What are the techniques for airway care and maintenance during the intra-operative period, including proper placement and safe removal of airway devices in patients undergoing general anesthesia or sedation?

Intraoperative Airway Management: Care, Maintenance, Verification, and Safe Removal

Intraoperative Airway Maintenance

Continuous monitoring with pulse oximetry (SpO₂) and end-tidal CO₂ waveform capnography is mandatory throughout the intraoperative period to detect hypoventilation, airway obstruction, or device displacement before catastrophic desaturation occurs. 1

Essential Monitoring Parameters

• Monitor SpO₂ continuously throughout all phases of anesthesia, as this is the primary real-time indicator of adequate oxygenation 1
• Monitor end-tidal or blood CO₂ levels whenever possible during the procedure, as hypoxemia detected by pulse oximetry alone may miss critical hypoventilation until dangerously late 1
• Assess ventilation parameters every 5-15 minutes including tidal volumes, airway pressures, and respiratory rate to detect early signs of airway compromise 1

Airway Device Options During Maintenance

The choice of airway device depends on procedure requirements, patient risk factors, and anesthetic technique 1:

• Endotracheal intubation provides the most secure airway with complete protection from aspiration and allows precise control of ventilation 1
• Laryngeal mask airway (LMA) offers intermediate airway security for procedures not requiring muscle relaxation or high airway pressures 1
• Face mask with manual or mechanical ventilation using conventional or bilevel positive pressure ventilators can be delivered via full face or nasal mask interfaces for shorter procedures 1
• Mouthpiece ventilation with leak-proof seal represents an alternative for select patients, particularly those with neuromuscular disease 1

Critical Intraoperative Pitfalls

• Avoid excessive positive pressure ventilation initially, as this can cause barotrauma, hemodynamic instability, or gastric insufflation with aspiration risk 2
• Ensure appropriately sized airway equipment is immediately available including suction, advanced airway devices, and positive pressure ventilation equipment in good working order 1
• Have at least one team member capable of establishing a patent airway and providing positive pressure ventilation present in the procedure room at all times 1

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Verification of Proper Airway Device Placement

Waveform capnography is the gold standard for confirming endotracheal tube placement and must be used immediately after intubation, as clinical assessment alone misses esophageal intubation in up to 25% of cases. 2, 3

Immediate Post-Intubation Verification

• Confirm placement with continuous waveform capnography immediately after tube insertion, as this is the only reliable method to distinguish tracheal from esophageal placement 2, 3
• Perform clinical assessment including bilateral chest rise, bilateral breath sounds in axillae, absence of gastric insufflation sounds, and fogging of the tube 2, 3
• Document tube depth at the teeth or lips (typically 21 cm at teeth for adult males, 19 cm for adult females, or 3× internal diameter in cm for pediatric patients) 2
• Secure the tube immediately after confirming correct placement to prevent displacement during patient positioning or surgical manipulation 2

Ongoing Verification During Maintenance

• Monitor continuous waveform capnography throughout the procedure, as loss of waveform indicates tube displacement, obstruction, or circuit disconnection 2, 3
• Reassess tube position after any patient repositioning or surgical manipulation of the head, neck, or chest 3
• Use videolaryngoscopy when available for initial intubation, as it increases first-pass success rates and allows documentation of tube passage through vocal cords 2, 3

Supraglottic Airway Device Verification

• Confirm LMA placement by observing bilateral chest rise, square-wave capnography, ability to achieve adequate tidal volumes at appropriate pressures (<20 cm H₂O), and absence of audible leak 3
• Test seal pressure by gradually increasing airway pressure while auscultating over the stomach; gastric insufflation indicates inadequate seal 3

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Safe Removal of Airway Devices

Extubate patients while awake with intact airway reflexes, as premature extubation in sedated patients causes airway obstruction, aspiration, and respiratory failure requiring emergent reintubation in 10-15% of cases. 2, 4

