Disclaimer
Introduction
Methods
Definitions
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Anticipated difficult airway. A difficult airway is predicted when the airway manager anticipates difficulty with any or all of FMV, tracheal intubation, SGA use, or eFONA.
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Awake tracheal intubation. Awake tracheal intubation (ATI) refers to tracheal intubation of a patient who is sufficiently conscious to maintain a patent airway unassisted, to maintain adequate gas exchange by spontaneous ventilation, and to protect the airway against the aspiration of gastric contents or other foreign material. Awake tracheal intubation can occur via the nasal, oral, or front of neck routes, and is facilitated by topical, regional, or local infiltrative airway anesthesia.
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At-risk tracheal extubation. The at-risk tracheal extubation is defined by the patient anticipated to be intolerant of tracheal extubation or who might be potentially difficult to re-intubate. Difficult re-intubation might be anticipated based on pre-existing or de novo conditions (e.g., neck fusion or immobilization; upper airway edema).
Prediction of difficulty with airway management
• Age > 46 yr • Male sex • Modified Mallampati grades 3 or 4 • Thyromental distance < 6 cm • Prominent, gapped, repaired, or fragile dentition • Limited cervical spine extension • Limited inter-incisor gap • Previous neck radiation • Increased body mass index (conflicting results) • History of obstructive sleep apnea • High upper lip bite test/limited mandibular protrusion • Increased neck circumference • History of difficult direct laryngoscopy or tracheal intubation • Absence of neuromuscular blockade |
• Abnormal neck anatomy (e.g., due to pathology, scar, remote radiation); thick neck • Male sex • Large tongue • Thyromental distance < 6 cm • Short sternothyroid distance • Limited cervical spine motion • Limited mouth opening • High upper lip bite test/limited mandibular protrusion • Upper airway soiled by blood or vomitus • Previously obtained high Cormack–Lehane grade during direct laryngoscopy • Surgery type (head and neck or cardiac) • Airway manager inexperience |
Predictors of difficulty with tracheal intubation using other devices |
Predictors of difficulty with optical stylet use37 |
• Increased body mass index • Decreased mouth opening • Higher Cormack–Lehane grade |
Predictors of difficult flexible bronchoscopic intubation under general anesthesia38 |
• Visibility impaired by blood or secretions • Higher neck skinfold thickness • Larger tracheal tube inner diameter relative to scope outer diameter |
• Age ≥ 46 yr • Body mass index ≥ 35 kg·m−2 • Male sex • History of snoring • Obstructive sleep apnea • Facial hair • Previous neck radiation • Thick and/or short neck • Absence of teeth • Modified Mallampati class 3 or 4 • Limited mandibular protrusion • History of difficult tracheal intubation • Absence of neuromuscular blockade |
Predictors of difficult face-mask ventilation combined with difficult direct laryngoscopy (increasing odds ratio of difficulty if four or more risk factors are present)44 |
• Age ≥ 46 yr • Body mass index ≥ 30 kg·m−2 • Male sex • Obstructive sleep apnea • Facial hair • Modified Mallampati class 3 or 4 • Decreased thyromental distance (e.g., < 6 cm) • Thick neck; neck mass or previous neck radiation • Presence of teeth • Limited cervical spine mobility • Limited mandibular protrusion. |
• No teeth or poor dentition • Reduced inter-incisor distance • Mallampati 3 or 4 • Limited head/neck mobility • Non-use of neuromuscular blockade • Increased body mass index • Neck circumference > 44 cm • Non-supine patient position • Use of desflurane • Use of smaller size supraglottic airway than recommended • Multiple insertion attempts |
Presumptive predictors of difficulty with front of neck airway access |
• Indistinct anatomic landmarks due to obesity, thick or short neck, subcutaneous emphysema, or surgical scarring • Overlying hematoma, induration, inflammation, or tumour • Previous neck radiation • Female sex • Laterally deviated larynx • Limitation to head or neck extension—e.g., fixed flexion deformity |
• Apnea intolerance, based on: ○ Decreased functional residual capacity ○ Increased oxygen consumption ○ Baseline hypoxemia; decreased PaO2/FiO2 ratio ○ Acid-base disturbance with respiratory compensation. • Full stomach or other major risk factor for aspiration. • Hemodynamic instability. |
Contextual issues that may impact airway management |
• Adverse location (e.g., remote location, difficult access to patient, adverse lighting conditions) • Help/backup unavailable (e.g., because of time of day or remote location) • Airway manager inexperience with chosen or required technique • Lack of equipment • Team inexperienced with difficult airway management • Poor team communication |
Published predictors of difficult airway management
The enhanced airway evaluation
Decision-making when difficult tracheal intubation is predicted
Can the patient cooperate with ATI and is there time?
