A 69-year-old man has been in the post-anesthetic recovery unit (PACU) for 6 hours with a slowly expanding neck hematoma following an uneventful left carotid endarterectomy under general anesthesia. Over the last 45 minutes he has become symptomatically short of breath. Neurosurgery has booked him to return to the operating room (OR) for wound exploration and evacuation of hematoma. Preoperatively, he was otherwise healthy, taking no medications, and was noted to have normal-looking airway anatomy. Post-induction at the original surgery, he was documented to have been easy to ventilate using a bag-mask, presented a Cormack/Lehane (C/L)1 Grade 1 view at direct laryngoscopy using a Macintosh #3 blade, and the trachea was easily intubated with an 8.5-mm internal diameter (ID) endotracheal tube (ETT).
In the PACU he is sitting upright, breathing oxygen at 10 L·min−1 via a non-rebreathing facemask. Although restless, he is rational, complaining of dyspnea, dysphagia, and neck pain. Blood pressure is 180/95 mm Hg, heart rate 100 beats per minute (bpm), respiratory rate 30 breaths per minute, and his SpO2 is 95%. He is audibly stridulous. Under a blood-stained dressing, the left side of his neck looks visibly enlarged and discolored (Figure 55-1). The patient is 5 ft 10 in (178 cm) in height and weighs 230 lb (105 kg). He has vascular access. An OR is being prepared for his return.
The patient. A dressing is covering the site of the surgical incision.
55.2.1 In What Ways Might This Patient Present Difficulty with Airway Management? What Are Key Aspects of the Airway Examination in This Situation?
This is an urgent situation. The patient must be quickly assessed and decisions made. Although some patients with neck hematomas are simply observed, case reports attest to difficulty in predicting if or when these individuals will go on to sudden and catastrophic airway obstruction.2-4 As part of the patient's evaluation, a formal airway examination should be performed, seeking predictors of difficulty in all aspects of airway management.5 Even though the patient's anatomy presented no difficulty with airway management earlier that day, the presence of a neck hematoma changes everything. With evidence of obstructing pathology in the airway—as manifested by stridor, neck swelling, and the patient's dyspnea and agitation—difficulty can now be anticipated with both bag-mask-ventilation (BMV) and use of an extraglottic device (EGD). Similarly, direct laryngoscopy in the presence of pathological obstruction may also be difficult as anatomic landmarks become distorted, displaced, or obscured. Finally, cricothyrotomy by percutaneous or open surgical routes may also be difficult as landmarks are shifted or become indistinct.
If time and patient cooperation permit, any patient with obstructing airway pathology can be considered for further assessment by nasopharyngoscopy. This is generally well tolerated and can give information about any displacement of the larynx to left or right; the degree of perilaryngeal edema, and vocal cord function.
55.2.2 What Other Patient Factors May Be Relevant in This Situation?
With predicted difficulty in all aspects of airway management limiting options in this patient, an awake approach at securing the airway is preferable. However, for awake airway interventions, substantial patient cooperation is generally needed. Patient cooperation may be lost (a) as hypoxemia occurs and/or (b) the patient panics as dyspnea worsens with progressive airway lumen narrowing. This speaks to the need for early identification of the patient requiring re-intubation, while cooperation can still be counted upon. Although sedative medications may help to render a patient more cooperative, sedating a patient with a tenuous airway is hazardous and may itself precipitate complete airway obstruction.6,7 Other patient comorbidities will assume secondary importance compared to the gravity of threatened loss of the airway.
