Management and treatment algorithm of airway complications after anterior cervical spine surgery: systematic review

Introduction

Anterior cervical spine surgery (ACSS) is a common surgical procedure performed for many cervical spinal pathologies. Airway-related complications are rare but can be devastating and compromise a successful outcome. The current article reviews strategies for treating patients at risk of such for airway complications following ACSS. The etiology and risk factors for airway compromise after ACSS will not be discussed in this review, as there have been recent reviews covering these topics, including the differences and importance of the timing of findings of a patient who is experiencing such a complication (1,2). Ultimately, this systematic review aims to equip the spine surgeon and anesthesiologist with the knowledge to deal with these complications and provide the most up-to-date practice guidelines. Although a full discussion of the anesthetic management of difficult airways is beyond the scope of this review, the authors provide surgeons with the evidence supporting various techniques and instruments to manage airway loss after ACSS.

The review begins with a brief overview of the relevant airway anatomy and protocols for preventing reintubation or airway crises. This will be followed by an overview on the management of difficult airways and difficult extubation. There will then be a discussion on the treatment strategies to manage an obstructed airway and how to approach the most common etiologies for airway obstruction. Finally, the authors present their proposed treatment algorithm for managing airway complications in patients undergoing ACSS.

We systematically reviewed the literature for papers on this topic and separated them into three categories according to the whether the content of the paper involved etiology, risk factors, or management. Due to the vast amount of information on this topic, the etiology and risk factors categories are not included in this review. We present this article in accordance with the PRISMA reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-23-32/rc).

Methods

A systematic search was conducted on PubMed. The search was then adapted for the following databases: Embase, National Health Service (NHS) Economic Evaluation Database, Cochrane Register of Controlled Trials, and the Cochrane Library Health Technology Assessment database. The search terms included a combination of keywords and controlled vocabularies: “airway complications”, “respiratory difficulty”, “intubation”, “airway obstruction”, “anterior cervical spine surgery”, “anterior cervical discectomy”, “anterior cervical fusion”, and “anterior corpectomy”. The date range was from 1 January 1990 to 21 December 2021. The full search strategy is provided in the Appendix. Studies were imported into the Covidence platform (Veritas Heal th Innovation Ltd; Melbourne, Australia), where duplicates were excluded and the screening process was completed by three of the authors (Y.K., L.F.C., and L.B.). First, all titles and abstracts were screened, followed by a full text review. All disagreements were resolved through an independent review by all of the authors. Any remaining disagreements after this secondary review were resolved through discussion after another full-text review. The selected studies included systematic reviews, meta-analyses, randomized controlled trials (RCTs), prospective cohort studies, retrospective cohort studies, case series, and case reports.

Each included paper was grouped into one of the three aforementioned categories based on the content of the paper—etiology, risk factors, and management. These were determined by all authors and any disagreements resolved after discussion and majority vote.

Results

The reviewed papers were categorized as follows: 39 as etiology, 42 as risk factors, and 37 as management. Of these, 28 qualified for two categories and two papers into all three categories. Five of the included papers were review articles. Each paper was assessed and evaluated for risk of bias utilizing previously published tools depending on the study types. For example, Cochrane Risk of Bias Tool was utilized for RCTs (3). The Risk of Bias in Non-randomized Studies - of Interventions (ROBINS-I) tool was used to evaluate non-randomized studies (4), Assessment of Multiple Systematic Reviews 2 (AMSTAR 2) measurement tool was used for reviews (5). Finally, case series and case reports were assessed utilizing the Methodological Quality and Synthesis of Case Series and Case Reports tool (6). The assessment results can be found in Tables 1-4.

Discussion

Review of anatomy

Working knowledge of the airway is critical for understanding obstructive pathology. The epiglottis separates the oropharynx from the laryngopharynx (at C4). The laryngopharynx has three main components: the supraglottic, glottic, and subglottic regions. The supraglottic region includes the epiglottis, aryepiglottic folds, arytenoids, and ventricular folds (false cords). The glottis includes the true vocal cords, which have a larger diameter posteriorly, making posterior lesions more obstructive. The subglottic region is distal to the vocal cord and includes the trachea. While susceptible to edema, the glottic and subglottic regions are protected from compression by the thyroid cartilage, cricoid cartilage, and tracheal rings, which are rigid and resist collapse due to inward pressure. However, the supraglottic region is soft and vulnerable to compression (28).

The retropharyngeal space can only accommodate a small amount of fluid before causing deviations in vital structures, such as the esophagus and trachea. In a cadaveric study, Glinski et al. demonstrated that a volume of 20 mL (mean pressure 2.39 mmHg) was sufficient to cause tracheal deviation but 39 mL of fluid was required to visualize neck contour changes on clinical examination (44). This is significant as the amount of fluid (i.e., from a hematoma) required to cause clinically identifiable changes is nearly double that required to cause deviation of vital structures.

Protocols to prevent reintubation/airway crisis

Guidelines for determining the risk of postoperative airway complications do not exist yet. Surgical and anesthetic judgement must be employed perioperatively to make rational decisions regarding airway care (30). However, several protocols have been suggested for airway management during high-risk anterior cervical procedures.

