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Cricoid pressure has been used to keep the stomach contents in the stomach, and out of the airway, since Dr. Brian A. Sellick wrote about it in 1961.[1] The problem is that the evidence does not show that it works.
This study looked at cervical CT (Computed Tomography) scans to see what anatomic relationship exists between the cricoid ring and the esophagus in a group of patients with some sort of reason to have a neck CT. These are people with necks that may have some abnormalities, but they do give us some information on whether cricoid pressure should be expected to work and how cricoid pressure would be expected to malfunction. About half of the CTs showed masses displacing the esophagus or cricoid ring and were excluded.
Lateral esophageal displacement was seen in 49% (25/51) of the CT images. Of those displaced, 92% were displaced leftward and 8% were displaced right-ward. When present, the length of displaced esophagus relative to the midline of the cricoid was 3.3 mm ± SD 1.3 mm (range 1.4 mm to 5.7 mm).[2]
Of the patients without masses displacing the anatomy, half of patients still did not have the esophagus directly alinged behind the cricoid ring.
Based on anatomy and common sense, an assumption has been made since Sellick introduced the technique of cricoid pressure in 1961: the esophagus lies directly posterior to the cricoid. While this relationship has been assumed to be true in the majority of the population, we have identified some degree of lateral esophageal displacement in 25 of 51 subjects.[2]
The displacement is not large, but how much displacement is required for it to be significant?
The purpose of cricoid pressure is to prevent gastric contents from entering the airway (and maybe to improve glottic view), but does it work? This study only looked at the anatomy, but we have other reasons for doubting the efficacy of cricoid pressure from other studies.
FIGURE 2 Computed tomography of the neck and line drawing demonstrating 1.5 mm of leftward lateral esophageal displace-ment. AJ = anterior jugular vein; C = carotid artery; Cr = cricoid cartilage; E = esophagus; IJ = internal jugular vein; SCM = stern-ocleidomastoid muscle; Th = thyroid gland; VB = vertebral body.[2]
Although there is only 1.5 mm displacement, would pushing straight back on the cricoid ring obstruct that esophagus?
However, previous reports of its failure to prevent regurgitation have never been explained adequately. Its use has also been associated with serious complications including distorted laryngeal view, increased difficulty with intubation, laryngeal trauma, cricoid fracture, and esophageal rupture.
11-15 [2]
Distorted laryngeal view?
All inadequately studied procedures should encourage caution.
A maneuver that makes it even harder to place an endotracheal tube should have received much more examination in the first four decades of use.
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Footnotes:
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[1] Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia.
SELLICK BA.
Lancet. 1961 Aug 19;2(7199):404-6. No abstract available.
PMID: 13749923 [PubMed – indexed for MEDLINE]
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[2] The cricoid cartilage and the esophagus are not aligned in close to half of adult patients.
Smith KJ, Ladak S, Choi PT, Dobranowski J.
Can J Anaesth. 2002 May;49(5):503-7.
PMID: 11983669 [PubMed – indexed for MEDLINE]
Page with link to Free Full Text Download in PDF format from Springerlink.
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Smith KJ, Ladak S, Choi PT, & Dobranowski J (2002). The cricoid cartilage and the esophagus are not aligned in close to half of adult patients. Canadian journal of anaesthesia = Journal canadien d’anesthesie, 49 (5), 503-7 PMID: 11983669
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I’ve only ever used cricord pressure to improve glottic view during intubation
The displacement between cricoid and esophagus could also be affected by patient position, chest orientation with respect to breathing, and organ position deviation caused by injury/infections.