To the Editor:—
We read with interest the article by Santoni et al.1
Maintaining manual in-line stabilization for direct laryngoscopy in patients with known or suspected cervical spine injury is a practice which would benefit from further research. However, we believe the protocol design in this study has limited the clinical relevance of the data generated.
The authors designed a prototype pressure-sensing laryngoscope blade specifically for this study. The protocol for intubation in this study was regulated by limitations of these pressure sensors. The research team prohibited external laryngeal manipulation and prohibited use of a stylet. Use of bougie was not mentioned. Both external laryngeal manipulation and use of stylet/bougie are accepted techniques to assist intubation when laryngoscopy is difficult, and are part of the difficult airway algorithm.2,3
Both of these techniques are commonly used in patients with suspected cervical spine injuries.4
The approach used in the study, which does not represent normal clinical practice, resulted in an increased burden of risk to the patients in this study (three failed intubations and one dental trauma in ten subjects), so that the trial was abandoned. The clinical benefit of a study in humans needs to be balanced against the risk assumed by the subjects. It would be valuable to repeat the study in a more realistic clinical setting, allowing clinicians to intubate the patient in whatever manner they are used to, and using intubation aids as required. It would be interesting to see if manual in-line stabilization still resulted in a doubling of applied pressure in that scenario.
Heather Loane, M.B.B.S., B.Med.Sci.*
James Shannon, M.B., B.C.H., B.A.O., B.Med.Sci., F.C.A.R.C.S.I.
Patrick Thornton, M.B., B.C.H., B.A.O., B.Med.Sci., F.C.A.R.C.S.I.
Jessica Tyler, B.Sc.
Roanne Preston, M.D., F.R.C.P.C.
*BC Women's Hospital, Vancouver, British Columbia, Canada. firstname.lastname@example.org
1. Santoni BG, Hindman BJ, Puttlitz CM, Weeks JB, Johnson N, Maktabi MA, Todd MD: Manual in-line stabilization increases pressures applied by the laryngoscope blade during direct laryngoscopy and orotracheal intubation. Anesthesiology 2009; 110:24–31
2. American Society of Anesthesiologists Task Force on Management of the Difficult Airway: Practice guidelines for management of the difficult airway: An updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98:1269–77
3. Henderson JJ, Popat MT, Latto IP, Pearce AC: Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia 2004; 59:675–94
4. Lavery GG, McCloskey BV: The difficult airway in adult critical care. Critical Care Medicine 2008; 36:2163–73
© 2009 American Society of Anesthesiologists, Inc.