Epstein et al. studied a protocol to prevent reintubation in 58 complicated, multi-level (≥3), anterior-posterior (A-P) cervical fusions lasting 10 hours with a high estimated blood loss (average transfusion of 2.6 units of packed red blood cells). All patients were prophylactically left intubated overnight and underwent fiberoptic visualization of vocal cords and tracheal swelling with assessment for a cuff leak by an anesthesiologist prior to extubation [cuff leaks are exhibited by deflating the endotracheal tube (ETT) balloon and listening for air leakage; if the airway is collapsed and swollen, no cuff leak will be evident]. Extubation was delayed if there was no cuff leak or if the patient showed signs of residual swelling on fiberoptic bronchoscopy. Forty patients were successfully extubated on day 1, followed by 5, 3, 2, 2, and 3 on postoperative days 2–7, respectively; the remaining three patients required an elective tracheostomy on postoperative day 7. Operative time greater than 10 hours, weight greater than 220 lbs, transfusion of >4 units, prior anterior neck surgery, 4-level operations, and asthma were risk factors for prolonged intubation and tracheostomy. Only one case required emergent reintubation (15).

Kim et al. established protocol to leave patients intubated overnight if they demonstrated any significant patient or operative risk factors for airway compromise. A lateral radiograph was obtained immediately after surgery and at 12 hours postoperatively; if swelling increased from preoperative measurements more than 250% at C2 or 150% at C5, the patient was left intubated for another 12 hours. If the X-ray measurements were below these cut-offs and the patient had a positive cuff leak, they were extubated. If the patient could not be extubated, a second check was performed 12 hours later. Patients who remained without cuff leak after 7 days underwent tracheostomy. The use of this protocol resulted in a significantly reduced incidence of postoperative airway complications. Notably, all patients without risk factors, radiographic or clinical evidence of prevertebral soft tissue swelling, were extubated immediately without complications (17).

Other techniques that may prevent airway compromise include atraumatic placement of the ETT (45) on the first attempt and limited retraction of the soft tissues intraoperatively (30). Moreover, extubation should only be performed when qualified practitioners are available in the event of failed extubation or the need for immediate reintubation (30). Releasing the pressure from the ETT cuff and examining for cuff leak can be a useful way to determine the appropriateness of extubation (30).

Combined A-P cervical fusions carry an increased risk of airway complications and should be considered for overnight intubation (24). Some authors suggest considering staging while others have not found significant differences in reintubation rates between single- and two-stage A-P cases (22).

Finally, patients with suspected unilateral vocal cord palsy, defined as current or past symptoms of hoarseness, thyroidectomy, carotid endarterectomy, ligation of patent ductus arteriosus, repair of a complex congenital cardiac anomaly, thoracic aortic aneurysm, or anterior cervical discectomy and fusion (ACDF), should be evaluated preoperatively by an ear, nose, and throat (ENT) specialist. Failure to do so can result in bilateral vocal cord paralysis leading to airway compromise (38).

Difficult airway

The American Society of Anesthesiologists (ASA) has developed guidelines for the management of difficult airways (defined as difficulty with mask ventilation, supraglottic intubation, tracheal intubation, or both) (46). While a full discussion on difficult airways is beyond the scope of this review, the salient points and evidence supporting certain methods of airway management in cervical spine surgery are presented below.

Airway evaluation in the elective setting begins with a history of risk factors for a difficult airway (obstructive sleep apnea, history of snoring, mediastinal mass, subglottic stenosis, ankylosing spondylitis, cervical spondylosis, Down syndrome, Treacher Collins syndrome, tonsillar hypertrophy, or a history of difficult intubation). An anesthesiologist should then examine the patient for structural factors that could make tracheal intubation difficult, including poor visibility of the uvula, short thyromental distance, shape of the palate, maxillary incisor protrusion, short neck, and limited cervical range of motion. Preoperative preparation includes a storage unit containing specialized equipment (Table 5), an assigned assistant who is available to help the primary anesthesiologist, face mask preoxygenation equipment, and supplemental oxygen delivery systems. The patient is preoxygenated and supplemental oxygen delivered throughout the intubation attempt. Strategies for managing a difficult airway include awake intubation, the use of intubating stylets or tube changers, rigid laryngoscopic blades, and fiberoptic bronchoscope (FOB) intubation. Once tracheal intubation is performed, it should be confirmed using capnography (46).

Manninen et al. prospectively studied anesthesiologists’ preferred method for intubation of patients undergoing cervical spine surgery. They noted that awake FOB was preferentially chosen for trauma, myelopathy, and spinal stenosis. However, they failed to find a correlation between the method of intubation (awake FOB, asleep FOB, or asleep while using other devices, such as trachlight and Glidescope^®) and postoperative airway complications (20). Video laryngoscopy (e.g., McGrath laryngoscope) is another alternative to a fiberoptic scope, which has been found to produce less upper cervical spine movement (10).