The “double set-up” in airway management: components |
• Mark the location of the cricothyroid membrane with the patient’s head and neck extended. Use ultrasound guidance if skilled. • Decide who will undertake eFONA. This should be someone other than the primary airway manager if possible. • Ensure equipment for the chosen eFONA technique is present in the room, opened, and ready to use. • Brief the team before induction, including the potential need for eFONA and triggers for proceeding with it. |
Rationale for the double set-up in airway management |
• The double set-up will help focus everyone’s attention on the anticipated airway management difficulty and patient risk. • Equipment and personnel are present in the room while the airway is being secured. • eFONA will be perceived as part of the plan, rather than the rescue of a failed plan. Timelier onset of eFONA may result. |
Implementation of the planned strategy when difficult tracheal intubation is predicted
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An additional experienced airway manager should be sourced. For more challenging situations, having this individual standing by in the room is advisable;
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The airway manager should brief the assembled team on the intended strategy for securing the airway;
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The briefing should include the planned response to failure of the intended technique;
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An SGA must be available for use as a rescue technique in the event of failed tracheal intubation;
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During the briefing, the airway manager should include triggers for declaring failure of one technique and proceeding to the next. At this time, all members of the team should be explicitly empowered to state when they believe a trigger has occurred.
Awake tracheal intubation in the patient with anticipated difficult tracheal intubation
Topical airway anesthesia for awake tracheal intubation
Adjunctive systemic medications during awake tracheal intubation
Choice of device to facilitate awake tracheal intubation
• Enables a broad view of anatomy and good spatial awareness; facilitates a shared mental model with other team members. • The tracheal tube can be directed to and observed to pass between the vocal cords. • The “pink-out” that can occur if a FB abuts mucosa is avoided. • Variously sized styleted tracheal tubes can be prepared; it is easier to substitute a smaller sized tracheal tube than re-load and re-insert a FB if the initial tube size is too large. • Space is created in the oropharynx with gentle lifting of the blade during VL. • As a familiar technique, VL may allow more rapid ATI than the FB. • VL may not be an option with some anatomic and pathologic abnormalities (e.g., very limited mouth opening, fixed neck flexion deformity, enlarged tongue, or base of tongue masses). |
Use of flexible bronchoscopy for awake tracheal intubation |
• Passage of the FB and tracheal tube can occur by the nasal route, if necessary. • Navigation is possible in all planes around obstructing masses (e.g., a base of tongue lesion). • Advanced to just above the carina, the FB acts as a guide for tracheal tube advancement to, through, and beyond the larynx. The FB can also be used to confirm successful tracheal intubation and can be used to ensure correct tube positioning above the carina. • The FB can be used for some situations where anatomic constraints preclude use of awake VL. Thus, airway managers must also attain and maintain skills with the FB for ATI. • Using the FB routinely for ATI maintains skills in a critical technique. • Permits examination of the trachea to rule out injury, or to ensure a tracheal tube is placed distal to a known or suspected penetrating tracheal injury or fistula. |
Failed awake intubation
Awake tracheotomy or awake cricothyrotomy
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For the patient presenting with advanced obstructing upper airway pathology that might cause significant technical difficulties during attempted awake oral or nasal intubation (e.g., a very friable, large base of tongue tumour);
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When the glottic opening is very small (e.g., because of obstructing tumour burden) and FB-aided awake oral or nasal intubation would transiently completely occlude the patient’s breathing during intubation, possibly causing panic and loss of patient cooperation;
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When both oral and nasal routes are not available (e.g., because of substantial disruption by trauma or distortion by advanced upper airway pathology);
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When a surgeon elects to do awake tracheotomy as an alternative to awake oral or nasal intubation if the airway manager is not confident that ATI is a feasible option.
The “impossible airway” and awake institution of extracorporeal membrane oxygenation as a primary technique
Management of the patient with anticipated difficult tracheal intubation after the induction of general anesthesia
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Position the patient optimally for the planned technique;
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Pre-oxygenate;
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Use apneic oxygenation throughout;
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Fully prepare equipment for the planned primary intubation approach;
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Fully prepare equipment for alternate intubation techniques;
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Prepare an appropriately sized second-generation SGA for rescue ventilation and oxygenation;
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Brief the team on the planned progression of techniques, with objective triggers for transitioning to the next technique;
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Review and communicate the exit strategy5 to be used if tracheal intubation fails;
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Ensure that an additional experienced airway manager has been sourced.
