Comparison of the Ambu AuraGain and Intersurgical i-Gel Laryngeal Masks in Elective Laparoscopic Cholecystectomy
Condition: Airway Management; Laryngeal Masks
Study type: Interventional

Summary: 
      Prospective, controlled, randomized study to compare Ambu AuraGain with Intersurgical i-Gel
      mask during mechanical ventilation in patients undergoing laparoscopic cholecystectomy.

      The investigators hypothesise that when comparing the Ambu® AuraGainTM with Intersurgical
      i-GelTM mask, the Ambu® AuraGainTM would exhibit a higher oropharyngeal leak pressure (OLP)
      during mechanical ventilation in patients undergoing laparoscopic cholecystectomy.

      The main goal is to compare the Ambu AuraGain with the i-Gel in terms of safety and efficacy
      during mechanical ventilation in critical phase of the pneumoperitoneum in lateral decubitus
      and reverse trendelemburg position. Secondary objectives are comparing insertion time, number
      of attempts, ventilatory airway peak pressure, time and success rates for gastric tube
      insertion and the incidence of side effects.
    

Detailed description: 
      Design: Prospective, controlled, randomized study. Participants: After approval by the local
      Clinical Research Ethics Committee, all patients scheduled for elective laparoscopic
      cholecystectomy at Hospital Plató (Barcelona) will be screened for participation. Patients
      will be informed about the study and they must provide written consent.

      The need for orotracheal intubation during surgery will be considered as a study withdrawal
      criterion.

      The primary outcome is the oropharyngeal leak pressure (OLP).

      The secondary outcomes are: insertion time, number of attempts, ventilatory airway peak
      pressure, time, and success rates for gastric tube insertion and side effects.

      Sample size has been calculated to detect a significant difference in oropharyngeal leak
      pressure (OLP) between two devices. According to the results of previous studies, the
      investigators assume a mean OLP of 29.2 (3.3) cmH2O for the i-Gel and of 34 (5) cmH2O for the
      Ambu AuraGain. In order to detect a difference of 10%, assuming a standard deviation of 5
      cmH2O for both devices, 44 patients are required per group with a power of 80% and an alpha
      error of 0.05. To cover against a dropout rate of 10%, a total of 98 patients will be
      recruited.

      The patients included in the study will be numbered consecutively and assigned to one of the
      two groups, 'LMA Ambu AuraGain' or 'i-gel', using a computer-generated random number table,
      by the principal investigator. The individual result will be kept in opaque envelopes. After
      the recruitment, the day of the procedure, the enrolling investigator will open sealed,
      opaque envelopes that conceal the group allocation. Participants will be blinded to their
      group allocation.

      Procedures In the operating room, intravenous access will be secured and routine monitoring
      using ECG, non-invasive blood pressure, heart rate, oxygen saturation, end-tidal carbon
      dioxide (EtCO2) and sevoflurane (EtSevo) (Datex-Ohmeda S/5 Compact Critical Care Monitor; GE
      Healthcare). After pre-oxygenation with 100% oxygen by facemask for 3 min, anaesthesia will
      be induced with intravenous Fentanyl 50 μg/ml (2μg/kg), Propofol 1% (2-3 mg/kg) and Rocuronio
      1% (0,6 mg/kg). The investigators will continue ventilating with 100% oxygen using a facemask
      at least for 1 min until optimum conditions for laryngeal mask insertion are achieved (loss
      of eyelash reflex, relaxation of the jaw, immobility, and apnoea).

      Anesthesia will be maintained with Sevoflurane 2% in an air-oxygen mixture using a circle
      system with a fresh gas flow of 2 l/min. Additional intravenous Fentanyl will be
      administrated as clinically needed during anesthesia by an increase of 10-20% in blood
      pressure or heart rate. Laryngeal masks size will be determined according to the
      manufacturers weight-based recommendations and the insertion technique will be according to
      the recommendations of the Instruction Manual. After successful insertion, the cuff will be
      inflated with air until 60 cmH2O intracuff pressure (ICP) measured using an Ambu® airway
      pressure manometer (AMBU, S.L. B- 81040149, Alcala, Madrid, Spain). The second measurement of
      intracuff pressure will be performed for surgeries taking over an hour to ensure that the
      intracuff pressure has not changed significantly (± 5 cmH2O) since the last calibrated
      intracuff pressure. An effective airway will be judged by a square wave capnograph trace,
      bilateral chest auscultation and no audible leak with peak airway pressures at 12 cmH2O or
      greater during gentle manual ventilation. The device will be connected to the respiratory
      machine (Datex-Ohmeda S/5 Compact Critical Care Monitor; GE Healthcare) and patients will be
      ventilated with a tidal volume of 8 ml/kg, adjusting the respiratory rate to an end-tidal CO2
      of 30-35mmHg.

      A gastric tube will be inserted via the drain tube. The correct placement of the gastric tube
      will be confirmed by free movement during insertion and by aspiration of gastric fluid or
      detection of injected air by epigastric auscultation. Oropharyngeal Leak Pressure (OLP) will
      be measured by closing the expiratory valve of the circle system at a fixed gas flow of 3
      liters/min (maximum allowed 40 cmH2O) recording the pressure at which equilibrium has been
      reached or audible air is leaking.

      The leak pressure will be recorded before peritoneal insufflation and during
      pneumoperitoneum. The peritoneal insufflation pressure will be set at 12 mmHg. At the end of
      the surgery, the anesthesiologist will remove the laryngeal masks when the patients obey
      commands. The patients will be transferred to the Post-Anaesthesia Care Unit (PACU) to be
      monitored after the surgery.

      Statistical Analysis Data will be entered into an Excel Database. All statistical analyses
      will be conducted using software from the Statistical Package for the Social Sciences (SPSS,
      Version 18.0, Chicago, IL, USA). The distribution of data will be determined using
      Kolmogorov- Smirnov analysis. The quantitative variables will be summarized with means and
      standard deviations or with medians and percentiles P25 and P75 in case of asymmetric
      distributions, and qualitative variables with frequencies and percentages. To study the
      relationships between qualitative variables, contingency tables will be made and the
      Chi-square or Fisher's tests will be used. The difference in oropharyngeal leak pressure
      (OLP) between two devices will be analyzed by a Student ́s t-test or the Mann-Whitney U test
      in case of non-normal distributions. To compare the incidence of side effects between the
      groups, the exact Fisher test or Chi-squared tests will be used. Significant differences will
      be quantified with 95% confidence intervals.
    

Intervention name(s): Oropharyngeal leak pressure during pneumoperitoneum.
Intervention type(s): Device
Intervention description(s): Oropharyngeal Leak Pressure (OLP) will be measured by closing the expiratory valve of the circle system at a fixed gas flow of 3 litres/min (maximum allowed 40 cmH2O) recording the pressure at which equilibrium has been reached or audible air is leaking.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Other
Keywords: Laryngeal mask; Oropharyngeal leak pressure; Laparoscopic Cholecystectomy