Minimizing trauma to the airway and providing inline stabilization are critical for preventing airway complications during ACSS. The Glidescope^® has been found to increase successful first attempt tracheal intubation and decrease intubation time (8). However, this tool may be associated with higher mean arterial pressures 2 min after intubation, as well as larger C2–5 Cobb angle changes than other intubation methods. Thus, it may be less suitable for cases with cardiovascular or cerebrovascular risk factors, or in cases of spinal cord injury where movement of the cervical spine is contraindicated.

Other intubation instruments such as the Bullard laryngoscope have been shown to decrease the time to intubation and reduce neck motion during the procedure (9). Additional advantages of the Bullard laryngoscope include portability, decreased cost, and increased device durability. A rigid video-stylet (e.g., Optiscope^®) is another good option for intubating ACSS patients, especially after traumatic injuries, since it has been found to produce less movement at the upper and subaxial cervical spine than the video laryngoscope (12).

Difficult extubation

There are currently no guidelines for assessing the risk of difficult extubation (46). The ASA recommends considering awake extubation and establishing a plan for airway management in patients unable to maintain adequate ventilation before attempting extubation. They also recommend using a device, such as a stylet, which can serve as a guide for expedited reintubation should the need arise (46). The PAEC can also be used as a stylet with a 4-mm external diameter hollow conduit by inserting it into the ETT prior to extubation. Oxygen can be delivered through the catheter at the desired flow rate. In the event of respiratory failure, an ETT can be reinserted using a catheter as a guide. Dosemeci et al. demonstrated that leaving a PAEC in place during complicated maxillofacial or major neck surgery facilitated reintubation in situations that would otherwise have been difficult, if not impossible, with direct laryngoscopy. PAEC may also facilitate direct laryngoscopy, but the two methods are not mutually exclusive (14). In addition, Antoine et al. wrote about a difficult extubation following a standard C5-C7 ACDF where the patient required extubation over an airway catheter. They reported that the airway catheter could provide oxygen to the patient and maintain a conduit for emergent reintubation. The airway catheter was left in place until the patient followed commands. Eventually, the patient was diagnosed with compression of the airway by the innominate artery and tracheomalacia (32). Another advantage of PAEC is that it allows those who have difficult reintubations to be extubated earlier and with less apprehension, possibly avoiding the costs and complications associated with prolonged tracheal intubation (14). This may be particularly useful in cases where laryngeal edema makes reintubation much more difficult or to avoid the need for tracheostomy, especially in cases of diffuse idiopathic skeletal hyperostosis (DISH) where preoperative laryngeal edema is common and may be exacerbated by surgery (37). These patients can have airways that are additionally compromised by anterior displacement of the airway, restricted cervical movement, and limited oropharyngeal space (43). Finally, fiberoptic bronchoscopy may be used intraoperatively and postoperatively to compare compression in the areas of the pharynx prone to swelling (aryepiglottic and vestibular folds). If serious swelling is present, this practice can help prevent extubation.

The obstructed airway

The obstructed airway is particularly important due to its lethality (47). It should be noted that urgent intubation of obstructed airways is not straightforward and is a high-risk procedure with potentially devastating complications, such as anoxic brain injury, cardiac arrest, and death. The goals of managing an obstructed airway are to maintain oxygenation and hemodynamic function (31). A common answer to the obstructed airway is awake fiberoptic intubation, but this has also been associated with serious complications (47). Obstructions are generally classified by anatomical location: laryngeal (or upper airway obstruction), mid-tracheal obstruction, and lower tracheal obstruction. The majority of obstructed airways in ACSS occur within 24 h but can occur in a delayed fashion postoperatively (21). Timing may suggest the cause of the obstruction; for example, those occurring within 12–72 hours postoperatively are most commonly due to hematoma or pharyngeal edema (29,30). While hematoma may occur at any point after surgery, delayed causes of obstruction are more commonly attributed to cerebrospinal fluid (CSF) collection or infection (29).

Upper airway obstruction

The upper airway, or pharyngeal airway (higher than C4) is susceptible to compression from swelling and hematoma following ACSS (19). Mason and Fielder’s guidance on obstructed airways in patients with head and neck tumors translates well to ACSS patients (47). The upper airway includes the pharynx and supraglottic, epiglottic, and subglottic areas. Stridor is a common sign of airway compromise, which occurs when >50% of the airway diameter is obstructed. In this setting, oral airways should be avoided during induction of light anesthesia, as this could lead to total collapse of the airway secondary to laryngeal spasm and coughing. Instead, a nasal airway is preferred to prevent the opposition of the soft palate to the posterior pharyngeal wall. Similarly, awake fiberoptic intubation may be dangerous because spontaneous and complete occlusion of the airway is possible. If the decision is made to proceed with laryngoscopy, only one or two attempts should be made, as continued attempts may result in complete obstruction. If the anatomy is too tenuous, a tracheostomy should be performed by a skilled ENT provider. A provider able to perform tracheostomy should always be available to help maintain the airway in the setting of the “can’t intubate, can’t ventilate” patient (47,48). Emergent front-of-neck access may be obtained using either a standard open approach or a cannula technique (48). In contrast, obstruction caused by lower tracheal lesions may be best managed with fiberoptic intubation as tracheostomy may not be an option.

