Airway assessment mnemonics - LEMON and BONES
Jan 13, 2025
Mastering the airway: your go to guide for nailing your airway assessment:
Airway assessment is the first step in formulating an airway plan, and should be performed for every patient encounter, regardless of the anaesthesia type! 🩺 The information gathered from this assessment can be extensive, with a range of factors for consideration. Using a structured method can provide guidance for your assessment and ensure vital information is not missed. Here are a couple of well-recognised airway mnemonics to help structure your next airway assessment! 📋
L.E.M.O.N:
Probably the most widely used and recognised airway assessment guide, this will help to identify potential difficult intubation:
👀 L - LOOK: This is an external assessment, looking for any signs that might indicate airway difficulty including external signs of facial/neck trauma, small mouth, prominent teeth, short or large neck, beard or moustache, large tongue.
🧐 E - EVALUATE: This step utilises the 3-3-2 rule for airway assessment. This involves measuring features of the airway using your fingers.
3️⃣ - Can the patient fit 3 fingers between their teeth? This indicates the degree of mouth opening that can be achieved.
3️⃣ - Three fingers spaced from the bottom of the chin to the hyoid bone. This indicates how much space there is likely to be in the pharynx during intubation. Less than three fingers makes for a crowded airway!
2️⃣ - 2 finger space distance from the hyoid bone to the thyroid cartilage. This indicates the position of the larynx, a short space will make visualization of the vocal cords more difficult (indicates anterior larynx - you might need some BURP!).
👄 M - MALLAMPATI: Used to assess the oral cavity anatomy, it can give an indication of the degree of difficulty with intubation. The higher the mallampati score, the more likely that visibility will be impeded by the tongue and other soft tissue structures. There are 4 classes of mallampati, and it is best to use a visual scale tool to make an accurate assessment. Mallampati score can correlate to Cormack Lehan laryngoscopy grades, however, this is not always the case (someone with a low mallampati score can still have a difficult laryngoscopy and vice versa!).
🚧 O - OBSTRUCTION: This step involves assessment of conditions that may cause airway obstruction, including obesity, foreign bodies, trauma and soft tissue swelling, and tumors.
🤸♂️ N - NECK MOBILITY: While your patient is awake and conscious, it is important to assess their usual range of motion with their neck. Assess how far they can flex their neck backward, and be mindful of conditions that may hinder neck movement such as arthritis, previous cervical spine surgery and fusion, and any current or previous neck trauma.
B.O.N.E.S:
Another commonly used mnemonic, this assessment will help to determine the degree of difficulty with bag-mask ventilation:
🧔 B - BEARD: The presence of facial hair will inhibit achieving an adequate seal on a face mask. In addition, beards can often hide other features such as a small, receding jaw, or facial abnormalities.
⚖️ O - OBESE: Excessive soft tissue around the face and neck can create difficulty with achieving an adequate seal with a face mask, and the presence of excessive soft tissue in the upper airway can increase the risk of airway obstruction.
😬 N - NO TEETH: The absence of teeth can cause instability during bag-mask ventilation, making it difficult to gain an adequate seal on the face mask. It can also make jaw support more difficult to perform correctly.
👵👴 E - ELDERLY: Elderly patients can often have reduced range of motion in their neck, making it more difficult to achieve a “sniffing” position. The aging process can also cause changes to airway anatomy, with some structures becoming more floppy and prone to airway obstruction. Elderly patients often have a loss of subcutaneous tissue in their face, causing their cheeks to sink in, making it difficult to achieve a seal with a face mask.
💤 S - SLEEP APNOEA/SNORING: Fairly self-explanatory, but patients that have a history of sleep apnoea or are known to snore are likely to obstruct, making bag-mask ventilation more difficult.
And there you have it - two very useful tools to help guide your next airway assessment! Remember, these tools are only part of the overall assessment and plan for your patient and are a guide to help prompt your assessment in conjunction with your critical thinking skills! 💡
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References:
Nickson, C. (2024). Airway Assessment. LITFL. https://litfl.com/airway-assessment/
Hernandez, A. (2024). Difficult airway assessment acronym.https://www.osmosis.org/answers/lemon-difficult-airway-assessment-acronym
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