External laryngeal manipulation (ELM) and cricoid pressure are distinct maneuvers with separate purposes, but are often mistakenly used interchangeably. It's important to know the difference because ELM will improve your chances of successful intubation while cricoid pressure may harm your patient.
Cricoid Pressure
Cricoid pressure is more likely to cause harm than benefit and is slowly disappearing from airway texts, yet persists in the minds of practitioners who were trained in its use.
First described in 1961 by the british anesthesiologist Brian Sellick (and also known as Sellick's maneuver), the purpose of cricoid pressure is to prevent gastric inflation during mask ventilation as well as regurgitation during an intubation attempt (Sellick, 1961). Hypothetically this would be done by occluding the esophagus between the more rigid cartilaginous rings of the trachea and the anterior portion of the cervical vertebral body.
In practice, CT and MRI research as shown that cricoid pressure does not occlude but rather displaces the esophagus laterally about 90% of the time (Smith, 2002 and 2003). Other research has shows that cricoid pressure reduces lower esophageal sphincter pressure, further arguing against it's role in preventing gastric inflation or regurgitation (Tournadre, 1997). Even more concerning is that compression of the cricoid ring may also compromise upper airway patency, making mask ventilation or even endotracheal tube passage difficult.
External Laryngeal Manipulation (ELM) or Bimanual Laryngoscopy
From an observer's point of view, ELM looks very similar to cricoid pressure, which might be why these maneuvers are confused. (PIC of someone applying cricoid and then ELM)
Cricoid Pressure
Cricoid pressure is more likely to cause harm than benefit and is slowly disappearing from airway texts, yet persists in the minds of practitioners who were trained in its use.
First described in 1961 by the british anesthesiologist Brian Sellick (and also known as Sellick's maneuver), the purpose of cricoid pressure is to prevent gastric inflation during mask ventilation as well as regurgitation during an intubation attempt (Sellick, 1961). Hypothetically this would be done by occluding the esophagus between the more rigid cartilaginous rings of the trachea and the anterior portion of the cervical vertebral body.
In practice, CT and MRI research as shown that cricoid pressure does not occlude but rather displaces the esophagus laterally about 90% of the time (Smith, 2002 and 2003). Other research has shows that cricoid pressure reduces lower esophageal sphincter pressure, further arguing against it's role in preventing gastric inflation or regurgitation (Tournadre, 1997). Even more concerning is that compression of the cricoid ring may also compromise upper airway patency, making mask ventilation or even endotracheal tube passage difficult.
External Laryngeal Manipulation (ELM) or Bimanual Laryngoscopy
From an observer's point of view, ELM looks very similar to cricoid pressure, which might be why these maneuvers are confused. (PIC of someone applying cricoid and then ELM)
The two main differences are that during ELM, (1) it is the thyroid rather than the cricoid cartilage that is manipulated and (2) the purpose is to improve the intubator's view of the glottis rather than protect against regurgitation or gastric inflation.
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In this direct laryngoscopic view, manipulation of the thyroid demonstrates that the larynx is a mobile structure and can be positioned in most any direction that could improve (or worsen) the intubator's view. Note that the larynx is most easily manipulated laterally and less so in the anterior/posterior axis. |
ELM is useful not only in direct but also in video laryngoscopy, particularly when the epiglottis seems to flop down and obstruct the vocal cords. Here, pressure on the thyroid cartilage helps to tuck the laryngoscope blade tip into the hyoepiglottic ligament, lifting the epiglottis out of the way. |
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ELM requires two people and is best coordinated with the intubator's right hand guiding the hand of an assistant. Once the best view of the glottis is achieved, the assistant can hold the thyroid cartilage in place while the intubator passes the endotracheal tube.
BURP (Backward, Upward, Rightward Pressure)
This 3rd maneuver risks further confusion but deserves mention. BURP is a estimation of where the thyroid cartilage should be moved to improve the view of the glottis on any given patient. While ELM during an intubation attempt might require backward, upward, or rightward pressure (or all three), some patients' airways may require different manipulations to find the best possible view. ELM is superior to BURP because the intubator has immediate visual feedback of exactly how much force to apply and in what direction, rather than operating on a best guess with BURP.
- B.A. Sellick. Cricoid pressure to control regurgitation of stomach contents during induction of anesthesia. Lancet, 2 (1961), pp. 404–406
- K.J. Smith, S. Ladak, P.T. Choi, et al. The cricoid cartilage and the esophagus are not aligned in close to half of adult patients. Can J Anaesth, 49 (2002), pp. 503–507
- K.J. Smith, J. Dobranowski, G. Yip, et al. Cricoid pressure displaces the esophagus: an observational study using magnetic resonance imaging. Anaesthesiology, 99 (2003), pp. 60–64
- J.P. Tournadre, D. Chassard, K.R. Berrada, et al. Cricoid cartilage pressure decreases lower esophageal sphincter tone. Anaesthesiology, 86 (1997), pp. 7–9
- Ellis DY, Harris T, Zideman D. Cricoid pressure in emergency department rapid sequence tracheal intubations: a risk-benefit analysis. Ann Emerg Med. 2007 Dec;50(6):653-65.
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