Suprazygomatic Block in Cleft Palate Surgery in Children
Condition: Cleft Palate
MeSH terms: Cleft Palate
Study type: Interventional
Phase: Phase 2

Summary: 
      Cleft palate (CP) is a common congenital malformation, with an incidence ranging from 0.1 to
      1.1 per 1000 births depending on the population group (liau et al, 2010). Early surgery is
      necessary to reduce phonation and feeding difficulties and reduce complications such as
      frequent sinusitis and other respiratory tract infections (Takemura et al., 2002).

      CP repair is painful, necessitating high doses of intravenous (I.V.) opioids. Therefore, the
      risk of postoperative respiratory depression and airway obstruction is important, and
      continuous monitoring is required during the initial 48h postoperatively (Roulleau et al,
      2003).

      Maxillary nerve block using the suprazygomatic approach is used in children since it presents
      a lower rate of complications (Captier et al, 2009). By this way, one can reach the nerve as
      it exits the skull at the foramen rotundum within the pterygopalatine fossa, before the
      location where its nervous branches innervate the palate (Prigge et al, 2014). This simple,
      reliable and almost risk-free approach can yield an effective and prolonged anesthesia with a
      clear decreased use of morphine agents during and after cleft lip-palate surgery in small
      children (Mesnil et al, 2010). The nerve block must be bilateral. The local anesthetic (LA)
      is directly injected in the middle part of the fossa at a distance from the foramen rotundum
      to avoid any trauma to the nerve or vascular injury, as soon as the tip of the needle has
      crossed the temporal muscle (Binet et al, 2015).

      Various adjuvants to local anesthetics to increase the duration of block are described in the
      literature and used in the daily clinical practice. Dexmedetomidine is a selective alpha 2
      (α2) adrenergic agonist with both analgesic and sedative properties. Animal studies showed
      that perineural dexmedetomidine added to bupivacaine or ropivacaine prolongs the duration of
      sensory and motor block (Brummett et al, 2011). Other clinical studies investigated the use
      of dexmedetomidine in patients undergoing ulnar nerve, axillary brachial and greater palatine
      nerve blocks, showed faster onset time and longer duration of block (Marhofer et al, 2013/
      Esmaoglu et al, 2010& Obayah et al, 2010).
    

Detailed description: 
      Preoperative assessment:

      The day prior to surgery, all patients will undergo pre-anesthetic checkup including detailed
      history, physical, systemic examination and weight of the patient. All patients will be
      investigated for exclusion of any of the above mentioned contraindications. Laboratory work
      needed will include: Complete Blood Count (CBC); Prothrombin Time and Concentration (PT& PC);
      Partial Thromboplastin Time (PTT) and Bleeding Time (BT). All children will be kept nil per
      mouth 6-8 h for solids and 2 h for clear liquids.

      Preparation of the patient:

      Written consent and emergency resuscitation equipments including airway devices, pediatric
      advanced life support drugs for LA toxicity will be available.

      Intraoperative management:

      All patients in this study will be anesthetized by the same team of anesthesiologists and
      operated upon by the same surgeon who will be unaware of the study medications.

      General anesthesia will be standardized for all patients in both groups using 8 MAC
      sevoflurane in 100% O2 with appropriate size face mask. Intraoperative monitoring will
      include ECG, pulse oximetry, noninvasive blood pressure, capnography and temperature probe.
      After intravenous access securing, endotracheal intubation with appropriate size to the
      patient's age will be performed after administration of 2 mg/kg propofol.

      After orotracheal intubation, assisted mechanical ventilation using Ayre's T- piece will be
      used to maintain end-tidal carbon dioxide at 35±5 mmHg. General anesthesia will be maintained
      with 2-3 MAC sevoflurane.

      Intraoperatively, patients will receive an infusion of normal saline 0.9% solution 4ml/ kg /
      h.

