INTRODUCTION — Complications can occur any time the airway is instrumented or managed. In addition to mechanical and physiologic effects that occur during the process of placing an airway device, medications used for induction of anesthesia and airway management can cause cardiovascular complications.
This topic will discuss the more common direct or traumatic complications that may occur during or immediately after endotracheal intubation, use of a supraglottic airway (SGA), or mask ventilation, as well as the indirect hemodynamic and physiologic complications that can occur.
Failure of airway management is discussed separately. (See "Management of the failed airway during anesthesia".)
Long-term complications of endotracheal intubation (eg, laryngomalacia, tracheomalacia, or laryngeal stenosis) are discussed separately. (See "Complications of the endotracheal tube following initial placement: Prevention and management in adult intensive care unit patients".)
INCIDENCE — Some of the minor complications of airway management (eg, sore throat) are relatively common, whereas major complications are very rare. The Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society (NAP4), published in 2011, collected major airway-related complications over a one year period in the United Kingdom in the operating room, the emergency department, and the intensive care unit [1]. Major airway events occurred in an estimated 1 in 21,598 cases. Major complications were defined as those that resulted in death, brain damage, the need for a surgical airway, or unplanned admission to the intensive care unit. A more recent study in the United Kingdom using the same methods as the NAP4 project found similar rates of complications, and higher rates in patients who were predicted to be difficult (1 in 315), but no complications of death or brain damage [2].
According to the American Society of Anesthesiologists Closed Claims analysis, 17 percent of claims were due to respiratory events and 7 percent of reported claims were due to airway injury [3].
The incidences of specific complications are discussed in sections below.
RISK FACTORS — Certain patient and situational risk factors may predispose a patient to both direct and indirect complications of airway management, including the risk of traumatic injury, and/or the risk of physiologic complications associated with delayed or unsuccessful placement of an airway device, as follows:
●Patient risk factors for difficulty with airway management, as shown in tables (table 1 and table 2 and table 3 and table 4 and table 5). (See "Airway management for induction of general anesthesia", section on 'Prediction of the difficult airway'.)
●Difficult intubation, including the need for multiple intubation attempts.
●Coagulopathy [4].
●Reintubation after failed extubation.
●Emergency endotracheal intubation [5]. (See 'Complications during emergency airway management' below.)
●Endotracheal intubation performed outside the operating room [6-8].
NAP4 identified several themes/factors that contributed to major complications associated with airway management [1]:
●Poor airway assessment
●Poor planning for airway management and for failure of intubation
●Multiple intubation attempts
●Inappropriate use of a supraglottic airway (SGA) device (ie, use of an SGA when an endotracheal tube [ETT] would have been more appropriate)
●Obesity
●Failure to correctly interpret capnography and recognize esophageal intubation
●Anesthesia for head and neck surgery
●Intubation in the emergency department or intensive care unit
COMPLICATIONS DURING EMERGENCY AIRWAY MANAGEMENT — Many airway complications are more likely to occur during emergency airway management [7-9]. Factors that are more likely during emergency airway management and that may increase the risk of complications include the following:
●Inadequate preoxygenation (due to lack of time, physiologic factors)
●Presence of hemodynamic instability
●Increased incidence of airway edema (failed extubation, anaphylaxis)
●Multiple intubation attempts, which are more frequent in emergency intubations
Most emergency airway management occurs outside the operating room, in the emergency department, the intensive care unit, on general wards, or in procedural areas (eg, radiology or gastrointestinal procedure suites). In out-of-operating room settings, trained personnel and airway equipment may not be immediately available, and access to the patient may be limited by space constraints. Risk may be reduced by standardization of airway equipment throughout the hospital with airway management carts, and by creating airway teams that respond to emergencies [10].
Major peri-intubation adverse events are common after emergency intubation and may be associated with increased mortality. (See 'Hemodynamic changes' below.)
PHYSIOLOGIC COMPLICATIONS RELATED TO AIRWAY MANAGEMENT — Induction of anesthesia for airway management or airway management itself can cause detrimental physiologic effects, including hemodynamic instability, arrhythmias, and/or hypoxia. Patients who require emergency intubation are at higher risk of these complications, as they are often critically ill [7,11,12].
Hypoxia — General anesthesia is typically induced prior to airway management; the patient is rendered unconscious and apneic. In most cases, the clinician performs mask ventilation or places an airway device to maintain oxygenation. If ventilation is not reestablished quickly, hypoxia can occur. Hypoxia can result from airway obstruction, aspiration, bronchospasm, laryngospasm, or esophageal intubation. If untreated, hypoxia can lead to hypotension, arrhythmias, brain damage, cardiovascular collapse, and death. In the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society (NAP4), hypoxia was the common theme in deaths caused by an airway problem in anesthesia cases, and those in the emergency department and the intensive care unit [1].
Hypoxia due to inadequate ventilation or apnea also causes hypercapnia, which can reduce pH and trigger arrhythmias and neurologic injury [11].
