Effect of Body-mass Index (BMI) on Median Effective Dose of Intrathecal Hyperbaric Bupivacaine

Study Overview
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Brief Summary
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The effect of Body-mass index (BMI) on requirements of local anesthetics used in spinal anesthesia has not been well established. The investigators tried to quantify the effect of BMI on spinal anesthesia by comparing the median effective dose of intrathecal bupivacaine between two different BMI groups.

Detailed Description
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The effect of BMI on requirements of local anesthetics used in spinal anesthesia has not been well established. The investigators tried to quantify the effect of BMI on spinal anesthesia by comparing the median effective dose (ED50)of intrathecal bupivacaine between two different BMI groups. The investigators determined the ED50 and ED 95 of intrathecal hyperbaric bupivacaine of subjects with BMI below 27.5 kg/m2, and subjects with BMI over 27.5 kg/m2, respectively. By comparing the difference of ED50 and ED95 between the groups, the investigators tried to quantify the effect of BMI on the bupivacaine dose requirement.

Official Title
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The Effect of BMI on Median Effective Dose (ED50) of Intrathecal Hyperbaric Bupivacaine for Total Knee Replacement Arthroplasty

Conditions
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Arthroplasty, Knee

Intervention / Treatment
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* Drug: BPV6NO
* Drug: BPV7NO
* Drug: BPV8NO
* Drug: BPV9NO
* Drug: BPV10NO
* Drug: BPV11NO
* Drug: BPV6O
* Drug: BPV7O
* Drug: BPV8O
* Drug: BPV9O
* Drug: BPV10O
* Drug: BPV11O


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients undergoing elective total knee replacement arthroplasty Exclusion Criteria: Patients with previous spine surgery, diabetic and other neuropathy, skin infection at the site of injection, allergy to bupivacaine and other common contraindications for spinal anesthesia were excluded from this study. The patients with height less than 140 cm or more than 160 cm, body-mass index (BMI) less than 20 or greater than 35 were also excluded.

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: BPV6NO<br> | Drug: BPV6NO<br>* intrathecal bupivacaine 6 mg for BMI less than 27.5 kg/m2<br>* Other names: epinephrine;|
| Experimental: BPV7NO<br> | Drug: BPV7NO<br>* intrathecal bupivacaine 7 mg for BMI less than 27.5 kg/m2<br>* Other names: epinephrine;|
| Experimental: BPV8NO<br> | Drug: BPV8NO<br>* intrathecal bupivacaine 8 mg for BMI less than 27.5 kg/m2<br>* Other names: epinephrine;|
| Experimental: BPV9NO<br> | Drug: BPV9NO<br>* intrathecal bupivacaine 9 mg for BMI less than 27.5 kg/m2<br>* Other names: epinephrine;|
| Experimental: BPV10NO<br> | Drug: BPV10NO<br>* intrathecal bupivacaine 10 mg for BMI less than 27.5 kg/m2<br>* Other names: epinephrine;|
| Experimental: BPV11NO<br> | Drug: BPV11NO<br>* intrathecal bupivacaine 11 mg for BMI less than 27.5 kg/m2<br>* Other names: epinephrine;|
| Active Comparator: BPV6O<br> | Drug: BPV6O<br>* intrathecal bupivacaine 6 mg for BMI over 27.5 kg/m2<br>* Other names: epinephrine;|
| Active Comparator: BPV7O<br> | Drug: BPV7O<br>* intrathecal bupivacaine 7 mg for BMI over 27.5 kg/m2<br>* Other names: epinephrine;|
| Active Comparator: BPV8O<br> | Drug: BPV8O<br>* intrathecal bupivacaine 8 mg for BMI over 27.5 kg/m2<br>* Other names: epinephrine;|
| Active Comparator: BPV9O<br> | Drug: BPV9O<br>* intrathecal bupivacaine 9 mg for BMI over 27.5 kg/m2<br>* Other names: epinephrine;|
| Active Comparator: BPV10O<br> | Drug: BPV10O<br>* intrathecal bupivacaine 10 mg for BMI over 27.5 kg/m2<br>* Other names: epinephrine;|
| Active Comparator: BPV11O<br> | Drug: BPV11O<br>* intrathecal bupivacaine 11 mg for BMI over 27.5 kg/m2<br>* Other names: epinephrine;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| success of spinal anesthesia | a bilateral T12 sensory level to pinprick within 10 min of the intrathecal drug administration with no additional epidural anesthetics required during the surgery | every ten minutes during the surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| time to first request for supplemental analgesia | for failure cases: it is the time of failure for success cases : it is the time of first postoperative pain | every ten minutes during and after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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spinal anesthesia, intrathecal bupivacaine, median effective dose, height