Priority Topic: Advanced Cardiac Life Support, Priority Topic: Pneumonia, Priority Topic: Trauma, Procedure: Oral Airway Insertion, Procedure: Bag-and-Mask Ventilation, & Procedure: Endotracheal Intubation

Advanced Cardiac Life Support

Key Feature 5: Ensure adequate ventilation (i.e., with a bag valve mask), and secure the airway in a timely manner. 
Skill: Clinical Reasoning, Selectivity 
Phase: Treatment 

Pneumonia

Key Feature 6: In the patient with pneumonia and early signs of respiratory distress, assess, and reassess periodically, the need for respiratory support (bilevel positive airway pressure, continuous positive airway pressure, intubation) (i.e., look for the need before decompensation occurs).
Skill: Clinical Reasoning, Selectivity
Phase: Treatment

Trauma

Key Feature 4: In trauma patients, secure the airway appropriately (ex: assume cervical spine injury, use conscious sedation, recognize a difficult airway, plan for back-up methods/cricothyrotomy).
Skill: Clinical Reasoning, Selectivity 
Phase: Treatment, Hypothesis generation 

Okay, this is going to be a ridiculously long post that goes over three procedures with regards to resuscitation of airway and breathing. My approach to these procedures comes directly from Procedures Consult: Basic Airway Management, Orotracheal Intubation, Laryngeal Mask Airway Insertion. Consider this whole blog post a direct quotation from these articles, minus the pictures, which are Google originals.

These procedures are life-saving maneuvers to employ in the patient with airway or respiratory compromise, or in those who are at impending risk of failure. There is a delicate balance between performing these intrusive procedures and potentially improving morbidity and mortality outcomes and intervening unnecessarily and causing undue harm. In patients who are in that limbo position, it is important to continue to monitor extremely closely and be prepared for signs of decompensation when they occur to allow for as much time as possible to avoid any of the many complications that may occur when employing these techniques.

​Oral Airway Insertion

Indications
Who needs an oral airway? Anyone with airway obstruction. Reasons for this include:

1. Prolapse of the tongue into the posterior pharynx because of loss of submandibular muscle tone is the most common cause of airway occlusion in an unconscious patient.
2. Other causes of airway obstruction include presence of foreign bodies, blood, and secretions.
3. Noises produced by the obstructed upper airway may make such obstruction easier to detect than poor respiratory effort. As an example, snoring or gurgling noises may be heard when the upper airway becomes partially obstructed by soft tissue or liquid. Complete airway obstruction is silent but may manifest transiently as retractions of the accessory muscles of respiration or cyanosis.

Contraindications
In whom is it contraindicated to insert an oral airway?

1.   Contraindications to oropharyngeal airway
   1. Oropharyngeal airways (OPAs) should only be used in a deeply unresponsive patient who is unable to maintain his or her airway.
   2. OPAs are contraindicated in responsive patients with a gag reflex because of the risk of vomiting and aspiration.
2. Contraindications to nasopharyngeal airway
   1. It is widely accepted that nasopharyngeal airways (NPAs) are contraindicated in patients with basilar skull fractures, because of concern about the airway device entering the cranial vault through a thin, disrupted cribriform plate. This is based on two case reports and must be considered in the risk/benefit assessment of providing airway support at the risk of an extremely rare complication.

Equipment

1. Supplies for universal precautions, including mask, gloves, eye protection
2. Oropharyngeal airway
   1. The OPA is a C-shaped, firm, hollow tube that can maintain a conduit between the mouth and the glottis and prevent the tongue or soft tissues from causing an obstruction. An OPA has a flange that, when properly inserted, rests against the patient's lips to prevent inadvertent inward migration of the OPA. This flange does not interfere with forming an adequate seal from a face mask. OPAs should only be used in a deeply unresponsive patient who is unable to maintain their airway.
   2. OPAs are contraindicated in responsive patients with a gag reflex because of the risk of vomiting and aspiration.
3. Nasopharyngeal airways (two)
   1. Also known as a nasal trumpet, the NPA is a soft rubber or plastic hollow tube that is passed through the nose into the posterior pharynx. It provides a conduit for air to pass and thereby prevents the tongue and other soft tissue from causing occlusion.
   2. It is widely accepted that NPAs are contraindicated in patients with basilar skull fractures, because of concern about the airway device entering the cranial vault through a thin, disrupted cribriform plate. This is based on two case reports and must be considered in the risk/benefit assessment of providing airway support at the risk of an extremely rare complication.
   3. Patients tolerate NPAs more easily than OPAs, so NPAs can be used when the use of an OPA is difficult, such as when the patient's jaw is clenched or the patient is semiconscious and cannot tolerate an OPA.
4. Water-soluble lubricant or anesthetic jelly

Procedure

1. Observe universal precautions, including the use of gloves and face protection, during all airway maneuvers.
2. Head-tilt chin-lift maneuver or jaw-thrust maneuver
   1. ​The head-tilt chin lift is one of two simple airway maneuvers that can improve airflow in the patient receiving basic airway management. It is the primary maneuver used in any patient in whom cervical spine injury is not a concern.
      1. Use one hand to apply downward pressure to the patient's forehead
      2. Use the tips of the index and middle fingers of the other hand to lift the mandible at the mentum. This will lift the tongue away from the posterior pharynx and has been shown in multiple studies to improve airway patency
   2. The jaw-thrust is another maneuver in basic airway management. It is the safest first approach to opening the airway of a casualty with a suspected neck injury. When properly performed, it can generally be accomplished without extending the neck. This maneuver moves the tongue anteriorly with the mandible, minimizing the tongue's ability to obstruct the airway.
      1. Stand at the head of the supine patient's bed.
      2. Place the heels of both hands on the temporal-parietal areas on each side of the patient's head.
      3. Grasp the angles of the mandible with your index and long fingers, and displace the jaw anteriorly.
3. Oropharyngeal airway insertion
   1. Once an open airway has been established, it must be maintained. An OPA is one basic airway adjunct that can help achieve this goal. Unless bag-mask ventilation is expected to be needed only transiently (ex: while naloxone takes effect), an OPA should be placed whenever bag-mask ventilation is required.
   2. OPAs come in multiple sizes. A line between the posterior angles of the mandible approximates the plane of the posterior oropharynx. Therefore, a rough method for choosing the correct OPA size is to hold the airway beside the patient's mandible, orienting it with the flange at the patient's mouth and the tip directed toward the angle of the mandible. The tip of an appropriately sized OPA should just reach the angle of the patient's mandible.
      1. Begin with the curved portion of the OPA inverted (i.e., directed cephalad).
      2. Insert the OPA into the mouth and rotate it 180 degrees as its tip reaches the posterior pharynx. This will prevent pushing the tongue into the posterior pharynx. Alternatively, use a tongue depressor to move the tongue out of the way as the airway device is passed, or simply take care to not push the tongue posteriorly with the tip of the OPA.
      3. The OPA may be supplemented by one, or even two, nasopharyngeal airways to improve oxygenation and ventilation.
4. Nasopharyngeal airway insertion
   1. An NPA is another basic airway adjunct that can maintain airway patency. NPAs come in sizes based on their internal diameter. The larger the internal diameter of the airway, the longer the tube. A length of 8.0 to 9.0 cm is used for a large adult, 7.0 to 8.0 cm for a medium adult, and 6.0 to 7.0 cm for a small adult. Selecting NPAs based on length, rather than diameter, improves accuracy. A rough method for choosing the correct NPA size is to hold the airway beside the patient's mandible, orienting it with the flared end at the tip of the patient's nose and the distal tip directed toward the angle of the mandible. The tip of an appropriately sized NPA should just reach the angle of the patient's mandible.
      1. Lubricate the NPA with water-soluble lubricant or anesthetic jelly. Contact time is insufficient for anesthetic jelly to make insertion more comfortable but may improve tolerance of the device after it is placed.
      2. Insert the NPA along the floor of the naris into the posterior pharynx behind the tongue. The floor of the naris inclines in a caudad orientation approximately 15 degrees.
   2. Using two NPAs (one in each nostril) may improve oxygenation and ventilation.

