Relationship between body surface area and arterial concentrations of bupivacaine following lumbar epidural anesthesia.
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.
Sharrock
N E
NE
Department of Anesthesiology, Hospital for Special Surgery, New York, New York 10021, USA.
Go
G
G
Mineo
R
R
Urmey
W F
WF
Arthur
G R
GR
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
D010656:Phenylephrine; D002045:Bupivacaine; D004837:Epinephrine