Patient positioning
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Positioning for laryngoscopy and intubation. Published literature suggests optimal patient positioning for direct- and Mac-VL is the “sniffing” position.91-94 This is typically obtained by aligning the patient’s tragus with their sternum in the horizontal plane, by flexing the lower neck and extending the head.95 In the obese patient, similar alignment can be achieved in several ways, including commercial positioning devices, back-of-bed elevation, or by creating a ramp with folded sheets.96-104 There is currently insufficient evidence to recommend a specific patient position for the use of hyper-angulated videolaryngoscopes, which can be used in both the sniffing and neutral positions of the head and neck. The patient positioned in the neutral position with cervical spine immobilization is sub-optimally positioned for DL and Mac-VL, so that an experienced airway manager and alternate devices such as an HA-VL should be available.105
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Positioning for SGA insertion. Product monographs for SGAs typically espouse a sniffing position for insertion, with head extension and lower neck flexion.108,109 Furthermore, a prospective study has indicated reduced neck mobility to be a risk factor for difficult SGA insertion.52 With respect to ventilation once placed, a systematic review and meta-analysis by Kim and colleagues compared the performance of a variety of SGAs in the flexed, neutral, and extended positions.110 Compared with the neutral position, the flexed position improved device seal but impaired ventilation as well as the view of the glottis obtainable with flexible endoscopy. Conversely, compared with the neutral position, the extended position worsened the device seal but had no effect on ventilation effectiveness or endoscopic view. These findings suggest that after insertion, SGAs should generally be used with the head and neck in the neutral position.
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Positioning for eFONA. Although published evidence is lacking, full extension of the head and neck is likely the optimal position for eFONA.4 This will be aided by placing a bolster or pillow under the patient’s shoulders. There is some evidence that full neck extension may increase the height of the CTM by as much as 30%.111 Pre-induction landmarking of the CTM (e.g., by ultrasound or palpation) should also occur in a position of full neck extension, as the CTM location may change significantly when re-positioning from a neutral to an extended position.111
Pre-oxygenation
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Low to moderate risk of oxygen desaturation: Describing many elective surgical patients with a predicted ample FRC and low shunt fraction, the FRC should be de-nitrogenated by pre-oxygenation with 100% oxygen for three minutes of tidal volume breathing, eight vital capacity breaths over 60 sec,112,113 or until the measured fraction of exhaled oxygen (FeO2) exceeds 0.9.114 More than one strategy has been described for standard pre-oxygenation: 1) use of a tightly applied cuffed face mask attached to an anesthetic circuit or manual resuscitator with O2 flow ≥ 10 L·min−1, or 2) use of a nonrebreathing face mask with oxygen flow at “flush rate” (i.e., ≥ 40 L·min−1).115 The high flow rate helps match the patient’s peak inspiratory flow rate, thus avoiding dilution by room air during peak demand. There is evidence that safe apnea time can be further extended with efforts to increase FRC, e.g., by patient positioning in the semi-seated (Fowler’s), reverse Trendelenburg, or seated upright position,116-120 if hemodynamics allow. This is particularly applicable to morbidly obese patients and term parturients.121-124 In addition, gentle FMV between loss of consciousness and beginning laryngoscopy is advocated.
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Moderate to high risk of oxygen desaturation: For the patient at higher risk of oxygen desaturation with the onset of apnea, such as those with lower FRC and increased shunt fraction, the optimal pre-oxygenation strategy likely involves use of positive end-expiratory pressure or non-invasive positive pressure ventilation (NIV) during pre-oxygenation,125-128 together with back up or reverse Trendelenburg positioning. The concurrent use of standard nasal cannulae with NIV can augment pre-oxygenation and subsequently provide apneic oxygenation during laryngoscopy and intubation,129 although to avoid hazardous gastric insufflation, airway patency must be assured. Use of high-flow nasal oxygenation (HFNO) devices running high flows under a tightly sealed mask should be avoided, e.g., during FMV, for fear of rapid gastric distention or pulmonary hyperinflation and subsequent barotrauma.
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High risk of oxygen desaturation due to refractory hypoxemia: The critically ill patient with substantial lung parenchymal disease and high shunt fraction is often refractory to pre-oxygenation and apneic oxygenation techniques, resulting in severely limited safe apnea time. The use of awake intubation and HFNO while maintaining spontaneous ventilation is one option to help address this scenario, if feasible.
Apneic oxygenation
Maintenance or ablation of spontaneous ventilation?
Assessing for FMV efficacy prior to administration of a neuromuscular blocking agent
Use of short or intermediate-acting neuromuscular blockade
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Pharmacologic modelling studies have indicated that succinylcholine may not necessarily wear off in time to allow resumption of spontaneous ventilation before hypoxemia occurs in the CVCO situation.168,169 In addition, the residual effects of the sedative/induction agent may persist, also impairing a return to adequate spontaneous ventilation.