Pre-Extubation Assessment Criteria

Before removing any airway device, verify ALL of the following 2, 4:

• Gag reflex present by gentle posterior pharyngeal stimulation 2
• Spontaneous swallowing observed and patient able to handle secretions without pooling in the oropharynx 2
• Effective cough demonstrated if secretions are present 2
• Adequate respiratory mechanics: tidal volume >5 mL/kg, respiratory rate 10-25/min, negative inspiratory force >-20 cm H₂O 4
• Hemodynamic stability without vasopressor requirement 2
• Normothermia (temperature >36°C) 4
• Reversal of neuromuscular blockade confirmed by train-of-four ratio >0.9 3

Extubation Technique for Standard Patients

• Position patient semi-upright (30-45 degrees) to reduce aspiration risk and improve respiratory mechanics 2
• Suction oropharynx thoroughly before cuff deflation to remove pooled secretions 2, 3
• Deflate cuff during positive pressure breath or during peak inspiration to blow secretions away from vocal cords 3
• Remove tube smoothly during inspiration when vocal cords are maximally abducted 3
• Apply supplemental oxygen immediately via face mask and monitor SpO₂ continuously for at least 30 minutes post-extubation 4

High-Risk Extubation Strategy

For patients with respiratory compromise (FVC <50% predicted), neuromuscular disease, or obesity with sleep-disordered breathing 1:

• Delay extubation until respiratory secretions are well controlled and SpO₂ is normal or at baseline in room air 1
• Extubate directly to noninvasive positive pressure ventilation (NPPV) using the patient's home interface when applicable 1
• Consider extubation in ICU setting rather than operating room or PACU for patients requiring baseline ventilatory support, avoiding transport in unstable condition 1
• Apply high-flow nasal oxygenation, CPAP, or nasal intermittent positive pressure ventilation for postextubation respiratory support when appropriate 3

LMA Removal Technique

• Remove LMA either deeply anesthetized or fully awake, never during emergence when airway reflexes are hyperactive causing laryngospasm 3
• For awake removal: ensure patient follows commands, has intact gag reflex, and adequate respiratory effort before deflating cuff and removing device 3
• For deep removal: maintain anesthesia depth, deflate cuff, remove device smoothly, and support airway with jaw thrust until patient awakens 3

Post-Removal Monitoring

• Monitor SpO₂ continuously for minimum 30 minutes after device removal, extending to 24 hours for high-risk patients 4, 5
• Assess for stridor, increased work of breathing, or desaturation indicating laryngospasm, airway edema, or residual obstruction 2, 4
• Have reintubation equipment immediately available including videolaryngoscope, supraglottic airway for rescue, and emergency surgical airway kit 1, 2

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Special Considerations for Neuromuscular Disease

Patients with Duchenne muscular dystrophy or similar conditions require modified protocols 1:

• Strongly consider extubation directly to NPPV for any patient with FVC <30% predicted who required intubation 1
• Consider extubation to NPPV for patients with FVC 30-50% predicted or anyone using NPPV preoperatively 1
• Use manually assisted cough and mechanical insufflation-exsufflation postoperatively in patients with peak cough flow <270 L/min or maximum expiratory pressure <60 cm H₂O 1
• If sedation causes hypoventilation, delay extubation 24-48 hours or use NPPV rather than attempting premature extubation 1, 4

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Emergency Airway Management Algorithm

When adequate ventilation cannot be achieved or maintained 2:

1. Call for help immediately and ensure code team or advanced airway support is en route 1, 2
2. Optimize head position (sniffing position with slight head extension and neck flexion) 2
3. Attempt bag-mask ventilation with 100% FiO₂, two-handed technique, and oral airway 2
4. Limit intubation attempts to maximum of three before moving to rescue strategies 2, 3
5. Place supraglottic airway (LMA) for rescue oxygenation if intubation fails 2, 3
6. Prepare for emergency surgical airway if cannot intubate, cannot oxygenate situation develops 2