Preoxygenation is routinely performed prior to induction of anesthesia, to increase oxygen reserves and to prolong the safe apnea time (duration of apnea without desaturation). Preoxygenation and apneic oxygenation (ie, administration of oxygen during laryngoscopy) are particularly important for the following categories of patients, who may be at increased risk of hypoxia during airway management:
●Patients who are expected to desaturate rapidly during apnea (eg, obese, pregnant, pediatric, or hypermetabolic patients)
●Patients with pulmonary or cardiovascular pathology leading to lower oxygen delivery/reserves (eg, chronic obstructive pulmonary disease [COPD]/emphysema, prior lung surgery, pulmonary hypertension, congestive heart failure, pulmonary edema, acute respiratory distress syndrome, any patient with decreased cardiac output, severe asthma, bronchospasm, COVID-19)
Preoxygenation and apneic oxygenation are discussed in detail separately. (See "Preoxygenation and apneic oxygenation for airway management for anesthesia".)
Hemodynamic changes — Induction of anesthesia and airway instrumentation can cause changes in blood pressure, heart rate, and rhythm. Airway manipulation can cause potent sympathetic and parasympathetic stimulation, with variable and sometimes unpredictable results.
●Hypotension – Hypotension is common during and after intubation. It occurs in up to 50 percent of critically ill patients, and is more likely in patients with impaired cardiac function [11,13]. Significant hypotension can progress to cardiac arrest. A retrospective single institution study of emergency intubation in critically ill patients reported a 2 percent incidence of cardiac arrest, the majority of which were also associated with severe hypoxia [7].
The cause of hypotension after intubation in critically ill patients is likely multifactorial, including patient factors, effects of anesthesia induction agents, and the transition from spontaneous ventilation to positive pressure ventilation. Even with minimal sedation, the transition from spontaneous ventilation to positive pressure ventilation can reduce venous return and trigger hypotension [14]. This can be exacerbated in the presence of hypovolemia.
Post-intubation hypotension cannot be reliably predicted or prevented in critically ill patients. Thus, guidelines suggest having adequate assistance during intubation, and being prepared to administer vasopressors and/or intravenous (IV) fluid boluses [12].
•Anesthesia induction agents – For many critically ill patients, etomidate or ketamine are often used rather than propofol to reduce the risk of hypotension. The choice and doses of induction agents based on patient factors and methods for avoiding hypotension and myocardial depression are discussed separately. (See "General anesthesia: Intravenous induction agents", section on 'Dosing considerations'.)
In a large international prospective cohort study of non-operating room intubation in approximately 3000 critically ill patients, major adverse events occurred in 45 percent of patients [15]. The most common adverse event was cardiovascular instability, which occurred in 42.6 percent of patients. Cardiac arrest occurred in 3.1 percent of patients, with an associated 50 percent mortality rate. Use of etomidate or ketamine for intubation was associated with a lower rate of cardiovascular instability compared with propofol or midazolam; etomidate and ketamine were used in a minority of cases. Of note, unadjusted 28 day mortality was higher in patients who had a major adverse peri-intubation event than in those who did not have an adverse event (38 versus 25 percent).
•Preinduction hemodynamic optimization – If time permits, it theoretically makes sense to optimize hemodynamic status prior to induction of anesthesia. This is recommended in airway management guidelines [12], though the benefits of preoperative optimization have not been proven. Options include prophylactic administration of vasopressors or inotropes, and if appropriate, IV fluid.
Routine administration of an IV fluid bolus has not been shown to reduce cardiovascular adverse events after induction. In two multicenter randomized trials and a multicenter cohort study of intubation in critically ill patients, routine administration of a 500 mL fluid bolus prior to induction did not reduce the incidence of post-intubation cardiovascular collapse [16-18].
●Sympathetic response – Airway instrumentation can trigger a sympathetic response, resulting in hypertension, tachycardia, or arrhythmias. Hypertension and tachycardia in this setting can lead to myocardial ischemia [19], cerebrovascular accident, bleeding, or heart failure, and ultimately can result in hypotension or cardiovascular collapse.
Both laryngoscopy and placement of an endotracheal tube (ETT) can trigger a hyperdynamic response [13,20]. Some studies have found reduced hyperdynamic responses to laryngoscopy with the use of videolaryngoscopy (VL) compared to direct laryngoscopy (DL) [21-24]. Hemodynamic responses to placement of a supraglottic airway (SGA) in an anesthetized patient are significantly less than with endotracheal intubation [25,26]. Flexible scope intubation, either awake with sufficient topical anesthesia and sedation or after induction of anesthesia, may be less stimulating than intubation with DL [27].
Risk factors for hypertension during airway management include the following [28-30]:
•Inadequate sedation
•Baseline hypertension
•Trauma patients
•Neurologic injury – seizures, head trauma, cerebrovascular accident, hydrocephalus
•Acute intoxication
•Difficult intubation, prolonged intubation, or multiple attempts
•Aggressive attempts to advance ETT
The sympathetic response to intubation can often be prevented by providing an adequate depth of anesthesia before airway instrumentation. Transient hypertension and/or tachycardia may not require treatment. Prolonged or significant hypertension may be treated by deepening anesthesia, or administration of medications that blunt the sympathetic response (eg, beta blockers or other antihypertensive agents). These should be administered carefully to avoid hypotension after the stimulation is attenuated.