55.2.3 What Are the Causes of Airway Obstruction in a Patient with a Postsurgical Neck Hematoma?
Neck hematomas originate from venous or capillary oozing more often than arterial bleeding.8-10 Although arterial bleeds may present earlier,8 neck hematomas arising from a venous or capillary source can be insidious and just as devastating in their ability to cause obstruction. The following mechanisms may contribute to the development of symptomatic airway obstruction in the patient with a neck hematoma:
Physical pressure effect: The presence of a hematoma in the neck can mechanically displace the laryngeal inlet dramatically away from the midline position4,8,11,12 in addition to physically compressing the lumen of the pharynx, laryngeal inlet, or tracheal airway. Some authors consider significant compression of the larynx and trachea unlikely due to their rigid cartilaginous structures.13,14 Carr and colleagues performed a bench study with pig tracheas and observed that with applied pressures of just over 250 mm Hg (ie, equivalent to maximal systolic blood pressure), they were unable to demonstrate more than a 20% loss of the original anterior-posterior tracheal diameter.14 However, as other authors have pointed out, the posterior, membranous portion of the trachea may still be significantly compressed by a hematoma.15 Indeed, there are published case reports showing CT scan images of impressive tracheal compression by hematomas.16,17 Bukht described a case18 in which an adult patient with a neck hematoma was intubated with difficulty with a 5 mm ETT. No leak was apparent even with the cuff deflated, however upon subsequent release of the hematoma, a large leak immediately developed, suggesting that tracheal or laryngeal compression can indeed occur with neck hematomas.
The development of peri-laryngeal edema: This is a consistent feature in case reports of patients with neck hematomas2-4,8,12,16,18-20 and is often out of proportion to any degree of externally visible neck swelling or discoloration. Most authors agree that this is due to interference with normal venous and/or lymphatic21 drainage by both the neck hematoma itself as well as blood tracking into tissue planes away from the hematoma.4,13,16,20,22 Release of tissue inflammatory mediators may also contribute to it.22,23 At direct laryngoscopy, the resulting edema is variously described as "swollen supraglottic mucosal folds"4,8 or a "watery, pale swelling of the mucosa"13,20 (Figure 55-2) which in many cases completely obscures the glottic opening. Interestingly, some case reports document the development of similar peri-laryngeal edema after neck surgery even without an obvious hematoma.8,24
Blood dissection along tissue planes in the neck: The parapharyngeal space is contiguous medially with the retropharyngeal space,15 which in turn extends from the skull base to the upper mediastinum.25 The parapharyngeal space also communicates anteriorly with pretracheal and submandibular spaces as well as subcutaneous tissues.25 Blood from a neck hematoma in any of these areas can thus spread remotely from its initial location to further compromise the airway. Retropharyngeal collections of blood are often manifested symptomatically with neck pain and dysphagia or odynophagia in addition to hoarseness and dyspnea. Retropharyngeal hematomas can cause airway obstruction by compression of the arytenoid cartilages, which may in turn adduct the vocal cords.26 In addition, retropharyngeal swelling can render direct laryngoscopy more difficult by (a) shifting the laryngeal inlet anteriorly;27 (b) apposing the posterior pharyngeal wall to the epiglottis; and (c) as it is a large, dark mass, a retropharyngeal hematoma can absorb light from the laryngoscope, worsening visibility.27
Typical findings seen during bronchoscopic intubation of a patient with a neck hematoma. A. As the bronchoscopic intubation begins, the practitioner simply advances the scope toward the opening appearing with expiration. B. With usual landmarks such as the epiglottis obscured, bizarre, edematous tissue appear in the distance. C. The scope is further advanced toward movement. D. With inspiration, swollen and edematous supraglottic tissues adduct to almost meet in the midline. E. With the next expiration, edematous tissues again move aside, allowing further advancement of the bronchoscope. F. The yellow tissue is a posteriorly located corniculate cartilage, with the entrance to the esophagus beneath, and a suggestion of glottic opening above, although still largely obscured by edematous tissue. G. Now beyond the edematous supraglottic tissue, the piriform sinus comes into view on the left, with an edematous, pale aryepiglottic fold in the middle of the view, and a suggestion of glottic opening on the right. H. Navigation of the bronchoscope to the right enables access to the glottic inlet.
It should be noted that of the causes of airway compromise mentioned earlier, edema and remotely tracking blood will not remit immediately upon evacuation of a neck hematoma, accounting for the variable success of urgently reopening a surgical incision in alleviating respiratory extremis in these patients.
Three other factors can also potentially contribute to postoperative airway compromise in patients undergoing routine head and neck surgery:
Large volumes of fluid administered intraoperatively can exacerbate airway edema.