Hematoma

Hematomas generally affect the upper airway and can cause tracheal deviation (35). Awake intubation may be attempted in such situations. Gwinnutt et al. reported a case of hematoma resulting in upper airway obstruction managed with inhalation induction of anesthesia; however, several attempts were required to attain successful intubation using a Macintosh laryngoscope (34). Notably, in cases of hematoma, venous drainage may be impaired in the cranial and facial systems. This can result in severe swelling of the tongue, retropharyngeal soft tissue, and the nasal mucosa. Inoue et al. reported a case of attempted nasal fiberoptic intubation in this situation, which resulted in massive epistaxis and thus should be avoided (35). A forceful intubation prior to hematoma evacuation should also be avoided (33). Song et al. proposed an algorithm for the management of postoperative hematomas, which involves immediate evacuation of the hematoma and hemostasis if any of the following are present: cyanosis, respiratory stridor, patient panic or anxiety, or lack of improvement after close observation. They recommend cricothyroidotomy for patients with cyanosis and unsuccessful re-intubation due to swelling and possible adhesion of the vocal cords in the postoperative period (23).

Palumbo et al. (29) detail a systematic approach to managing postoperative hematoma after ACSS:

• Early multidisciplinary recruitment in this process is essential (Spine Surgery, Anesthesiology, and ENT). The operating room (OR) staff should be alerted, and a tracheostomy tray should be prepared.
• A rapid bedside assessment should be performed, including evaluation of vital signs, particularly oxygen saturation, and examination of the neck/wound for an expanding hematoma or swelling.
• Supplemental oxygen via nonrebreather should be administered immediately, followed by an assessment of the severity of airway compromise. Therefore, sedation should be minimized.
• Noncritical airway compromise occurs with partial obstruction, which is not life-threatening. Vital signs are normal, and there may be mild dyspnea or stridor.
• ­­ The patient is transferred to the OR.
• ­­ Awake FOB intubation is attempted.
• ­­ If this fails, the hematoma should be evacuated while maintaining bag mask ventilation.
• ­­ An attempt at intubation should be made. If this fails, a surgical airway is used.
• Critical airway compromise occurs with near-total obstruction. Vitals may be altered and the patient may appear panicked and anxious.
• ­­ Treatment is initiated at bedside.
• ­ If bag mask ventilation was inadequate, awake fiberoptic intubation was attempted. This may be very difficult, if not impossible, for a patient experiencing respiratory distress. If awake FOB intubation cannot be performed, bedside hematoma removal should be considered. If the patient cannot be intubated, emergent tracheostomy or cricothyrotomy should be performed (40,41).

Following evacuation of the hematoma, the patient should undergo a detailed history for any evidence of a clotting disorder, bleeding disorder, or anticoagulation use as recurrent hematomas are possible (39). A coagulation lab panel should be ordered with hematology consultation if there are any abnormalities.

Implant failure and graft extrusion

Implant failure and anterior graft extrusion may result in airway compromise and unanticipated difficulty in reintubation. Joshi reported a case of a 65-year-old female with plate failure and graft extrusion in which a TruView laryngoscope, which allows for anterior visualization through the use of a prism, was used following induction of anesthesia. However, the larynx could not be identified and they switched to a Macintosh blade and performed the intubation using a stylet (36). In these situations, it is important to anticipate anterior displacement of the airway due to implant failure. Schoenhage et al. reported two cases of difficulty with endotracheal intubation secondary to protrusion of the cervical hardware. These protrusions were eventually navigated with FOB, but resulted in unanticipated difficulty. It is necessary for the spine surgeon to discuss possible obstructions with the anesthesiologist prior to induction as this situation can rapidly deteriorate into a “can’t intubate, can’t ventilate” situation (42). These patients should either have a preoperative tracheostomy or an ENT should be prepared to perform an emergency airway.

CSF leak

If CSF leak is the suspected cause of obstruction, a computed tomography (CT) myelogram may be obtained to confirm the diagnosis, assuming that the patient is not in respiratory distress. Subsequently, the CSF leak should be evacuated, and the dural tear repaired as recurrent CSF fluid collection may cause secondary obstruction (40).

Emergency airway access

An emergent surgical airway, or a cricothyroidotomy, should be established in the “can’t intubate, can’t oxygenate” scenario. Both spine surgeons and anesthesiologists should be familiar with the basic techniques to provide this life-saving procedure if necessary. The tracheal cartilage corresponds to laryngeal prominence and is a key landmark. The cricothyroid membrane is a finger breadth below this point and indicates a region of the airway below the vocal cords. Surgical placement of airways in or above the vocal cords can lead to significant morbidity. In the setting of a previous anterior cervical approach, the surgical incision should be extended to the midline (if horizontal). The cricothyroid membrane is then identified between the cricoid cartilage and tracheal cartilage and repeatedly confirmed by palpation. The airway should be stabilized by the non-dominant hand, and a horizontal incision is made in the membrane close to the cricoid cartilage. The incision is then dilated using a hemostat forcep followed by insertion of a tracheostomy tube (6 cm) and inflation (26). Tracheostomy involves creating an opening in the anterior tracheal wall and is used for airway access. The procedure can be performed percutaneously or as an open procedure (27).