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Similarly, a proportion of patients given sugammadex for reversal of rocuronium or vecuronium would also critically desaturate during the time required to draw up and administer the drug and for it to work, particularly if apnea intolerant.169 In one simulation study of a CVCO situation,170 a substantial time passed from a decision to use the drug, obtaining it, and its administration to the patient. Therefore, the immediate availability of sugammadex is recommended in all airway management locations. It should be noted that sugammadex will not necessarily reverse CVCO situations related to obstructing airway pathology.171,172
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In critically ill patients where airway management is being performed as part of a resuscitation, expectations of a return to effective spontaneous ventilation is unrealistic when the clinical trajectory is rapidly deteriorating. Use of succinylcholine or a plan to reverse rocuronium if difficulty occurs is not a reliable plan if it is the only difficult airway strategy being deployed.
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Use of an intermediate-acting NMBA to facilitate tracheal intubation will optimize conditions for the duration of airway management should more than one attempt be required, including change of device or operator.
Choice of equipment
Difficulty encountered with a first attempt at tracheal intubation
Difficult tracheal intubation predicted—other options
Avoiding predicted difficult tracheal intubation—use of regional or local anesthesia for a surgical case
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As complications from the surgical procedure itself, administered local anesthetic or sedative medications could all present the need for airway management despite the use of a regional technique, a complete airway evaluation must still occur, and a management strategy determined.
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The surgical procedure must be of a predictable duration, and the block must be shown to be effective before proceeding.
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Ideally, there should be easy access to the patient’s airway intraoperatively.
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Before proceeding, the team should be briefed on the patient’s difficult airway status, together with the plan for intraoperative airway management if needed.
Deferring management of the patient with predicted difficult tracheal intubation
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Transferring an elective surgical patient to a more fully equipped hospital;
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Transferring a pediatric surgical patient with known facial dysmorphism to a specialized pediatric hospital for management;
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Rescheduling a semi-urgent surgical procedure from overnight hours until daytime staff have arrived;
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Deferring tracheal intubation of a critically ill patient by temporizing with the use of non-invasive ventilation or HFNO while additional expertise and equipment is sourced, or until the patient is transferred to a different location (e.g., the OR) for the intubation.
Use of an SGA in the patient with known or predicted difficult tracheal intubation
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For the case normally undertaken with tracheal intubation, electively choosing to proceed with an SGA simply to avoid a difficult tracheal intubation situation has been shown to be hazardous.1 The CAFG recommends against this practice. Rather, the difficult intubation situation should be safely dealt with “up front”.
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For a case where an SGA would normally be used, using an SGA in a patient with anticipated difficult tracheal intubation is often successful, although the airway manager must recognize that the fallback option of defaulting to tracheal intubation should the SGA fail may not easily succeed. This might suggest consideration of initial tracheal intubation as the safer plan when general anesthesia is required. If using an SGA regardless, at the very least, there should be a pre-determined plan for airway management should SGA ventilation fail.
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Despite the above, SGA use is often (appropriately) recommended as a fallback option after failed tracheal intubation in the induced patient.5,6 The SGA can be used to maintain oxygenation and temporize the situation pending the patient’s awakening, while obtaining more equipment or expertise, or it might be used as a conduit to facilitate FB-aided intubation. In an urgent situation (e.g., failed tracheal intubation during emergency Cesarean delivery under general anesthesia), a risk to benefit analysis might justify continuing with the SGA.
Special situations
The patient with a known or suspected highly infectious respiratory pathogen
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Team safety. The risk of transmission of a highly infectious pathogen such as SARS-CoV-2 to a healthcare worker in the immediate peri-intubation period depends on the pathogen and precautions taken.176,177 Spread for most pathogens is assumed to occur by direct contact with droplet containing viral particles, and/or from aerosols generated during a patient cough or an airway procedure (i.e., aerosol-generating medical procedure [AGMP]). Whether it is an elective surgical patient who has tested positive for a highly infectious pathogen, a critically ill patient with unknown status, or a patient requiring tracheal intubation because of primary respiratory disease caused by a highly infectious pathogen, airway manager and team safety is paramount. Hastening to manage one of these patients without considering team safety may result in healthcare worker infections. The number of people in the room should be kept to a minimum, with a pre-assigned primary airway manager, an airway assistant, and ideally a third clinical support practitioner.
