What are the devices and techniques used for airway management in anesthesia, including management of difficult airways and safe removal of airway devices?

Airway Management in Anesthesia: Devices, Techniques, and Algorithms

Devices for Airway Management

Primary Airway Devices

The fundamental airway devices include face masks, supraglottic airways (SGAs), and endotracheal tubes, with videolaryngoscopy now considered superior to direct laryngoscopy for difficult airways. 1

• Face masks provide basic ventilation and oxygenation, serving as the first-line device for preoxygenation and initial airway management 1
• Supraglottic airways (SGAs) offer intermediate airway control without tracheal intubation, with second-generation devices providing superior airway seal and reduced aerosol generation 2, 3
• Endotracheal tubes provide definitive airway control with cuff inflation to 20-30 cmH₂O pressure for optimal seal 2
• Videolaryngoscopes demonstrate 92-100% success rates for rescue intubation after failed direct laryngoscopy in emergency difficult airways 1

Laryngoscope Blade Options

• Standard blades (Macintosh, Miller) serve as initial devices for routine intubation 1
• Alternative rigid laryngoscopic blades of different designs and sizes improve intubation success when standard blades fail 1
• Hyperangulated versus nonangulated videolaryngoscopes provide different visualization angles, with hyperangulated devices offering better glottic view in difficult anatomy 1
• Channel-guided versus non-channel-guided videolaryngoscopes differ in tube delivery mechanisms 1

Adjunct Intubation Devices

Bougies demonstrate superior first-attempt success (96%) compared to stylets (82%) in difficult airways and should be the primary adjunct. 1

Mechanical Adjuncts

• Introducers and bougies facilitate tube passage when glottic visualization is limited, with documented 96% first-attempt success in emergency departments 1
• Stylets provide tube rigidity and shape control, achieving 82% first-attempt success 1
• Airway exchange catheters enable tube exchange while maintaining airway access and can provide emergency ventilation with expiratory ventilation assistance 1
• Optical/video stylets combine visualization with tube guidance 1

Advanced Visualization Devices

• Flexible intubation scopes (fiberoptic bronchoscopes) achieve 78% success for rescue intubation after failed direct laryngoscopy 1
• Rigid bronchoscopes provide both visualization and ventilation capability 1
• Alternative optical laryngoscopes offer different viewing angles and approaches 1

Specialized Devices

• Intubating laryngeal mask airways (ILMA) enable blind or fiberoptic-guided intubation through the SGA, with 100% success when performed by experienced operators 4
• Lighted stylets provide transillumination-guided intubation 1
• Retrograde intubation equipment allows wire-guided tube placement from cricothyroid membrane 1

ASA Difficult Airway Algorithm Management

The 2022 ASA algorithm structures management into four distinct scenarios: awake intubation, adequate ventilation with difficult intubation, cannot ventilate/cannot intubate, and emergency invasive rescue. 1, 5, 2

Pre-Management Assessment and Preparation

• Evaluate multiple anatomical features in combination: Mallampati score, thyromental distance, sternomental distance, interincisor distance, neck circumference, hyomental distance, mouth opening, ability to prognath, head/neck mobility, prominent incisors, beard presence, and upper lip bite test 1, 2
• Never rely on single predictors—combined assessment provides superior prediction 2
• Ensure immediate equipment availability: airway management equipment in room and portable difficult airway cart immediately accessible 1, 2
• Assign skilled assistance to be present or immediately available when difficult airway is known or suspected 1, 2

Scenario 1: Awake Intubation Strategy

Perform awake intubation when any single factor applies: difficult ventilation anticipated, increased aspiration risk, patient cannot tolerate brief apnea, or expected difficulty with emergency invasive rescue. 1, 2

• Awake intubation improves success and reduces adverse outcomes compared to post-induction attempts 1
• Flexible fiberoptic intubation remains the gold standard for awake intubation 4
• Alternative awake techniques include videolaryngoscopy, optical stylets, and ILMA with sedation 1

Scenario 2: Adequate Ventilation, Difficult Intubation

Identify a preferred sequence of noninvasive devices before beginning, limit attempts to prevent injury, and test mask ventilation after each attempt. 1, 2

• Maintain continuous awareness of time passage, attempt number, and oxygen saturation 1, 2
• Limit total attempts at intubation or SGA placement to avoid laryngeal edema and hemorrhage that critically compromises airway maintenance 2, 6
• Use combination techniques when individual methods fail: direct/video laryngoscopy combined with bougie, optical stylet, flexible scope, airway exchange catheter, or retrograde wire 1
• Consider SGA as rescue device between attempts, particularly second-generation devices for superior seal 2, 3

Scenario 3: Cannot Ventilate, Cannot Intubate Emergency

Call for help immediately, call for invasive airway access, maximize oxygenation with nasal oxygen/high-flow nasal cannula, and proceed rapidly to emergency front-of-neck access if alternative approaches fail. 2

• Attempt emergency ventilation via tube exchangers with expiratory ventilation assistance 1
• High-flow nasal oxygen (HFNO) and transnasal humidified rapid insufflation ventilatory exchange provide apneic oxygenation 1, 7
• Do not delay transition through algorithm—minimize attempts at each technique 2
• Proceed to emergency invasive airway if ventilation deteriorates or alternative approaches fail 2

Scenario 4: Emergency Invasive Airway Rescue

The scalpel-bougie-tube technique is preferred for emergency cricothyrotomy, particularly in COVID-19 patients due to reduced aerosolization. 2

