Difficult Airway Assessment

Introduction to Mallampatti Score

The Mallampatti score is a significant tool for predicting difficult intubation and is given the highest score (5) in the MACOCHA score, reflecting its crucial role, according to the American Society of Anesthesiologists 1, 2
The Mallampatti score is a four-level classification system that assesses the visibility of the oropharynx:

A Mallampatti score of III or IV increases the risk of difficult intubation and is the most important predictor in the MACOCHA score (5 points), as recommended by the American Society of Anesthesiologists 1, 2, 3
The incidence of difficult intubation in the ICU ranges from 8% to 23%, which is higher than in the operating room, according to the Society of Critical Care Medicine 2, 4

The MACOCHA score is a predictive score for risk factors of difficult intubation:

A cut-off of 3 or more in the MACOCHA score is suitable for ruling out difficult intubation with high negative predictive value (97-98%) and sensitivity (73-76%), as recommended by the American Society of Anesthesiologists 1, 2
The Mallampatti score can be used not only to predict difficult intubation but also to predict the difficulty of proper placement of a laryngeal mask airway (LMA) 1, 2, 3

Intubation procedures in the ICU should be standardized, and an intubation algorithm with assessment of risk factors for difficult intubation should be implemented in each unit, according to the Society of Critical Care Medicine 1, 2
For patients at risk of difficult intubation, a difficult airway trolley and bronchoscope should be immediately available, as recommended by the American Society of Anesthesiologists 1, 5

The British Journal of Anaesthesia recommends ensuring all equipment is immediately available and functional, including laryngoscope, endotracheal tubes, stylet/bougie, suction, and backup airway devices, and verifying waveform capnography is ready for mandatory confirmation of tube placement 6
The Anaesthesia journal suggests administering high-flow oxygen to achieve maximal oxygen saturation before induction, particularly critical in ICU patients with reduced functional residual capacity 7
The British Journal of Anaesthesia recommends positioning the patient in optimal position with head elevated and neck extended, unless contraindicated, to reduce airway swelling and improve laryngoscopic view 6

The British Journal of Anaesthesia suggests using neuromuscular blocking agents (NMBAs) as they significantly reduce intubation complications in critically ill patients, and rocuronium is preferred over succinylcholine due to its numerous side effects 6
The British Journal of Anaesthesia recommends limiting attempts to a maximum of three laryngoscopy insertions, with each blade entry constituting one attempt, and using videolaryngoscopy as it is superior to direct laryngoscopy 6, 8
The Anaesthesia journal suggests monitoring for complications including hypotension, desaturation, and tube displacement after intubation 7

The British Journal of Anaesthesia recommends watching for "airway red flags" including absence or change of capnograph waveform, increasing airway pressure, reducing tidal volume, or inability to pass a suction catheter 8
The British Journal of Anaesthesia suggests never attempting more than three laryngoscopy attempts, declaring "failed intubation" and moving to rescue strategies, and never assuming tracheal placement without capnography confirmation 6

The American Society of Anesthesiologists recommends applying topical local anesthesia to the airway before awake intubation procedures, as part of a comprehensive approach to managing difficult airways 9
In cases of extreme airway difficulty, flexible bronchoscopy is considered a safe method, with 52 women successfully undergoing awake flexible bronchoscopic intubation in obstetric cases, highlighting the importance of careful planning and execution 9
Awake nasendoscopy/laryngoscopy can be performed preoperatively to assess the laryngoscopic view before deciding on technique, allowing for more informed decision-making 9
The Anaesthesia society suggests that a comprehensive assessment, including factors such as neck movement, cervical spine mobility, mouth opening, and previous difficult airway history, is crucial in identifying patients at high risk for difficult intubation 9
Elective surgery should not proceed if a high Mallampati score is identified late, as advanced planning may be rendered impossible, increasing risk, as seen in obstetric cases where 22 women with chronic airway conditions were identified only at short notice 9

The American Society of Anesthesiologists recommends evaluating cervical spine mobility by assessing both flexion and extension of the head and neck, as limited movement was mentioned in 75 cases of difficult airways and shows 99% specificity for predicting difficult intubation 10, 11
The Anesthesiology society suggests that neck movement assessment is particularly critical in patients with cervical spine disease, ankylosing spondylitis, or degenerative osteoarthritis 12
The American Society of Anesthesiologists recommends measuring the distance between upper and lower incisors with the mouth maximally opened, as this was assessed in 68 difficult airway cases 10, 11
The Anesthesiology society notes that measuring the distance from the thyroid cartilage to the mentum with the head fully extended is a well-established predictor of difficult airways 12, 13
The American Society of Anesthesiologists recommends evaluating the patient's ability to protrude the lower jaw beyond the upper incisors, as jaw protrusion/micrognathia was assessed in 24 difficult airway cases 10, 11

The American Society of Anesthesiologists suggests specifically inquiring about and documenting any history of difficult airway management, as this was noted in 14 cases and represents a critical predictor 10, 11
The Anesthesiology society recommends reviewing prior anesthetic records when available 12, 13

The American Society of Anesthesiologists suggests considering awake flexible laryngoscopy or nasendoscopy to directly visualize the larynx before making decisions on anesthetic technique, as this was performed in 15 cases 10, 11
The Anesthesiology society recommends utilizing ultrasound to measure skin-to-hyoid distance, tongue volume, and distance from skin to epiglottis, as these measurements can predict difficult airways 12, 13
The British Journal of Anaesthesia suggests that ultrasound is more accurate than palpation for identifying the cricothyroid membrane, its size, depth, and any deviation 14
The American Society of Anesthesiologists recommends palpating and assessing the neck for potential cricothyroid membrane access using the "laryngeal handshake" technique, as this was mentioned in only 1 report but is critically important 10, 14