Things to Consider​

1. Patients requiring basic airway maneuvers or adjuncts will either
   1. Improve to the point of not requiring these devices/techniques, or
   2. Require definitive airway management with endotracheal intubation
2. Possible complications
   1. A common problem associated with basic airway is inadequate airway opening maneuvers: Ensure the jaw-thrust and other maneuvers are being done effectively to open the airway.
   2. Complications of head tilt-chin lift maneuver in a patient with a cervical spine injury: This maneuver should not be attempted in a patient with a potential unstable cervical spine.
   3. OPA complications
      1. Pushing the tongue posteriorly: If the tongue is pushed posteriorly, the airway obstruction will worsen.
      2. Using an incorrectly sized device: Too small a device is ineffective and can be lost in the oropharynx, possibly causing obstruction. Too large a device can press against the epiglottis and obstruct the larynx.
      3. Soft tissue trauma: Catching the tongue or lips (usually the lower lip) between the OPA and the teeth may cause soft tissue trauma. Make sure that the lips and tongue are out of the way before OPA insertion.
      4. Vomiting: Using the device in a patient with intact airway reflexes can induce vomiting. The OPA must be removed if protective reflexes are present.
   4. NPA complications
      1. Using an incorrectly sized device: Using a nasal airway that is too long may cause the tip to enter the esophagus, increasing gastric distention and decreasing ventilation during rescue efforts.
      2. Soft tissue trauma: Injury to the nasal mucosa and subsequent bleeding occurs in 30 percent of insertions and can lead to aspiration of blood or clots.
      3. Intracranial NPA placement: Although there are two case reports of intracranial NPA placement in patients with basilar skull fractures, such extreme complications are rare and can only occur with devastating disruption of the basal skull, improper insertion technique (angling the NPA cephalad in the naris, instead of following the floor of the naris), or both.
         

Bag-and-Mask Ventilation (BMV)

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Indications
Who requires BMV? Anyone with inadequate respiratory effort. Causes may be intrinsic (ex: due to patient disease) or extrinsic (ex: toxins such a opioids). Inadequate respiratory effort may be difficult to ascertain. Detection depends on close observation of chest wall movement and requires that the patient be undressed so the respiratory rate, pattern and depth of breathing, use of accessory muscles, and signs of injury can be seen.

Contraindications
In whom is it contraindicated to provide BMV? 

1. A patient with severe facial trauma or severe airway obstruction (a surgical airway may be indicated instead)
2. A patient with foreign matter in the airway (this should be removed before attempting BMV)
3. A patient with cervical spine injury (not contraindicated per se, but instead of the usual head positioning with neck extended and head thrust forward, instead a jaw thrust manoeuvre is employed)

Equipment

1. Supplies for universal precautions, including mask, gloves, eye protection
2. Mask and positive-pressure ventilation bag

    3. Oxygen supply

Procedure

1. Observe universal precautions, including the use of gloves and face protection, during all airway maneuvers.
2. Head-tilt chin-lift maneuver or jaw-thrust maneuver (as outlined above)
3. BMV
   1. Successful BMV depends on three things: a patent airway, an adequate mask seal, and proper ventilation.
      1. Open the airway. The airway should be opened using the airway maneuvers and devices may be used to optimise this (oropharyngeal or nasopharyngeal airway devices).
      2. Place the mask on the patient's face. The nasal portion of the mask should be spread slightly and placed on the bridge of the patient's nose. The body of the mask is then placed onto the patient's face, covering the nose and mouth. The three facial landmarks that must be covered by the mask are the bridge of the nose, the two malar eminences, and the mandibular alveolar ridge. Neither the wrists of the person performing bag-mask ventilation nor the mask cushion should rest on the patient's eyes during bag-mask ventilation, because this can cause a vagal response or damage to the eyes.
      3. If the mask has an inflatable collar, make sure that the collar is inflated correctly to form an adequate seal.
   2. There are two methods for holding the mask in place: the single-hand (one hand-one person) mask hold and the two-hand (two hand-two person) mask hold. Although the two-hand mask hold is most effective and minimizes provider fatigue, it requires a second clinician. Therefore, it is important to be comfortable with both techniques.
      1. Single-handed technique
         1. Place one hand on the mask with the web space between your thumb and index finger resting against the mask connector.
         2. Place your web space in the center of the mask, to allow for a more even application of pressure.
         3. Do not exert force via the palm of your hand, because it is off center and more likely to produce an air leak.
         4. Place your other three fingers (i.e., middle, ring, and little) along the patient's mandible and pull the mandible up into the mask in a chin-lift maneuver, allowing the airway to open further. The correct technique is to lift the mandible up into the mask with the middle, ring, and little fingers, while holding the mask tightly against the patient's face with the thumb and index finger.
         5. Pull up only on the bony parts of the mandible; pressure to the soft tissues of the neck may occlude the airway.
      2. Two-handed technique
         1. Two operators are required for the two-handed technique for bag-mask ventilation.
         2. One provider's sole responsibility is to use both hands to create a good mask seal and to maintain an open airway, whereas the second provider is responsible for squeezing the bag and ventilation.
         3. The most experienced airway manager available should handle the mask, because proper placement and holding of the mask are essential for a good seal and are the most difficult aspects of bag-mask ventilation.
         4. Use both thumbs and index fingers to hold pressure along the inferior and superior ridges of the mask.
         5. The other three fingers on each hand hold the mandible, in a fashion similar to the one-handed mask hold, and perform a simultaneous chin-lift and jaw-thrust maneuver.
         6. This position may not be comfortable to maintain for long periods of time.
         7. You may also use an alternative technique that uses the stronger thenar eminences to hold the mask in place. The thenar eminences are positioned parallel to each other along the long axis of each side of the mask, allowing the four remaining fingers to provide chin-lift and jaw-thrust maneuvers. This technique is easier to perform, allows stronger hand muscles to maintain a proper seal, minimizing provider fatigue, and enables four fingers to perform the chin-lift and jaw-thrust.
         8. Edentulous patients will be easier to ventilate with dentures in place — the presence of the dental framework in the mouth facilitates mask fit. If the patient is edentulous and does not have dentures, rolls of gauze placed in the mouth between the lips and the gums can aid in a mask seal. Patients with facial hair (beards) can be difficult to ventilate due to poor mask seal related to the beards. Applying KY jelly to the face where the mask contacts skin can form a seal and facilitated ventilation
   3. Connect the bag to the mask and ventilate the patient. Use a tidal volume just large enough to cause chest rise. The ventilatory rate should not exceed 10 to 12 breaths per minute.
   4. Gastric inflation will occur if there is enough pressure to open the gastroesophageal sphincter. This most commonly occurs when the bag is squeezed explosively, the entire volume of the bag is delivered repeatedly, or if the airway is not adequately open and increased pressure is applied. Remember to squeeze the bag steadily over approximately one full second and deliver volumes just enough to cause chest rise.

