Can Head Position Improve Surgical Field During Ear Surgery?
Condition: Intra-operative Bleeding
MeSH terms: Blood Loss, Surgical
Study type: Interventional

Summary: 
      Middle ear surgeries utilizes microscope in a narrow field. They are better performed under
      controlled hypotension, to minimize bleeding and improve surgical field visualization and
      hence improve results.Head-up or anti-trendelenburg position influences intraoperative
      bleeding by generating regional ischaemia in sites elevated above the level of the heart.
      Also by augmenting the effect of vasodilators through pooling of blood in dilated veins.
    

Detailed description: 
      After obtaining local ethical committee approval and written informed consent from the
      patients, 225 adult patients, scheduled for elective middle ear surgery in Ain Shams
      University hospitals will be enrolled in this randomized, prospective controlled study.

      After applying basic monitors (ECG, pulse oximetry, non-invasive blood pressure monitoring
      and capnography), all patients will be premedicated with midazolam 0.02 mg.kg -1 IV and
      ranitidine 50 mg IV, 15 min. prior to surgery.

      All patients will receive dexmedetomidine 1mcg. Kg-1 loading dose over 10 min just before
      induction, followed by continuous infusion of 0.4 mcg.kg-1hr-1. Rate of infusion will be
      adjusted to maintain MAP 20% below baseline. Dexmedetomidine infusion will be stopped after
      graft insertion. Total dexmedetomidine consumption will be recorded.

      In the operating room and after 5 min preoxygenation, general anesthesia will be conducted
      using the same protocol for all patients: fentanyl 1 μg.Kg-1, propofol 1.5-2 mg.kg -1
      titrated to loss of verbal response, atracurium 0.5 mg. Kg-1 to facilitate endotracheal
      intubation.

      Anaesthesia will be maintained using isoflurane 1 % in oxygen and air mixture 1:1 and
      atracurium 0.1 mg. Kg-1 every 20 mim. Positive pressure ventilation will be set to maintain
      normocapnia.

      Patients will be randomly and evenly assigned to one of three groups, 75 patients each.

      Group I (control): Patients will be positioned supine. Group II: patients will be positioned
      10° anti-trendelenburg position. Group III: patients will be positioned 20°
      anti-trendelenburg position. Randomization will be done using computer generated list. The
      anaesthesia nurse recording the data is blinded to the study groups.

      At the end of surgery, isoflurane will be discontinued and residual neuromuscular blockade
      will be reversed. Recovery time will be recorded (Defined as: the time from discontinuation
      of volatile anaesthetic till the patient is able to respond to verbal command). Patients will
      then be transferred to PACU.

      During surgery, if the surgeon found it difficult to complete the surgery in the
      anti-trendelenburg (groups II and III), surgery will be continued in the supine position.
      Patients will still be calculated in the pre-assigned group with recording of such event, and
      assuming surgeon satisfaction to be 5 in these patients.
    

Intervention name(s): Head-Up Position; Dexmedetomidine; Induction and maintenance of anaesthesia
Intervention type(s): Procedure; Drug; Drug
Intervention description(s): Anti-Trendelenburg Position; Controlled hypotension: All patients will receive dexmedetomidine 1mcg. Kg-1 loading dose over 10 min just before induction, followed by continuous infusion of 0.4 mcg.kg-1hr-1; Induction of anaesthesia: fentanyl 1 μg.Kg-1, propofol 1.5-2 mg.kg -1 titrated to loss of verbal response, atracurium 0.5 mg. Kg-1 to facilitate endotracheal intubation.
Maintenance:Anaesthesia will be maintained using isoflurane 1 % in oxygen and air mixture 1:1 and atracurium 0.1 mg. Kg-1 every 20 mim.
Other intervention name(s): Anti-Trendelenburg Position; controlled hypotension; Anaesthetic drugs
Intervention MeSH terms: Dexmedetomidine; Anesthetics
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Supportive Care