Simply undergoing certain operations in the head and neck region may transiently cause narrowing of the upper airway, even in the absence of a neck hematoma. Carmichael and colleagues28,29 demonstrated a significant loss (up to 32%) of airway volume after routine carotid endarterectomy, greatest in the region of the hyoid but also present at the level of the arytenoids and cricoid ring.
Neck surgery can result in transient palsies to cranial nerves (IX-XII)30,31 due to direct injury during dissection, retractor pressure, or other causes.32 If unilateral, such palsies may be asymptomatic; however, particularly in patients with a history of previous neck surgery or presenting for staged bilateral procedures, (eg, carotid endarterectomies), bilateral nerve damage can result in complete airway obstruction. Vocal cord palsy can result from damage to the vagal trunk or its recurrent laryngeal branches, while bilateral hypoglossal nerve palsies can result in airway obstruction from loss of innervation to the intrinsic muscles of the tongue and pharyngeal musculature.30 One final point to note in the patient undergoing staged bilateral carotid endarterectomies is that ablation of the carotid bodies bilaterally will result in loss of the ventilatory response to hypoxia.33
55.3.1 Pending the Decision of Whether and Where to Re-Intubate, How Can the Patient Be Symptomatically Temporized?
It should be reiterated that patients with partial airway obstruction are unpredictable in when, where, and if they will go on to complete airway obstruction. Indeed, some case reports document a decision to conservatively manage neck hematoma patients by observation, only to be confronted with sudden and catastrophic complete airway obstruction some hours later.3,4 In addition, patients going on to complete airway obstruction in this setting can do so without first developing the physical sign of stridor.2,3,8 It follows that nursing staff and airway managers must be educated to recognize the early signs of impending obstruction from a possible neck hematoma, including subtle voice changes and hoarseness, with later progression to agitation, dyspnea, and eventually stridor. Stridor, a late sign of airway compromise, is variously considered to be a sign of an extrathoracic airway narrowed by 50%34 or to a diameter of 4 mm or less.35 The patient in the presented case should be assumed to be in respiratory extremis. Once a compromising neck hematoma is suspected, plans should be undertaken for immediate definitive care: release and reexploration of the neck wound, and securing of the airway.
For temporizing a case such as this on the short term, (eg, while organizing a return to the OR, or while obtaining equipment for re-intubation), a number of maneuvers can be undertaken:
The head of the bed should be elevated, anywhere from 30 degrees to fully sitting, to promote venous drainage and improve the mechanics of breathing. The patient with significant airway compromise will most likely naturally wish to assume the sitting position.
Heliox can be administered. Heliox, a mixture of helium gas with oxygen, is less dense than air or pure oxygen. With its lower density, a helium-oxygen mixture minimizes the work of breathing by converting some or all of the turbulent flow through a critically narrowed airway to laminar flow.36,37 Heliox is available in different oxygen-helium dilutions from 20/80 to 40/60: to maximize its clinical effect, the mixture with the highest concentration of helium should be used that is consistent with adequate oxygenation. Improved flow with heliox can lead to larger tidal volumes and less alveolar shunting, sometimes with improved oxygenation.36,38,39 In addition, as a patient breathes more easily with alleviation of dyspnea-associated anxiety, the lessened negative inspiratory pressure applied to the obstructed area may result in less airway collapse, thus actually improving the degree of obstruction.36 Heliox use in the patient with a critically narrowed airway can provide dramatic symptomatic relief, in turn potentially improving patient cooperation. In the setting of a neck hematoma, however, it should be assumed that heliox has no definitive therapeutic effect and is strictly a temporizing agent.
Early consideration should be given to reopening the neck wound when a postsurgical neck hematoma is causing airway compromise. Some,18,40 although certainly not all8,20,41 case reports document rapid clinical improvement following this maneuver. While a significant hematoma mass may be decompressed immediately, associated laryngeal edema and/or blood tracking remotely from the hematoma site will resolve more slowly. Clinical judgment dictates where and when to open the neck wound: the patient in respiratory extremis should have it opened immediately, while others may be safely managed upon returning to the more controlled conditions of the OR. However, any attempt at tracheal intubation should generally be preceded by release of the neck wound, whether in or out of the OR. It should be noted that this directive contrasts with the management of the patient with penetrating neck trauma, in whom the possible presence of damaged major vessels mandates securing the airway by intubation prior to neck exploration.