Things to Consider

1. Patients requiring basic airway maneuvers or bag-mask ventilation will either
   1. Improve to the point of not requiring these devices/techniques, or
   2. Require definitive airway management with endotracheal intubation
2. Possible complications
   1. Common problems associated with basic airway management
      1. Inability to ventilate using the one-handed technique: when ventilation using a one hand-one person technique is unsuccessful despite oral and nasal airway placement, a two hand-two person technique should be used.
      2. Inadequate mask seal: patients with facial hair may need KY jelly or water applied to improve the seal; edentulous patients should have their false teeth reinserted or their cheeks expanded with 4 X 4 gauze.
      3. Improper mask size: ensure that the corners of the mouth and all airway adjuncts are inside the body of the mask, thereby not interfering with the mask seal.
      4. Inadequate airway opening maneuvers:
         1. Ensure the jaw-thrust and other maneuvers are being done effectively to open the airway.
         2. Lack of airway adjuncts (i.e., nasopharyngeal and oropharyngeal airways)
         3. Verify that airway adjuncts are being used and in proper position.
      5. Inexperienced personnel: Determine if a more experienced clinician needs to be recruited to provide effective bag-mask ventilation. In particular, a more experienced operator may be helpful in creating an optimal mask seal.
   2. Complications of head tilt-chin lift maneuver
      1. Cervical spine injury: This maneuver should not be attempted in a patient with a potential unstable cervical spine.
   3. Complications of bag-mask ventilation
      1. Gastric distention: Gastric inflation inhibits maximal lung ventilation. It can also lead to regurgitation and aspiration. In the past, it was believed that these can be avoided during bag-mask ventilation by bagging the patient correctly and by performing the Sellick maneuver. However, in recent years, use of Sellick’s maneuver has garnered some controversy, since improperly positioned pressure or improper amounts of pressure can actually cause airway obstruction and injury. Its effectiveness in preventing aspiration has also been questioned. Should the patient require orotracheal intubation, a nasogastric or orogastric tube should be inserted once the intubation is completed to relieve any gastric distention.

​Endotracheal Intubation

Indications
There are four principal scenarios in which intubation is required and should be done immediately if initial corrective measures fail.

1. Failure of airway maintenance or protection
   1. Sufficient oxygenation and ventilatory effort are reassuring but do not necessarily provide information about airway patency or protection.
   2. Decreased mental states place patients at risk for aspiration of gastric and oropharyngeal secretions, a precursor to chemical pneumonitis and pneumonia.
   3. Airway obstruction can occur in the form of foreign bodies, angioedema, neck hematomas, or simply relaxed hypopharyngeal soft tissue. The latter can occur in patients who are not alert enough to keep this passage open.
   4. Initial measures to open an airway include a jaw thrust, chin lift, and removal of foreign bodies. 
   5. Oropharyngeal and nasopharyngeal airways may bypass select upper airway obstructions, but in patients with impending airway closure or loss of airway protective reflexes, intubation is required.
   6. Clinically, a patient who can phonate and swallow has a patent, protected airway.
2. Failure to oxygenate
   1. The lung’s primary function is to oxygenate pulmonary arterial blood. All vital organs in the body require oxygen to perform cellular respiration. Certain specialized tissues, such as neuronal tissue, undergo irreversible damage if deprived of oxygen for only a few minutes.
   2. Patients with head injury, hypoxia, and hypotension experience accelerated secondary brain injury and worse neurologic outcomes.
   3. With rare exception, persistent hypoxia despite maximum supplemental oxygen requires intubation. Acute cardiogenic pulmonary edema often may be effectively managed with continuous positive noninvasive ventilation, thus avoiding the need for intubation.
3. Failure to ventilate
   1. A by-product of cellular metabolism is carbon dioxide (CO2). Ineffective ventilation results in CO2 retention, acidosis, and ultimately altered mental status. Although CO2 diffuses across alveolar membranes with greater ease than oxygen, airway obstruction, toxic ingestion, or muscular weakness can result in hypopnea and CO2 accumulation.
   2. Patients with acute ventilatory failure, unless immediately reversible, require intubation. Opioid overdose resulting in respiratory depression or arrest may be effectively managed with naloxone. In select patients with acute exacerbations of chronic obstructive pulmonary disease (COPD), bi-level positive airway pressure (BiPAP) can obviate intubation; however, close observation is required because many patients fail BiPAP trials and will require intubation.
4. Expected need for intubation
   1. This criterion for intubation is less straightforward and requires the most judgment.
   2. Frequently, severely ill or injured patients do not meet one of the first three indications for intubation. However, the underlying pathophysiologic process or its treatment may result in hypoxia, hypoventilation, or intense pain; or require the patient to travel outside a monitored setting (ex: to the CT scanner).
   3. One example may be a trauma patient with an open femur fracture and pelvic fracture, complicated by substantial hypotension. The patient arrived awake and talking with normal oxygen saturation but has significant hypotension and incipient shock. In addition to the need for fracture fixation, the patient requires imaging and possibly interventional radiology procedures, both of which require the patient to leave the relatively safe confines of the resuscitation bay. The increasing metabolic burden of the persistent hypotension and the need for prolonged time outside the resuscitation area argue that the patient should have his/her airway protected early to avoid a crisis later.

