How to manage low tidal volumes due to subglottic stenosis?

From the Guidelines

Managing low tidal volumes due to subglottic stenosis requires a multifaceted approach focused on maintaining adequate ventilation while minimizing airway trauma, and the primary recommendation is to use airway dilation as a primary intervention for benign, simple, and subglottic tracheal stenosis, as suggested by the American College of Chest Physicians clinical practice guideline 1.

Key Recommendations

• Use smaller endotracheal tubes (typically 4.0-6.0 mm internal diameter) that can pass through the stenotic area without causing further damage.
• Adjust ventilator settings to accommodate the narrowed airway, including lower tidal volumes (4-6 mL/kg ideal body weight), higher respiratory rates (20-30 breaths/minute), and careful monitoring of peak airway pressures (keeping below 30 cmH2O when possible) 1.
• Consider permissive hypercapnia, allowing PaCO2 to rise to 45-60 mmHg as long as pH remains above 7.25.
• Use helium-oxygen mixtures (heliox) to reduce turbulent flow and work of breathing.
• For patients with inflammation contributing to stenosis, consider corticosteroids such as methylprednisolone (1-2 mg/kg/day) or dexamethasone (0.5-1 mg/kg/day) for 3-5 days.
• Nebulized epinephrine (1:1000 solution, 0.5 mL in 3 mL normal saline) can temporarily reduce mucosal edema.
• Adequate humidification is essential to prevent secretion thickening.

Rationale

The American College of Chest Physicians clinical practice guideline suggests airway dilation as a primary intervention for benign, simple, and subglottic tracheal stenosis 1. This approach is supported by studies that demonstrate the effectiveness of airway dilation in managing subglottic stenosis 1. Additionally, the use of smaller endotracheal tubes, lower tidal volumes, and higher respiratory rates can help minimize airway trauma and optimize gas exchange 1. The use of helium-oxygen mixtures, corticosteroids, and nebulized epinephrine can also help reduce airway resistance and minimize further trauma 1.

From the Research

Management of Low Tidal Volumes due to Subglottic Stenosis

• Low tidal volumes due to subglottic stenosis can be managed using various airway management techniques and surgical approaches, including the use of laryngeal mask airways (LMAs) and endoscopic treatments 2, 3, 4.
• The LMA technique has been shown to be effective in managing ventilation while allowing for unencumbered flexible bronchoscopic access for laser surgery, balloon dilation, and mitomycin C application for airway stenosis 4.
• Endoscopic treatment of subglottic and tracheal stenosis using a flexible fiber-based CO2 laser, balloon dilation, and topical application of mitomycin C has been reported to be successful in achieving long-term success in treating stenosis 4.
• The use of an i-gel supraglottic airway has also been described as a suitable option for airway management in patients with subglottic stenosis, providing a good seal and allowing for controlled ventilation with acceptable peak pressures 5.
• A multimodality surgical approach, including endoscopic and open surgical procedures, can be employed to avoid tracheotomy dependence and maintain airway patency, although multiple procedures are usually required 6.

Airway Management Techniques

• Laryngeal mask airways (LMAs) can be used to manage ventilation during airway intervention, allowing for flexible bronchoscopic access for laser surgery, balloon dilation, and mitomycin C application 2, 3, 4.
• The i-gel supraglottic airway can be used as an alternative to LMAs, providing a good seal and allowing for controlled ventilation with acceptable peak pressures 5.
• Endotracheal intubation can be challenging in patients with subglottic stenosis, and the use of a narrow endotracheal tube may be necessary 5.

Surgical Approaches

• Endoscopic treatment of subglottic and tracheal stenosis using a flexible fiber-based CO2 laser, balloon dilation, and topical application of mitomycin C can be effective in achieving long-term success in treating stenosis 4.
• Open surgical procedures, such as cricotracheal resection, can be used to treat subglottic stenosis, although they may be associated with higher morbidity and reintervention rates 6.
• A multimodality surgical approach, including endoscopic and open surgical procedures, can be employed to avoid tracheotomy dependence and maintain airway patency 6.