Proposed airway management algorithm

• Assess for preoperative airway risk factors.
  • It is critical to assess for risk factors preoperatively and incorporate these risks into the preoperative surgical discussion and informed consent process. These risk factors are discussed separately in previously published reviews (1,2).
  • Prepare for intubation: have an assistant available as well as adequate airway adjuncts [laryngeal mask airway (LMA), FOB, Glidescope^®].
  • Preoxygenate patient and provide supplemental oxygen throughout the intubation process.
  • If possible, atraumatic intubation on the first attempt by a senior anesthesia provider would be ideal.
  • Consider awake intubation for expected difficult airways.
  • Consider the use of an advanced intubation technique with FOB, lighted stylet, or video-assisted laryngoscopy.
  • Tracheostomy should be available in situations where a difficult tracheal intubation is anticipated.
• Plan for the unexpected: pre-operative ENT examination if vocal cord paralysis is suspected—such as with previous neck surgery. Adjust the approach accordingly.
  • Spinal surgeons should evaluate any anticipated anterior airway displacement secondary to deformity or hardware complications and discuss the possibilities and challenges with the anesthesiologist. Patients should be counseled of possible airway complications in these situations as well as the need for possible tracheostomy.
  • Techniques to limit neck movement in trauma patients undergoing cervical spine surgery (25):
    • Apply cricoid pressure using a two-hand technique to limit cervical spine motion: one hand on the back of the neck and another on the cricoid.
    • Direct laryngoscopy with manual in-line traction and stabilization.
    • Use of helpful devices, such as stylets, with alternative airways available, such as levering laryngoscopes, fiberoptic laryngoscopes, video laryngoscopes, or other imaging devices.
    • Failure to intubate may necessitate alternative methods such as establishing a LMA. However, these devices may exert pressure against the vertebrae and lead to posterior displacement of the cervical spine, which is not ideal in cases of trauma, instability, or severe stenosis.
    • Extreme emergencies—retrograde tracheal intubation or emergent cricothyroidotomy.
• Assess for intraoperative risk factors: blood loss >300 mL, operative time >5 h, >3 level operation, combined A-P cervical surgery.
  • Lateral radiographs may be obtained to assess swelling prior to extubation.
  • If positive, leave the patient intubated for 12 additional hours and perform the cuff leak test (see below).
  • Use propofol for maintenance of anesthesia (as opposed to sevoflurane) (11).
• Assess for cuff leak.
  • A cuff leak test should be performed in patients with more than one risk factor for airway compromise after ACSS or in those who fail an extubation attempt.
  • If positive, attempt extubation when appropriate personnel are available. Consider leaving the airway catheter for another 12–24 hours.
  • If negative, obtain lateral radiograph or perform FOB to evaluate for swelling.
    • If significant swelling on lateral radiograph or FOB, keep the patient intubated and recheck in 12 hours.
    • If there was significant swelling but a cuff leak test failed, keep the patient intubated and recheck in 12 hours.
  • Tracheostomy should be considered in patients who remain intubated on postoperative day 7 due to failed cuff leak tests and/or multiple extubation attempts.
• Managing the obstructed airway.
• When a patient develops signs (e.g., stridor) or symptoms (panic) of airway obstruction in the acute postoperative period, an immediate bedside assessment should be performed with the delivery of oxygen via nonrebreather and constant monitoring of vital signs.
• Alert the appropriate multidisciplinary staff—spine surgeon, anesthesiologist, on-call ENT, respiratory therapist, OR staff—for an emergency trip to the OR.
• In patients with obvious neck swelling, hematoma should be suspected, and bag mask ventilation should be initiated.
• Abnormal vital signs and panic should be considered critical:
• If bag mask ventilation is inadequate, attempt awake fiberoptic intubation.
• If this fails, evacuate the hematoma at the bedside, and then re-attempt awake fiberoptic intubation.
• If this fails, perform an emergent surgical airway.
• Once an airway is secured, the surgical wound and hematoma should be addressed in the OR (i.e., re-evaluation for hemostasis).
• Normal vital signs without panic should be considered non-critical:
• Bring patient to OR in an urgent fashion.
• Attempt awake fiberoptic intubation.
• If this fails, attempt to evacuate hematoma under bag mask ventilation.
• Repeat awake fiberoptic intubation.
• If this fails, consider a surgical airway.
• When hematoma is not suspected, perform immediate bedside lateral cervical spine X-ray.
• Severe soft tissue swelling/edema present.
• Insert nasal airway.
• Attempt intubation with gentle laryngoscopy.
• If this fails, transfer patient to OR for a surgical airway.
• Graft extrusion suspected.
• Transfer patients to the OR for revision surgery if able to maintain stable vital signs with oxygen therapy.
• If this fails, provide bag mask ventilation while transferring patient to OR.
• If this fails, insert nasal airway and attempt laryngoscopic intubation in OR.
• If this fails, proceed with the surgical airway and revision surgery when the patient is hemodynamically stable.
• CSF leak suspected.
• This rarely presents acutely.
• If able to maintain oxygenation via nonrebreather, obtain CT myelogram.
• If positive, proceed with revision surgery when patient is hemodynamically stable.
• Postoperative monitoring: patients should be instructed to self-monitor for up to 2 weeks and given instructions on possible airway complications and signs of eminent airway collapse, such as stridor, swelling, shortness of breath, or an increase in anxiety associated with any of the aforementioned.

