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Effect of Body Mass Index on the Dose of Intrathecal Hyperbaric Bupivacaine for Elective Cesarean Section

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ClinicalTrials.gov Identifier: NCT00403663
Recruitment Status : Completed
First Posted : November 27, 2006
Last Update Posted : July 30, 2009
Sponsor:
Information provided by:
Samuel Lunenfeld Research Institute, Mount Sinai Hospital

Tracking Information
First Submitted Date  ICMJE November 23, 2006
First Posted Date  ICMJE November 27, 2006
Last Update Posted Date July 30, 2009
Study Start Date  ICMJE October 2006
Actual Primary Completion Date December 2007   (Final data collection date for primary outcome measure)
Current Primary Outcome Measures  ICMJE
 (submitted: November 7, 2007)
The primary outcome will be the success/failure of the block. Success meaning a sensory block level at least at T6 within 15 minutes after intrathecal injection and no requirement of any supplemental analgesic by the patient throughout the CS. [ Time Frame: 15 minutes ]
Original Primary Outcome Measures  ICMJE
 (submitted: November 24, 2006)
The primary outcome will be the success/failure of the block. Success meaning a sensory block level at least at T6 within 15 minutes after intrathecal injection and no requirement of any supplemental analgesic by the patient throughout the CS.
Change History
Current Secondary Outcome Measures  ICMJE
 (submitted: November 7, 2007)
  • Upper level of sensory blockage determined by the pinprick at midaxillary line [ Time Frame: 60 minutes ]
  • VAPS during surgery [ Time Frame: 60 minutes ]
  • Dose of lidocaine 2% required as supplementation [ Time Frame: 60 minutes ]
  • Dose of IV fentanyl or ketamine required as supplementation [ Time Frame: 60 minutes ]
  • Conversion to general anesthesia [ Time Frame: 60 minutes ]
Original Secondary Outcome Measures  ICMJE
 (submitted: November 24, 2006)
  • Upper level of sensory blockage determined by the pinprick at midaxillary line
  • VAPS during surgery
  • Dose of lidocaine 2% required as supplementation
  • Dose of IV fentanyl or ketamine required as supplementation
  • Conversion to general anesthesia
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
 
Descriptive Information
Brief Title  ICMJE Effect of Body Mass Index on the Dose of Intrathecal Hyperbaric Bupivacaine for Elective Cesarean Section
Official Title  ICMJE Effect of Body Mass Index on the ED95 of Intrathecal Hyperbaric Bupivacaine for Elective Cesarean Section
Brief Summary Combined spinal - epidural (CSE) anesthesia is a well established technique used for elective Cesarean section. As its name suggests, it combines two anesthesia techniques - spinal and epidural. Adjusting the dose of freezing medication for body size is not as simple as giving a larger dose to a larger person. This study asks a simple, yet important question: does your body mass index (BMI) influence the amount of freezing medication needed for adequate CSE anesthesia for Cesarean section? BMI is a number calculated from your height and weight. In patients with a higher BMI, freezing medication appears to spread farther (to a higher level) in the spinal fluid. When freezing is too high, it can cause unwanted side effects. Therefore, in order to provide optimal spinal anesthesia to patients with a higher BMI, it may be advisable to administer less freezing medication. In this study, we want to find the ideal dose of freezing medication for patients with a higher body mass index, and compare it to the dose found to be ideal for patients with normal body mass index.
Detailed Description

Spinal anesthesia is the most common anesthetic technique used for Cesarean section. It offers many advantages over epidural and general anesthesia. However, one of the limitations of spinal anesthesia in Obstetrics is the use of a single shot technique as the continuous technique is associated with unacceptable incidence of PDPH. It is difficult to predict the exact level of sensory block because many factors affect the spread of local anesthetic injected into the CSF. Theoretically, obese patients may have greater intra-abdominal pressure, leading to compression of the inferior vena cava and engorgement of the epidural venous plexus, which in turn increases the pressure inside the epidural space. This augmented pressure is transmitted to the dural sac and diverge the CSF from the lumbosacral region, leading to a decrease in CSF volume. It has been demonstrated that the volume of CSF in lumbosacral region is an important factor affecting intrathecal spread of anesthetics.