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Personal protective equipment (PPE). While there has been significant controversy surrounding what defines “safe” PPE for practitioners caring for patients infected by a highly infectious pathogen, it remains possible that airway management poses a significant potential risk for clinicians.178 During airway management involving AGMPs, an important risk period occurs while removing (doffing) PPE. Incorrectly donning PPE or using inadequate PPE also poses a risk to the airway manager. Airborne, contact, and droplet precaution PPE for practitioners directly performing or assisting in airway management includes an N95 respirator, eye shield, Association for the Advancement of Medical Instrumentation level 3 gown, neck cover, and gloves.176,178 Training in donning and doffing PPE should be performed regularly and practitioners should be checked to ensure adequate PPE coverage before entering the patient care room.
CAFG recommendations for airway management of the patient with known or suspected highly infectious respiratory infectious disease spread by droplet or airborne mechanism | |
Environment and pre-procedure | • If out of the operating room/theatre, an airborne infection isolation room is preferred for tracheal intubation. • A negative pressure environment is preferred regardless of location, but ventilation rate/air exchanges are more important than positive or negative pressurization. • Minimize team members in the room. The most experienced available airway manager should perform tracheal intubation. • Supervised personal protective equipment (PPE) donning should occur. • Perform team briefing; use a checklist. • Simulation-based team training is valuable. |
Equipment | • Place a viral filter between tracheal tube, face mask, or supraglottic airway (SGA) and more proximal ventilation equipment. • Sidestream capnography aspiration to be located proximal to the viral filter. • Use video laryngoscopy as primary technique: ○ To increase first-pass success ○ To avoid close proximity to patient’s face and respiratory tract ○ To enable a shared mental model and situation awareness of non-intubating team members. • Consider using SGAs for airway rescue scenarios only—not as a planned technique. Second-generation devices are recommended for their higher seal pressures. • Take pre-packaged kits with required equipment into the room. • Position a standby airway cart (+/− additional personnel in PPE as “runners”) outside room. |
Pre-oxygenation | • Pre-oxygenate with a well-applied face mask. • Add PEEP valve to bag-valve mask set-up, if using. • Limit flow rates to the least required to obtain desired fraction of exhaled oxygen value (e.g., 0.9). This may not always be achievable. |
Induction | • Intravenous induction with NMB preferred. • FMV discouraged while awaiting onset of NMB unless clinically significant hypoxemia has occurred or is expected. • Avoid apneic oxygenation with HFNO. • If apneic oxygenation is used, consider use of low oxygen flows (e.g., 5 L min−1). |
Intubation | • Most experienced airway manager available should manage the airway. • Ensure a styleted tracheal tube or bougie is available, as appropriate to the video laryngoscope blade in use. • Institute positive pressure ventilation only after tracheal tube cuff inflation. • If high airway pressures are encountered, ensure tracheal tube cuff pressure is 5 cm H20 higher than peak inspiratory pressure. |
Unanticipated difficult airway | • Use FMV between intubation attempts only if needed to re-oxygenate the patient. • If FMV is undertaken, use two-handed mask application with thenar eminence (“V-E”) grip to maximize seal and jaw lift effectiveness. • Use waveform capnography to confirm efficacy of rescue ventilation. • Avoid excessive ventilation. Respiratory rate, volume and inspiratory pressure should ideally be guided by objective feedback (waveform capnography, pressure manometer). • For the elective surgical patient, if SGA rescue is used, consider using a second-generation device that supports FB-aided tracheal intubation. • If SGA rescue has occurred, then patient awakening is preferred: if not feasible, other options include FB-aided intubation through the SGA, or FONA during SGA-supported ventilation. Proceed with surgery only if considered safe. • Above all, the safety of the team must be prioritized. |
CVCO and eFONA | • Scalpel-bougie emergency FONA is the recommend technique. • Transiently discontinue attempted FMV or SGA ventilation during incision of cricothyroid membrane. |
Awake tracheal intubation | • Avoid awake intubation unless high risk of a CVCO situation with induction of general anesthesia/RSI. • VL or flexible bronchoscopy can be used for awake tracheal intubation, skills allowing. Consider use of an SGA as a conduit for the FB. • Consider alternatives to local anesthetic nebulization or aerosolization for topical airway anesthesia, e.g., local anesthetic gels/ointments or nerve blocks. |
Intraoperative phase | • Avoid circuit disconnections. • Place ventilator into standby mode if disconnection is needed. • Disconnect circuit proximal to viral filter if feasible; if not, then consider temporarily clamping the tracheal tube, seeking to avoid damaging it or its pilot line. |
Extubation | • Tracheal extubation is an AGMP with potentially higher risk for aerosol generation than intubation185. • Use pharmacologic measures to help prevent cough, agitation, or vomiting during or after extubation. • Place a surgical or procedure mask on the patient before awake extubation and extubate while the mouth, nose, and nasal prongs are covered by the mask; leave the mask on the patient during subsequent transfer186. • Avoid airway exchange procedures if possible. |
Post-procedure | • Dispose of airway management equipment appropriately. • Doff PPE under supervision. |
The patient with obstructing airway pathology or a traumatized airway
The morbidly obese patient
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The potential for technical difficulty with both tracheal intubation and other modes of ventilation, coinciding with likely apnea intolerance, suggests that the airway manager should carefully consider whether ATI might confer a safety benefit (Fig. 1).