The use of epinephrine aerosols42 and systemic steroids has been described for upper airway edema; however, there is no published evidence of their short-term efficacy in the setting of neck hematoma-induced airway compromise.
55.3.2 Should the Trachea of This Patient Be Intubated in the PACU or in the Operating Room? How Do You Decide?
The short answer is that the patient with a neck hematoma is ideally re-intubated in the controlled conditions of the OR. The OR has the advantage of a more sterile environment, with availability of surgical equipment and staff for an airway double setup (Table 55-1) together with easier access to difficult airway equipment and expert help. In addition, the OR offers the option of an inhalational induction if desired. Ultimately the decision about re-intubation on the spot versus a return to the OR will be tempered by the following factors:
Table 55-1 The Airway Double Setup ||Download (.pdf)
Table 55-1 The Airway Double Setup
|The presence of equipment and personnel for the purpose of moving rapidly to cricothyrotomy should an attempted tracheal intubation from above result in a failed airway situation.|
|Attempted oral or nasal tracheal intubation in the patient with an advanced degree of pathologic airway obstruction can result in complete loss of the airway during the attempt. If the patient cannot be oxygenated with BMV, and intubation with direct laryngoscopy fails, rapid cricothyrotomy is needed to avoid a hypoxemic arrest.|
|The following conditions should be met:|
|Personnel: scrubbed/gowned scrub nurse; circulating nurse; scrubbed/gowned ENT, plastic, neuro, or general surgeon in addition to anesthesia staff;|
|Equipment: surgical instruments for an open surgical cricothyrotomy. A percutaneous cricothyrotomy kit may be available;|
|Patient: in position of comfort; cricothyroid membrane identified; overlying skin marked, prepped, and possibly infiltrated with local anesthetic.|
|Cricothyrotomy commences as soon as a failed airway, cannot intubate, cannot ventilate/oxygenate is declared. Generally, a single attempt at EGD placement is warranted before putting knife to skin.|
|Some patients with obstructing pathology may have marked submandibular swelling as part of their disease process that extends down to and obscures landmarks of the cricothyroid membrane. As this may preclude easy and rapid cricothyrotomy, the safety margin provided by the airway double setup is diminished. As such, it may be an indication that the primary technique of choice should be awake tracheotomy under local anesthesia, rather than attempted intubation from above.|
Is the patient in extremis? If so, the airway should be secured on the spot.
If the patient is becoming increasingly dyspneic, is the rate of decline such that a return to the OR may be safely undertaken?
How far is the OR from the patient's present location and is the OR located on the same floor as the PACU?
If the patient obstructs during transport to the OR, will one be able to bag-mask ventilate the patient? The extensive upper airway edema accompanying most neck hematomas may make BMV impossible once the patient has fully obstructed.
