma bupivacaine concentrations measured (gas chromatography) at 10-minute intervals for the first 60 minutes following lumbar epidural injection of 25 mL 0.75% bupivacaine plain. Hemodynamic stability was maintained with either low-dose epinephrine (EPI) or phenylephrine (PHE) intravenous infusions.
  
  
  RESULTS
  A significant relationship between arterial bupivacaine concentration and BSA was noted for both EPI and PHE groups at each observation point (P < .05). In addition, Cmax for each group was correlated to both BSA and body mass (P < .05). Arterial plasma bupivacaine concentrations were significantly higher in patients at 10, 20, 30, and 40 minutes following epidural injection in patients receiving PHE than EPI (P < .05).
  
  
  CONCLUSIONS
  Between 20% and 40% of the variability in the arterial concentrations of bupivacaine following lumbar epidural injection in elderly patients can be accounted for by differences in BSA.
authors.affiliation: Department of Anesthesiology, Hospital for Special Surgery, New York, New York 10021, USA.
authors.forename: N E
authors.initials: NE
authors.lastname: Sharrock
authors.forename: G
authors.initials: G
authors.lastname: Go
authors.forename: R
authors.initials: R
authors.lastname: Mineo
authors.forename: W F
authors.initials: WF
authors.lastname: Urmey
authors.forename: G R
authors.initials: GR
authors.lastname: Arthur
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000767:Anesthesia, Epidural; D001830:Body Surface Area; D002045:Bupivacaine / Q000097:blood*; D004837:Epinephrine / Q000097:blood; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010656:Phenylephrine / Q000097:blood
chemical_list: D010656:Phenylephrine; D002045:Bupivacaine; D004837:Epinephrine