Basic Airway Management: LMA, ETT, and BMV
- Airway management is a fundamental skill in anesthesia and emergency medicine, ensuring adequate oxygenation and ventilation. Three commonly used airway devices are the laryngeal mask airway (LMA), endotracheal tube (ETT), and bag-mask ventilation (BMV). Each has specific indications, advantages, and limitations.
Mallampati Classification
- The Mallampati classification is a grading system (ranging from Class I to IV) used by anesthesiology providers to assess the ease or difficulty of endotracheal intubation based on the visibility of oropharyngeal structures. A Class I airway, where the soft palate, uvula, and tonsillar pillars are fully visible, suggests an easy intubation, while a Class IV airway, where only the hard palate is visible, indicates a potentially difficult intubation due to limited visualization of airway structures. This assessment helps guide airway management strategies and anticipate the need for advanced techniques or adjuncts.
- Other measures that are part of the airway exam and are used to assess which patients could have a potentially difficult airway included thyromental distance (distance between tip of thyroid cartilage and tip of chin), and asking the patient to move their neck around.
- Other questions and relevant details in the airway exam also include screening for GERD and obstructive sleep apnea; obesity could also indicate a difficult airway.
1️⃣ Bag-Mask Ventilation (BMV)
What is BMV?
BMV is a non-invasive technique used to oxygenate and ventilate patients using a self-inflating bag (Ambu bag) connected to a face mask.
Indications:
✅ Initial oxygenation before securing a definitive airway (e.g., pre-oxygenation for intubation)
✅ Temporary ventilation in unconscious patients with inadequate respiratory effort
✅ Emergency situations where intubation is difficult or delayed
Advantages:
✅ Quick and easy to use without specialized equipment
✅ No need for deep sedation or muscle relaxation
✅ Effective for short-term ventilation
Limitations:
❌ Requires a good mask seal, which can be difficult in certain patients (e.g., facial trauma, obesity)
❌ Can lead to gastric insufflation and aspiration risk
❌ Operator fatigue with prolonged use
2️⃣ Laryngeal Mask Airway (LMA)
What is an LMA?
- The LMA is a supraglottic airway device that sits above the vocal cords, forming a seal around the laryngeal inlet. It allows for spontaneous or positive pressure ventilation without passing a tube into the trachea.
Indications:
✅ General anesthesia for short, non-complicated surgeries
✅ Failed or difficult intubation
✅ Pre-hospital/emergency airway management when intubation is not feasible
Advantages:
✅ Easier to insert than an ETT
✅ Less stimulation of the airway, reducing the risk of laryngospasm and bronchospasm
✅ Useful in patients where intubation is difficult
Limitations:
❌ Not a definitive airway – does not protect against aspiration
❌ Poor seal in obese patients or those with high airway resistance
❌ Less effective for long surgeries requiring muscle paralysis
3️⃣ Endotracheal Tube (ETT) Intubation
What is an ETT?
An ETT is a flexible tube inserted through the vocal cords into the trachea to provide a definitive airway for mechanical ventilation and protection against aspiration.
Indications:
✅ General anesthesia for major surgeries
✅ Airway protection in unconscious or at-risk patients (e.g., trauma, aspiration risk)
✅ Mechanical ventilation in critically ill patients
Advantages:
✅ Provides definitive airway protection against aspiration
✅ Allows for precise control of oxygenation and ventilation
✅ Compatible with mechanical ventilation for long-term airway management
Limitations:
❌ Requires skilled personnel for insertion
❌ Can cause airway trauma, sore throat, or vocal cord injury
❌ Needs sedation and muscle relaxation for comfortable placement
📚 References
1️⃣ Miller RD. Miller’s Anesthesia. 9th ed. Philadelphia, PA: Elsevier; 2020.
2️⃣ Morgan GE, Mikhail MS, Murray MJ. Morgan & Mikhail’s Clinical Anesthesiology. 6th ed. New York, NY: McGraw Hill; 2018.
3️⃣ Steiner J. Anesthesia Made Easy: The Survival Guide to Make Your First Anesthesia Rotation a Success. 2nd ed. Independently Published; 2019.