Let’s keep this simple. You’re considering using the most widely used general anaesthetic. Slow breathing, or no breathing and a drop in blood pressure are all clear possibilities. And the rescue strategy for hypoxia is bagging (bag-valve-mask ventilation).

So, beware the following “at risk” patients:

  • Those patients who are predictably difficult to ventilate
  • The elderly (particularly those on numerous medications)
  • The sick (who may be hypoxic, hypotensive or at least dehydrated, even before you say hello)
  • The morbidly obese (who are prone to desaturating quickly and are a challenge to ventilate)
  • The unfasted
  • Patients with a known or suspected allergy to soy or eggs (propofol is 10% soybean oil and 1% egg phospholipid)

The above list is clearly a generalisation. All (save the allergies) are relative contra-indications. Where they exist, consider the urgency of the proposed procedure, alternative strategies to deep sedation including targeting a lighter level, alternative or adjunctive techniques (e.g. injecting local anaesthetic into a dislocated shoulder) or referral for a general anaesthetic in theatre. Above all else, apply common sense. Discuss with a senior colleague if you remain unsure.


Fasting deserves further mention, given that the link between aspiration and the fasting state of the patient is controversial. A comprehensive review of the emergency procedural sedation literature found no supporting evidence of this [11]. Nevertheless, for those patients who have recently eaten or drunk, it remains good practice to carefully weigh up the risk/benefit of deep sedation, particularly in vulnerable patients (see below), and consider other options as described above. This is the College recommendation [6]. You may find a consensus-based clinical practice advisory on fasting status useful additional reading [12].

We will specifically revisit ‘at risk’ patients later, once we’ve covered a standardised approach.

Vulnerable patients

At risk patients for aspiration are those with:

  • A hiatus hernia
  • Gastrointestinal obstruction (including those with previous upper GI surgery)
  • A pregnancy
  • Morbid obesity

Learning Bite

Identify ‘at risk’ patients and consider alternatives to deep sedation for them (or alternative medication).

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