Contraindications

1. Do Not Resuscitate Order
   1. Endotracheal intubation is lifesaving for many patients and has only one absolute contraindication. Patients, often elderly or chronically ill, who have an advanced directive with a Do Not Resuscitate (DNR)/Do Not Intubate (DNI) order should not be intubated.
2. Tracheal transection
   1. Orotracheal intubation is relatively contraindicated in patients with known or suspected partial transection of the trachea, because the procedure may cause complete transection and subsequent loss of the airway.
   2. Emergent consultation with a thoracic surgeon or otorhinolaryngologist should be obtained if available, because surgical airway management may be necessary.
3. Cervical spine injury
   1. Orotracheal intubation is not contraindicated in patients with cervical spine injuries; however, strict in-line immobilization of the cervical spine must be performed by an assistant.
4. Difficult airway
   1. Difficult orotracheal intubation may arise in a variety of clinical scenarios, including:
      1. Patients with oropharyngeal tumors, trauma, or infection
      2. Patients with limited neck mobility, small mandibles, inability to open the mouth, or pharyngeal structures that are difficult to visualize through an open mouth
   2. If difficult intubation is suspected, then contingency plans, including preparation for an alternative airway control technique (ex: laryngeal mask airway insertion, surgical airway management, or fiberoptic airway technique) and emergent specialist consultation, should be made.

Equipment

1. Equipment for universal precautions (mask, gloves, etc.)
2. Standard direct laryngoscope
   1. Laryngoscope blades
      1. Types of Laryngoscope Blades
         1. Macintosh/curved blades
            1. This blade has a gentle curve and is designed to have its tip placed in the vallecula.
            2. With gentle forward and upward pressure the epiglottis is elevated indirectly to expose the vocal cords.
         2. Miller/straight blades
            1. This blade is straight and should be placed under the epiglottis and lifted directly to expose the vocal cords.
         3. The choice of blade is based on operator preference and experience. Pediatric patients are often easier to intubate using a straight blade because of the pliability of the tissues of the upper respiratory tract, but either blade can be used. For infants, use a straight blade.
      2. Laryngoscope handle with batteries
3. ETTs and accessories
   1. ETTs, variable sizes
      1. Various sizes are available depending on the patient's size, weight, or length.
      2. A 7.0 or 7.5 ETT will suffice for most normal-sized adult patients.
      3. A smaller backup tube should always be available in case the larger tube cannot navigate the laryngeal inlet.
      4. A water-based lubricant should be applied to the cuff of the ETT. This provides a better seal, reduces friction during placement, and decreases aspiration.
   2. Malleable ETT stylet
      1. A malleable stylet should be used during intubation to provide shape and strength to the ETT.
      2. It is inserted into the lumen of the tube with the tip inside the ETT, 1 to 2 cm from the end of the ETT.
      3. Do not let the stylet protrude beyond the ETT tip, because this can cause airway trauma.
      4. A 20- to 30-degree angle should be introduced proximal to the cuff. Angles greater than 35 degrees have been associated with an increased rate of difficult or impossible intubation.
   3. 10-mL syringe
   4. ETT tape or commercial ETT holder
4. Basic airway equipment
   1. Bag and mask ventilation device
   2. Oropharyngeal and/or nasopharyngeal airways
   3. Oxygen source and tubing
5. Sedative and NMB agents
   1. Sedatives
      1. In the absence of a planned “awake” intubation of a patient with an identified difficult intubation, an induction agent (potent sedative given in a dose capable of inducing general anesthesia) is administered before intubation, using a rapid sequence technique. Rapidly acting agents, such as etomidate or propofol, are excellent induction agents.
   2. NMB agents
      1. Depolarizing: Succinylcholine is the only depolarizing NMB agent approved in the United States and is the most commonly used paralytic during emergent airway management. At a dose of 1.5 mg/kg, it induces paralysis within 45 to 60 seconds by maintaining open ion channels at the neuromuscular junction. This prevents repolarization and further muscular activity. It should NOT be used in patients at risk for succinylcholine-induced hyperkalemia (examples include patients with burns, recent high-spinal paralysis, neuro-muscular disease, Guillain-Barré, known history or family history of malignant hyperthermia, and end-stage renal disease).
      2. Nondepolarizing (competitive): Vecuronium and rocuronium are commonly used in patients with contraindications to succinylcholine. They can be used as first line agents as well. Rocuronium in a dose of 1 mg/kg provides relaxation times approaching those achieved with succinylcholine.
      3. Disadvantages to vecuronium and rocuronium, however, are significant: significantly longer time to achieve intubation conditions, and significantly longer time for return of spontaneous ventilation in the case of failed intubation. A recent Cochrane Database review comparing rocuronium versus succinylcholine concluded that succinylcholine was superior to rocuronium in providing excellent intubation conditions for rapid sequence induction and intubation.
6. Water-based lubricant
7. Yankauer suction catheter and tubing
8. General resuscitation equipment
   1. Peripheral IV (in place)
   2. Cardiac monitor
   3. Oxygen saturation probe
   4. Blood pressure cuff
9. End-tidal CO2 detector
10. Rescue devices
    1. Laryngeal mask airway or laryngeal tube
       1. When intubation is unsuccessful but ventilation is possible, an extraglottic rescue device, such as a laryngeal mask airway (LMA) or Combitube, may be used to ventilate the patient until assistance can be obtained, or a plan can be made to place a definitive airway. Both devices are easy and quick to place, even in the hands of a novice. (See below for laryngeal mask airway insertion.)
       2. The Combitube has the advantage of higher leak pressures compared to a standard LMA, so it may be more effective in patients with high ventilatory resistance, such as those with acute asthma or chronic obstructive pulmonary disease (COPD).
    2. Intubating stylet (bougie)
       1. Intubating stylets should be immediately available for use when direct laryngoscopy provides suboptimal (partial) view of the cords, because they can serve as an effective adjunct for difficult airways.
       2. An intubating stylet is a thin, hard, plastic rod angled anteriorly at the distal tip.
       3. When placed in the trachea, the curved tip runs along the tracheal rings, providing tactile feedback that confirms its location.
       4. An ETT can then be placed over the stylet using a Seldinger type of technique.
11. Ventilator

Procedure

1. Explain the procedure
   1. If the patient is conscious, explain in plain terms the reason for intubation and that he/she will be asleep and kept comfortable until the breathing tube can be removed.
   2. Inform any family members present, and exclude DNR/DNI status.
   3. Consent is not required in emergency situations.
2. Assess the airway
   1. Before intubation, perform an airway assessment.
      1. Intubation success correlates directly with how visible the vocal cords are.
      2. Certain patient characteristics result in poor upper airway geometry, difficult laryngoscopy, poor cord view, and subsequently higher failed intubation rates. These characteristics include poor mouth opening, large tongue, short mandible, reduced neck mobility, and airway obstruction.
      3. Mallampati et al. correlated the number of posterior pharyngeal structures viewed through the patient’s mouth with failed intubation rates and developed four classes ranging from class 1 (full view) to class 4 (tongue only). Mallampati class 4 was found in preoperative patients to be associated with a 10% failed airway rate. Although this has subsequently been shown to be a crude estimate at best, a Mallampati class 4 should raise your suspicion for a difficult airway.
   2. Patients who exhibit certain characteristics can be both difficult to ventilate with a bag-mask and/or intubate.
      1. Difficult airway assessment must be performed before undertaking intubation, especially when using neuromuscular blocking agents. Predicted difficulty with bag and mask ventilation changes the approach, such that muscle relaxants should be used only with great care and consideration or avoided altogether (because of the potential for inability to intubate a patient who is paralyzed and sedated). Failed placement of an endotracheal tube after paralysis results in one of two subsequent scenarios: you can't intubate but can ventilate, or you can't intubate and can't ventilate. The latter is obviously a potentially fatal occurrence.
3. Assess for difficult bag-valve-mask ventilation.
           MOANS
               Mask seal difficulty (ex: bearded, abnormal facial structure or trauma)
               Obesity (due to redundant upper airway tissue)
               Advanced Age
               No teeth (poor mask seal results)
               Stiffness with ventilation (resistance to ventilation)
4. If difficulty with either bag and mask ventilation or intubation is likely, an individual with expertise in airway management should be called, if available, for assistance.
5. Position the patient
   1. Position the patient so that his head is at the end of the bed. The bed height should be comfortable for the operator; generally, the patient’s head should be at the level of your sternum.
6. Just before intubation, place the patient into the “sniffing position”
   1. Flex the neck on the body and extend the head on the neck to achieve the sniffing position. This maneuver aligns the axes of the oral cavity, pharynx, and larynx and facilitates direct visualization of the glottic structures.
7. Prepare the equipment
   1. Gather and check the working status of all the required equipment before administering sedatives or muscle relaxants.
8. Preoxygenate the patient
   1. If the need for intubation is not immediate, preoxygenate all patients with 100% high flow O2 by nonrebreather mask for at least 3 to 4 minutes.
   2. If the patient does not have effective ventilation to begin with, or the oxygen saturation does not increase above 90% with supplemental oxygen, use bag and mask ventilation rather than a face mask.
      1. Proper alveolar saturation with 100% oxygen allows a longer period of safe apnea before desaturation (SaO2<90%) occurs. In general, if you are able, you should preoxygenate the patient without bagging (to limit gastric insufflation and aspiration). If the patient desaturates during the intubation sequence and an ETT is not in place, stop the attempt and initiate two-person bag ventilation supported by insertion of an oral airway. (See above)
9. Sedate and paralyze the patient.
   1. Rapidly acting sedatives coupled with NMBs result in the best possible intubating conditions by creating a comatose, relaxed state and allowing the least amount of resistance during laryngoscopy.
   2. The combination of etomidate or propofol with either succinylcholine or rocuronium will achieve optimal intubating states in less than 1 minute in nearly all patients.
   3. The use of sedatives and paralytics (i.e., rapid sequence induction) is safe and highly successful with few complications when used in appropriately selected patients. If paralysis is contraindicated, based on the difficult airway assessment, then use lower doses of etomidate and midazolam along with fentanyl and/or topical anesthetics to perform “awake” laryngoscopy (during which the patient maintains spontaneous respirations).
   4. As soon as the paralytic medication is given, an assistant should apply direct posterior pressure on the cricoid cartilage (Sellick maneuver). This may help prevent aspiration and should be maintained during the entire procedure until the endotracheal cuff is up and tube placement is confirmed.
10. Perform laryngoscopy
    1. Grasp the laryngoscope.
    2. Hold the laryngoscope with your left hand, regardless of which hand is dominant.
    3. Cradle the laryngoscope handle between the pads of the fingers and thumb as you insert it into the patient’s mouth.
    4. Firmly grip the proximal portion of the handle and back of the blade while you visualize the vocal cords.
11. Place the patient into the “sniffing position.”
    1. Flex the neck on the body and extend the head on the neck to achieve the sniffing position. This maneuver aligns the axes of the oral cavity, pharynx, and larynx and facilitates direct visualization of the glottic structures.
    2. This maneuver is contraindicated in patients with suspected or known cervical trauma.
12. Insert the laryngoscope blade into the mouth.
    1. Once the patient is relaxed and in good position, open the mouth using the “scissor” technique with your right hand. Push the upper and lower rows of teeth apart with your index finger and thumb. If false teeth are present, remove them.
    2. Gently insert the laryngoscope blade along the right side of the tongue. Make sure there is neither the lip nor tongue caught between the blade and the patient’s teeth.
    3. With gentle but firm lifting pressure, displace the tongue forward and to the left into the mandibular fossa
13. Visualise the glottic structures.
    1. First, identify the epiglottis.
    2. Correct positioning of the tip of the laryngoscope blade depends on whether a curved or straight blade is used.
       1. Place the tip of the curved blade into the vallecula (anterior to the epiglottis), and lift anteriorly to expose the vocal cords.
       2. Place the tip of a straight blade under (posterior to) the epiglottis, and lift anteriorly to expose the vocal cords.
    3. Once the tip of the blade has been correctly positioned, lift the laryngoscope forward and upwards. Direct the force along the axis of the laryngoscope blade, aimed at the ceiling over the patient’s feet
    4. Avoid rotating the blade handle backward, because this can damage both the teeth and structures near the blade tip and does not improve the view of the glottis.
    5. In some cases, you can see the laryngeal inlet on the first attempt without the use of excessive lifting force or external manipulation. If this does not occur, confirm that the blade is midline, then search for identifiable structures. Are the epiglottis, arytenoid cartilages, or part of the vocal cords seen? If so, you may need to advance the laryngoscope, reposition the patient’s head, or apply extra lifting force. Occasionally, the application of cricoid pressure may obscure the view of the glottis. In that case, partially or completely release the cricoid pressure.
    6. Having an assistant apply backward, upward, rightward pressure to the larynx (the “BURP” maneuver) may be useful if midline structures are identified but cords are not seen. This pushes the larynx inferiorly and has been shown to improve laryngoscopic view during most intubations
14. Once you see the vocal cords, do not take your eyes off the target.
15. Occasionally, there is a poor view of the glottic opening and the vocal cords cannot be visualized. You may make one attempt to place the tube just under the very middle of the epiglottis.
16. Insert the endotracheal tube.
    1. Ask an assistant to place the ETT in your right hand.
    2. Introduce the ETT into the right side of the patient’s mouth and run along the course of the laryngoscope blade towards the larynx. Do not insert the tube along the midline, because this will obstruct your view of the glottis
    3. Watch the tube traverse the cords into the trachea, and then advance it so that the tip of the tube lays about 4 cm distal to the cords.
    4. Use of a malleable stylet that is shaped in either a gentle curve or straight with a 20- to 30-degree angle proximal to the cuff (i.e., “hockey-stick”) will facilitate intubation.
    5. Having an assistant pull gently outward on the right cheek may improve working space and visualization in the oral cavity
17. Inflate the balloon
    1. Inflate the endotracheal cuff balloon with air, using a 10-mL syringe.
    2. Use only enough air to prevent air leaks during tidal volume ventilation. This usually requires less than 10 mL of air.
18. Confirm tube placement
    1. Place the end-tidal CO2 detector in-line between the bag-valve mask and the ETT. Most end-tidal CO2detectors will change color when exposed to exhaled carbon dioxide. Although visualization of tube placement and auscultation are important steps in confirmation of ETT placement, the most accurate way to confirm tracheal tube placement is by end-tidal CO2detection.
       1. End-tidal CO2detection may be inaccurate during cardiopulmonary resuscitation because of impaired pulmonary gas exchange.
    2. Auscultate over the epigastrium to assess for gurgling, which indicates esophageal placement. Also auscultate each lung in the midaxillary region to assess for symmetrical breath sounds. If lung sounds are heard on the right side but not the left, right main-stem bronchus intubation has likely occurred, and the tube should be withdrawn until symmetrical sounds are heard.
19. Troubleshooting
    1. Poor glottic exposure: If you have difficulty obtaining a view of the cords during direct laryngoscopy, there are several things that can help.
       1. Patient position: Make sure the patient is in the sniffing position, if appropriate. Maintain a neutral position in patients with cervical spine precautions.
       2. Blade choice: A curved blade may not be as good as a straight blade in situations where the epiglottis is large and excessively mobile. Switching to a straight blade may provide a better view.
       3. BURP maneuver: This maneuver can improve the laryngoscopic view and should be applied if the initial view is poor. You can also manipulate the larynx with the right hand during direct laryngoscopy to determine the best positioning of the larynx for optimal view (OELM: Optimal External Laryngeal Manipulation).
       4. Paralysis: Allow adequate time after giving a paralytic to achieve full relaxation. Premature attempts at laryngoscopy before paralysis can be difficult or impossible.
          1. If more than 3 minutes has elapsed and paralysis is incomplete, then make sure the IV is working and the dose of paralytic was correct. More medication may be required.
       5. Release of cricoid pressure may improve the view.
    2. Inability to pass an ETT through the cords
       1. Obstruction or edema may make passage of an ETT difficult or impossible despite an adequate view of the vocal cords.
       2. Try a smaller ETT. If an 8.0 tube does not fit, attempt intubation with a 7.0 tube.
       3. Make sure a malleable stylet is in the ETT. This provides shape and stiffness that is helpful in navigating mild laryngeal narrowing.
       4. Make sure the shape of the stylet is either a gentle curve or straight with a 20- to 30-degree angle placed proximal to the cuff. Exaggerated angles will make placement of the ETT into a narrow, straight tube like the trachea more difficult.

