AMBU AScope2 Fiberoptic Intubation Versus Fastrach Intubating LMA

Supraglottic Airway

Laryngeal Mask Airway, LMA, Intubation, AMBU, AScope, Aura-I, Fastrach, Fiberoptic, Disposable Fiberoptic, Blind Intubation, Fiberoptic Intubation

The purpose of this study is to compare two types of supraglottic airways (SGA), the Ambu® Aura-I and the Intubating Laryngeal Mask Airway (ILMA), regarding time to intubate, ease of insertion, sealing properties, optical view upon fiberoptic examination regarding the Ambu Aura-I, ease and success rate of intubation, airway morbidity, and patient comfort in patients undergoing general anesthesia for elective surgery.

The study will include a total of 66 patients. Patients will be randomized into 2 groups through a computer generated randomization schedule. Patients in group A (N= 30) will be intubated using Ambu Aura-I and the Ambu aScope and patients in group B (N= 30) will be intubated using Intubating LMA. Patients will only be tested with one device.In the operating room, standard monitoring devices will be applied including a pulse oximeter, 3 lead (at least) ECG and blood pressure cuff; the latter could be invasive or non-invasive depending on the nature of the surgery. Baseline measures of BP, pulse, oxygen saturation, and CO2 will be made. The time will be noted before any sedation or anesthesia is administered. Vital signs will be recorded after induction of anesthesia, after insertion of SGA, and again after successful intubation. General anesthesia will be induced by bolus administration of propofol (1.5 to 2mg/kg) and fentanyl (1mcg/kg), and maintained with an inhalational agent. Rocuronium (0.6 mg/kg) will be administered to provide muscle relaxation and a mixture of sevoflurane or isoflurane and nitrous oxide will be utilized for maintenance of anesthesia once the ability to mask ventilate is confirmed. The lungs will be mechanically ventilated with a semi-closed circle system to maintain an end-tidal CO2 near 35 mmHg. Patients' lungs will be ventilated via anesthesia mask 100% oxygen until the patient is completely relaxed. The size of the SGA device used will be based on manufacturer's recommendations and clinical evaluation of the anesthesiologist. The SGA device will be placed using standard technique and jaw lift will always be performed to aid in placement. The user will record ease of insertion on a scale (1-5) and number of insertions required will also be recorded. A new attempt is considered to begin if the tip of the cuff is withdrawn to the level of the lips. Accurate ventilation is achieved when the CO2 signal is rectangular and the mask is airtight at a respiratory pressure of up to 20 cm H2O. Time will be recorded from when the tip of the device cuff is at the mouth opening and stopped when first CO2 waveform is recorded. Once ventilation is achieved, the patients in group A will be intubated through the shaft of Aura-I via the the Ambu aScope. If the epiglottis is down folded and obscuring optical view, jaw lift can be performed by an assistant to improve visualization of the cords. The aScope will be advanced until the carina is visualized and then the ETT is railroaded via the aScope into position (5cm above carina or cuff of ETT just below vocal cords). Once the ETT is successfully inserted, the cuff of the Aura-I will be deflated and the patient is ventilated via the ETT. If it is not possible to intubate, the ETT should be rotated 90° counterclockwise and jaw lift should be performed to help with intubation. If unsuccessful after two attempts, the anesthesiologist will proceed to intubate in standard fashion. The patients in group B will be intubated by ETT via the Intubating LMA as is standard procedure. Once the procedure has finished and the patient is adequately reversed as determined by nerve stimulation, the cuff will be reinflated and the ETT will be removed. Ventilation will resume via the SGA. Once the ETT is withdrawn, the cuff will be adjusted to 60cm H2O using a cuff pressure manometer. The oropharyngeal leak pressure(OLP) is determined with a 60 cm H2O intracuff pressure by closing the expiratory spill valve and then closing the expiratory valve of the circle system at a fixed gas flow of 3 L/min, without any respiration. The airway pressure at which equilibrium is reached and air leaks from the mouth or into the stomach, as sign of leak of the laryngeal mask is noted. Esophageal leak is determined by stethoscopy of the epigastrium and oropharyngeal leak is dectected listening for air leak over the mouth. The peak airway pressure is not allowed to exceed 40 cmH2O. After OLP measurement and once the patient is adequately breathing on their own, the SGA can be removed.

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