There are multiple devices and airway adjuncts available to help the laryngoscopist obtain and secure the difficult airway. Airway adjuncts include ETT guides, lighted stylets, rigid laryngoscopes, indirect rigid fiberoptic laryngoscopes, flexible FOBs, supraglottic ventilation devices, videoscopes, and any device or piece of equipment that supports airway management.5 Ultimately, the selection of an airway adjunct for airway management is based on familiarity and skill with the device, as well as (1) the need for airway control; (2) the ease of laryngoscopy; (3) the ability to use supralaryngeal ventilation; (4) aspiration risk; and (5) the patient’s tolerance for apnea.8
Failed or difficult and prolonged intubation may be associated with several complications such as oxyhemoglobin desaturation, sympathetic stimulation leading to hypertension and tachycardia, and even hypoxemic cardiac arrest causing permanent neurological sequel or death.3 (Learn more about airway history and assessments in “Difficult Airways—Part 1“). The standard procedure for securing the airway is endotracheal intubation by means of conventional direct laryngoscopy (DL)6
Despite the unpredictability and urgency of emergency intubation, the success rate of DL usually exceeds 85%.10 However, intubation safety may be affected by the short preparation time, the possible lack of control over events in the vicinity, the varying degree of training of the persons performing the intubation, and the patient’s unstable state and lowered cardiorespiratory reserves.6
Intubation with direct laryngoscopy requires flexing the lower cervical spine and extending the upper cervical spine to create a “line of sight,” and a Macintosh blade is commonly used to retract the tongue to enable passage of a tracheal tube.3 Failed or difficult intubation is associated with complications, including increased risk of hypertension, desaturation, unexpected admissions to the intensive care unit (ICU) and death.7
There are indications of a strongly positive correlation between the number of intubation attempts and the rate of complications.11 To increase the safety of intubation, therefore, the number of intubation attempts should be minimized, and the first-pass success rate maximized.6
Alternatives to the Macintosh blade rely on fiberoptic or digital technology to transmit an image from the tip of the laryngoscope to an eyepiece or monitor, where it is viewed by the intubator.3 Video laryngoscopy (VL) visualizes the vocal cord level indirectly by means of an inbuilt camera and a video screen, thus significantly improving the view of the glottis.3 VL can be used in the event of failure to achieve intubation with DL.1
One example of a video laryngoscope is the GlideScope (GS; Verathon Inc.). In the hands of the novice, GS has been shown to have higher intubation success rates than conventional DL.2 GlideScope has been shown to be of some benefit in the known or suspected difficult airway, providing an improved view of the glottic opening, albeit requiring longer time to intubate and not always yielding higher success in placing the endotracheal (ET) tube.12 Other benefits of the GlideScope include the following: tracheal tube exchange in the critical care setting, facilitation of the placement of nasogastric tubes, removal of hypopharyngeal foreign bodies, awake intubation in the patient with traumatic cervical spine injury, minimizing increase in intraocular pressure during intubation before eye surgery for traumatic injury, and rescue after failed flexible fiberoptic intubation.4
The laryngeal mask airway (LMA) is considered a SAD because the distal end of the LMA sits above the glottic opening. The LMA can be used as the primary airway device during appropriate surgical procedures and is considered a valuable airway tool when managing a difficult airway.5
Compared to original SAD designs, second-generation SADs (1) attempt to reduce the risk of aspiration by incorporating a channel for gastric decompression and suctioning of secretions; (2) have reinforced tips that prevent folding; (3) incorporate improved cuff designs to help create a better cuff seal with higher ventilation pressures; and (4) are more rigid in their design to prevent rotation and to facilitate easier insertion.9 Several different types of second-generation devices exist including, but not limited to, the LMA ProSeal (PLMA) and LMA Supreme (Teleflex, Wayne, PA), i-gel (Intersurgical, Wokingham, UK), and the AuraGain (Ambu, Glen Burnie, MD).5
Intubating stylets are used to guide the operator with placing an ETT, frequently when an appropriate view is not found. Some devices have a light on the tip to aid in proper placement of the distal end.
The Trachlite (Laerdal Medical) is a lighted stylet that uses the transillumination of the neck to accomplish endotracheal intubation.5 As the intubator inserts the stylet through the glottic opening, a glow is visualized around the thyroid cartilage. An appropriately sized ETT is then slid down the stylet through the glottis and secured as normal. The device is less affected by anterior placement of the larynx, is less stimulating than conventional laryngoscopy, and may be associated with a lower incidence of sore throat.5
The Eschmann stylet is a 15-French flexible stylet that is 60 cm in length with a 40-degree bent distal tip and is used when the glottic opening is difficult to visualize.5 To place the bougie, DL is performed to visualize the epiglottis and, if possible, the posterior arytenoid cartilage. The bougie is then placed behind the epiglottis, in the direction of the glottic opening. The tip of the bougie is then advanced through the glottis, with the device tip potentially running along the tracheal rings further confirming placement into the airway. The stylet should be advanced until the 25-cm marking is at the lip, where the stylet is then held in place.5 The pre-loaded ETT is then advanced along the stylet and secured in the normal fashion.
Flexible bronchoscopes can be used to evaluate the airway, facilitate intubation in a patient with a difficult airway, check ETT placement, change an existing ETT, and perform post-extubation evaluations.5
Indications for fiberoptic intubation of the patient include the following:5
There are many devices that can be used to help oxygenate, ventilate, and secure the airway in a difficult airway patient. The most important point is that those involved need to have experience with the device being used before the need arises. The person responsible should practice on the non-difficult airway to gain familiarity with the tool so there won’t be any questions or surprises regarding what they need to do in an emergency.