Things to Consider

1. Postprocedure 
   1. Secure the ETT.
      1. Once the ETT placement is confirmed by end-tidal CO2 measurement and auscultation, secure the tube to the patient.
         1. A variety of commercially manufactured endotracheal tube holders are available and should be used preferentially over tape.
         2. Endotracheal tube tape may be used if an ETT holder is not available. First secure the tape to the patient’s cheek, then wrap it circumferentially around the tube, and finally secure it to the other cheek.
   2. Obtain a chest radiograph
      1. The radiograph may be useful in detecting intubation of a main stem bronchus or complications of mechanical ventilation, such as pneumothorax.
      2. Always obtain a portable chest x-ray after intubation to evaluate the depth of insertion of the endotracheal tube. The tip of the ETT should be positioned in the midtrachea, with the tip several centimeters above the carina.
   3. Insert a nasogastric or orogastric tube.
      1. Insert a nasogastric or orogastric tube after intubation and place it on continuous low wall suction. (See nasogastric tube insertion above.)
         1. Even with a cuffed endotracheal tube in place, aspiration is possible.
         2. Although most aspiration pneumonias are from oropharyngeal (not gastric) secretions, paralyzed patients do not have esophageal sphincter tone and may have stomach dilatation resulting in reflux of gastric contents
   4. Check arterial blood gases.
      1. This is not required immediately after intubation but should be checked within 10 to 15 minutes, and periodically thereafter, to assess the effectiveness of ventilation. 
   5. Continue sedation and pain control.
      1. Infusions of midazolam and fentanyl are commonly used to maintain sedation and control pain
      2. Maintain adequate sedation, pain control, and, if necessary, paralysis.
2. Complications
   1. Unrecognised esophageal intubation
      1. Intubation of the esophagus, if undetected, results in gastric insufflation, vagal nerve stimulation with severe bradycardia, and possibly perforation.
      2. More importantly, failure to intubate the trachea results in hypoxia, hypercapnia, and eventually death.
      3. Esophageal intubation is easily recognized through the routine use of end-tidal CO2detectors, pulse oximetry, and auscultation.
      4. Esophageal intubation should normally be immediately apparent and corrected. Failure to detect and correct esophageal intubation constitutes malpractice.
   2. Main-stem intubation
      1. There are no data to suggest that main-stem intubation is immediately dangerous, but it should be recognized quickly and corrected.
      2. Assess for main-stem intubation via auscultation to confirm bilateral breath sounds, and confirm appropriate ETT placement with a portable chest radiograph.
   3. Dental, pharyngeal, and airway trauma
      1. The rate of dental and airway trauma is unknown but likely correlates inversely with experience and directly with intubation difficulty.
      2. Dental trauma is often seen when backward rotation is placed on the laryngoscope, resulting in cracking or fracture of the upper incisors from the proximal part of the blade.
      3. Pharyngeal and upper airway trauma from the blade tip can occur during difficult laryngoscopic attempts, when excessive force can cause blunt trauma, bleeding, cord edema, or pharyngeal perforation.
         