●Arrhythmias – Bradycardia can occur during airway management and may be accompanied by hypotension, and if unrecognized and/or untreated, cardiac arrest. The most common cause of bradycardia during airway management in both children and adults is hypoxia [7]. Bradycardia in this setting may also represent a vagal response to airway manipulation, especially in children, who have higher vagal tone (see 'Hypoxia' above). Other risk factors include preexisting bradycardia due to medications or cardiovascular pathology.
Treatment for bradycardia is correction of hypoxia if present, since it is the most likely cause. Once hypoxia is ruled out, if bradycardia persists, anticholinergic agents such as glycopyrrolate or atropine can be considered, and other causes of bradycardia should be investigated. Succinylcholine has been associated with bradycardia in children as well as in adults if repeated doses are given, but has also been associated with other arrhythmias as well.
More severe arrhythmias, such as supraventricular tachycardia, ventricular tachycardia, ventricular fibrillation, or cardiac arrest, are much less common but can occur with prolonged hypoxia and hypotension, especially in critically ill patients [7,8]. Severe arrhythmias should be managed per advanced cardiac life support protocols. (See "Advanced cardiac life support (ACLS) in adults".)
The risk of cardiac arrest during airway management is much higher outside the operating room setting [1].
SORE THROAT — Sore throat is a common complication of endotracheal intubation or placement of a supraglottic airway device (SGA) for anesthesia, with reported incidence of 14 to 62 percent [31-35]. Sore throat encompasses a wide range of conditions including pharyngitis, laryngitis, or tracheitis. Injury of the uvula can also cause sore throat [36-38]. Symptoms vary and can include pain, dry throat, cough, hoarseness, or dysphagia. Most symptoms are short-lived, resolving within 48 hours. Severe symptoms, or symptoms that persist should be evaluated by an otolaryngologist, as prolonged hoarseness can be due to causes such as laryngeal injury. (See 'Injuries of the larynx and vocal cords' below.)
The etiology of sore throat may be trauma (ie, during laryngoscopy, placement of the airway device, or suctioning), or irritation or injury of the mucosa or airway structures from the airway device itself.
Risk factors for sore throat — Risk factors for sore throat after placement of an airway device may include the following [35]:
●Use of larger endotracheal tubes (ETTs) [32,39,40]
●Higher ETT or SGA cuff pressure [41-43]
●Female gender, may relate to ETT size [39].
●Use of a nasogastric tube during surgery [44]
●Use of a double lumen tube [45]
●Coughing during emergence [31]
●Tracheal intubation without neuromuscular blockade [46]
Strategies to reduce sore throat — The most effective strategies to minimize sore throat are careful airway manipulation, using an appropriately sized ETT (ie, smaller rather than larger), and avoiding high airway device cuff pressures.
●ETT size – Selection of the appropriate-sized ETT can also minimize sore throat risk. In general, a 6.0 to 7.5 mm internal diameter (ID) ETT is appropriate for females, and a 7.0 to 8.0 mm ID ETT is appropriate for males. Several studies have found that the use of a 6.0 mm ID tube in female patients was associated with a significant reduction in sore throat [39,40]. Specialized tubes such as double lumen tubes and hi-lo evacuation tubes may have a larger external diameter that can impact sore throat risk. If specialized ETTs are necessary, the smallest appropriate sizes may be selected to reduce risk.
●Cuff pressure – Higher cuff pressures in both ETTs and SGA devices have been associated with increased incidence of sore throat.
•ETT – ETT pressures should be maintained below 20 mmHg.
•SGA – SGA cuff pressures should be maintained below 60 mmHg [42,43].
If possible, cuff pressures should be measured periodically during a surgical procedure, as the use of nitrous oxide [47] or changes in patient positioning can increase cuff pressure. Several studies have found that the use of manometry to monitor and adjust ETT cuff pressures can reduce the incidence of sore throat [48-50]. Some newer SGAs incorporate a cuff manometer into the device.
●Choice of airway device
•ETT versus SGA – It is not clear whether the choice of airway device (ie, SGA versus ETT) has an effect on the incidence of sore throat [35,51-53]. In practice, the airway device used for general anesthesia is typically based on patient factors and the planned procedure, rather than on the possibility of avoiding sore throat. (See "Airway management for induction of general anesthesia", section on 'Choice of airway device'.)
The literature comparing the incidence of sore throat after the use of ETT versus SGA is inconclusive. In a 2010 meta-analysis of 29 randomized trials that compared outcomes after endotracheal intubation versus use of one of three types of SGAs, there was a statistically significant difference in the incidence of sore throat, but the difference was of questionable clinical significance (22 percent with the laryngeal mask airway [LMA] versus 34 percent with an ETT) [51]. A 2017 systematic review of 19 randomized trials that compared use of an ETT with various SGAs found no clear difference in the incidence of airway complications, with significant heterogeneity among studies with respect to the patient populations, management of the cuff pressure, sizing of the devices, and the type and duration of surgery [53].
