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Three Part Question

In [patients undergoing emergency RSI] does [cricoid pressure] reduce the [incidence of aspiration of gastric contents/ morbidity/mortality]?

Clinical Scenario

You are about to perform a rapid sequence intubation on a 26 year old man with a severe head injury. You have been told that the gentleman has consumed a significant amount of alcohol in the last 3 hours. The nurse asks you whether the application of Cricoid pressure will stop him aspirating.

Search Strategy

Medline 1950-July 2005 via OVID
EMBASE 1988-July 2005 via OVID
Cochrane Database of systematic review 2005
Medline and EMBASE
[{Sellick's manoeuvre.mp} OR {Cricoid pressure.mp} OR /cricoid pressure] LIMIT to HUMAN and ENGLISH and ABSTRACTS

Search Outcome

Medline
241 papers in total of which 3 papers were relevant to the question.
EMBASE
119 citations, no new references found.
Cochrane
No new papers found

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Smith KJ et al. July 2003 Canada	22 Healthy volunteers.	Observational study. MRI scans of necks were taken with and without the application of cricoid pressure	Oesophageal displacement laterally relative to the cricoid without cricoid pressure	52.6% of cases	Healthy awake volunteers were used, not paralysed patients undergoing RSI. Findings maybe influenced by muscle tone & the swallowing reflex.
			Oesophageal displacement laterally relative to the cricoid with cricoid pressure	90.5% of cases
			Unopposed oesophagus without cricoid pressure.	47.4% of cases
			Unopposed oesophagus with cricoid pressure.	71.4% of cases
			Lateral laryngeal displacement	66.7% of cases
			Airway compression	81% of cases
Brimacombe JR 1997 Australia	Clinical & Cadaver studies	Meta-analysis	Evidence of aspiration	No high quality studies proving that Cricoid pressure is beneficial in preventing aspiration.	No search strategy given. No inclusion criteria. No assessment of quality of studies. Various outcome measures used. No definitions for aspiration pneumonia given.
				Some studies report acid aspiration despite Cricoid pressure.
			Airway patency	Some reports of cricoid pressure impeding airway patency.
			Upper oesophageal sphincter pressure	Some evidence suggesting cricoid pressure increases Upper oesophageal sphincter pressure.
			Gastric insufflation with BVM	Some evidence cricoid pressure reduces gastric insufflation during BVM.
			Airway /Soft tissue injury	Case reports of cricoid injury/ soft tissue injury
Sellick BA 1961 UK	26 high-risk anaesthesia cases in which cricoid pressure was applied.	Observational study	Incidence of reflux of gastric/ oesophageal contents when cricoid pressure released post-intubation of trachea.	In 3 out of 26 cases release of cricoid pressure was followed by immediate reflux of gastric contents into pharynx.	Observational study in few patients. Study conducted in 1961 using anaesthetic techniques available at that time.

Comment(s)

Cricoid pressure has been described as the 'linchpin of rapid sequence induction' and has become widely accepted as the standard of practice during anaesthesia in the UK and US. However, it is not widely used in some continental countries. Although it is a simple manoeuvre there have been concerns about its safety and efficacy. Opinion on its use varies widely from those who believe it should remain the standard of care to those who urge for re-evaluation of the technique. Concern has been expressed that Cricoid pressure may interfere with airway management, obscuring the laryngeal view and creating difficulties in passing the endotracheal tube. This may lead to a failure of airway tecniques and subsequent morbidity and mortality. The evidence presented in this review would suggest that none of the papers confirm the perceived clinical benefit of cricoid pressure in reducing the incidence of aspiration during an emergency RSI. It will be interesting to see whether a technique that is now so widely engrained in anaesthetic practice will ever be submitted to a more rigorous evaluation.

Clinical Bottom Line

There is little evidence to support the widely held belief that the application of cricoid pressure reduces the incidence of aspiration during a rapid sequence intubation.

References

1. Smith KJ, Dobranowski J, Yip G, Daulphin A, Choi PTL. Cricoid pressure displaces the esophagus: An observational study using Magnetic Resonance Imaging. Anesthesiology 2003;99:60-4.
2. Brimacombe JR, Berry AM. Cricoid pressure. Canadian Journal of Anaesthesia 1997;44(4):414-25.
3. Sellick BA. Cricoid pressure to control regurgitation of stomach contents during induction of anaesthesia. Lancet 1961:2:404-6