         

​Laryngeal Mask Airway Insertion

Indications

1. Primary rescue adjunct in the difficult airway
   1. The LMA is a rescue device for adult emergency airway management
   2. The LMA is a usually successful rescue device for rescue ventilation in the “cannot-intubate/cannot-ventilate” situation.
   3. The LMA allows adequate ventilation in 98% of adults with known difficult airways and in 90% to 95% of those with unexpected difficult airways.
   4. The LMA is useful in patients with brisk bleeding above the glottis or with difficult face-mask ventilation due to a beard, severe facial trauma, or obesity.
2. Potential backup device for difficult pediatric airways
   1. The LMA should be considered as a primary rescue device for pediatric emergency airway management
   2. The LMA is particularly useful as a rescue device in difficult pediatric airways. There are two descriptive studies and case reports describing the use of the LMA for difficult pediatric airways. In these reports, ventilation was adequate with the LMA in nearly all pediatric patients.
   3. Intubation of pediatric patients through the LMA is usually possible with a small fiberoptic scope.
   4. Case series and case reports also suggest that the LMA can provide an effective rescue airway in neonatal resuscitation if bag-mask ventilation and endotracheal intubation fail.
3. Rescue device in cases of failed bag-mask ventilation
   1. The LMA may provide a more secure and reliable means of ventilation than a face-mask.
4. Difficult intubation
   1. Patients who are difficult to intubate by direct laryngoscopy are often easy to intubate with the LMA, because many anatomic factors that cause difficult direct laryngoscopy do not affect placement or function of the LMA devices.
5. Situations in which airway control is desirable but tracheal intubation is difficult or contraindicated
   1. Patients trapped in sitting position
   2. Suspected cervical spine trauma
   3. Inability to extend or rotate the cervical spine
      1. Severe rheumatoid arthritis or osteoarthritis
      2. History of cervical spine fusion
      3. History of atlantoaxial dislocation

Contraindications

1. The LMA is relatively contraindicated in awake patients, especially those with a full stomach.
   1. Insertion of the LMA in an awake patient will cause coughing, gagging, or vomiting. If the LMA is inserted when the patient is awake and the stomach is full, vomiting and aspiration may occur.
   2. In an emergency, the LMA should only be used if the patient is unconscious or after paralytic agents have been given.
   3. Once the LMA is inserted and ventilation is established, the patient should not be allowed to wake up fully, because this will elicit gagging.
   4. Consider using a long-acting paralytic agent or multiple doses of succinylcholine, with adequate sedation, once adequate ventilation is established.
2. Decreased mouth opening may make insertion of the LMA difficult or impossible.
3. Insertion of the LMA may also be difficult or impossible in patients with severely distorted upper airway anatomy, especially those with scarring secondary to cervical radiation therapy.
4. Conditions predisposing to aspiration
   1. Full stomach
   2. Intestinal obstruction
   3. Severe gastrointestinal reflux disease
   4. History of gastric bypass
   5. Second or third trimester pregnancy
5. Major trauma to the maxilla, mandible or larynx
6. Unusual operative position (ex: prone)
7. Major intrathoracic or intraabdominal surgery
8. Morbidly obese patients requiring high inspiratory pressures
9. Tracheoesophageal fistula
   
   

Equipment

1. Equipment for mask ventilation, including emergency medications, supplies, and equipment
2. Suction equipment
3. Lubricating jelly
4. Tape to secure the LMA after placement
5. Source of supplemental oxygen
6. LMA device
   1. All of the LMA devices consist of an airway tube attached to an oval mask, which is rimmed by an inflatable cuff. The cuffed mask is designed to form a seal around the glottis when the device is properly placed
   2. It is important to realize that there are several different types of LMA devices. For emergency airway management, the original LMA and the intubating LMA are the most practical.
      1. Emergency airway providers should be aware that the procedure for placing the ILMA is much different from the procedure for placing the LMA. It is prudent to learn how to use both devices, because many emergency departments use the ILMA in adults and the LMA in children.
      2. The intubating LMA is called the LMA Fastrach, and it is specially designed to facilitate tracheal intubation. There is a disposable version of the intubating LMA called the LMA Fastrach Single Use.
   3. The original LMA is now called the LMA Classic. The LMA Classic can be used up to 40 times before being replaced.
   4. There is a disposable version of the original LMA called the LMA Unique. The LMA Unique is a single-use version of the LMA Classic. The LMA Unique has the same dimensions as LMA Classic but is made out of plastic instead of silicone and is less expensive.
   5. The LMA Classic and LMA Unique are both available in all sizes up to 5, including pediatric and neonatal sizes. The Classic is also currently available in size 6.
   6. The LMA is less expensive than the ILMA, but insertion and tracheal intubation through this device are more complicated.
      

Procedure

1. Positioning of patient
   
   1. The best patient position for LMA insertion is the sniffing position, with the neck flexed and the head extended, unless the patient has a suspected or known neck injury
      
2. Preparation
   
   1. Use universal precautions
      
   2. Informed consent is not necessary and often not possible in an emergency situation; however, when possible, consent should be obtained.
      
3. Placement of the LMA
   
   1. Select the appropriate size LMA.
      
      1. The LMA is available in a wide range of sizes, from size 1 for neonates weighing < 5 kg to size 6 for adults weighing > 100 kg. The disposable version is available in sizes 1 through 5, but not size 6
         
   2. After selecting the proper size, completely deflate the LMA cuff while pushing it posteriorly, so that it forms a smooth wedge shape without any wrinkles.
      
   3. Place a small amount of water-based lubricant onto the posterior surface of the LMA mask just before insertion.
      
   4. Finger insertion technique
      
      1. Hold the LMA like a pen, with the index finger at the junction of the airway tube and the cuff
         
      2. Have an assistant open the patient’s mouth.
         
      3. Insert the LMA with the posterior tip pressed against the hard palate just behind the upper incisors., and the “bowl” of the LMA facing downward (toward the larynx instead of the palate)
         
      4. Under direct vision use the index finger to slide the LMA along the hard palate and into the oropharynx 
         
      5. As the LMA is inserted further, extend the index finger and push the posterior cuff along the soft palate and into the posterior pharynx.
         
