From the Guidelines
The most specific exam finding for predicting difficult endotracheal (ET) intubation is a Mallampati score of III or IV, as identified in the MACOCHA score, which is a predictive score for difficult intubation developed and externally validated in the ICU setting 1. This score assesses various factors, including the patient's airway anatomy, co-existing pathology, and the operator's expertise. The Mallampati classification is a key component of this score, with classes III and IV indicating a higher risk of difficult intubation due to reduced visibility of oropharyngeal structures. Other important predictors of difficult intubation include obstructive sleep apnoea syndrome, reduced mobility of the cervical spine, limited mouth opening, coma, severe hypoxaemia, and the presence of a non-anaesthesiologist operator. When evaluating a patient for potential difficult airway, a comprehensive airway assessment should be performed, including the Mallampati classification, thyromental distance, neck extension, and presence of prominent upper incisors. The MACOCHA score can help identify patients at high risk of difficult intubation, allowing for alternative intubation techniques to be considered, such as awake fiberoptic intubation or video laryngoscopy, to minimize the risk of complications and improve patient outcomes, as recommended in recent guidelines for the management of tracheal intubation in critically ill adults 1 and for awake tracheal intubation in adults 1. Additionally, a narrative literature review on anticipated difficult airway during obstetric general anaesthesia highlights the importance of airway assessment and management in this population, emphasizing the need for a thorough evaluation of the patient's airway anatomy and medical history to predict potential difficulties with intubation 1. Overall, the Mallampati score, as part of the MACOCHA score, is a valuable tool for predicting difficult endotracheal intubation and guiding airway management decisions in various clinical settings.
From the Research
Exam Findings for Predicting Difficult Endotracheal Intubation
The most specific exam finding for predicting difficult endotracheal (ET) intubation can be identified through various studies.
- The Mallampati classification is a commonly used test to predict difficult intubation, with a higher classification indicating a more difficult intubation 2, 3, 4, 5, 6.
- The upper lip bite test (ULBT) has been shown to have high sensitivity for diagnosing difficult laryngoscopy 3.
- A combination of clinical and radiological data, including thyrosternal distance, thyromental distance, Mallampati classification, depth of spine C2, and angle A, can also be used to predict difficult laryngoscopy and intubation 2.
- Other factors such as mouth opening, sternomental distance, and body mass index (BMI) have also been evaluated as potential predictors of difficult intubation 3, 5, 6.
Comparison of Exam Findings
- The upper lip bite test (ULBT) has been found to have the highest sensitivity for diagnosing difficult laryngoscopy 3.
- The Mallampati classification has been found to be a useful predictor of difficult intubation, but its sensitivity and specificity can vary depending on the population being studied 2, 3, 4, 5, 6.
- A total airway score (TAS) that combines multiple airway assessment factors, including the Mallampati classification, ULBT, and others, may be a useful tool for predicting difficult intubation 6.