55.3.3 How Should Such an Airway Be Approached, and Why?
Patients with significant narrowing of the airway due to pathological processes are in a dangerous situation. Onset of dyspnea, and then stridor, suggests critical airway narrowing, and in the setting of a neck hematoma should generally be regarded as signs of impending complete obstruction. Our airway assessment has suggested the potential for difficulty with BMV, laryngoscopic intubation, EGD rescue ventilation, and surgical airway. Careful consideration must therefore be given as to how best to proceed. A number of options exist:
Local or regional anesthesia. One published case series in the surgical literature documents hematoma evacuation in eight patients under local anesthesia with no morbidity, which contrasted significantly with the 57% complication rate in seven other patients done under general anesthesia.9 Hematoma evacuation and exploration using local or regional anesthesia may be feasible before the patient is significantly short of breath and is still able to lie flat and cooperate. However, regional anesthesia, (eg, superficial cervical blockade) may be difficult to perform if an enlarging hematoma obscures anatomic landmarks.8
Awake cricothyrotomy or tracheotomy under local anesthesia. Some authorities suggest that patients with advanced degrees of obstructing airway pathology, particularly those with lesions of sufficient size to preclude passage of even a small ETT, should have their airways secured with awake tracheotomy under local anesthesia.34,43 In expert hands and with patient cooperation, this is a procedure that can be done relatively quickly and painlessly. Technical difficulty can be encountered if midline landmarks are shifted or obscured by an expanding hematoma. In addition, airway edema can also occur internally at the level of the cricoid ring, potentially impacting ease of cricothyrotomy.23
Awake oral or nasal (trans-laryngeal) intubation. Awake translaryngeal intubation (via oral or nasal routes) confers the advantage of having a breathing patient who is maintaining and protecting the airway, and would be judged the method of choice by many experts in this situation. In the setting of a neck hematoma, grossly distorted anatomy can be anticipated, (see Section 55.2.3 earlier), yet in the awake patient, movement of swollen mucosal folds (and possibly, bubbles) may help locate the laryngeal inlet (Figure 55-2). An attempted awake intubation from above must, however, confer a high probability of success in order to outweigh the risk of loss of the airway during the attempt25 (which can happen even in expert hands6). Attention to topical airway anesthesia (see Section 3.3.4 as well as Section 55.3.11 later), good flexible bronchoscopic equipment, and the expertise to use it will be necessary.8,44 Alternatively, direct laryngoscopy has also been described for awake intubations in the setting of neck hematomas.10
Inhalational induction. An inhalational induction has been espoused in a number of reports as an option to facilitate intubation of a patient with a neck hematoma.8,21,25,34 However, during an inhalational induction, while spontaneous ventilatory efforts are generally maintained, it must be appreciated that volatile anesthetics have deleterious effects on upper airway tone and patency similar to those of intravenously administered sedatives.45 While the inhalational induction may be considered for the patient unable to cooperate with an awake intubation or tracheotomy, an airway double setup should be arranged, the neck wound should be opened before beginning, and close attention should be paid to maximizing airway patency as the patient loses consciousness (Table 55-2). Inhalational inductions in the setting of neck hematomas in published case reports have generally been successful although in some cases prolonged or difficult.4,8,18,25
Intravenous (IV) induction. Unless the patient is asymptomatic and a nasopharyngoscopic assessment has ruled out significant edema or laryngeal displacement, this route cannot be recommended as the method of choice for the patient with obstructing airway pathology due to a neck hematoma. IV induction of anesthesia with or without muscle relaxant administration is fraught with hazard in this setting with case reports attesting to the lack of any identifiable landmarks at direct laryngoscopy,4,46 often in conjunction with the inability to bag-mask ventilate the patient.8,46
Table 55-2 Strategies to Help Maximize Upper Airway Patency during Difficult Inhalational Inductions ||Download (.pdf)
Table 55-2 Strategies to Help Maximize Upper Airway Patency during Difficult Inhalational Inductions
|1. Maintain the patient in a sitting or semi-sitting position|
|2. Keep the head and upper C-spine extended and lower C-spine flexed, to maintain longitudinal traction on the upper airway, thus decreasing its collapsibility45|
|3. Apply a jaw thrust to increase retropalatal and retrolingual airway caliber45|
|4. Through a nostril already topically anesthetized, insert a nasopharyngeal airway to help overcome approximation of the soft palate to the posterior pharyngeal wall, while the patient is still too light to tolerate an oropharyngeal airway34|
|5. Application of PEEP during the inhalational induction may help to splint open collapsible supraglottic structures|
55.3.4 How Should We Proceed in This Case?
Our Plan A here is for an awake intubation under topical airway anesthesia, a viable option if good equipment and expertise are available with the flexible bronchoscope, and if patient cooperation can be enlisted. In the event of an uncooperative patient, an inhalational induction could be considered. Plan B, in the event of loss of the airway during the attempt at awake intubation or inhalational induction, would be rapid conversion to a cricothyrotomy.