      6. Use your other hand to exert counterpressure on the back of the patient’s head during insertion.
         
      7. Push the LMA into the hypopharynx until you feel resistance.
         
      8. Use the other hand to hold the proximal end of the LMA airway tube while you remove your index finger from the patient’s mouth
         
      9. Significant resistance as the tip enters the back of the mouth often reflects obstruction by the relaxed tongue. Several maneuvers can be used to ease passage
         
         1. Simple jaw thrust
            
         2. Lifting the tongue out of the mouth by grasping the tip with two fingers using an unfurled, cotton 4 x 4; and
            
         3. Direct laryngoscopy
            
   5. After the LMA is fully inserted, let go of the proximal end of the airway tube and inflate the cuff enough to achieve a good seal with the glottis. This may only require half of the maximum cuff volume. Never overinflate the LMA cuff (see the product packaging for maximal cuff volumes).
      
   6. Attach a bag and ventilate the patient, using chest rise, breath sounds, and capnography to confirm adequate gas exchange.
      
   7. If bagging is easy and there is good ventilation, the aperture of the LMA is probably correctly aligned over the glottic opening. Proper positioning of the LMA aperture with the glottic opening allows optimal ventilation.
      
4. Troubleshooting inadequate ventilation
   
   1. The best way to ensure proper ventilation is to optimize the insertion technique by carefully following the above directions, positioning the patient’s head and neck properly, and ensuring that the patient is deeply anesthetized or paralyzed.
      
   2. Listen for an audible cuff leak to ensure a good mask seal. It may be necessary to adjust the cuff volume to improve the mask seal and ensure optimal ventilation.
      
      1. Just adding more air to the cuff will not necessarily improve the mask seal with the glottis. Cuff overinflation may cause a leak, while deflation and repositioning may improve the seal.
         
   3. Moving the patient into a better sniffing position or into the chin-to-chest position may significantly improve the LMA cuff seal. Adjusting the patient’s head and neck position may be easier than trying to change the position of the LMA.
      1. If a better sniffing position or moving the patient into the chin-to-chest position does not help or is not possible, try a jaw-thrust or a chin-lift maneuver.
         
   4. It may be useful to apply anterior neck pressure to help push the glottis down into contact with the LMA mask. This technique can be used in combination with any of the above maneuver
      
   5. If simple positional maneuvers fail to correct inadequate ventilation
      
      1. Consider withdrawing, advancing, or rotating the LMA cuff.
         
      2. Consider completely removing and reinserting the LMA, with careful attention to the details described above.
         
      3. Consider changing LMA size. Using a larger size LMA will usually improve ventilation even if it is more difficult to insert. It is much more common to need to increase LMA size rather than decrease LMA size.
         
      4. Consider using the ILMA or the Combitube or performing a surgical airway when ventilation with the LMA is not adequate.

Things to Consider

1. Postprocedure
   1. Confirm adequate airway placement by checking for bilateral breath sounds and chest movement with ventilation.
      
   2. After successful placement of the LMA, placement of an endotracheal tube may be indicated in patients who require ongoing airway management.
      
      1. The first method is simply to pass an appropriately sized endotracheal tube down the lumen of the LMA, rotate the tube 90 degrees so that the tip easily passes through the fenestrations, and advance it through the larynx to the trachea. Success rates vary widely from 0% to 93% depending on operator experience and technique.
         
      2. The second method involves the use of a tracheal tube exchanger or gum elastic bougie passed blindly down the lumen of the LMA and into the trachea. The LMA is then removed and an endotracheal tube is passed over the tracheal tube exchanger. The more flexible bougie may be preferable, as the tube exchanger has been shown to pass into the esophagus in up to 70% of attempts.
         
      3. The third and most dependable method of intubation with an LMA in place is via a fiberoptic scope. A lubricated, appropriately sized endotracheal tube is mounted over a fiberoptic scope, and this combination is advanced through the lumen of the LMA, out through the mask, and through the larynx. The scope is then removed, but the LMA may be left in place with the cuff deflated.
         
      4. If the LMA must be removed after a tracheal tube has been successfully placed through it, pass a tracheal tube exchanger down the tube, remove the tracheal tube/LMA combination, and replace it with a tracheal tube. After any manipulation of the LMA or with any tracheal tube placement, ventilation of the lungs must be confirmed
         
2. Possible complications
   1. Aspiration of gastric contents
      
      1. The most important complications associated with using the LMA are aspiration of gastric contents and hypoxia. Providers should remember that the LMA does not protect against aspiration and may actually cause vomiting if the patient reacts to placement of the device. A 2004 case series and review of aspiration with the LMA Classic reaffirms the extremely low rate of aspiration with the LMA (est. <0.02%) that is similar to the rate with endotracheal intubation. The series reaffirms the importance of avoidance of LMA use in patients with increased baseline aspiration risk while also demonstrating that significant aspiration can occur regardless of ventilation strategy employed. A 2010 systematic review examining risks of airway complications with LMA versus endotracheal tubes for general anesthesia, risks of aspiration were not significantly different between groups, while risks of sore throat, coughing on emergence, and hoarseness were greater with endotracheal intubation versus LMA insertion.
         
      2. In fasted, anesthetized patients the incidence of aspiration is very low, about 2 per 10,000 cases. There are many descriptive studies and case reports of LMA use for difficult airways with no mention of significant aspiration.
         
      3. Although the risk for aspiration is surely higher than 2 per 10,000 when the LMA is used as a rescue device in the emergency setting, there is evidence that it provides some protection from passive regurgitation and produces less gastric inflation than bag-mask ventilation.
         
   2. Failure to adequately ventilate and oxygenate
      
      1. Difficult or failed bag-mask ventilation and failed intubation are the most common reasons for using the LMA in the emergency setting. In this situation, failure to adequately ventilate and oxygenate with the LMA occurs in about 6% of cases. Another 6% of patients with difficult airways will suffer episodes of hypoxia during attempts to intubate through the LMA.
         
      2. There is evidence that the ILMA performs better in the “cannot-intubate/cannot-ventilate” situation. Failure to ventilate with the ILMA occurs in only about 2% of cases, and hypoxia after ILMA placement is very rare. Also, there are more technical difficulties when using the LMA, compared to the ILMA, for difficult airways. This is probably due to the fact that the LMA requires more skill for proper insertion and was not specifically designed to facilitate tracheal intubation.