Dexmedetomidine Different Doses as Adjuvant to Entropy-assisted General Anesthesia During Functional Endoscopy Sinus Surgery.
Condition: Pain Management; Dexmedetomidine; Anesthesia
Study type: Interventional

Summary: 
      The aim of work to assess the effect of different doses of Dexmedetomidine when used as an
      adjuvant to entropy-guided general anesthesia on the intraoperative surgical field quality,
      inhaled anesthesia consumption and postoperative analgesia requirement during FESS surgeries.
    

Detailed description: 
      This randomized comparative study is designed to:

        -  To assess between the effect of different dose Dexmedetomidine infusions on the surgical
           field quality.

        -  To determine the effect of different dose of Dexmedetomidine infusions on the required
           MAC of isoflurane needed to maintain entropy between 40-60.

        -  To determine the effect of different of Dexmedetomidine on the patient recovery time,
           and the postoperative analgesic requirement.

      Hypothesis

      The primary objective of this study is to find out the optimum infusion dose of
      Dexmedetomidine for the best surgical field quality, reduces inhalational anesthetic
      requirement without affecting recovery time.

      On arrival to the operating room, an 18G cannula will be inserted and 500 ml Ringer acetate
      solution will be started slowly. Standard monitoring (electrocardiography, pulse oximetry and
      non-invasive blood pressure monitoring) will be connected to the patient, baseline blood
      pressure and heart rate will be measured and recorded. The 3-electrode sensor of the entropy
      (GE carestation 650) will be applied to the patient's forehead and the baseline state entropy
      (SE) and response entropy (RE) will be recorded. The patient will be premedicated with
      intravenous Ranitidine 50 mg and Metoclopramide 10 mg. Patients will be equally divided into
      three equal groups and will be given the following according to group allotted.

      G0.2: (33) patients will receive after induction of anesthesia DEX at 1 mcg/kg for 10 minutes
      followed by infusion at the rate of 0.2 mcg/kg/hour G0.4: (33) patients will receive after
      induction of anesthesia DEX at 1 mcg/kg for 10 minutes followed by infusion at the rate of
      0.4 mcg/kg/hour G0.6: (33) patients will receive after induction of anesthesia DEX at 1
      mcg/kg for 10 minutes followed by infusion at the rate of 0.6 mcg/kg/hour

      Induction of general anesthesia will be carried out using fentanyl 2mcg/kg Propofol 1.5-2
      ml/kg and endotracheal intubation will be facilitated with Atracurium 0.5mg/kg.

      General anesthesia will be maintained using isoflurane, the vol % will be adjusted at 1.2% to
      2% to maintain a target entropy 40-60. The repeated doses of Atracurium 0.1 mg/kg every 20-30
      minutes will be administered guided by peripheral nerve stimulator.

      Hemodynamics including mean arterial blood pressure and heart rate along with entropy will be
      recorded every 5 minutes for the first 20 minutes after induction of GA and every 15 minutes
      till the end of surgery. Bradycardia (Heart rate < 50 beat/min) will be treated with atropine
      0.02 mg/kg. Hypotension (MAP < 55 mmHg) will be treated with fluids and Ephedrine 5mg iv. All
      surgeries will be accomplished by the same surgeon using the same surgical technique. The
      surgical field quality will be rated by the surgeon once the surgery started and every 30
      minutes using a 6-point scale for evaluation of operative field visibility (Boezaart Surgical
      Field Grading Scale).

      Grade Assessment 0 No bleeding (cadaveric conditions)

        1. Slight bleeding - no suctioning required

        2. Slight bleeding - occasional suctioning required

        3. Slight bleeding - frequent suctioning required; bleeding threatens surgical field a few
           seconds after suction is removed

        4. Moderate bleeding - frequent suctioning required and bleeding threatens surgical field
           directly after suction is removed

        5. Severe bleeding - constant suctioning required; bleeding appears faster than can be
           removed by suction; surgical field severely compromised

      The lowest isoflurane vol % needed to keep a target of 40-60 reading on entropy recorded on
      the same time table used for the vital signs measured throughout the study. 1 gm of
      paracetamol will be give intra-venous at the end of surgery.The residual effect of the muscle
      relaxant will be reversed with administration of neostigmine 0.05 mg/kg and atropine 0.02
      mg/kg once TOF count is 2/4. When the patients is able to obey verbal commands, endotracheal
      tube will be removed after suctioning the airway under direct vision, the patient will then
      moved to the Post Anesthesia Care Unit (PACU). The recovery time (between stopping of
      inhalational anesthesia till time of patient obeying) and the duration of Anesthesia defined
      as time interval between induction of Anesthesia and endotracheal extubation will both
      calculated and recorded.

      Upon arrival to PACU, patients will be monitored with non-invasive blood pressure and pulse
      oximeter. Oxygen masks will placed on the patients with a flow rate of 6 L/min. The pain will
      be assessed using the visual analogue scale, and sedation will be assessed using the Ramsay
      sedation scale every thirty-minutes for two hours. Rescue analgesia will be provided with
      Pethidine 0.5mg/kg intravenously for those who complained of pain or with VAS score greater
      than 3.

      After two hours, patients that have a score of nine or more on the modified Aldrete discharge
      scoring system will be discharged to the ward.
    

Intervention name(s): Dexmedetomidine
Intervention type(s): Drug
Intervention description(s): patients will receive after induction of anesthesia DEX at 1 mcg/kg for 10 minute followed by infusion
Intervention MeSH terms: Dexmedetomidine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Supportive Care
Keywords: Entropy; FESS