55.3.5 How Will You Prepare for the Awake Intubation?
In the OR, an airway double setup should be readied (Table 55-1), with scrubbed surgical staff and equipment available for urgent cricothyrotomy. The difficult airway cart should be in the room. IV access should be assured, monitors applied, and the patient positioned in his position of comfort (often sitting). The cricothyroid membrane should be identified, marked, and prepped. If not already done, all layers47,48 of the surgical incision should be opened, any easily accessible clot removed, and covered with a sterile dressing. Psychological preparation should be undertaken with confident reassurance that successful intubation will totally alleviate the patient's dyspnea, while at the same time explaining the gravity of the situation and emphasizing the need for cooperation. If heliox had been applied, it should be interrupted for only brief periods during application of topical airway anesthesia. Topical airway anesthetic agents and techniques have been addressed elsewhere (see Chapter 3). Ideally, systemic sedation should be omitted. An adult flexible bronchoscope (eg, 6.2-mm OD) should be loaded with a small (eg, 7 mm ID) ETT. An assistant should apply gentle tongue traction.
55.3.6 What Can You Expect during the Awake Flexible Bronchoscopic Intubation?
Awake flexible bronchoscopic intubation of the patient with extensive upper airway edema due to a neck hematoma differs substantially from that done in a patient without obstructing pathology. In the patient with no obstructing pathology, navigation of the bronchoscope can proceed from landmark to landmark in the upper airway, for example, from uvula to base of tongue, to epiglottis, then to and through cords. In the patient with upper airway edema, both the epiglottis and glottic opening may be obscured by clouds of edematous tissue (Figure 55-2). Often this leaves tissue movement and the suggestion of an opening as the only indication of the path to the vocal cords. As the patient exhales, the edematous tissues will abduct somewhat, giving an impression of an opening (Figure 55-2A/B). Small bubbles may also appear during this phase of respiration. As this happens, the bronchoscope is advanced in a slow and controlled fashion toward the opening or bubbles (Figure 55-2C). During inspiration, the tissue may adduct somewhat and the view will likely become obscured (Figure 55-2D). It is important to have the bronchoscope remain motionless in the airway during this phase, simply waiting for the view to reappear during the next expiration (Figure 55-2E), prior to resuming scope advancement. Often in this setting, one simply continues navigating toward the opening suggested by movement until the cords suddenly appear just in front of the scope (Figures 55-2F-H).
As the only landmarks leading to the airway after the uvula, presence of both movement and bubbles on expiration are crucial clues—this is one reason why it is critical to avoid ablation of spontaneous respirations in these patients.
It should also be noted that a neck hematoma can significantly push the larynx to the left or right of its expected location—this can be anticipated before beginning the bronchoscopic intubation by examining the front of the neck, looking or feeling for the location of the thyroid cartilage.
55.3.7 During Application of Topical Airway Anesthesia, the Patient Obstructs. What Should You Do Now?
If the patient obstructs, common sense should prevail. You should do what you would always do to ventilate the apneic patient: attempt an airway-opening maneuver and perform BMV, using a two-person technique. An oropharyngeal or nasopharyngeal airway may be used, depending on the level of consciousness of the patient. PEEP should be applied during bag-mask-ventilation to help splint open collapsed tissues and ease any laryngospasm.45,49
55.3.8 What If the BMV Fails? Should a Surgical Airway Be Performed?
A failed airway situation can be defined as the inability to maintain adequate O2 saturation with BMV and failure to intubate on at least one occasion (see Section 2.5.5). Despite the failure to bag-mask ventilate the patient, failed airway criteria are only met if the patient also cannot be intubated. A single attempt at direct laryngoscopic intubation should be made. If this is unsuccessful, a failed airway is declared, and the default response becomes cricothyrotomy.
55.3.9 At Direct Laryngoscopy, Only Extensive Edematous Mucosa Is Seen, Along with the Tip of the Epiglottis, Deviated to the Right
If the patient is already unconscious from hypoxemia, it may be worth performing a single chest compression to see if a bubble is produced, indicating the entrance to the airway. With or without a bubble, a tracheal tube introducer or small tube can be blindly placed where the glottic opening would be expected to be, beneath the epiglottis. If this single attempt fails, however, the default maneuver is to directly proceed to cricothyrotomy in order to maximize the chances of salvaging a bad situation. Often, the decision to proceed with cricothyrotomy is made too late to salvage the patient.