Conclusions

This review summarizes the most recent and relevant literature regarding management of airway complications after ACSS. Currently, the literature lacks high-level evidence (I or II) supporting any specific management or prevention strategy for patients undergoing these surgeries. The authors aim to provide guidelines based on the available literature on airway compromise in ACSS. The following are additional recommendations outside of this proposed algorithm based on our systematic review.

Additional recommendations/guidelines

• Intraoperative: deflation of the ETT after retractor placement. Subsequent ETT re-inflation to the just-sealed pressure. Repeat if the retractor position is changed or with noted elevation in cuff pressure (13,16).
• Postoperative: delayed (>24 hours) extubation in patients with risk factors for unplanned reintubation even without clinical signs of respiratory distress, but extubation as quickly as safe in patients without risk factors (18). The following are the risk factors for airway complications.
  • Medical comorbidities or functional dependence.
  • Patients with DISH or ossification of the posterior longitudinal ligament (OPLL).
  • Trauma.
  • Combined A-P surgery.
  • Operative time >5 hours.
  • Estimated blood loss >300 mL.
  • Revision surgery.

When encountering a difficult airway, it is preferable to use a Glidescope^®, although a Bullard laryngoscope may provide faster intubation, whereas a rigid video-stylet may cause less motion across the cervical spine. Any spine surgeon or anesthesiologist taking care of ACSS patients should be equipped to perform an emergency airway in the setting of the acute loss of an airway. This study has several limitations. As previously mentioned, the available literature on this topic is mostly anecdotal, retrospective, small series and opinion based studies. Therefore, the proposed algorithm was formulated as the opinion of the authors based on the available evidence. Some of the recommendations are controversial, such as deflation of the ETT after retractor placement with reinflation and pressure adjustment. Although we reference studies supporting this practice (16,18), others have found it does not affect the incidence of postoperative vocal fold immobility (7).

Despite the presented studies, there remains a paucity of evidence to fully support these recommendations. Future studies are needed to provide high-level evidence that spine surgeons and anesthesiologists can rely on to make clinical decisions and to create evidence-based practice guidelines. Ideally, some of the provided recommendations could be evaluated with RCTs; however, considering the danger to patients, this may pose an ethical challenge. With the recent development and use of artificial intelligence algorithms for medical research, we hope that future studies can use machine learning from large databases to understand the most important etiological and risk factors for airway complications after ACSS while establishing sound management protocols.

Acknowledgments

The authors would like to acknowledge Bridget Jivanelli, medical librarian, for conducting a literature search and providing the manuscript with an appendix of all searched terms and medical subject headings.

Funding: None.

Footnote

Reporting Checklist: The authors have completed the PRISMA reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-23-32/rc

