Supraorbital Pressure Versus Jaw Thrust for Assessing the Adequate Depth of Anesthesia for LMA Insertion in Children
Condition: Laryngeal Masks
Study type: Interventional

Summary: 
      BACKGROUND AND OBJECTIVES

      The purpose of this study is to assess whether the loss of motor response to supraorbital
      pressure can be an alternative to that of jaw thrust to predict optimal condition for
      laryngeal mask airway (LMA) insertion in children.

      METHODOLOGY

      Fifty children (ASA I-II), aged 2 to 10 years, scheduled to receive general anesthesia that
      required LMA insertion were randomized to receive either supraorbital pressure (SOP) (n = 25)
      or jaw thrust (JT) (n = 25), after the loss of verbal response and body movements with a
      standard anesthetic. When motor response to the study intervention was absent, the LMA was
      inserted.
    

Detailed description: 
      The investigators enrolled fifty consecutive participants (aged one to ten years) with ASA
      physical status I or II scheduled to receive general anesthesia for various surgical
      procedures. Participants were allowed to have solid food, formula milk or cow's milk up to
      six hours, mother's milk up to four hours and clear fluid up to two hours before surgery.

      On reaching the pre-operative room, when the participant was still on mothers lap or on the
      bed baseline measurements of non-invasive blood pressure (NIBP), pulse oximeter (SpO2) and
      electrocardiography (ECG) were taken. Fifteen minutes before induction of anesthesia, all
      participants were premedicated with ketamine, either 4mg/kg intramuscularly into the gluteal
      region with 26 G needle, or with 0.5mg/kg intravenously if intravenous (IV) cannula was in
      place.

      Devices for ECG, SpO2 and NIBP monitoring were attached to the participant after arrival in
      the operating room. IV line was then inserted, if not already present. Pre-oxygenation was
      done with 100% oxygen using an appropriate size face mask. Anesthesia was induced with IV
      fentanyl (2mcg/kg), and propofol (2-4 mg/kg) until the loss of response to verbal contact or
      loss of eyelash reflex. Spontaneous ventilation was first assisted and then controlled
      manually to maintain an end-tidal carbon dioxide partial pressure of 33-40 mmHg. No
      neuromuscular blocking agent was administered.

      Supraorbital pressure or jaw thrust was performed after loss of response to verbal contact,
      or absence of body movements. In group SOP, supraorbital pressure was applied over the
      supraorbital notch for five seconds. In group JT, the jaw thrust was applied gently by
      lifting the angles of the mandible vertically upward for five seconds. An IV bolus dose of
      propofol (1 mg/kg) was added if there was a motor response to the supraorbital pressure or
      the jaw thrust and the test was repeated after ten seconds. A second bolus dose of propofol
      was repeated if positive motor response was still present. A negative physical response to
      the test was considered as the end point of induction to perform LMA insertion. A classic LMA
      of appropriate size was inserted immediately. Ease of insertion and mouth opening,
      development of coughing, swallowing, movement, laryngospasm, or gross purposeful movements
      during or within one minute of LMA insertion and additional dosage of propofol if required
      were recorded. The LMA insertion was considered unsuccessful if LMA could not be inserted
      after administration of second bolus dose of propofol. The number of attempts and the
      insertion conditions were recorded using a six variable three points scoring system(31)

        -  Mouth opening: 1 - Full, 2 - Partial (not ideal but permits easy opening of mouth), 3 -
           Nil

        -  Ease of LMA insertion 1 - Easy, 2 - Difficult, 3 - Impossible.

        -  Swallowing: 1 - Nil, 2 - Mild, 3 - Severe

        -  Coughing: 1 - Nil, 2 - Mild, 3 - Severe

        -  Laryngospasm: 1 - Nil, 2 - Mild (relieved by positive pressure ventilation), 3 - Severe
           (desaturation<90%)

        -  Movement: 1 - Nil, 2 - Mild (Finger) (some movement but did not affect positioning of
           LMA), 3 - Severe (Arm/leg) (holding of LMA was required and additional dose of induction
           agent given).

      The investigators summed all the five scores to give a LMA insertion condition summed score
      which ranged from 0 to 12, a lower summed score indicating more favourable LMA insertion
      conditions.

      Table: Laryngeal mask airway insertion score.

      Variables 0 1 2

      Mouth opening Complete Partial Impossible Ease of insertion Easy Difficult Impossible
      Swallowing Nil Partial Complete Coughing Nil Partial Complete Laryngospasm Nil Partial
      Complete Movement Nil Partial Gross

      LMA cuff was inflated with air and was connected to Jackson-Rees modification of the Ayre's
      T-piece. Effective ventilation was determined by observing chest wall and bag movement,
      auscultation, and capnography.

      Blood pressure, heart rate and percentage saturation of oxygen were recorded in the
      pre-operative room, immediately after LMA insertion, five, ten and fifteen minutes after LMA
      insertion.

      Anesthesia was maintained with isoflurane in oxygen. After the closure of skin incision,
      removal of LMA was done when the participant was still in deep plane of anesthesia.
    

Intervention name(s): Supraorbital pressure; Jaw thrust maneuver
Intervention type(s): Other; Other
Intervention description(s): Supraorbital pressure is applied by applying pressure over the notch on the inner aspect of eyebrow.; Jaw thrust is performed by placing the index and middle fingers to physically pull the posterior aspects of the mandible upwards while their thumbs push down on the chin to open the mouth.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Other