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Regardless of the chosen approach, close attention to patient positioning is recommended, with ramping to ensure the patient’s tragus is aligned with the sternum.96,98 “Back up” or reverse Trendelenburg positioning will help delay oxygen desaturation.116-124 If general anesthesia is elected, careful pre-oxygenation must occur, with a goal of achieving FeO2 ≥ 0.9.
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Apneic oxygenation is recommended during laryngoscopy and intubation of all morbidly obese patients when managed after the induction of general anesthesia.
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Given the anticipated short apnea time and potential for difficulty with fallback ventilation options, primary use of VL (with appropriately selected blade type) is recommended for tracheal intubation to help maximize first-pass success.
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Careful planning and documentation should occur before embarking on airway management of the obese patient. The team should be briefed on the strategy in the event that difficulty is encountered; this should include the triggers for moving to the next step in the plan. Given the potential for rapid oxygen desaturation, the airway manager should consider having a second experienced airway manager stand by for assistance if required.
The patient with an increased risk of aspiration
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There may still be a role for correctly applied CP in some settings (e.g., obstetrics). Given the limited data available, the ultimate decision to use CP is at the discretion of the airway manager;
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When a significantly elevated risk of aspiration coincides with an anticipated difficult airway, performing ATI with minimal sedation may confer a safety benefit;
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If the airway manager decides to intubate the at-risk patient after the induction of general anesthesia, practical advice includes suctioning a nasogastric tube if already present (consider inserting one if not) before induction, placing the patient in the back up or reverse Trendelenburg position, and having two suction devices immediately available for oropharyngeal suctioning. Before induction, an in situ nasogastric tube should be attached to continuous low-pressure suction to prevent intra-gastric pressure accumulation following induction210;
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Use of VL allows airway team members to assess the laryngeal view, the impact of CP (if used) on the view of the glottis, and provides heightened situational awareness during a critical time. Nevertheless, should massive regurgitation occur, the camera may be obscured. Thus, unless difficulty in glottic visualization is anticipated, use of Mac-VL is preferable in the patient at high risk of regurgitation, to allow direct, eye-to-glottis visualization if necessary;
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If CP is deemed to be impeding either laryngoscopy or tracheal intubation, it should be removed;
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The use of FMV with low inspiratory pressure during RSI, before or between attempts at tracheal intubation, can extend safe apnea time without oxygen desaturation;
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If the planned tracheal intubation attempts fail, a second-generation SGA should be inserted, and the integrated drainage port used to drain the esophagus. If CP had been applied, it should be removed for insertion of the SGA and not reapplied.
The patient with a bleeding upper airway
Tracheal extubation
The at-risk tracheal extubation
Potential causes for an at-risk tracheal extubation |
Potential causes of failure to tolerate tracheal extubation |