•Type of SGA – Multiple types of SGAs are now available for anesthesia and rescue airway management in out-of-operating room settings. Existing evidence suggests little difference in the incidence of sore throat among the various options, with the possible exception of the i-gel SGA, which does not have an inflatable cuff [54]. In a randomized trial that compared the i-gel with the AuraOnce SGA in 204 surgical patient who were paralyzed and ventilated, the incidence of postoperative sore throat at 24 hours was lower after use of i-gel (12 percent versus 23 percent) [55]. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults", section on 'Choice of supraglottic airway'.)
●Videolaryngoscopy versus direct laryngoscopy – Limited evidence suggests that the use of videolaryngoscopy (VL) may be associated with lower rates of sore throat compared to conventional direct laryngoscopy (DL), particularly in the first 24 hours after surgery [56,57].
●Medications – A variety of medications have been suggested to reduce the incidence of sore throat, but the benefits of these medications are unclear. The author routinely administers intravenous (IV) lidocaine near the end of surgery to reduce coughing. Medications that have been studied include the following:
•Lidocaine administered intravenously, via aerosol, or via gel to the airway device cuff [58,59]
•Glucocorticoids administered intravenously or via gel or paste applied to the airway device cuff [60,61]
•Nonsteroidal anti-inflammatory drugs such as topical benzydamine applied to the airway device or oropharynx [62,63]
•Lozenges, including flurbiprofen, zinc, Strepsils (over-the-counter brand), magnesium [64]
•Topical magnesium or ketamine [65,66]
TRAUMATIC COMPLICATIONS
Dental injury — Injuries to teeth are some of the most common patient complaints after anesthesia, and are the most frequent cause for malpractice claims against anesthesia clinicians [67,68]. The upper central incisors are the most frequently injured teeth [69,70].
Teeth can be loosened, cracked, avulsed, or dislodged completely. Avulsed teeth or tooth fragments can be aspirated into the trachea and lead to significant morbidity, and may require bronchoscopy for removal. (See "Airway foreign bodies in adults".) Dental injuries may also require expensive dental restoration.
Dental injury can occur with any type of airway management, and can also occur at any time during anesthesia or recovery [71]. Injury can occur during intubation or placement of a supraglottic airway (SGA), during pre-extubation suctioning with a rigid suction device, during extubation, or post-extubation. Patients can bite down on the airway device or bite block during or after extubation and damage teeth.
●Incidence of dental damage – The reported incidence of dental damage related to anesthesia varies widely in the literature, depending on the way injuries are defined and assessed [69,71-73]. As an example, in a single institution prospective review of approximately 162,000 anesthetics, dental injury was reported in 1 in 2073 anesthetics (0.05 percent), with dental injury defined as any notable change in the patient's dentition reported by clinicians or the patient [69]. In contrast, a prospective study of 536 patients who underwent direct laryngoscopy (DL) for intubation reported a much higher rate of dental injury, at 25 percent [70]. In this study, dental injury included any new abnormality, including enamel fracture, found on examination by a dental consultant, whether noticed by the patient or not. Any teeth dislodged during laryngoscopy should be retrieved and retained in saline. Dislodged teeth are at risk of being lost in the oral cavity, trachea, or esophagus during airway management. Dental consultation should be obtained postoperatively for any dental injury, especially if the tooth was dislodged.
●Risk factors – Risk factors for dental injury during general anesthesia include difficult intubation and preexisting poor dentition or dental reconstruction [69]. During preanesthesia assessment, patients should be asked about dental problems and restorations (eg, caps, bridges, implants, veneers), and teeth should be examined. Part of informed consent should include the risk of dental damage.
●Prevention of dental injury – Careful technique is likely the most important factor for preventing dental injury, though not all injuries can be avoided. It may be expected that videolaryngoscopy (VL) would result in less dental damage than DL, but this has not been demonstrated in the literature. In a retrospective single institution database review of dental injury associated with over 55,000 general anesthetics, VL with a McGrath Mac videolaryngoscope was associated with an increased risk of dental damage compared with DL (odds ratio 2.51, 95% CI 1.24-5.09) [72]. However, causality cannot be determined, since the VL may have been used when dental damage was anticipated.
Several authors have recommended use of dental protective devices during airway management for patients with poor dentition [74-76]. However, mouth guards may give a false sense of security during laryngoscopy, and may not protect against dental damage. In an observational study of 120,000 patients who underwent general anesthesia, over 12,000 of whom had a mouth guard placed because of anticipated dental damage, the incidence of dental injury was similar in patients who had a mouth guard placed, and those who did not [77].