• Invasive interventions include: surgical cricothyrotomy (scalpel-bougie-tube), large-bore cannula cricothyrotomy, needle cricothyrotomy with pressure-regulated device, surgical tracheostomy, or percutaneous tracheostomy 1, 2
• Ensure trained operator performs invasive airway whenever possible 1
• Perform as rapidly as possible to minimize hypoxic time 1
• Identify alternative invasive intervention if selected approach fails or is not feasible 1

Techniques for Proper Airway Device Placement Confirmation

Capnography or end-tidal CO₂ monitoring is mandatory for confirming tracheal intubation and leads to fewer adverse outcomes. 1

Primary Confirmation Methods

• Continuous waveform capnography provides real-time confirmation and is preferred over auscultation, which risks PPE contamination 1, 2
• End-tidal CO₂ detection verifies tracheal placement and prevents unrecognized esophageal intubation 1

Secondary Confirmation Techniques

• Esophageal detectors or self-inflating bulbs provide additional verification when capnography is equivocal 1
• Fiberoptic visualization directly confirms tracheal tube position 1
• Chest movement observation and bilateral breath sounds serve as adjunctive signs but are insufficient alone 5

When Tube Position is Uncertain

• Determine whether to remove tube and attempt ventilation or use additional confirmation techniques rather than proceeding with uncertain placement 1
• Never proceed without definitive confirmation—unrecognized esophageal intubation causes preventable death 1

Intraoperative Airway Care and Maintenance

Monitoring Requirements

• Monitor according to ASA standards throughout the procedure 1
• Assess signs of inadequate ventilation continuously: absent/inadequate exhaled CO₂, absent/inadequate chest movement, decreasing oxygen saturation, changed mental status or somnolence 5

Tube Security and Position

• Inflate tracheal tube cuff to measured pressure of 20-30 cmH₂O immediately after intubation 2
• Secure tube adequately to prevent displacement during positioning or surgical manipulation 7
• Reassess tube position after patient repositioning or surgical field changes 7

Oxygenation Strategies

• Provide supplemental oxygen via nasal cannulae, facemask (including humidified high-flow), or SGA insufflation during airway management 1
• Preoxygenate for 3-5 minutes to achieve end-tidal oxygen concentration ≥0.90 before induction 1
• Continue supplemental oxygen during intubation attempts to delay desaturation 1

Special Techniques for Specific Procedures

• Use SGAs rather than endotracheal intubation for brief superficial procedures without airway manipulation, as this reduces laryngospasm and hypoxemia during removal 3
• Consider jet ventilation or tubeless field techniques for laryngeal surgery requiring surgical access 7

Safe Removal of Airway Devices

Awake extubation reduces airway-related adverse outcomes and should be performed whenever possible. 1

Extubation Criteria

• Ensure patient is fully awake with intact airway reflexes before extubation 1
• Verify adequate spontaneous ventilation and oxygenation 1
• Assess ability to follow commands and maintain airway patency 1

Extubation Technique

• Suction oropharynx before cuff deflation to remove secretions 6
• Deflate cuff completely before tube removal 6
• Remove tube during inspiration when vocal cords are abducted 6
• Provide supplemental oxygen immediately after extubation via facemask, blow-by, or nasal cannulae 1

High-Risk Extubation Management

• Consider airway exchange catheter for patients at risk of reintubation difficulty 1
• Maintain deeper anesthesia during SGA removal to reduce laryngospasm risk, particularly in pediatric patients 3
• Have reintubation equipment immediately available including videolaryngoscope and difficult airway cart 2

Post-Extubation Monitoring

• Evaluate for potential complications: edema, bleeding, tracheal/esophageal perforation, pneumothorax, aspiration 1
• Advise patients of warning signs: sore throat, face/neck pain or swelling, chest pain, subcutaneous emphysema, difficulty swallowing 1
• Provide supplemental oxygen and monitor oxygen saturation, respiratory rate, and work of breathing 1

Documentation and Communication

Document the nature of airway difficulty, techniques used (indicating beneficial or detrimental role of each), and communicate this to the patient and future providers. 1, 2

Required Documentation Elements

• Record difficult airway plan prominently and display visibly on patient's chart 2
• Document specific anatomical findings that contributed to difficulty 1, 2
• Describe all techniques attempted and their outcomes 1, 2
• Note successful approach and any complications encountered 1

Patient Communication

• Provide written report or letter to patient documenting difficult airway and management 1
• Consider notification bracelet or equivalent identification device 1
• Communicate with patient's surgeon or primary caregiver about airway management 1
• Advise patient to inform future anesthesia providers of difficult airway 1

Institutional Communication

• Place chart flags or electronic alerts for future encounters 1
• Communicate plan to staff at shift changeovers to ensure continuity 2
• Consider registration with emergency notification service to reduce subsequent adverse outcomes 1

Critical Pitfalls to Avoid

• Never rely on single airway assessment tool—multiple features must be assessed in combination 2
• Never perform repeated unsuccessful attempts—this causes laryngeal edema or hemorrhage that critically compromises airway maintenance 2, 6
• Never delay calling for help in cannot ventilate/cannot intubate situations 2
• Never proceed without capnographic confirmation of tracheal intubation 1, 2
• Never use endotracheal intubation routinely for brief superficial procedures where SGA is adequate—this increases laryngospasm and hemodynamic instability without benefit 3
• Never defer mask ventilation initially—consider second-generation SGA as alternative between attempts 2