The origins of the sniffing position and the Three Axes Alignment Theory for direct laryngoscopy.

The Three Axes Alignment Theory and the sniffing position for direct laryngoscopy are the anatomical basis for direct laryngoscopy. This position has been one of the hallmarks of airway management and yet its development is based on a small number of descriptive texts published between 1852 and 1944. This paper explores the origins of direct laryngoscopy and how the sniffing position came to be described. The seemingly incongruent techniques of the rigid bronchoscopist and direct laryngoscopist are discussed from an historical perspective.