For procedures in which an ETT is used without muscle relaxation, especially when motor evoked potentials are used, a soft bite block or specially designed bite block may be preferred to reduce dental injury [78]. Soft bite blocks may also be preferred for intubated patients in the prone position (see "Neuromonitoring in surgery and anesthesia", section on 'Motor evoked potentials'). A bite block is also recommended for patients undergoing electroconvulsive shock therapy [79].
●Management – Any tooth dislodged during laryngoscopy should be retrieved and retained in saline, and all tooth fragments should be found and removed. Dental consultation should be obtained postoperatively for any dental injury, especially if the tooth was dislodged. Some anesthesia departments have created protocols for handling dental damage and the cost of restoration.
Soft tissue injury — Soft tissue and other injuries of airway structures may occur whenever the airway is instrumented. Patients with coagulopathy, oropharyngeal edema, neck radiation, and difficult intubation are at higher risk of significant injury [80,81].
●DL – The most common cause of soft tissue injury is trauma due to the laryngoscope blade [82]. Most injuries are superficial and result in bleeding and/or minor laceration. More significant lacerations may require surgical intervention. Hematomas may cause sore throat and dysphagia depending on the location, and can become infected, requiring antibiotics.
More serious injuries, such as perforation of the pyriform sinus and distal injuries to larynx and tracheal mucosa, have been reported [83]. These can result in odynophagia, airway edema, and even airway obstruction. Treatment may be conservative, or antibiotics and steroids may be indicated if edema is present.
●VL – Injuries of the pharynx and hypopharynx, vocal cords, and trachea have all been reported with the use of VLs, though these injuries are very rare. The literature comparing laryngeal and airway trauma with the use of VL versus DL is mixed. A 2017 meta-analysis of 22 randomized trials found that VLs reduced laryngeal and airway trauma (OR 0.68, 95% CI 0.48-0.96) [84]. In contrast, a single institution review of approximately 14,800 intubations found a higher rate of oropharyngeal injury with VL (0.234 versus 0.025 percent) [85]. Conclusions from this study are limited because a total of only six injuries occurred. Of note, many of these and other reported oropharyngeal injuries with the use of VL were not discovered until extubation.
During VL, injury can occur when inserting the VL blindly or when passing the ETT blindly between the back of the pharynx (the point at which the operator loses direct sight of the tip of the ETT) and when it is visible with the camera at the laryngeal inlet. Injuries have been reported to the tonsils and palate due to blind ETT placement [85]. Injury may be minimized by inserting both the VL and the ETT into the mouth under direct vision (rather than looking at the monitor) until they pass beyond the soft palate.
●SGAs – Injuries or edema of the uvula, epiglottis, tongue and pharynx have rarely been reported with the use of SGAs [86-89]. The risk of injury may be reduced by avoiding over-inflation of the oropharyngeal cuff and troubleshooting/repositioning a poorly functioning SGA.
●Mask ventilation – Soft tissue injury as a result of ventilation by face mask is rare and usually minor, and may include jaw soreness, or irritation of the skin or lip under the mask itself. Corneal abrasion has been reported, and can be avoided by choosing the correct size face mask, and by securing the eyes closed (ie, with tape or occlusive dressing) [90] immediately after induction of anesthesia.
●Other devices – Optical stylets, bougies [91], tube exchangers, temperature probes, esophageal stethoscopes, and oral or nasal gastric tubes are all rigid or semi-rigid devices that can cause airway soft tissue injuries, including tracheal or bronchial laceration. Pneumothorax has been reported after use of a tube exchanger [92].
Injuries of the larynx and vocal cords
Arytenoid cartilage dislocation — The posterior arytenoid cartilages are part of the cricoarytenoid joint that allows vocal cord abduction and adduction. These cartilages are rarely subluxed or dislocated during intubation or extubation, especially if the ETT cuff is not deflated completely before removal. Risk factors may include poor visualization of the larynx during intubation, as well as certain diseases that predispose to dislocation, such as inflammatory joint diseases and rheumatoid arthritis [80]. Arytenoid dislocation has also been reported after the use of an SGA [93].
Arytenoid dislocation should be suspected in patients with persistent hoarseness (beyond three to five days postoperatively), a breathy and weak voice, and weak cough. Patients with suspected arytenoid dislocation should be evaluated by an otolaryngologist for diagnosis and potential reduction.
In a prospective study of approximately 3100 patients who were intubated for surgery, postoperative hoarseness was found in half of the patients on the day of surgery, 11 percent on postoperative day 3, and 0.8 percent on day 7. Arytenoid dislocation was found in 0.1 percent of patients [94].
Evaluation of hoarseness is discussed in detail separately. (See "Hoarseness in adults".)
Vocal cord injury — The vocal cords can easily be injured during intubation, especially if visualization is difficult, the intubation is traumatic, a bougie is used, or a large ETT is placed. Vocal cord injury may be more likely if the ETT is passed blindly (railroaded) over a bougie, a tube exchanger, or a flexible intubating scope, in which case the edge of the ETT can impinge on the vocal cord.