      Bilateral SMB will be performed before surgery in anesthetized children, after aseptic
      preparation of the skin. The patient will be in supine position with the head in neutral
      position. The puncture site will be at the frontozygomatic angle, at the junction of the
      upper edge of the zygomatic arch and the frontal bone. A needle with 50 mm length and 25
      gauge will be inserted perpendicular to the skin. It will be advanced to reach the greater
      wing of sphenoid at approximately 20 mm depth, then withdrawn a few millimeters and will be
      redirected toward the nasolabial fold in a 20° forward and 10° downward direction. The
      progression in the pterygopalatine fossa will be 35 to 45 mm. Loss of resistance after
      passing through the temporalis muscle will assist in determining the puncture depth. After a
      negative blood aspiration test, 0.2 ml/kg of the blinded study solution will be injected on
      each side (Captier et al, 2009).

      MAP, HR, SPO2 and end-tidal CO2 will be recorded before induction of anesthesia, before
      block, after the block and every 10 minutes till end of surgery. Skin incision will be made
      20 minutes after SMB block. An increase in HR and MAP above 20% of baseline values with skin
      incision will be considered as a sign of inadequate analgesia. In this case, fentanyl 1 µg/kg
      will be given intravenously, and the case will be excluded from the study.

      Immediate complications related to regional anesthesia will be recorded:

        -  Systemic toxicity related to local anesthetics (seizures, heart rhythm, or conduction
           disorder)

        -  Bleeding at puncture site

        -  Pupil alteration and ocular lesion

      Before the end of surgery, IV paracetamol 15 mg/kg and dexamethasone 0.2 mg/kg will be
      administered.

      After completion of the surgical procedure, extubation will be done after ensuring adequate
      orogastric suction and patients will be transferred to the postanesthesia care unit (PACU).

      In PACU: MAP, HR, modified CHEOPS, POV and sedation score will be recorded on admission to
      PACU, 1, 4, 8, 12, 18, 24h postoperatively by an observer who will be unaware of the study
      protocol.

      Postoperative pain will be measured using a modified Children's Hospital of Eastern Ontario
      Pain Scale (CHEOPS) (Taddio et al, 1995).

      CHEOPS = SUM (points for all 6 parameters)

      Interpretation:

        -  minimum score: 4

        -  maximum score: 13 Patients with modified CHEOPS > 6 will be given rescue analgesia with
           15 mg/kg paracetamol intravenously. Those with modified CHEOPS of 4-5 will be given
           paracetamol 25-40 mg/kg as suppository. Pain scores will be recorded every 10 minutes
           after administration of rescue analgesia to evaluate pain relief or need for further
           rescue analgesia. The number of children who will need postoperative rescue analgesics
           and the duration of analgesia that will be taken at the time when an analgesic is
           required will be recorded.

      Postoperative vomiting episodes will be recorded and treated with intravenous metoclopramide
      0.5 mg/kg. Postoperative sedation will be assessed using sedation score described by Culebras
      et al, 2001 (1. Awake and alert. 2. Sleeping but easily arouses to voice or light touch. 3.
      Arouses to loud voice or shaking. 4. Arouses with painful stimuli only. 5. Unarousable).

      Delayed complications of the blocks will be also investigated and recorded as hematoma,
      restricted mouth opening, vision, sensory or motor deficit, eating disorder, and local
      infection.

      The parents will be asked to evaluate their satisfaction regarding pain control at the end of
      48h postoperatively through 5-point Likertscale (1 = very satisfied, 2 = satisfied, 3 =
      neither satisfied nor dissatisfied, 4 = dissatisfied, 5 = very dissatisfied).

      Patients will be discharged from the hospital when they are pain free and there is no other
      medical reason to admit them to a surgical ward.
    

Intervention name(s): Bupivacaine; Dexmedetomidine; paracetamol
Intervention type(s): Drug; Drug; Drug
Intervention description(s): The study drugs will be prepared by an anesthesiologist not involved in performing the block, patient care or in data collection. Patients will be randomly allocated into two groups of 40 patients each:
Group A: will receive 0.2 ml/kg/side of bupivacaine (0.125%).; Group B: will receive 0.2 ml/kg/side of bupivacaine (0.125%) + 0.5 µ/kg of dexmedetomidine.; paracetamol
Intervention MeSH terms: Acetaminophen; Dexmedetomidine; Bupivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: comparison of the analgesic effect of adding dexmedetomidine to bupivacaine with the analgesic effect of using bupivacaine alone in bilateral SMB for children undergoing CP repair under general anesthesia.
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: suprazygomatic block, dexmedetomidine