Difficult Airway Management for Intensivists

Published on 26/03/2015 by admin

Filed under Critical Care Medicine

Last modified 26/03/2015

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 3414 times

W1 Difficult Airway Management for Intensivists

image Supraglottic Airway Placement: Before Procedure

Indications

Supraglottic airway placement (SGA) use for managing the airway:

image Anatomy

Though there are a variety of SGAs that occupy the periglottic area and surround the glottic opening with a cuff, most models differ very little except in the manufactured materials, their flexibility or rigidity, ease of use, weight, and effectiveness. Most but not all (e.g., Igel laryngeal mask) have an inflatable cuff that lies in the hypopharynx and essentially seals the supraglottic region (from the epiglottis down the cricopharyngeal sphincter). A sealed airway allows positive pressure ventilation to be delivered but is limited by the effectiveness of the cuff seal/periglottic mucosal surface interface. Many will allow effective delivery of pressure breathing to 10 to 20 cm H2O pressure before leaking, while other models are specifically designed to allow much higher sealing thresholds (25-35 cm). These latter models are particularly effective generating ventilatory support for the obese and morbidly obese patient and when confronted by low pulmonary compliance situations (congestive heart failure, acute respiratory distress syndrome, abdominal distention, pregnancy, ascites, and pulmonary fibrosis).

In general, placement of the SGA can be performed in the exaggerated “sniff” position to the other extreme, a neutral cervical spine. The SGA generally can be placed effectively when faced with little to no neck flexibility. The SGA is lubricated and then passed toward the roof of the mouth across the hard to soft palate, encouraging smooth advancement along the posterior throat so as to minimize getting hung up on the epiglottis. It typically comes to lie with its distal tip in the cricopharyngeal region. Unfortunately, the cuff end may buckle over on itself, come to lie over the glottic opening, or be displaced in a contorted position that impedes effective ventilation and oxygenation. The SGA may indeed be placed incorrectly but still function in near perfect form with effective ventilation; it is a peculiar airway device. It can be forgiving, yet it still requires skill and finesse to place it properly in most situations. Guidance by a skilled and frequent user is the best method to learn the details of its proper use. Ideally, it lies just over the glottic opening and allows access to the trachea. However, the SGA is frequently malpositioned or the epiglottis is folded over to a lesser or greater degree, partially or completely blocking the pathway to the glottic opening, yet ventilation and oxygenation remain unabated. This may be adequate for airflow to and fro but not for the passage of an ETT into the glottic opening. Hence, most generic SGA models do require fiberoptic-guided placement of an ETT because of the uncertain position of the SGA.

image Outcomes and Evidence

The LMA design offers a relatively short learning curve for the airway novice and affords fewer episodes of desaturation, less difficulty in maintenance of a patent airway, larger tidal volume than mask ventilation, and decreased arm and hand fatigue when compared with a conventional face mask. Its value in the ICU setting for assistance during emergency airway management is undeniable, especially during difficult intubation or when ventilation is not possible with a standard bag-mask assembly. Blind or fiberoptic-assisted tracheal intubation is an extremely attractive asset the SGA device offers the clinician and provides an entirely novel rescue approach when conventional laryngoscopy and tracheal intubation prove troublesome or impossible. It is also useful in maintaining airway support in the intensive care unit (ICU) setting for patients who require repetitive general anesthetic or heavy sedation-analgesia for brief procedures, fiberoptic bronchoscopy, or diagnostic visualization of the airway. Recent work suggests that the SGA is better tolerated and produces fewer cardiovascular side effects than tracheal intubation. Insertion in the patient with an unstable cervical spine may be far easier than direct laryngoscopy, because its insertion does not absolutely require neck manipulation.

The device may be difficult to place into the hypopharynx in the presence of a small mouth, a large tongue or tonsils, hypertrophied lingual tissue, or a posteriorly displaced pharynx. However, the SGA often proves easier to use than conventional methods of airway control such as direct laryngoscopy. The threat of gastric dilatation and regurgitation/aspiration may lead some to avoid its use in the critically ill, but its excellent track record and very low incidence of regurgitation/aspiration (0/278 emergency insertions, Hartford Hospital, TCM) supports its role as a primary airway rescue device when conventional methods fail. The role of the SGA as a rescue device in the elective and emergency setting is unparalleled, but further studies into its use in the emergency setting are needed to solidify its standing as the premier rescue airway device, regardless of which model is used.

image Bougie-Assisted Intubation: Before Procedure

Indications

Assist with passing ETT into trachea when limited by the “line of sight”:

Partially obstructed view of laryngeal inlet:

image Procedure

image Anatomy

The ILMA is similar to other SGA devices that occupy the periglottic area and surround the glottic opening with a cuff. Passing the ILMA into the oral cavity is easier than the comparative standard LMA, since is designed with an intrinsic curve that allows easier passage into the hypopharynx. The inflatable cuff lies in the hypopharynx and essentially seals the supraglottic region (from the epiglottis down the cricopharyngeal sphincter). The rigid construction of the ILMA is limited by its diameter, so adequate mouth opening is a prerequisite. The sealed ILMA allows positive-pressure ventilation to be delivered. Occasionally, the ILMA will afford effective ventilation if the standard LMA model fails, and vice versa.

In general, placement of the ILMA can be performed in the exaggerated “sniff” position or the other extreme, a neutral cervical spine. The ILMA is lubricated and then passed along the roof of the mouth across the hard to soft palate, encouraging smooth advancement along the posterior throat so as to minimize getting hung up on the epiglottis or causing its downfolding. The distal tip of the ILMA typically comes to lie with its distal tip in the cricopharyngeal region. Unfortunately, the cuff end may buckle over on itself, come to lie over the glottic opening, or be displaced in a contorted position that impedes effective ventilation and oxygenation (Figures W1-9 through W1-16).

ILMA use should be learned prior to its deployment in an emergency airway crisis. Training on a mannequin or humans under elective conditions by a skilled practitioner is best.

image Procedure

Two maneuvers are handy to improve success in ILMA placement and intubation:

Troubleshooting in the event of failure to intubate (typically caused by a downfolded epiglottis, ETT impaction on the periglottic tissues, too large or too small ILMA, or patient is resisting intubation because of inadequate sedation/analgesia/muscle relaxation/anesthesia):

image After Procedure

Suggested Reading

image Retrograde Wire Intubation: Before Procedure

Indications

image Procedure

Retrograde tracheal intubation: