Effect of Ondansetron on Spinal-induced Hypotension for Percutaneous Nephrolithotomy
Condition: Percutaneous Nephrolithotomy
MeSH terms: Hypotension
Study type: Interventional
Phase: Early Phase 1

Summary: 
      Percutaneous nephrolithotomy (PCNL) is the surgical standard for treating large or complex
      renal stones. The stones are removed by passing a small telescope through the side of the
      patient directly into the kidney, so the stone can be broken up and the fragments are removed
      .PCNL can be performed under general anesthesia or spinal anesthesia. SA has some advantage
      over GA, such as lower postoperative pain, lower consumption of analgesic drugs and avoidance
      of side effects from multiple medications used in GA.However, SA induced sympathetic block
      leads to a decrease in the systemic vascular resistance and subsequent drop in the arterial
      blood pressure. Furthermore, anesthesia for PCNL usually requires a high sensory level
      reaching T4,resulting in a high incidence (nearly 33%) of hypotension. Also, to meet the long
      duration of surgery, drugs, ;like dexmedetomidine, are added to intrathecal local anesthetics
      , increasing the incidence of hemodynamic instability induced by the spinal anesthesia.

      Decreasing the systemic vascular resistance (SVR) and the venous return to the heart result
      in a reflex vasodilation, bradycardia and hypotension. This reflex is called Bezold -Jarisch
      reflex and is mediated by serotonin receptors (5_HT3) located on the vagus nerve and within
      the wall of the cardiac ventricles.

      Ondansetron; an antiemetic drug used for treatment of perioperative nausea and vomiting, was
      investigated as a 5HT antagonist for inhibition of Bezold - Jarisch reflex. While some
      studies proved its efficacy in prevention of spinal anesthesia induced hypotension , other
      studies could not support this conclusion .
    

Detailed description: 
      This study aims to assess the effect of Ondansetron on spinal induced hypotension when
      bupivacaine and dexmedetomidine are used intrathecally during spinal anesthesia for
      percutaneous nephrolithotomy.This prospective randomized double-blinded study will be carried
      out at Urology and Nephrology center, Mansoura University after approval of Institutional
      Research Board, Faculty of Medicine, Mansoura University. Written informed consents will be
      obtained from participants after explanation of the used drug and its possible consequences.

      Basal readings for blood pressure, heart rate, and ECG analysis and oxygen saturation will be
      recorded before the start of spinal anesthesia.

      Upon arrival to OR, wide bore intravenous access (20 gauge cannula) will be secured for
      preoperative fluid preloading (10 ml/kg ringer solution intravenously).All patients will be
      monitored for non-invasive blood pressure (BP), Heart rate (HR) , ECG and pulse oximetry ,
      measurements will be recorded every 5 min for first 30 minutes then every 15 min till the end
      of surgery .Patients will be randomly divided into two groups, using a computer generated
      random table;

        -  Group S:patients will be injected with 10 ml normal saline intravenous 5 min before
           spinal anesthesia

        -  Group O:patients will be injected with 4mg Ondansetron diluted with normal saline IV 5
           minutes before spinal anesthesia Spinal anesthesia will be delivered in the sitting
           position under complete aseptic condition using 25-gauge spinal needle (quinckle type),
           the needle will be advanced at level L 4-5 or L 3 - 4. After a clear flow of CSF, 3ml
           0.5 % hyperbaric bupivacaine (15mg)will be injected followed by 5 Mcg dexmedetomidine in
           insulin syringe diluted to 1ml .After anesthesia, patients will be positioned supine
           immediately, sensory level will be assessed each 2 minutes by pinprick test, a sensory
           block at T4-6 will be considered sufficient to start surgery.o BP, HR and oxygen
           saturation will be recorded every 5 minutes for first 30 minutes then every 15 minutes
           till the end of surgery. Hypotension will be defined as a decrease blood pressure more
           than 20% of basal BP or decrease systolic than 90 mmHg and will be treated with IV
           ephedrine (5mg bolus). Bradycardia will be defined as heart rate less than 50 beat / min
           and will be treated with IV atropine (0.5mg).The maximum level of sensory block will be
           assessed every 2 minutes till reaching maximum level of sensory block by pin prick test
           or cold sensation using alcohol swab.The incidence of ECG changes(dysrhythmia, ST
           changes).The incidence of pruritus.The incidence of nausea and /or
           vomiting.Postoperative data( HR, BP, SPo2) will be measured every 15 minutes for 2
           hours.
    

Intervention name(s): Ondansetron group; Saline group
Intervention type(s): Drug; Drug
Intervention description(s): patients will be injected with 4 mg Ondansetron diluted with normal saline IV 5 minutes before spinal anesthesia; patients will be injected with 10 ml normal saline intravenous 5 min before spinal anesthesia
Intervention MeSH terms: Ondansetron
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Two groups were enrolled in this study. They will randomized into two groups •Group S:patients will be injected with 10 ml normal saline intravenous 5 min before spinal anesthesia •Group O:patient swill be injected with 4 mg Ondansetron diluted with normal saline IV 5 minutes before spinal anesthesia
Masking: Double (Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Ondansetron, hypotension,vasopressor