Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Anesthesiology. 2011 Mar;114(3):529-35. doi: 10.1097/ALN.0b013e318209a92d.

ED(50) and ED(95) of intrathecal bupivacaine in morbidly obese patients undergoing cesarean delivery.

Author information

  • 1Department of Anesthesia, Stanford University School of Medicine, Stanford, California 94305, USA. bcarvalho@stanford.edu

Abstract

BACKGROUND:

It has been suggested that morbidly obese parturients may require less local anesthetic for spinal anesthesia. The aim of this study was to determine the effective dose (ED(50)/ED(95)) of intrathecal bupivacaine for cesarean delivery in morbidly obese patients.

METHODS:

Morbidly obese parturients (body mass index equal to or more than 40) undergoing elective cesarean delivery were enrolled in this double-blinded study. Forty-two patients were randomly assigned to receive intrathecal hyperbaric bupivacaine in doses of 5, 6, 7, 8, 9, 10, or 11 mg (n = 6 per group) coadministered with 200 μg morphine and 10 μg fentanyl. Success (induction) was defined as block height to pinprick equal to or more than T6 and success (operation) as success (induction) plus no requirement for epidural supplementation throughout surgery. The ED(50)/ED(95) values were determined using a logistic regression model.

RESULTS:

ED(50) and ED(95) (with 95% confidence intervals) for success (operation) were 9.8 (8.6-11.0) and 15.0 (10.0-20.0), respectively, and were similar to corresponding values of a nonobese population determined previously using similar methodology. We were unable to measure ED(50)/ED(95) values for success (induction) because so few blocks failed initially, even at the low-dose range. There were no differences with regard to secondary outcomes (i.e., hypotension, vasopressor use, nausea, and vomiting).

CONCLUSIONS:

Obese and nonobese patients undergoing cesarean delivery do not appear to respond differently to modest doses of intrathecal bupivacaine. This dose-response study suggests that doses of intrathecal bupivacaine less than 10 mg may not adequately ensure successful intraoperative anesthesia. Even when the initial block obtained with a low dose is satisfactory, it will not guarantee adequate anesthesia throughout surgery.

Comment in

PMID:
21307769
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for Silverchair Information Systems
    Loading ...
    Write to the Help Desk