55.3.10 What Is the Role, If Any, for an EGD Such as a Laryngeal Mask Airway?
An EGD such as a laryngeal mask airway (LMA) may fail to oxygenate the patient in this setting as (a) correct seating in the pharynx may be difficult due to a displaced laryngeal inlet and (b) extensive edema at or above the level of the cords may preclude effective ventilation. However, several centers have reported successful oxygenation of patients with LMAs in failed airway situations due to neck hematomas41,46,50 or other obstructing pathology.51,52 This may occur as the EGD bypasses more proximal edematous and obstructing soft tissues, allowing positive pressure ventilation from a position immediately in front of the laryngeal inlet. While the correct response in the failed airway (cannot intubate/cannot ventilate) situation is a cricothyrotomy, it is worth a single attempt at EGD insertion while obtaining and opening cricothyrotomy equipment.
55.3.11 I Thought that Awake Bronchoscopic Intubation Was the Foolproof Gold Standard for Difficult Airway. Why Did the Patient Obstruct during Application of Topical Airway Anesthesia?
Loss of the airway during application of topical airway anesthesia49,52,53 or awake bronchoscopic intubation6,41,54 from above in the patient with a neck hematoma or other obstructing pathology is well described. Apart from the natural progression of the disease process, this may occur for a number of reasons:
Systemically administered sedative agents. These may have adverse effects on airway patency.6,45
Laryngospasm. This may occur during the airway topicalization process,34,52,55 particularly in the patient with heavier degrees of sedation.
Patient panic. As the dyspneic patient desperately tries to inspire, the high negative inspiratory pressure applied to an already narrowed, collapsible upper airway may contribute to complete collapse.55,56
Direct effect of local anesthetic agents on upper airway mechanoreceptors. The existence of laryngeal and supra-laryngeal pressure and stretch receptors has been hypothesized, responsible for maintaining airway patency by responding to negative intra-luminal airway pressure via increasing neural and muscular activity.57,58 The activity of such receptors can be affected or abolished by application of topical airway anesthesia.57,58 This in turn can significantly affect inspiratory flow, even in normal individuals. Pulmonary function studies in volunteers have demonstrated a significant reduction in maximal,59 peak, and forced60 inspiratory flow rates following topical airway anesthesia. Studies of the sleep-apnea population in whom topical airway anesthesia has been applied have also shown worsening of obstructive parameters. This is an underappreciated side effect of topical airway anesthesia and in the patient with a tenuous airway may be an important phenomenon to consider (see Section 3.3.4). It does not preclude choosing awake intubation with topical airway anesthesia, but does underscore the need for planning and an airway double setup.
55.4.1 What Should Be the Postoperative Disposition of a Patient Re-Intubated for a Neck Hematoma?
Although the immediate mechanical compression of the airway caused by the hematoma may be relieved after surgical reexploration and blood evacuation, other mechanisms of airway compromise, for example, laryngeal inlet edema and blood dissection along tissue planes may take longer to resolve. Caution must prevail and strong consideration should be given to keeping the patient intubated and ventilated for a period of time, (eg, 24 hours) in an intensive-care setting. The patient should be nursed head-up to promote venous drainage, and consideration can be given to administering steroids. Admittedly, many randomized controlled trials looking at the effect of steroid administration on upper airway29 and laryngeal edema61 or post-extubation stridor62 in adults have failed to demonstrate a beneficial effect. Results of studies in the pediatric setting have been mixed.63,64 Future studies looking at alternative doses, dosing intervals, or specific subpopulations may yet identify a beneficial effect of steroid administration.