• Functional airway obstruction and/or inadequate management of secretions, due to: ○ Skeletal muscle weakness from residual neuromuscular blockade or intrinsic neuromuscular disease ○ Pre-existing obesity or OSA combined with opioids, residual anesthetics, or other sedative agents ○ Impaired neurologic status or excess drowsiness. • Anatomic airway obstruction from: ○ Airway edema, due to: ▪ Prolonged prone or Trendelenburg intraoperative positioning; ▪ Known traumatic or multiple attempts at tracheal intubation; ▪ Administration of large volumes of crystalloid fluid; ▪ Residual edema after tracheal intubation for neck hematoma or airway infection;217 ▪ In ICU patients, prolonged intubation, large tracheal tube diameter, female sex, unplanned extubation;221 ▪ Pre-existing edema (e.g., burns or neck radiation). ○ Extrinsic airway compression, e.g., due to neck hematoma, mediastinal mass ○ Airway obstruction from secretions or blood ○ Tracheal collapse, (e.g., tracheomalacia after goitre excision or prolonged intubation) ○ Laryngospasm ○ Unilateral or bilateral vocal cord paresis or paralysis ○ Cervical spine pre-vertebral swelling222 ○ Multi-level cervical spine fusion225 • Cardiopulmonary issues (especially in ICU): ○ Respiratory failure due to non-resolution of an underlying problem ○ Compromised functional residual capacity from obesity, gastric distension with air, incisional pain, or other reason ○ Atelectasis; pneumothorax ○ Advanced chronic obstructive pulmonary disease ○ Left or right ventricular dysfunction ○ Fluid overload. • Other perioperative issues including hypothermia, altered acid-base status and uncontrolled pain. |
Potential causes of difficult tracheal re-intubation |
• The original tracheal intubation was difficult. • Interval development of airway edema. • Anatomic changes as a result of a surgical intervention: ○ Upper airway surgery ○ Upper cervical spine fusion. • Applied mechanical constraints, including: ○ Intermaxillary fixation ○ Halo jacket. |
Strategies to address the at-risk patient upon tracheal extubation |
Strategies to address the risks of failure to tolerate extubation |
• At risk of functional airway obstruction: ○ Plan a multi-modal analgesia strategy for a surgical patient to help minimize need for opioids. ○ Consider continuation of ventilation in the short- or medium-term to allow full recovery from inhaled or intravenous anesthetic or sedative agents. ○ Ensure recovery from neuromuscular blocking agents quantitatively; non-depolarizing agents should have recovery to a train of four ≥ 0.9 before extubation.230 For the at-risk patient, consider use of sugammadex as a reversal agent for rocuronium or vecuronium. ○ Tracheal extubation awake, rather than deep. ○ Extubation in a head-up or back up position. ○ Early transition to CPAP mask, NIV231-233 or HFNO232,234 if indicated. If used, close monitoring must still occur after extubation, and use of these modalities must not delay re-intubation if indicated. • At risk of airway edema: ○ Consider more objective assessment of the degree of edema by use of a cuff leak test and/or indirect visualization of pharynx and larynx with VL or flexible endoscopy. ○ Consider deferral of extubation pending a period of short- or medium-term ventilation with head-up positioning and/or administration of steroids.235 • Optimize cardiac, pulmonary, neurologic, acid-base and body temperature status. • Consider whether elective tracheotomy might offer a higher margin of safety. |
Strategies to address the risks of difficult tracheal re-intubation |
• Extubate only with a team briefing regarding the plan for re-intubation if needed. • Consider deferral of extubation until patient condition is optimized, location is optimal, and equipment and skilled personnel are available for re-intubation if required. • Consider extubation over a place-holder airway exchange catheter (see narrative). • Consider whether elective surgical airway might offer a higher margin of safety. |
Lower risk (“routine”) tracheal extubation
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As extubation of the surgical patient is often accompanied by airway manager fatigue and team distraction, a “sterile cockpit” concept of minimizing non-essential conversation during emergence and extubation of the surgical patient is advocated.
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Supplemental oxygen delivery should occur during transportation of all recently extubated patients to high-dependency nursing units including postanesthesia care units. Pulse oximetry monitoring should also be used. Handover should routinely detail the type and ease of airway management.
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In critical care or ED settings, if a consulting service has recommended tracheal extubation of an intubated patient, direct communication should occur between that service and critical care/ED attending staff about the rationale and timing of extubation. Documentation of intubating conditions/difficulty should be clearly available to consulting services to help guide the extubation plan.
Extubation over an airway exchange catheter (AEC)
Human factors and the anticipated difficult airway
Potential human factor issues during patient evaluation and airway management decision-making, with suggested mitigation strategies | |||
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Issue | Possible mitigation strategies: | ||
by the airway manager | by the assembled team | by the organization | |
Failure to match planned strategy with the findings of airway evaluation (anatomy, physiology, and clinical context) | • Review your planned strategy for a high-risk or difficult case with a colleague. • With predicted difficulty, before proceeding, ensure that all equipment for your airway strategy (i.e., planned primary and fallback techniques) is physically present, sized for the patient, and arranged in the order of anticipated use. This well help ensure you have thought through the situation. | • For all patients, brief the team on your chosen strategy, including your alternate plans if the intended technique fails, together with triggers for moving to an alternate plan. • During the briefing, specifically empower team members to speak up if they think that a trigger has occurred. | • The organization should mandate inclusion of the airway strategy in the first surgical safety checklist. • Airway management education programs should include material on safe decision-making, rather than only teaching “hands-on” skills. |
Maintenance of competence. Use of ATI is decreasing243. When difficulty is predicted, lack of recent experience, confidence, or skills in ATI might tempt the airway manager to avoid its use despite indicators of it being the safest approach. Lack of suitable equipment might also be a factor in some cases. | • Enlist a colleague to help perform ATI: you will both benefit from the experience. • Seek opportunities to perform ATIs, rather than using excuses to avoid them. • If the patient’s anatomy is amenable, consider using a more familiar device for ATI (e.g., VL). | • For the patient requiring ATI with obstructing pathology, a surgeon should be physically present to perform fallback eFONA. | • The organization should provide training and maintenance of competence workshops in ATI techniques, including use of the FB. • Provide airway simulators or standard airway training manikins for individual practice at any time. • Ensure equipment for all aspects of ATI is easily accessible at airway management locations. • Package all equipment and local anesthetics needed for topical airway anesthesia together in easily-accessed “grab kits”. |
“Production pressure” to get a case done might lead to an unsafe decision to manage a difficult airway patient after the induction of general anesthesia, when ATI might be the safer approach. | • When sensing production pressure, (whether self-induced or from another source) push back by deliberately slowing to reflect on whether the pressure is adversely impacting your patient’s safety. • Pre-empt any pushback on planned ATI by using “safest for the patient” language. | • Increase team buy-in by early communication with the surgeon and team when ATI is needed for an operative case. | • Multidisciplinary team training or rounds on adverse airway events might help improve communication and cooperation for future difficult airway situations that involve multiple specialties. |
“Normalization of deviance3”: the airway manager might have managed a series of patients after the induction of general anesthesia where despite predictors of difficulty, none occurred. On the basis of thus “getting away with it” over time, inducing such patients might become a clinician’s normal practice, rather than even considering ATI. | • With significant predicted difficulty, if considering tracheal intubation after the induction of general anesthesia, as a thought exercise, satisfy yourself that it can occur with a margin of safety equal to or greater than ATI. If not, proceed with the ATI. • Beware of “gambler’s fallacy”: the false belief that the outcome of the current case is less (or more) likely given results of previous events. Judge every case on its own, based on findings from the airway evaluation. | • Team members should be encouraged to speak up if uncomfortable with the airway manager’s chosen approach. The “PACE” (probe-alert-challenge-emergency) or similar mnemonic can be used as a prompt by team members to question the planned approach. | • Appoint a hospital “airway lead”244 in your department or hospital, tasked with ensuring a full array of difficult airway equipment is readily available across the institution, arranging airway education, including skills in ATI, and to help constructively debrief airway-related critical incidents and near-events. |
Summary and key recommendations
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Airway evaluation of the patient should always occur before embarking on airway management;
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Airway evaluation includes bedside examination seeking predictors of technical difficulty with FMV, SGA use, tracheal intubation, and eFONA. Patient physiology and contextual issues should also be assessed. Review of previous airway management records, databases, and imaging studies will contribute to a complete evaluation. Nasopharyngoscopy or VL under local anesthesia can add useful information about the patient with known or suspected glottic or supraglottic pathology;
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Information gleaned from the airway evaluation must be synthesized into the safest decision on how to proceed with airway management. The use of ATI may provide an extra margin of safety when significant difficulty is predicted with VL or DL. It is also useful if difficulty is predicted with more than one mode of airway management (e.g., tracheal intubation and FMV), or predicted difficulty coincides with significant physiologic (e.g., apnea intolerance or aspiration risk) or contextual issues;
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Awake tracheal intubation can proceed via oral, nasal, or front of neck routes. In some cases, oral or nasal ATI can be facilitated by a variety of devices (e.g., flexible bronchoscopy or VL);
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If a lack of patient cooperation or time precludes ATI, and airway management after the induction of general anesthesia must proceed, it should proceed with “double set-up” preparation allowing for immediate eFONA;
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Management of the anticipated difficult airway after the induction of general anesthesia should only occur with an appropriate pre-determined strategy for difficulty if/when encountered. A second airway manager should be sourced, the team briefed, and the required equipment brought to the room. Attention should be paid to patient positioning, pre-oxygenation, and apneic oxygenation;
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Regardless of the chosen approach when difficulty is predicted, the airway manager must clearly communicate the planned management strategy to the team, including the triggers for moving from one technique to the next;
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Extra care should be used in the planning and implementation of care for the patient with head and neck pathology, obesity, or increased aspiration risk;
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Tracheal extubation of the at-risk patient must be carefully planned in terms of assessing whether the patient can tolerate extubation and whether re-intubation might be difficult;
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As unanticipated difficulty with airway management can occur despite none being predicted, the airway manager must be ready with a strategy for difficulty occurring in every patient, and the institution must make difficult airway equipment readily available and easily accessible;
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As pandemic conditions add complexity to both routine and difficult airway decision-making and management, individual and institutional preparedness should be mandated.