The main purpose of patient assessment is to identify features of the patients anatomy, physiology or pathology that will require you to deviate from the standard RSI approach. This requires a step beyond a basic ‘airway assessment’ to make a plan to suit THIS patient and the resources available.
I am sure many people are familiar with the mneumonics for airway assessment
LEMON – Difficult laryngoscopy
MOANS – Difficult bag mask ventilation
SMART – Difficult cricothyroidotomy
RODS – Difficult supraglotic airway (LMA/Laryngeal tube)
If you like mneumonics you can test your memory by clicking the link to Ron Walls Manual of emergency airway management.
My problem is that I have trouble remembering what ABC stands for let alone the 19 letters in the above mneumonics. Furthermore, LEMON only has a positive predictive value of about 50% so:
At least half of difficult intubations are likely to be unexpected (Emerg Med 2005; 22:2 99-102).
In a recent lecture for the difficult airway society Dr Keith Greenland presents a simple “3 column” approach to difficult airway assessment. I’m alot more likely to remember 3 columns rather than 19 mneumonics letters. Although I believe we should approach all airways as potentially difficult, Dr. Greenland’s method is useful for identifying anatomical factors that may make laryngoscopy difficult. More importantly, he links assessment to management by indicating advantages and disadvantages of various airway devices for particular problems.
However, there is more to a difficult airway than just difficult laryngoscopy. In subsequent posts we will address physiological factors contributing to airway difficulty such as:
- Head Injury
- Upper GI bleeding
An editorial in Anaesthesia (Anaesthesia, 2002 57: 105–109) suggests we should dispel the myth that assessment actually helps us in predict difficulty accurately. The safe approach is to prepare for failure every time. Remember, no on has ever died from failure to intubate but may have died from failure to OXYGENATE!