Cormack–Lehane classification system

The Cormack–Lehane classification system is a grading system used in anesthesiology to assess the visibility of the vocal cords through a laryngoscope during intubation. It was first described by R.S. Cormack and J. Lehane in 1984 in an effort to improve communication between anesthesiologists regarding the ease or difficulty of intubation. This system is crucial for predicting the challenges that might be encountered during the airway management process, which is a fundamental aspect of administering general anesthesia and in emergency situations where securing the airway is paramount.

Classification

The Cormack–Lehane system divides the view obtained during laryngoscopy into four grades, based on the structures that are visible:

• Grade 1: The entire vocal cords are visible.
• Grade 2: Only the posterior part of the vocal cords is visible.
• Grade 2a: More than half of the glottis is visible (a later addition to improve the original classification).
• Grade 2b: Less than half of the glottis is visible (also a later addition).
• Grade 3: Only the epiglottis is visible, none of the glottis can be seen.
• Grade 4: Neither the glottis nor the epiglottis can be seen.

The visibility of the vocal cords is a critical factor in determining the ease of intubation. A Grade 1 view is typically associated with an easy intubation, while a Grade 4 view suggests a difficult or potentially impossible intubation using conventional laryngoscopy techniques.

Clinical Significance

The Cormack–Lehane classification is widely used in clinical practice to guide anesthesiologists in preparing for and performing intubations. It helps in anticipating difficult airways and in the decision-making process regarding the use of alternative airway management tools and techniques, such as a fiberoptic bronchoscope, video laryngoscope, or supraglottic airway device when a difficult intubation is anticipated.

Modifications and Extensions

Over the years, several modifications and extensions to the original Cormack–Lehane system have been proposed to increase its utility and accuracy. These include the subdivision of Grade 2 into 2a and 2b, as well as the introduction of additional tools and scores to further categorize the airway's visual aspects and predict intubation difficulty.

Limitations

While the Cormack–Lehane classification is a valuable tool in airway management, it has its limitations. The system is subjective, with variability in grading between observers. Additionally, it does not account for other factors that may influence intubation difficulty, such as patient mobility, mouth opening, or the presence of secretions and blood.

Conclusion

The Cormack–Lehane classification system remains a fundamental part of airway management in anesthesiology, providing a simple and effective method for communicating and predicting intubation difficulty. Despite its limitations, it is an essential tool in the anesthesiologist's arsenal for planning and executing safe and effective airway management.