Traumatic extubation and prolonged postoperative intubation can also increase the risk of injury [95,96]. Injuries can range from erythema, lacerations, granulomas, and ulcers. The majority of these heal over time but may result in prolonged dysphonia [83,94,97]. (See "Complications of the endotracheal tube following initial placement: Prevention and management in adult intensive care unit patients", section on 'Laryngeal injury'.)
Vocal cord paralysis can rarely develop from short-term or long-term intubation. Unilateral vocal fold paralysis is more common than bilateral paralysis, with symptoms similar to arytenoid dislocation (ie, prolonged hoarseness, weak voice and cough), and it can be difficult to distinguish between the two conditions. Vocal cord paralysis can also cause aspiration. (See "Complications of the endotracheal tube following initial placement: Prevention and management in adult intensive care unit patients", section on 'Vocal cord paralysis'.)
Importantly, bilateral vocal fold paralysis can cause stridor or severe respiratory distress, and may require reintubation. (See "Hoarseness in adults", section on 'Bilateral vocal fold paralysis' and "Anesthesia for laryngeal surgery", section on 'Bilateral vocal fold paralysis'.)
The etiology of vocal fold paralysis after intubation is unclear and may be multifactorial. Ischemia due to pressure on the recurrent laryngeal nerve from the ETT cuff is a suggested cause [80,83] (see "Complications of the endotracheal tube following initial placement: Prevention and management in adult intensive care unit patients", section on 'Vocal cord paralysis'). The recurrent laryngeal nerve may also be injured directly during surgery in the neck (eg, thyroid surgery, anterior cervical spine surgery).
Symptoms tend to resolve over time, although interventions such as vocal fold injections, vocal cord medialization, or thyroplasty may be required to improve glottic closure during the recovery process.
Temporomandibular joint dislocation — The temporomandibular joint (TMJ) can be dislocated during anesthesia any time the mouth is opened widely. TMJ dislocation has been reported during laryngoscopy, placement of an SGA, mask ventilation, and during surgical procedures that involve the mouth (eg, endoscopy, bronchoscopy, transesophageal echocardiography) [98-100]. Patients with preexisting TMJ pathology or facial skeletal abnormalities may be at increased risk of TMJ dislocation during anesthesia. Baseline TMJ dysfunction is common, and is often unrecognized by the patient [101].
Postoperative TMJ dislocation should be suspected in patients with inability to close the jaw, periauricular pain, distorted speech, and drooling (see "Temporomandibular joint (TMJ) dislocation", section on 'Clinical features'). Oral surgery should be consulted quickly if the diagnosis is entertained, as delay in treatment may make reduction more difficult due to muscle spasm. Unrecognized TMJ dislocation can lead to long-term sequelae [102].
Cervical spine injury — Movement of the cervical spine during airway management in patients with cervical spine pathology such as stenosis, myelopathy, or trauma may result in injury. Airway management in patients with acute spine injury is discussed separately. (See "Anesthesia for adults with acute spinal cord injury", section on 'Airway management'.)
Barotrauma — Positive pressure ventilation at high pressures (including during mask ventilation) can cause barotrauma and potentially pneumothorax. Patients with COPD or other lung pathology may be at higher risk of barotrauma. An unrecognized main stem intubation can also result in barotrauma to the solely inflated lung.
Signs of barotrauma may include hypercapnia, hypoxia with oxygen desaturation, high peak airway pressures [103], and hemodynamic instability. Pneumothorax [104] can be diagnosed via chest radiography. If unrecognized and untreated, pneumothorax due to barotrauma can lead to hypotension, arrhythmias, and even cardiac arrest. Pneumothorax should be treated via placement of a needle thoracostomy or chest tube to relieve the pressure. Treatment of barotrauma (if pneumothorax is absent) is mostly supportive with supplemental oxygen and close monitoring of airway pressures [105].
Barotrauma and pneumothorax are possible during oxygen insufflation or jet ventilation through the narrow lumen of an airway exchange catheter [106].
COMPLICATIONS ASSOCIATED WITH NASAL INTUBATION — Nasal intubation can cause many of the same complications as oral intubation. Complications unique to nasal intubation include the following:
●Bleeding of the nasal passages – The nasal cavity is highly vascular, and is therefore at risk of bleeding during nasal intubation. A topical vasoconstrictor (eg, oxymetazoline 0.05% or phenylephrine 0.5%) should be applied to the nasal mucosa to reduce the chance of bleeding (see "Flexible scope intubation for anesthesia", section on 'Nasal preparation'). Lubrication and warming of the endotracheal tube (ETT) to soften it may also reduce the risk of bleeding [107]. Bleeding can make visualization of the airway structures more difficult and may require nasal packing if not self-limited.
●Nasal trauma – Injuries to the structures of the nasal cavity (nasal septum, turbinates), the nasopharynx, and adenoid tissues can also occur during nasal intubation. Risk factors may include the presence of a deviated septum and the use of an oversized ETT. Application of a topical vasoconstrictor and warming the ETT may reduce the risk of trauma.
Most mucosal injuries related to intubation resolve with conservative treatment. More severe injuries (eg, septal perforation, turbinate avulsion, large hematoma) require otolaryngology consultation.
