What is the effectiveness of cricoid pressure in preventing regurgitation and aspiration of stomach and intestinal contents in a patient with a high-grade small bowel obstruction of four days duration?

Cricoid Pressure Effectiveness in High-Grade Small Bowel Obstruction

Cricoid pressure should be applied during rapid sequence induction in this patient with high-grade small bowel obstruction, but you must be prepared to immediately release it if airway difficulties arise, as it does not provide 100% protection against aspiration and can significantly complicate airway management. 1

Evidence for Effectiveness

The reality is that cricoid pressure has never been proven effective in preventing aspiration in living patients:

• No randomized controlled trials have demonstrated that cricoid pressure actually prevents aspiration in clinical practice - the evidence base consists only of cadaver studies showing prevention of liquid movement from esophagus to pharynx 1

• One large observational study of 4,891 obstetric patients found no significant difference in regurgitation rates between patients who received cricoid pressure versus those who did not 1

• Case reports exist documenting aspiration occurring despite proper application of cricoid pressure, indicating it cannot guarantee protection 1

• The NAP4 audit concluded that rapid sequence induction with cricoid pressure does not provide 100% protection against regurgitation and aspiration, though it remains the standard for at-risk patients 1

Why It Remains Standard Practice Despite Limited Evidence

Despite the lack of proof, cricoid pressure remains standard practice in the UK and many countries because aspiration, while rare (1/7000 in scheduled surgery), carries devastating consequences:

• The NAP4 study documented 8 deaths from aspiration of gastric contents in 2,872,600 general anesthetics, making it the single most common cause of death in anesthesia events 1, 2

• Of 36 aspiration cases identified, 29 required ICU admission and half required prolonged hospitalization 2

• The mortality rate from aspiration is 1/1,000, but when it occurs, the morbidity and mortality are catastrophic 2

• NAP4 identified several cases where omission of cricoid pressure despite strong indications led to patient harm or death from aspiration, but found no cases where cricoid pressure itself caused major complications 1

Critical Application Guidelines for Your High-Risk Patient

Apply 10 N force initially in the awake patient, increasing to 30 N (3 kg) after loss of consciousness 1, 3, 4:

• This patient with 4-day small bowel obstruction has massively increased aspiration risk due to accumulated intestinal contents under pressure

• The force must be measured or trained - most practitioners apply either too little (ineffective) or too much (causing complications) 1

• Excessive force (>30 N) can trigger retching and vomiting - the very problem you're trying to prevent 1, 4

Anatomical Reality That Limits Effectiveness

The esophagus sits posterolateral to the cricoid ring (mainly left-sided) in 50-91% of patients, not directly posterior as originally assumed 4:

• Traditional midline cricoid pressure may not achieve esophageal compression in half of patients 1, 4

• Cricoid pressure actually compresses the hypopharynx, reducing its anteroposterior diameter by 35%, not the esophagus itself 2

• This anatomical variation explains why aspiration can occur despite "proper" technique 4

Serious Complications That Threaten This Patient

Cricoid pressure can cause complete airway obstruction in up to 50% of patients and makes failed intubation nearly 8 times more frequent 1, 4:

• It impairs facemask ventilation by increasing inspiratory pressures and reducing tidal volumes 1

• It distorts laryngeal structures, worsening laryngoscopic view 1

• It impedes placement of supraglottic airways if intubation fails 1

• In a patient with bowel obstruction who may already have difficult anatomy from distension, these complications could be catastrophic

Mandatory Release Criteria

You must immediately release cricoid pressure if any of the following occur 1, 3, 4:

• Active vomiting begins - continuing pressure risks esophageal rupture 1, 4, 2

• Difficult laryngoscopy or poor glottic view 3, 4

• Inability to ventilate by facemask 3

• Difficulty placing supraglottic airway device 3

• Release should be done under direct vision with suction immediately available and assistant ready to reapply if regurgitation occurs 1

Practical Algorithm for This Case

1. Optimize preoxygenation - achieve end-tidal oxygen >90% over 2-3 minutes with 100% oxygen at >10 L/min, as this patient may desaturate rapidly 3

2. Position head-up if possible - reduces force needed to 20 N and decreases aspiration risk 1

3. Have most experienced anesthesiologist perform first intubation attempt - you get maximum 3 attempts 4

4. Trained assistant applies 10 N initially, 30 N after induction - assistant must be empowered to release immediately if requested 3, 4

5. If airway difficulty encountered, reduce or release cricoid pressure without hesitation - failed intubation is more immediately life-threatening than aspiration 3, 4

6. Have suction immediately available and front-of-neck access equipment ready - this is a predicted difficult airway 3

Bottom Line for Clinical Practice

Apply cricoid pressure in this high-risk patient because the consequences of aspiration are devastating and NAP4 documented harm from its omission, but prioritize successful intubation over theoretical aspiration prevention 1, 4. The evidence shows cricoid pressure may not work as intended, can cause serious airway complications, but remains standard practice because we have no better alternative and aspiration mortality is catastrophic when it occurs 1, 5, 6.