Our hypothesis is that obese women require less intrathecal hyperbaric bupivacaine than do normal weight women to achieve satisfactory surgical anesthesia for elective Cesarean section.Two groups of patients will be studied separately. Patients with BMI greater than or equal to 30 will be included in the obese group, also denominated study group. Patients with BMI less than 25 will be included in the normal weight group, also denominated control group. BMI will be calculated based on the patient's pre-pregnancy weight. For each group, the up-down sequential allocation method based on the Narayana rule will be used to find the minimum effective dose of intrathecal hyperbaric bupivacaine 0.75% associated with opioids necessary for satisfactory outcome in 95% of the pregnant women undergoing cesarean section, i.e. ED95.

There are two possible outcomes in our study: a satisfactory outcome is defined if the sensory block reaches at least at T6 and the patient does not complain of any pain or discomfort that requires intraoperative supplemental drugs; an unsatisfactory outcome is defined if the sensory block reaches a level lower than T6 or the patient complains of pain or discomfort that requires intraoperative supplemental drugs. The decision whether or not the supplementation is required will be made exclusively by the patient, and not by the physician in charge.

Study Type  ICMJE Interventional
Study Phase  ICMJE Not Applicable
Study Design  ICMJE Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Single (Participant)
Primary Purpose: Treatment
Condition  ICMJE
  • Pain
  • Obesity
Intervention  ICMJE Drug: bupivacaine 0.75% with fentanyl and morphine
the following administered once, by spinal injection; 9-12 mg 0.75% hyperbaric bupivacaine 10 mcg fentanyl 100 mcg morphine
Study Arms  ICMJE Not Provided
Publications * Not Provided

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Recruitment Information
Recruitment Status  ICMJE Completed
Actual Enrollment  ICMJE
 (submitted: July 29, 2009)
52
Original Enrollment  ICMJE
 (submitted: November 24, 2006)
80
Actual Study Completion Date  ICMJE December 2007
Actual Primary Completion Date December 2007   (Final data collection date for primary outcome measure)
Eligibility Criteria  ICMJE

Inclusion Criteria:

  • Obese group: All pregnant women at term (over 37 weeks) scheduled for elective Cesarean section, with pre-pregnancy BMI greater than 30
  • Normal weight group: All pregnant women at term (over 37 weeks) scheduled for elective Cesarean section, with pre-pregnancy BMI less than 25.

Exclusion Criteria:

  • Patient's refusal.
  • Patients with any absolute or relative contraindication for spinal/epidural anesthesia.
  • Patients with BMI between 25 and 30.
  • Patients with more than one fetus.
  • Patients unable to communicate in English effectively.
Sex/Gender  ICMJE
Sexes Eligible for Study: Female
Ages  ICMJE 18 Years to 40 Years   (Adult)
Accepts Healthy Volunteers  ICMJE Yes
Contacts  ICMJE Contact information is only displayed when the study is recruiting subjects
Listed Location Countries  ICMJE Canada
Removed Location Countries  
 
Administrative Information
NCT Number  ICMJE NCT00403663
Other Study ID Numbers  ICMJE 06-02
06-0206-E
Has Data Monitoring Committee No
U.S. FDA-regulated Product Not Provided
IPD Sharing Statement  ICMJE Not Provided
Responsible Party Not Provided
Study Sponsor  ICMJE Samuel Lunenfeld Research Institute, Mount Sinai Hospital
Collaborators  ICMJE Not Provided
Investigators  ICMJE
Principal Investigator: Jose CA Carvalho, MD PhD Department of Anesthesia and Pain Management, Mount Sinai Hospital, University of Toronto
PRS Account Samuel Lunenfeld Research Institute, Mount Sinai Hospital
Verification Date July 2009

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP