Christopher A Godlewski, MD
Division of Multispecialty Anesthesia
Department of Anesthesiology and Perioperative Medicine
University of Alabama Birmingham Medical Center
A novel technique is presented, as are examples from cases.
The management of the difficult airway is an extremely stressful situation for both the patient and the anesthesiologist, for several different reasons. For the patient, this situation can be an uncomfortable and unpleasant ordeal to experience, coupled with the fact that a lost airway can result in death. At the same time, the patient must surrender control and trust that the anesthesiologist will be successful in securing the airway. For the anesthesiologist, the knowledge that he or she may get only one attempt at the procedure, and that the patient could suffer imminent death if our efforts should fail, can be extremely anxiety-provoking.
An additional challenge is that often these patients are unable to lie flat due to airway compromise from extrinsic compression, inability to clear blood or secretions, work of breathing, and a variety of other factors. Once oxygen deprivation sets in, patients quickly become combative and panicked, which makes airway management nearly impossible and turns into a life-threatening situation for the patient.
Often, there are other extenuating circumstances that can make a difficult airway even more tenuous. A large mediastinal or airway mass, extensive parenchymal lung disease with an unfavorable airway, inability to clear oropharyngeal secretions, naso- or oropharyngeal bleeding, and various forms and fashions of airway obstruction all can make placing a patient in the supine position uncomfortable, impossible, and possibly life-threatening. Many anesthesiologists have had the unpleasant experience of having to intubate the drooling or bleeding patient who is “tripodding,” much like a child with epiglottitis.
A novel way to instrument the difficult airway is presented below, which has numerous advantages over the tried-and-true, supine, awake fiber-opticintubation. The technique first will be described, and then case examples in which the technique was successful in both elective and emergency situations will be presented.
Performance of the Technique
As with any awake fiber-optic technique, proper preoperative counseling, airway anesthesia, and gentle sedation are paramount inasmuch as the patient is not in extremis. I have found that a major factor in the success of an awake intubation is an extensive pre-op discussion with the patient, telling them what to expect and encouraging them to try to keep calm and refrain from panic should they become uncomfortable. I actively enlist and solicit their help and participation when needed during the procedure. I find that this visit can be a very powerful anxiolytic.
What I have discovered in my practice is what I call “the importance of the left hand.” I encourage the patient to let me know early on if they are becoming uncomfortable by raising their left hand so we may apply more local anesthetic or sedation; this often can preclude the “rodeo of disaster,” in which the anesthesiologist is on the verge of passing the endotracheal tube (ETT) through the vocal cords, only to have an uncomfortable and panic-stricken patient pull out all the airway equipment.
For this reason, if at all possible I leave one of the upper extremities untethered by IV tubing or free from lines from monitors. The patient is given back some control and made to be a participant in the process by being able to simply raise a hand when uncomfortable, which provides tremendous psychological relief from the all-too-common fear that they will be strapped to the gurney while we anesthesiologists force instruments into their airway. An added advantage is that they can signal us without having to attempt phonation or verbalization, which can ruin the intubation attempt.
In terms of local anesthesia, while I am not opposed to nebulized 4% lidocaine, I personally prefer topical anesthesia with aerosolized benzocaine and viscous lidocaine jelly for comfort while I perform local nerve blocks. Often by the time the patient goes from the pre-op area, where they have been nebulized, to the operating room (OR) and all monitors have been established and equipment readied, the nebulized lidocaine is already wearing off. After blocking the glossopharyngeal nerve, I will either perform a transtracheal block with an angiocatheter or run an epidural catheter through the injector port of the fiber-optic scope to the tip of the scope to topicalize the vocal cords prior to passing the ETT through the glottic opening.
I find that the catheter delivers a more satisfactory jet of anesthetic that can be aimed onto the cords than the injector port, which has a tendency to dribble out of the end of the scope and risks missing the vocal cords altogether. Ultrasound can be a helpful adjuvant for the transtracheal block in the patient with a large neck, but I have found that my level of comfort and margin of safety is higher by using an epidural catheter to anesthetize the cords in this patient population.
Glycopyrrolate is given at least 20 minutes preprocedure to assist in drying out the airway. For sedation, I have adopted using dexmedetomidine almost exclusively with very gently titrated midazolam for preprocedure anxiolysis if deemed appropriate—no more than 1 to 2 mg. The dose is reduced by up to 30% if the patient has been premedicated with narcotics or other central nervous system depressants. A small amount of a short-acting narcotic can facilitate patient comfort and help attenuate airway reflexes, but again, these are used judiciously or not at all. I have never used more than 50 mcg during any sort of awake intubation.
Once monitors are established, I start a dexmedetomidine infusion at 0.5 to 0.7 mcg/kg per hour immediately to establish a background steady state. I give half of the recommended bolus (1 mcg/kg) early on to assess patient sedation response and bradycardic response, followed by the other half prior to instrumentation, if needed. While there are many different methods of providing sedation, it has been my experience that dexmedetomidine provides a gentle, calm sedation akin to physiologic sleep devoid of disinhibition or excessive salivation—both of which complicate the technique.1-5 Although bradycardia is a known side effect of dexmedetomidine, when glycopyrrolate is given appropriately and in a timely fashion, it can mitigate or abolish the bradycardic response.
