Atropine or Ephedrine Pretreatment for Preventing Bradycardia in Elderly Patients

Study Overview
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Brief Summary
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Spinal anesthesia is widely used for lower extremity surgery, and sedation is often required during surgery. For sedation, propofol, midazolam and dexmedetomidine are frequently used. Dexmedetomidine is a highly selective alpha 2 receptor agonist, and has sedating and analgesic effect. Compared with propofol and midazolam, it has little or no respiratory inhibition and hemodynamically stable. It also has the effect of reducing delirium in the elderly. Dexmedetomidine has also been reported to prolong the duration of sensory and motor blockade effects of spinal anesthesia. However, several studies have reported that administration of dexmedetomidine in spinal anesthesia increases the incidence of bradycardia. In a study of healthy young adults, concurrent administration of atropine with dexmedetomidine in spinal anesthesia significantly reduced the frequency of bradycardia requiring treatment. However, in elderly patients, it is often reported that there is little response to atropine in bradycardia, and ephedrine is more effective in treating bradycardia than atropine in the elderly. The investigators therefore compared ephedrine and atropine as pretreatment to reduce the incidence of bradycardia when using dexmedetomidine as a sedative in elderly patients undergoing spinal anesthesia.

Official Title
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Comparison of Effect of Atropine or Ephedrine Pretreatment for Preventing Bradycardia Under Sedation With Dexmedetomidine After Spinal Anesthesia in Elderly Patients

Conditions
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Anesthesia, Spinal, Dexmedetomidine, Bradycardia

Intervention / Treatment
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* Drug: normal saline
* Drug: atropine 0.5mg
* Drug: ephedrine 8mg


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists (ASA) classification I-II Undergoing orthopedic surgery under spinal anesthesia Exclusion Criteria: Contraindication for spinal anesthesia Atrial fibrillation, atrial flutter Cardiac valve disease Neurologic disease initial systolic blood pressure in operating room > 160mmHg

Ages Eligible for Study
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Minimum Age: 65 Years
Maximum Age: 100 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

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Control group<br>intravenous normal saline pretreatment | Drug: normal saline<br>* intravenous normal saline pretreatment at the onset of dexmedetomidine infusion<br>|
| Experimental: Atropine group<br>intravenous atropine 0.5mg pretreatment | Drug: atropine 0.5mg<br>* intravenous atropine 0.5mg pretreatment at the onset of dexmedetomidine infusion<br>|
| Experimental: Ephedrine group<br>intravenous ephedrine 8mg pretreatment | Drug: ephedrine 8mg<br>* intravenous ephedrine 8mg pretreatment at the onset of dexmedetomidine infusion<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incidence of intervention for bradycardia | The number of treatment for bradycardia which is defined as heart rate under 50 beats per minute | for 1 hour after spinal anesthesia | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incidence of intervention for hypotension | The number of treatment for hypotension which is defined as systolic blood pressure in under 100 mmHg or systolic blood pressure under the 30% of baseline systolic blood pressure | for 1 hour after spinal anesthesia | 
| Systolic/ mean/ diastolic blood pressure | Systolic/ mean/ diastolic blood pressure | for 1 hour after spinal anesthesia |