To the Editor:—
The principle finding in the article by Adnet et al.1
is that the oral, pharyngeal, and laryngeal axes are not aligned in an awake, supine patient in the “sniffing position.” However, this finding does not contradict the common wisdom that the sniffing position facilitates intubation, because the authors did not compare laryngeal views in any of the three positions examined. After all, the proposed advantage of the sniffing position is in reducing the effort required to expose the glottis during laryngoscopy. Axis alignment may be irrelevant to ease laryngoscopy or intubation, but the article by Adnet et al.1
does not address this issue.
I would like to present another perspective on the sniffing position. I believe that the neutral position (no occipital support) and simple head extension (also no occipital cushion) as described in the article are not neutral, anatomic, or even desirable for induction or intubation. Most patients in the supine position are far more comfortable with several centimeters of occipital support; this is especially true for the elderly, who are often intolerant of lying flat on the operating table without a pillow. I believe that a pillow, which incidentally approximates the sniffing position, is preferred by supine, awake patients because it is, in effect, a reconstitution of the thoracic kyphosis and cervical lordosis found in normal, relaxed, upright posture. Therefore, the sniffing position is not a unique anatomic relation; it is how we normally carry ourselves.
Cervical flexion or extension can alter airway dynamics. 2
It is possible that normal posture minimizes work of breathing and length of the upper airway. 3
Perhaps, for this reason the same position minimizes the effort required to achieve a line of sight to the upper airway.
Guy L. Weinberg, M.D.
1. Adnet F, Borron SW, Dumas JL, Lapostolle F, Cupa M, Lapandry C: Study of the “sniffing position” by magnetic resonance imaging. A nesthesiology 2001; 94: 83–6
2. Amis TC, O’Neill N, Wheatley JK: Oral airway flow dynamics in healthy humans. J Physiol 1999; 1515: 293–8
3. Thut DC, Schwartz AR, Roach D, Wise RA, Permutt S, Smith DL: Tracheal and neck position influence upper airway airflow dynamics by altering airway length. J Appl Physiol 1993; 75: 2084–90
© 2001 American Society of Anesthesiologists, Inc.