Injury of the nasal ala has also been reported, as a result of ischemia related to distortion of the tissue by the ETT [108]. Nasal ETTs should be taped such that there is no traction on the nasal ala, and padded if necessary.
●Sinus effusion and infection – Nasotracheal intubation has been associated with the development of sinusitis due to an inflammatory response to the presence of the ETT, most commonly with intubation for several days [109]. Sinus effusion (fluid in the sinuses) is more common than sinus infection. Sinusitis often presents with fever, may be accompanied by nasal discharge or facial swelling, and can be treated with nasal lavage and antibiotics.
If long term intubation is expected after surgery that requires nasal intubation, changing the ETT to an oral ETT at the end of the procedure may be considered to avoid sinus infection.
ASPIRATION — Since induction of anesthesia results in loss of airway protective reflexes, pulmonary aspiration is a risk during anesthesia, especially if the airway is not sealed with an inflated endotracheal tube (ETT) cuff. Aspiration can occur during mask ventilation, with the use of a supraglottic airway (SGA), and during the interval between induction of anesthesia and inflation of the ETT cuff in patients who are intubated. Patient factors that increase the risk of aspiration are shown in a table (table 6).
Risk factors for aspiration, indications and procedures for rapid sequence induction and intubation to prevent aspiration, and the risk of aspiration with use of SGAs are discussed separately. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults", section on 'Aspiration'.)
BRONCHOSPASM AND LARYNGOSPASM — Airway instrumentation can trigger bronchospasm in susceptible patients (eg, patients with asthma, chronic obstructive pulmonary disease [COPD], smoking). Airway management, recognition and management of bronchospasm, and other aspects of anesthetic management in such patients are discussed separately. (See "Anesthesia for adult patients with asthma" and "Anesthesia for patients with chronic obstructive pulmonary disease".)
Laryngospasm can occur at any time during anesthesia (ie, induction, maintenance, or emergence) in patients without an endotracheal tube (ETT) in place, as a result of laryngeal stimulation from the airway device or secretions that reach the larynx. Laryngospasm is often the result of light anesthesia during airway stimulation.
Prevention, recognition, and management of laryngospasm are discussed separately. (See "Complications of pediatric airway management for anesthesia", section on 'Laryngospasm' and "Extubation following anesthesia", section on 'Risk factors for extubation failure'.)
ESOPHAGEAL INTUBATION — Esophageal intubation accounted for six percent of major airway complications identified by the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society (NAP4) [1]. Difficult laryngoscopy with a poor view of the vocal cords increases the risk of esophageal intubation.
The use of capnography can significantly reduce the incidence of unrecognized esophageal intubation and its use is recommended to confirm airway device placement [110]. Use of videolaryngoscopy (VL), allowing visualization of the endotracheal tube (ETT) entering the trachea, has been associated with a decreased risk of unrecognized esophageal intubation [111].
Correct placement of the ETT into the trachea should be confirmed with bilateral breath sounds as well as end tidal capnography. Confirmation of correct tube placement is discussed separately. (See "Direct laryngoscopy and endotracheal intubation in adults", section on 'Excluding esophageal intubation'.)
UNPLANNED EXTUBATION — Unplanned extubation, defined as unintentional and uncontrolled removal of an endotracheal tube (ETT), can result in hypoxemia, hemodynamic instability, and cardiac arrest. Unplanned extubation can also cause vocal cord injury from the inflated ETT cuff, and/or aspiration of airway secretions. Most of the literature on the incidence of unplanned extubation involves the intensive care unit setting, which is discussed separately. (See "Complications of the endotracheal tube following initial placement: Prevention and management in adult intensive care unit patients", section on 'Displacement and unplanned extubation'.)
Risk stratification and planning for extubation after anesthesia are also discussed separately (see "Extubation following anesthesia"). Unplanned extubation or removal of a supraglottic airway (SGA) in the operating room are discussed here.
Unplanned extubation can occur during surgery in patients who are prone, when changing the patient's position, as a result of surgical manipulation, due to a variety of mechanical issues (eg, accidental traction on the breathing circuit, removal of surgical drapes that are adhering to the airway device), or via self extubation as the patient emerges from anesthesia.
Risk factors — There are no data on the incidence of unplanned extubation during surgery. Based on the mechanisms and case reports, unplanned extubation may be more likely in the following circumstances:
●Procedures performed in the prone or lateral position, during positioning or during the procedure
●Procedures involving or in close proximity to the head, neck, or airway
●Procedures for which the anesthesiologist cannot see and directly monitor the airway device (eg, with the operating table rotated 180 degrees with the head away from the anesthesia machine)
●Procedures performed without muscle relaxation, including procedures using an SGA device with spontaneous ventilation
●Inadequately secured ETT or SGA
Signs of accidental extubation — During procedures in which the anesthesia clinician doesn't have direct access to the airway (eg, prone, lateral, head covered, operating room table rotated), it may be more difficult to detect an unplanned extubation via direct visualization. Signs that the ETT or SGA has been dislodged or removed may include the following:
●Loss of end-tidal carbon dioxide waveform
●Oxygen desaturation
●Sudden decrease in tidal volumes
●Sudden leak in the ventilation system
●Leak around the ETT despite cuff inflation, which may signify a dislodged ETT with the cuff herniated above the vocal cords
Management
●Unplanned extubation during emergence – Reintubation may not be required if adequate ventilation can be maintained. If ventilation cannot be established, the patient should be managed as for a failed extubation. (See "Management of the failed airway during anesthesia".)