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-23-32/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-23-32/coif). T.J.A. receives royalties or licenses from DePuy Synthes Spine and Zimmer Biomet. He also has leadership or fiduciary role in Back Story, LLC; Hospital for Special Surgery; Orthopedics Today; Spine Universe. He has ownership interest in Augmedics; Care Equity, CytoDyn Inc.; HS2, LLC; Innovative Surgical Designs, Inc.; Invivo Therapeutics; Morphogenesis; Paradigm Spine, LLC; Parvizi Surgical Innovations, Physician Recommended Nutriceuticals; Precision Orthopedics; Pulse Equity; Spinicity; Strathspey Crown; Surg. IO LLC. And book royalties from Elsevier, Inc., JP Medical Publishers, Springer, and Thieme Medical Publishers. Y.K. has the stock or stock options from Radius Health. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Colón LF, Barber L, Soffin E, et al. Airway Complications After Anterior Cervical Spine Surgery: Etiology and Risk Factors. Global Spine J 2023;13:2526-40. [Crossref] [PubMed]
2. Debkowska MP, Butterworth JF, Moore JE, et al. Acute post-operative airway complications following anterior cervical spine surgery and the role for cricothyrotomy. J Spine Surg 2019;5:142-54. [Crossref] [PubMed]
3. Higgins JP, Altman DG, Gøtzsche PC, et al. The Cochrane Collaboration's tool for assessing risk of bias in randomised trials. BMJ 2011;343:d5928. [Crossref] [PubMed]
4. Sterne JA, Hernán MA, Reeves BC, et al. ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions. BMJ 2016;355:i4919. [Crossref] [PubMed]
5. Shea BJ, Reeves BC, Wells G, et al. AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. BMJ 2017;358:j4008. [Crossref] [PubMed]
6. Murad MH, Sultan S, Haffar S, et al. Methodological quality and synthesis of case series and case reports. BMJ Evid Based Med 2018;23:60-3. [Crossref] [PubMed]
7. Audu P, Artz G, Scheid S, et al. Recurrent laryngeal nerve palsy after anterior cervical spine surgery: the impact of endotracheal tube cuff deflation, reinflation, and pressure adjustment. Anesthesiology 2006;105:898-901. [Crossref] [PubMed]
8. Brück S, Trautner H, Wolff A, et al. Comparison of the C-MAC(®) and GlideScope(®) videolaryngoscopes in patients with cervical spine disorders and immobilisation. Anaesthesia 2015;70:160-5. [Crossref] [PubMed]
9. Cohn AI, Zornow MH. Awake endotracheal intubation in patients with cervical spine disease: a comparison of the Bullard laryngoscope and the fiberoptic bronchoscope. Anesth Analg 1995;81:1283-6. [PubMed]
10. Dutta K, Sriganesh K, Chakrabarti D, et al. Cervical Spine Movement During Awake Orotracheal Intubation With Fiberoptic Scope and McGrath Videolaryngoscope in Patients Undergoing Surgery for Cervical Spine Instability: A Randomized Control Trial. J Neurosurg Anesthesiol 2020;32:249-55. [Crossref] [PubMed]
11. Hans P, Marechal H, Bonhomme V. Effect of propofol and sevoflurane on coughing in smokers and non-smokers awakening from general anaesthesia at the end of a cervical spine surgery. Br J Anaesth 2008;101:731-7. [Crossref] [PubMed]
12. Nam K, Lee Y, Park HP, et al. Cervical Spine Motion During Tracheal Intubation Using an Optiscope Versus the McGrath Videolaryngoscope in Patients With Simulated Cervical Immobilization: A Prospective Randomized Crossover Study. Anesth Analg 2019;129:1666-72. [Crossref] [PubMed]
13. Apfelbaum RI, Kriskovich MD, Haller JR. On the incidence, cause, and prevention of recurrent laryngeal nerve palsies during anterior cervical spine surgery. Spine (Phila Pa 1976) 2000;25:2906-12. [Crossref] [PubMed]
14. Dosemeci L, Yilmaz M, Yegin A, et al. The routine use of pediatric airway exchange catheter after extubation of adult patients who have undergone maxillofacial or major neck surgery: a clinical observational study. Crit Care 2004;8:R385-90. [Crossref] [PubMed]
15. Epstein NE, Hollingsworth R, Nardi D, et al. Can airway complications following multilevel anterior cervical surgery be avoided? J Neurosurg 2001;94:185-8. [PubMed]
16. Jung A, Schramm J. How to reduce recurrent laryngeal nerve palsy in anterior cervical spine surgery: a prospective observational study. Neurosurgery 2010;67:10-5; discussion 15. [Crossref] [PubMed]
17. Kim M, Choi I, Park JH, et al. Airway Management Protocol After Anterior Cervical Spine Surgery: Analysis of the Results of Risk Factors Associated With Airway Complication. Spine (Phila Pa 1976) 2017;42:E1058-66. [Crossref] [PubMed]
18. Kim M, Rhim SC, Roh SW, et al. Analysis of the Risk Factors Associated with Prolonged Intubation or Reintubation after Anterior Cervical Spine Surgery. J Korean Med Sci 2018;33:e77. [Crossref] [PubMed]
19. Kim SW, Jang C, Yang MH, et al. The natural course of prevertebral soft tissue swelling after anterior cervical spine surgery: how long will it last? Spine J 2017;17:1297-309. [Crossref] [PubMed]
20. Manninen PH, Jose GB, Lukitto K, et al. Management of the airway in patients undergoing cervical spine surgery. J Neurosurg Anesthesiol 2007;19:190-4. [Crossref] [PubMed]