55.4.2 What Criteria Should Be Met Prior to Extubation?
In addition to usual extubation criteria, prior to extubation of the patient intubated for airway pathology, such as a neck hematoma, an attempt should be made to evaluate both the caliber of the subglottic airway and the condition of the laryngeal inlet. Traditionally, presence of a cuff leak has been sought as a reassuring sign of an airway patent enough to withstand extubation. Clinically, testing for a cuff leak has been described in a number of ways:
In the spontaneously breathing patient, simply deflating the ETT cuff, briefly manually occluding the end of the ETT, and evaluating the patient's ability to breath around the tube.65,66
With the cuff deflated, delivering a positive pressure volume, with a satisfactory result being the presence of a leak at a delivered peak pressure of 15 cm H2O or less.4,8
A more objective evaluation has been described by having a ventilator deliver a set volume (eg, 10 mL·kg−1) with the ETT cuff deflated, then measuring the expired volume in milliliters67,68 or as a percentage of the delivered inspiratory volume.69,70
Most65,67,70,71 but not all68 studies on the subject agree that the presence of a leak (present qualitatively or measured quantitatively69) is predictive of successful extubation (ie, absence of stridor post-extubation and/or no need for re-intubation). Conversely, many studies also showed that the absence of a leak did not necessarily preclude successful extubation.66,69,70,72 This latter group of patients, however, would be particularly good candidates for further evaluation of the upper airway prior to extubation, for example, through direct or indirect (eg, with a nasopharyngoscope or oral video laryngoscope such as a GlideScope®) laryngoscopic assessment, looking for three parameters:
An appropriate midline location of the laryngeal inlet
The lack of significant perilaryngeal edema
Appropriate bilateral vocal cord movement32
If extubation is elected in this group, consideration should be given to extubating over an airway exchange catheter. In worrisome cases, extubation can be done in the OR as this may facilitate inspection of the laryngeal inlet with direct or indirect laryngoscopy, in addition to permitting easier access to equipment for a difficult re-intubation.
55.4.3 What Other Situations or Types of Surgery Incur the Risk of Neck Hematomas? Are There Any Risk Factors or Preventive Measures that Can Be Undertaken?
Any surgery of the head, neck, and thorax can lead to airway-compromising hematomas. Common examples include carotid endarterectomies,8,73 parathyroid and thyroid surgery,13,20 and anterior cervical discectomy/fusion,40 with most reported series suggesting a neck hematoma incidence of 1% to 5%.10,74-80 Case reports have also documented central line insertion attempts2,3,11,12,16,81 and stellate ganglion blocks82 in the development of life-threatening neck hematomas. Spontaneous bleeds resulting in neck hematomas have also occurred, in both anticoagulated and non-anticoagulated patients.25,83-87 Blunt trauma has been contributory in some.88,89
At least for carotid artery surgery, risk factors for the development of post-op hematomas include antiplatelet agents;4,8 the nonreversal of intraoperatively administered heparin;22,73,90,91 use of a vein graft,92 shunt,91 and experiencing significant intraoperative hypotension91 or postoperative hypertension (eg, systolic blood pressure of >200 mm Hg).4,8,22,73 This latter underscores the importance of aggressive control of hemodynamics in a high-dependency care environment postoperatively. Surgical drains have not demonstrated a benefit in the prevention of post-op neck hematomas in the setting of thyroidectomy47,74 or carotid endarterectomy.93
55.4.4 How Does a Neck Hematoma Affect the Patient's Prognosis?
The occurrence of a postsurgical neck hematoma in the patient undergoing carotid endarterectomy increases the risk of stroke or death 2.5 to 4-fold.77,94 At least part of this morbidity and mortality may be related to the significant airway compromise that can accompany this complication.
Once a postsurgical neck hematoma has been identified, the patient should be observed in a high-dependency nursing unit until a decision is made on definitive care. If re-intubation is required for worsening respiratory distress, it should occur early, while patient cooperation allows the option of awake intubation. Even with awake intubation or an inhalational induction in the patient with a postsurgical neck hematoma, the risk of complete loss of the airway is always present during the procedure. Primary awake tracheotomy will avoid this eventuality in the patient with severe airway compromise, or, if intubation from above is attempted, it should be with prior release of the neck wound, and must always be with the airway double setup availability of equipment and personnel to allow an emergency cricothyrotomy, should it become necessary.