Midodrine for Improving Hemodynamics After Spinal Anesthesia
Condition: Hypotension After Spinal Anesthesia
MeSH terms: Hypotension
Study type: Interventional

Summary: 
      Neuraxial blockade such as spinal anaesthesia can cause severe hypotension due to
      pharmacological sympathectomy resulting in potential deleterious consequences for the
      patient. Prevention of this spinal anaesthesia induced hypotension is of utmost importance.
      Techniques currently in use for preventing hypotension include intravenous fluid
      prehydration, sympathomimetic drugs, and physical methods such as leg bindings and
      compression stockings. Midodrine is a direct acting α1-adrenoceptor agonist which causes
      venous and arterial vasoconstriction through stimulation of α1- receptors located in the
      vasculature. The aim of this study is to evaluate the efficacy and safety of prophylactic
      midodrine use with preoperative fluid hydration before spinal anesthesia in the prevention of
      hypotension in patients undergoing elective orthopedic surgery. We hypothesize that
      intraoperative hypotension would be less in patients given midodrine and intravenous fluid
      prehydration preoperatively before spinal anesthesia.
    

Detailed description: 
      Neuraxial blockade such as spinal anaesthesia can cause severe hypotension due to
      pharmacological sympathectomy resulting in potential deleterious consequences for the
      patient. Prevention of this spinal anaesthesia induced hypotension is of utmost importance.
      Several techniques and methodologies have been adopted for the prevention of this neuraxial
      hypotension with varying degree of success. Techniques currently in use for preventing
      hypotension include intravenous fluid prehydration, sympathomimetic drugs, and physical
      methods such as leg bindings and compression stockings. Midodrine is a direct acting
      α1-adrenoceptor agonist which causes venous and arterial vasoconstriction through stimulation
      of α1- receptors located in the vasculature. The net result is an increase in vascular tone
      and systolic blood pressure. Cardiac β-receptors are unaffected and there is no significant
      blood brain barrier penetration. We hypothesize that intraoperative hypotension would be less
      in patients given midodrine and intravenous fluid prehydration preoperatively before spinal
      anesthesia. The study will include 80 patients who will be scheduled for elective orthopedic
      surgery on the lower extremities undergoing spinal anesthesia. It will be conducted in
      Mansoura University Hospital after getting approval from Institutional Review Board (IRB),
      Faculty of medicine, Mansoura University. Informed written consents will be obtained from all
      subjects in the study after ensuring confidentiality. Patients will be randomly allocated
      using computer generated random numbers to either treatment with midodrine (group M) or
      control (group C) using the sealed opaque envelope technique. Patients in group M will
      receive oral 10 mg tablet of midodrine with small sips of water one hour before arrival in
      the operation room while patients in group C will receive inert tablet containing sugar
      (placebo) at the same time. All patients will be monitored in with noninvasive blood pressure
      as well ascontinuous electrocardiogram (ECG) and pulse oximetry (SpO2). Before placement of
      spinal anesthesia, all patients will receive an IV bolus of 10mL/kg of Lactated Ringer's.
      Spinal anesthesia (midline puncture) will be performed in sitting position by a staff
      anesthetist at L3-L4 or L4-L5 with a 25-gauge Withacre needle injecting 12.5 mg of hyperbaric
      0.5% bupivacaine (2.5 mL) with 10μg fentanyl. After injection,the patients will be turned
      supine. The baseline arterial blood pressure (mean) will be calculated as the average of 3
      consecutive measurements before placement of the SA every 15 min after taking midodrine and
      every 5 min for 30 min after spinal anesthesia. Any vasovagal syncopes will be recorded.
      After placement of the SA, the patient's heart rate will be obtained every five minutes for
      30 minutes and thereafter, in accordance with standard clinical practice, every 5 minutes
      until the end of surgery. The dermatome level of the sensory block using loss of pinprick
      will be checked every 5 minutes for 20minutes. The modified Bromage scale (0 = no motor
      block, 1 = straight leg hip flexion blocked, 2 = knee flexion blocked, 3 = complete motor
      block) will be used to quantify the degree of motor block at 20 minutes. Reqirements of
      ephedrine and atropine and fluide intake will be recorded. time to onset of the first
      hypotension, the proportion of patients without hypotension, and the number of bradycardic
      episodes per patient will also be recorded. Perioperative copmlications such as reactive
      hypertension, nausea, vomiting, hypothermia, shivering and postdural puncture headache will
      be recorded. An investigator who is blind to type of intervention wil be responsible for
      collection of data.
    

Intervention name(s): Midodrine Oral Product; Inert tablet containing sugar (placebo)
Intervention type(s): Drug; Drug
Intervention description(s): Patients will receive oral 10 mg tablet of midodrine with small sips of water one hour before arrival in the operation room. All patients will be monitored in with noninvasive blood pressure as well as continuous electrocardiogram (ECG) and pulse oximetry (SpO2). Before placement of spinal anesthesia, all patients will receive an IV bolus of 10mL/kg of Lactated Ringer's . Spinal anesthesia (midline puncture) will be performed in sitting position by a staff anesthetist at L3-L4 or L4-L5 with a 25-gauge Withacre needle injecting 12.5 mg of hyperbaric 0.5% bupivacaine (2.5 mL) with 10μg fentanyl. After injection,the patients will be turned supine.; : Patients will receive Inert tablet containing sugar (placebo) with small sips of water one hour before arrival in the operation room. All patients will be monitored in with noninvasive blood pressure as well as continuous electrocardiogram (ECG) and pulse oximetry (SpO2). Before placement of spinal anesthesia, all patients will receive an IV bolus of 10mL/kg of Lactated Ringer's . Spinal anesthesia (midline puncture) will be performed in sitting position by a staff anesthetist at L3-L4 or L4-L5 with a 25-gauge Withacre needle injecting 12.5 mg of hyperbaric 0.5% bupivacaine (2.5 mL) with 10μg fentanyl. After injection,the patients will be turned supine
Other intervention name(s): spinal anesthesia; spinal anesthesia
Intervention MeSH terms: Midodrine; Anesthetics
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Prospective, randomized, double blind study
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment
Keywords: midodrine before spinal anesthesia