21. Nagoshi N, Fehlings MG, Nakashima H, et al. Prevalence and Outcomes in Patients Undergoing Reintubation After Anterior Cervical Spine Surgery: Results From the AOSpine North America Multicenter Study on 8887 Patients. Global Spine J 2017;7:96S-102S. [Crossref] [PubMed]
22. Siemionow K, Tyrakowski M, Patel K, et al. Comparison of perioperative complications following staged versus one-day anterior and posterior cervical decompression and fusion crossing the cervico-thoracic junction. Neurol Neurochir Pol 2014;48:403-9. [Crossref] [PubMed]
23. Song KJ, Choi BW, Lee DH, et al. Acute airway obstruction due to postoperative retropharyngeal hematoma after anterior cervical fusion: a retrospective analysis. J Orthop Surg Res 2017;12:19. [Crossref] [PubMed]
24. Terao Y, Matsumoto S, Yamashita K, et al. Increased incidence of emergency airway management after combined anterior-posterior cervical spine surgery. J Neurosurg Anesthesiol 2004;16:282-6. [Crossref] [PubMed]
25. Bonhomme V, Hans P. Management of the unstable cervical spine: elective versus emergent cases. Curr Opin Anaesthesiol 2009;22:579-85. [Crossref] [PubMed]
26. Bribriesco A, Patterson GA. Cricothyroid Approach for Emergency Access to the Airway. Thorac Surg Clin 2018;28:435-40. [Crossref] [PubMed]
27. Cheung NH, Napolitano LM. Tracheostomy: epidemiology, indications, timing, technique, and outcomes. Respir Care 2014;59:895-915; discussion 916-9. [Crossref] [PubMed]
28. Eskander A, de Almeida JR, Irish JC. Acute Upper Airway Obstruction. N Engl J Med 2019;381:1940-9. [Crossref] [PubMed]
29. Palumbo MA, Aidlen JP, Daniels AH, et al. Airway compromise due to wound hematoma following anterior cervical spine surgery. Open Orthop J 2012;6:108-13. [Crossref] [PubMed]
30. Palumbo MA, Aidlen JP, Daniels AH, et al. Airway compromise due to laryngopharyngeal edema after anterior cervical spine surgery. J Clin Anesth 2013;25:66-72. [Crossref] [PubMed]
31. Umobong EU, Mayo PH. Critical Care Airway Management. Crit Care Clin 2018;34:313-24. [Crossref] [PubMed]
32. Antoine J, Hussain Z, El-Sayed I, et al. The unrecognised difficult extubation: a call for vigilance. Anaesthesia 2010;65:946-8. [Crossref] [PubMed]
33. Chang DG, Park JB, Kim HJ, et al. Delayed onset postoperative retropharyngeal hematoma after anterior cervical surgery with a sequela of tracheal stricture: a case report. Eur J Med Res 2021;26:77. [Crossref] [PubMed]
34. Gwinnutt CL, Walsh GR, Kumar R. Airway obstruction after anterior cervical spine surgery. J Neurosurg Anesthesiol 1992;4:199-202. [Crossref] [PubMed]
35. Inoue S, Fujimoto Y, Kawano Y, et al. Difficult passage of the endotracheal tube and massive nasal bleeding during awake nasal fiberoptic intubation in a patient with airway obstruction caused by neck hematoma--a case report. Middle East J Anaesthesiol 2011;21:125-7. [PubMed]
36. Joshi N, Khurana P, Malhotra R, et al. Difficult intubation in a patient with anterior displacement of cervical spine implant. Anaesth Intensive Care 2012;40:1070-1. [PubMed]
37. Kim YS, Lee JJ, Chung YH, et al. Postoperative obstructing laryngeal edema in patients with diffuse idiopathic skeletal hyperostosis of cervical spine -A report of two cases. Korean J Anesthesiol 2011;60:377-80. [Crossref] [PubMed]
38. Manski TJ, Wood MD, Dunsker SB. Bilateral vocal cord paralysis following anterior cervical discectomy and fusion. Case report. J Neurosurg 1998;89:839-43. [Crossref] [PubMed]
39. Paradells VR, Pérez JB, Vicente FJ, et al. Esophageal, pharyngeal and hemorrhagic complications occurring in anterior cervical surgery: Three illustrative cases. Surg Neurol Int 2014;5:S126-30. [Crossref] [PubMed]
40. Penberthy A, Roberts N. Recurrent acute upper airway obstruction after anterior cervical fusion. Anaesth Intensive Care 1998;26:305-7. [Crossref] [PubMed]
41. Roy SP. Acute postoperative neck hematoma. Am J Emerg Med 1999;17:308-9. [Crossref] [PubMed]
42. Schoenhage KO, Koenig HM. Unanticipated difficult endotracheal intubations in patients with cervical spine instrumentation. Anesth Analg 2006;102:960-3. [Crossref] [PubMed]
43. Thompson C, Moga R, Crosby ET. Failed videolaryngoscope intubation in a patient with diffuse idiopathic skeletal hyperostosis and spinal cord injury. Can J Anaesth 2010;57:679-82. [Crossref] [PubMed]
44. Glinski AV, Elia C, Yilmaz E, et al. Space-Occupying Lesions of the Retropharyngeal Space: An Anatomical Study With Application to Postoperative Retropharyngeal Hematomas. Global Spine J 2021;11:704-8. [Crossref] [PubMed]
45. Riew KD, Sethi NS, Devney J, et al. Complications of buttress plate stabilization of cervical corpectomy. Spine (Phila Pa 1976) 1999;24:2404-10. [Crossref] [PubMed]
46. Levine AI, DeMaria S Jr. An updated report by the American Society of Anesthesiologists Task Force on management of the difficult airway: where is the aspiration risk assessment? Anesthesiology 2013;119:731-2. [Crossref] [PubMed]
47. Mason RA, Fielder CP. The obstructed airway in head and neck surgery. Anaesthesia 1999;54:625-8. [Crossref] [PubMed]
48. Greenland KB, Bradley WPL, Chapman GA, et al. Emergency front-of-neck access: scalpel or cannula-and the parable of Buridan's ass. Br J Anaesth 2017;118:811-4. [Crossref] [PubMed]