 Many classification systems have been developed in an effort to predict difficulty of tracheal intubation , including the Cormack @-@ Lehane classification system , the Intubation Difficulty Scale ( IDS ) , and the Mallampati score . The Mallampati score is drawn from the observation that the size of the base of the tongue influences the difficulty of intubation . It is determined by looking at the anatomy of the mouth , and in particular the visibility of the base of palatine uvula , faucial pillars and the soft palate . Although such medical scoring systems may aid in the evaluation of patients , no single score or combination of scores can be trusted to specifically detect all and only those patients who are difficult to intubate . Furthermore , one study of experienced anesthesiologists , on the widely used Cormack – Lehane classification system , found they did not score the same patients consistently over time , and that only 25 % could correctly define all four grades of the widely used Cormack – Lehane classification system . Under certain emergency circumstances ( e.g. , severe head trauma or suspected cervical spine injury ) , it may be impossible to fully utilize these the physical examination and the various classification systems to predict the difficulty of tracheal intubation . In such cases , alternative techniques of securing the airway must be readily available . 
