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ED(50) and ED(95) of intrathecal bupivacaine in morbidly obese patients undergoing cesarean delivery.
Anesthesiology. 2011 Mar; 114(3):529-35.A

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.

Authors+Show Affiliations

Department of Anesthesia, Stanford University School of Medicine, Stanford, California 94305, USA. bcarvalho@stanford.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

21307769

Citation

Carvalho, Brendan, et al. "ED(50) and ED(95) of Intrathecal Bupivacaine in Morbidly Obese Patients Undergoing Cesarean Delivery." Anesthesiology, vol. 114, no. 3, 2011, pp. 529-35.
Carvalho B, Collins J, Drover DR, et al. ED(50) and ED(95) of intrathecal bupivacaine in morbidly obese patients undergoing cesarean delivery. Anesthesiology. 2011;114(3):529-35.
Carvalho, B., Collins, J., Drover, D. R., Atkinson Ralls, L., & Riley, E. T. (2011). ED(50) and ED(95) of intrathecal bupivacaine in morbidly obese patients undergoing cesarean delivery. Anesthesiology, 114(3), 529-35. https://doi.org/10.1097/ALN.0b013e318209a92d
Carvalho B, et al. ED(50) and ED(95) of Intrathecal Bupivacaine in Morbidly Obese Patients Undergoing Cesarean Delivery. Anesthesiology. 2011;114(3):529-35. PubMed PMID: 21307769.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - ED(50) and ED(95) of intrathecal bupivacaine in morbidly obese patients undergoing cesarean delivery. AU - Carvalho,Brendan, AU - Collins,Jeremy, AU - Drover,David R, AU - Atkinson Ralls,Lindsey, AU - Riley,Edward T, PY - 2011/2/11/entrez PY - 2011/2/11/pubmed PY - 2011/4/16/medline SP - 529 EP - 35 JF - Anesthesiology JO - Anesthesiology VL - 114 IS - 3 N2 - 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. SN - 1528-1175 UR - https://www.unboundmedicine.com/medline/citation/21307769/ED_50__and_ED_95__of_intrathecal_bupivacaine_in_morbidly_obese_patients_undergoing_cesarean_delivery_ L2 - https://pubs.asahq.org/anesthesiology/article-lookup/doi/10.1097/ALN.0b013e318209a92d DB - PRIME DP - Unbound Medicine ER -