Two operators are required for the technique. The patient can either be left on the transport gurney or transferred to the operating table; either way, they are allowed to sit as upright as is comfortable for them; a belt is then put around their waist or upper thighs for safety. In fact, the more upright the patient is, the less physically fatiguing it is to employ the fiber-optic scope.
If the patient is supine, the operator has to partially suspend the scope over the patient, which can fatigue the shoulders and upper extremities. By placing the patient upright, I will rest the body of the bronchoscope on my dominant shoulder, using my thumb to control ante- and retroflexion and holding the fiber-optic cable portion taut with my nondominant hand. Rotation of the scope is achieved easily with minimal dorsiflexion and palmar flexion of the dominant wrist, which is resting on the shoulder. In short, if the patient is sitting upright, it is much more ergonomic and less physically taxing for the operator—which can be significant during prolonged attempts at a difficult airway.
Once the patient is adequately topicalized and sedated, the operator of the video laryngoscope will grasp the patient’s mandible with their nondominant hand and provide a gentle jaw thrust. At our institution we have the C-MAC (KARL STORZ), which is the video laryngoscope that I personally use in this technique, but there are other video laryngoscopes that are suitable. With the dominant hand grasping the video laryngoscope of choice upside down, the anesthesiologist will insert it into the oropharynx until a view of the glottic opening is obtained. Once the view is obtained the second operator will insert the fiber-optic bronchoscope (FOB) that has been preloaded with an ETT into the airway.
Insertion of fiber-optic bronchoscope while the assistant maintains the view obtained by the video
At this point, the first operator can release the mandible and provide gentle pressure on the neck to assist coupling of the scope with the glottic opening. The fiber-optic scope operator can guide the scope through the vocal cords under direct visualization with the monitor from the video laryngoscope or by the conventional method of looking through the bronchoscope, then use the fiber-optic scope to confirm placement and position in the trachea.
Overall, I have found that this novel technique does not take any more time than an awake fiber-optic intubation; in fact, I have found the opposite to be true. Although the technique requires two operators, it has been my experience that time to intubation is much shorter than the conventional method with a scope because the fiber-optic operator is easily able to see the target and is not getting lost in the oropharynx.
Case 1. Respiratory Distress Secondary to Angioedema and Airway Swelling
The patient is a 74-year-old woman with a fairly extensive medical history consisting of non–insulin-dependent diabetes mellitus, hypertension, coronary atherosclerosis with history of myocardial infarction, congestive heart failure, morbid obesity, end-stage renal disease dependent on dialysis, cerebrovascular accident, pulmonary hypertension, and chronic hypoxemic respiratory failure requiring constant oxygen supplementation. Her home medications include allopurinol, aspirin, a statin, carvedilol, levothyroxine, a proton pump inhibitor, and sevelamer. She has a known allergy to ACE inhibitors, which caused angioedema and airway swelling.
The patient presented to our emergency department in respiratory distress secondary to angioedema and airway swelling. Anesthesia was called to assist because of concern about a potentially difficult airway. The patient was awake and oriented on presentation and able to maintain her oxygen saturation with rebreather facemask. It was decided at that time to transport the patient directly to the OR for airway management in a more controlled environment, with readyavailability of extra assistance and equipment.
Because of the emergent nature of her condition and dependence on oxygen, an adequate airway exam could not be performed. The patient was left sitting supine in her most comfortable possible position during transport and airway instrumentation. After appropriate monitoring was established and preoxygenation performed, the patient was given 2 mg of midazolam and 60 mcg of dexmedetomidine IV for sedation. After observing her response, an additional 20 mcg of dexmedetomidine was given. The author inserted the video laryngoscope while a senior resident used the FOB.
The glottic opening was visualized, but the patient’s respiratory efforts made manipulation of the FOB into the trachea difficult. In light of the fairly easy visualization of all necessary structures, the author at that point decided to administer additional sedation to assist in instrumentation, and 50 mg of propofol was given to quiet the patient’s respiratory efforts. The bronchoscope was again inserted, but the senior resident had some difficulty revisualizing the glottic opening. The author manipulated the trachea externally with a resultant grade 1 view of the glottic opening. The senior resident then easily drove the FOB into the trachea, watching the video laryngoscope screen, and confirmed placement of the endotracheal intubation with the FOB alone. Both operators were able to stand comfortably facing the patient during the procedure, and at no point did the intervention require changing the position of the patient.
Case 2. Laryngeal Mask Rescue Fails Despite Promising Airway Exam
The patient is a 53-year-old woman who initially presented several months earlier for a LeFort I with genioplasty and removal of a chin implant for mandibular hypoplasia. Her medical history was significant for obstructive sleep apnea, anxiety, depression, and dyslipidemia. Her medications included amitriptyline, aspirin, gabapentin, hydromorphone, metformin, and simvastatin (Zocor, Merck). She was allergic to codeine, latex, morphine, acetaminophen and oxycodone, and propofol. The author was the attending anesthesiologist for the procedure.
Her preoperative airway exam was reassuring; she was a Mallampati I with a slight overbite but adequate thyromental distance. After induction of anesthesia, the author found mask ventilation to be difficult despite use of oral and nasal airways as well as the two-hand technique. Attempted rescue with a laryngeal mask (LM) airway also was unsuccessful. A video laryngoscope provided an adequate view of the vocal cords, but the author was unable to pass an ETT or a bougie. Ultimately, an FOB was required to navigate the ETT into the trachea.
The patient presented 8 months later for removal of her mandibular hardware. Although she had undergone corrective surgery to provide a more favorable airway, in light of the previous difficulties, the author elected to employ the technique described above to preclude difficulty. She was left in the seated position for preoxygenation and airway instrumentation. After induction of anesthesia, she was able to be mask-ventilated. Using the described technique, the anesthesiologist easily and expeditiously intubated the patient without complication.
Case 3. Elderly Patient With Macroglossia and Abnormal Airway Anatomy
The patient is an elderly woman with a history of dilated and ischemic cardiomyopathy, coronary artery disease, diabetes, hypertension, sleep apnea, and morbid obesity. Initially, she was admitted to our cardiac ICU for decompensated heart failure and volume overload. The trauma and emergency anesthesia team was paged to emergently intubate the patient for hypoxic/hypercarbic respiratory failure and rapidly progressive angioedema, presumably caused by an ACE inhibitor.
A prior attempt to intubate the patient by the cross-cover medicine service had failed because the patient had decompensated rapidly when they placed her supine in preparation for direct laryngoscopy. Prior to our arrival, she was returned to a seated position, which was the only way to prevent complete respiratory arrest.
On our arrival, the patient was obtunded and minimally responsive, but still breathing spontaneously. Her oxygen saturation was in the mid-80s on non-rebreather facemask, and she was tachypneic with markedly increased work of breathing. The initial plan was to attempt a conventional awake fiber-optic intubation; however, I was concerned that our chance of success would be poor based on the distorted airway anatomy and macroglossia as a result of angioedema and body habitus.
The airway was anesthetized with aerosolized benzocaine, but we were hesitant to give further sedation in order to maintain spontaneous respiration and prevent complete and catastrophic airway obstruction. The patient tolerated insertion of the video laryngoscope well, likely because of aggressive topicalization as well as somnolence induced by hypercapnia. The view from the video laryngoscope indeed demonstrated markedly abnormal anatomy due to edema and redundant tissue, which would have made conventional fiber-optic intubation difficult.
The glottic opening was visualized and the FOB passed easily through, resulting in a smooth and expeditious intubation. Once ETT placement was confirmed, the patient was sedated to enhance comfort and synchrony with the ventilator.
With the advent of video laryngoscopy, it appears that the number of awake fiber-optic intubations being performed has decreased.6-10 Awake fiber-opticintubation is still the gold standard for management of the difficult airway; however, the novel technique described provides the best of both worlds. It is also an excellent rescue technique for the unanticipated difficult airway.
We feel there are many advantages to the described technique over video laryngoscopy or fiber-optic intubation in isolation. Usually patients in respiratory distress or with obstructing masses are more comfortable sitting upright, and this technique allows the patient to sit in their position of maximal comfort. While fiber-optic intubation can be performed with the patient seated, conventional video laryngoscopy would be very difficult.
One of the more common problems with conventional fiber-optic intubation is loss of orientation, or getting lost in the oropharynx, another problem that is precluded by the described technique. Furthermore, the use of video laryngoscopy in the conventional manner often can limit space and make ETT passage challenging, both through the mouth and when in the airway. In the described technique, the video laryngoscope is not advanced all the way in following the conventional manner, but rather used to provide a panoramic view from afar to allow the FOB operator an easy method to target the glottic opening.
If needed, video laryngoscopy also can be used in the conventional manner to indirectly displace the epiglottis to facilitate passage of the bronchoscope and ETT, or if the blade is long enough, to be advanced even deeper to directly displace the epiglottis if needed—akin to a Miller blade. As the author has discovered, intubation can be greatly facilitated by the video laryngoscopist using the free hand to maneuver the trachea toward the FOB, enhancing the other operator’s ability to couple the two together.
Often when the patient is supine, it can be difficult when utilizing the FOB to overcome gravity to achieve adequate mandibular and tongue displacement. In addition, redundant or patulous soft tissue can fall back and obstruct the airway, and thus also the view from the FOB—especially in the obtunded or unconscious patient with lost muscle tone. Additionally, when the patient is supine, all secretions from the oropharynx tend to pool in a more dependent position, which is often in the path of the FOB. What we have found using the technique with the patient in the upright position is that the mandible can assume a more favorable position and that soft tissue is not falling into the direct path of the FOB, providing a much more expansive and clear view.
Additionally, since the patient is upright and secretions do not pool in the oropharynx, we have a much drier operating field with a much clearer view, with both the video laryngoscope handle and the FOB.
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