Essentials of Airway Management, Oxygenation, and Ventilation: Part 2
B Rosenberg, DMD, J. C Phero, DMD, and D. E Becker, DDS
- Part 1 in this series (Click here for the summary of part 1) on emergency airway management focused on basic and fundamental considerations for supplying supplemental oxygen to the spontaneously breathing patient and utilizing a bag-valve-mask system including nasopharyngeal and oropharyngeal airways to deliver oxygen under positive pressure to the apneic patient.
- This article will review the evolution and use of advanced airway devices, specifically supraglottic airways, with the emphasis on the laryngeal mask airway, as the next intervention in difficult airway and ventilation management.
- Management of the unexpected difficult airway during deep sedation and general anesthesia remains the most important aspect in avoiding mortality and morbidity because of the severe consequences of inadequate ventilation and oxygenation, especially in out-of-operating-room locations.1
- The devices are only as good as the clinical judgment of the provider and his or her training and experience. The introduction of any critical airway rescue device must be rehearsed and practiced to assure that the device will, in fact, make the difference in patient safety and outcome.
Supraglottic Airways (SGA)
- An SGA is any airway device that sits outside the larynx and forms a seal around it, permitting increased ventilation pressure between 20 and 40 cm H2O and reducing the chance of gastric distention that can be encountered during face-mask ventilation.
- SGA combines the features of the face mask with those of the endotracheal tube and permits ventilation with more pressure than is possible with face-mask ventilation, as face-mask ventilation may permit drop of the epiglottis, partially or completely blocking the glottis, when ventilation pressure exceeds 20 cm H2O.
- The initial SGA was the esophageal obturator airway, which evolved into the Combi-Tube. Both of these devices had problems related to confirming correct placement, esophageal injury, and limited size availability.
- Although endotracheal intubation has been and continues to be the standard to secure the airway during urgent or emergent situations, the use of an SGA is extremely beneficial as a primary airway rescue device. Rapid control of the airway is critical in airway rescue for patients with acute apnea and/or airway obstruction.
- SGA is a lifesaving maneuver when intubation of the trachea is not an option or not possible within the American Heart Association recommendation of 30 seconds, especially when patient comorbidities may include obesity, bronchospasm, and/or emphysema, which potentially would create bag-mask ventilation pressures greater than 20 cm H2O.
- If the patient is pulseless, the SGA optimizes CPR chest compressions, because once the SGA is placed, there is no need for a pause in the compressions to allow time for ventilations.
- New single-use SGAs possess a gastric port to decompress the pressure in the patient’s gastrointestinal system and provide solutions to the above limitations of the original laryngeal mask airway (LMA).
- The tips of the newer are reinforced to prevent folding and their bodies are more rigid to prevent rotation and allow for easier insertion.
The LMA Supreme (LMA of North America) is a fixed-curve device designed for easier insertion, gastric access, separation of the respiratory and alimentary tracts, and an integral bite block.10
It provides airway management control by integrating gastric venting access and intubation capability in an anatomically curved single-use device that facilitates rapid establishment of a safe airway and an integrated bite absorption area to prevent airway occlusion. This LMA has a bite block and reinforced tip. The LMA cuff must be inflated to guarantee a seal.
The i-gel (Intersurgical) is a noninflatable SGA that is manufactured from medical grade thermoplastic elastomer that creates an anatomical seal of the laryngeal, perilaryngeal, and pharyngeal structures after placement.
The i-gel a) does not require air inflation to seal over the glottis; (b) has a tip that does not flex forward/backward; (c) can vent gastric pressure if bag-mask ventilation has pressurized the stomach; and (d) has a bite block to prevent loss of airway if the patient bites down.
It is a double-lumen, silicone tube with a large oropharyngeal blocking cuff and smaller esophageal blocking cuff that lies in the esophagus below the glottis. The ventilation port is situated between these cuffs.