●Unplanned extubation during surgery – Unplanned extubation mid-procedure requires reintubation or insertion of an SGA. If the initial intubation was difficult, if the airway is edematous (eg, after a prolonged procedure in the prone position), or if the patient's head is secured for the procedure (eg, in Mayfield pins for neurosurgery), airway management can be quite challenging. Various airway management strategies have been reported for patients with unplanned extubation in the prone position, including turning the patient supine, reintubation through an SGA, and flexible scope intubation [112-115]. A strategy for management during surgery is described here. An algorithm shows a strategy for management of unplanned extubation in the prone position (algorithm 1).
•Call for help and for difficult airway management equipment.
•Alert the surgeon. Stop the surgical procedure if possible; for prone patients, prepare to turn the patient supine if necessary.
•Provide 100 percent oxygen.
•Perform mask ventilation while preparing for insertion of an airway device.
•If mask ventilation is difficult or impossible, and for prone patients, place an SGA.
-If ventilation is adequate with an SGA, determine whether to proceed with surgery using the SGA, or to intubate, through the SGA or using another technique.
-If ventilation is inadequate through the SGA, proceed as for a failed intubation. For patients in the prone or lateral position, turn supine for airway management. Reintubation may require advanced airway equipment such as video laryngoscopy or flexible scope intubation. If oxygen saturations are low or the patient becomes unstable, be prepared to perform a surgical airway. (See "Management of the failed airway during anesthesia".)
Prevention — To minimize the risk of unplanned extubation during surgery, high-risk procedures should be identified and discussed during the surgical timeout. For high-risk procedures, the ETT should be secured well. For prone procedures, some clinicians routinely secure the ETT with benzoin under the ETT tape, and clear plastic dressings over the tape.
During position changes assign a clinician to hold the ETT in position to prevent dislodgement.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Airway management in adults".)
SUMMARY AND RECOMMENDATIONS
●Risk factors – Patients requiring urgent or emergency intubation, who have difficult intubation, or requiring intubation outside the operating room are at higher risk of complications of airway management. (See 'Risk factors' above and 'Complications during emergency airway management' above.)
●Physiologic complications
•Patients with hemodynamic instability or cardiovascular disease are at higher risk of hypotension and arrhythmias during airway management. Induction agents should be chosen and dosed carefully to reduce the risk of hypotension. (See 'Hemodynamic changes' above.)
•The most common cause of bradycardia during airway management is hypoxia. Patients at higher risk of hypoxia during airway management include those with high oxygen consumption, low oxygen reserves, pulmonary or cardiovascular pathology, or difficult intubation. Prolonged hypoxia can lead to brain damage or cardiac arrest. (See 'Hypoxia' above.)
•Stimulation during airway management can cause hypertension and tachycardia. (See 'Hemodynamic changes' above.)
●Sore throat – Sore throat is a common complication of endotracheal intubation and the use of a supraglottic airway (SGA). The most effective strategies to minimize sore throat are careful airway manipulation, using an appropriately sized endotracheal tube (ETT; ie, smaller rather than larger), and avoiding high airway device cuff pressures. (See 'Sore throat' above.)
●Traumatic injury
•Dental injury is one of the most common patient complaints after anesthesia. Difficulty with intubation and preexisting poor dentition or dental restoration are risk factors for dental injury. Careful technique is likely the most important factor for preventing dental injury, though not all injuries can be avoided. (See 'Dental injury' above.)
•Injuries of soft tissues and airway structures are possible any time the airway is instrumented. Injury may be more likely when devices are placed blindly, such as during placement of a bougie, or passing an ETT over a bougie, airway exchange catheter or flexible intubating scope. (See 'Traumatic complications' above.)
●Complications of nasal intubation – Nasal intubation is associated with epistaxis, injury of nasal passages and structures, and sinusitis. (See 'Complications associated with nasal intubation' above.)
●Esophageal intubation – Use of capnography as well as videolaryngoscopy (VL) have been associated with a reduced incidence of esophageal intubation. (See 'Esophageal intubation' above.)
●Unplanned extubation – Unplanned extubation can occur during surgery or during emergence from anesthesia, and can result in hypoxemia, hemodynamic instability, or airway injury. Management depends on whether reintubation or insertion of an SGA is required. If unplanned extubation occurs during surgery in the prone position, preparation should be made to turn the patient supine in case ventilation by mask or through an SGA, or reintubation in the prone position are not possible (algorithm 1).
