The Influence of Body-mass Index on the Outcome of Spinal Anesthesia for Total Knee Replacement Arthroplasty

Study Overview
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Brief Summary
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In these prospective observational study, the investigators are trying to evaluate (1) the influence of body-mass index on spinal anesthetic outcome and (2) the determinants on spinal anesthetic outcome by logistic regression analysis.

Detailed Description
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Although the spread of spinal anesthetic drug is unpredictable, patients factors (age, gender, height,weight, body-mass index), spinal anatomy, anesthetic drug dose, and lumbosacral cerebrospinal fluid volume are known to be the determinants of sensory block level. Among these determinants, the influence of body-mass index (BMI) on spinal anesthesia is controversial, and there is no specific guideline showing the relative priority of these determinants. Therefore, in these prospective observational study, the investigators are trying to evaluate (1) the influence of body-mass index on spinal anesthetic outcome and (2) the relative influence of these determinants on spinal anesthetic outcome by logistic regression analysis.

Official Title
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The Influence of Body-mass Index on the Outcome of Spinal Anesthesia for Total Knee Replacement Arthroplasty

Conditions
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Spinal Anesthesia, Success or Failure of Spinal Anesthesia

Intervention / Treatment
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* Drug: Spinal anesthesia (heavy bupivacaine)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients who are undergoing spinal anesthesia in Samsung Medical Center during study period American Society of Anesthesiologist Physical Status classification I   III Exclusion Criteria: Bupivacaine allergy medical history of spinal surgery Diabetic neuropathy active infection at the lumbosacral area other contraindication of spinal anesthesia

Ages Eligible for Study
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Minimum Age: 20 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Obese group<br>patients with BMI >= 30.0 kg/m2 who received spinal anesthesia with heavy marcaine | Drug: Spinal anesthesia (heavy bupivacaine)<br>* Spinal anesthesia with heavy bupivacaine of 6, 7, 8, 9, 10, 11 mg<br>* Other names: heavy bupivacaine;|
| Non-obese group<br>patients with BMI < 30.0 kg/m2 who received spinal anesthesia with heavy marcaine | Drug: Spinal anesthesia (heavy bupivacaine)<br>* Spinal anesthesia with heavy bupivacaine of 6, 7, 8, 9, 10, 11 mg<br>* Other names: heavy bupivacaine;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| spinal anesthetic success/ failure | when (1) a bilateral T12 sensory block to pinprick within 15 minutes of intrathecal drug administration with sensory/motor block scale ≥ 2 and (2) the level of sensory block at the end of surgery was higher than or equal to T12 with sensory/motor block scale ≥ 2. | at 2 hour after the anesthetic induction | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Peak level of sensory block at anesthesia induction | Sensory block levels determined by pinprick test | during 20 min after anesthetic induction | 
| Spinal anesthesia sensory/motor block level at the end of surgery | Spinal anesthesia block level as determined by Pinprick sensory test with Bromage scale. Sensory 0 = an ability to appreciate a pinprick as sharp; 1 = perception of a pinprick as less sharp than in unblocked areas; 2 = perception of a pinprick as touch but not sharp (analgesia); 3 = an inability to feel pinprick(anesthesia). Bromage Scale 0 = ability to lift an extended knee at the hip; 1 = ability to flex the knee but not to lift an extended leg; 2 = ability to flex toes only; 3 = inability to move. | 2 hours after induction (at the end of surgery) | 
| the incidence of tourniquet pain | the incidence of tourniquet pain during the tourniquet time reported by the patient (NRS >= 2) | at 90 min afer anesthetic induction | 
| Incidence of hypotension, bradycardia | Incidence of hypotension, bradycardia total dose of ephedrine Lowest mean blood pressure Incidence of vomiting, shivering | during 2 hours after anesthesia induction | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Spinal anesthesia, determinant, duration