Author: Fiqry Fadhlillah / Editor: Beth Newstead / Reviewer: Tadgh Moriarty / Codes: RP1, RP3, RP4, RP5, RP8, SLO3, SLO4, SLO6 / Published: 02/08/2021

Intubation forms an integral role in the treatment of the critically ill or injured patients presenting to the ED with a failed or at-risk airway. The acuity of their presentation may often necessitate a rapid placement of an endotracheal tube (ETT). There are many different strategies to achieve this; one such technique is rapid sequence induction (RSI). RSI is designed to minimise the time between loss of airway reflexes and placement of an ETT in the trachea. It minimises the risk of aspiration in patients who are inadequately starved, have impaired gastric emptying or are known to have gastric reflux. The term ‘rapid sequence induction’ emphasises the use of a sequential technique in achieving rapid intubation by minimising the time delay between loss of airway reflexes and tube placement.

The traditional definition of rapid sequence induction (RSI) is an established method of inducing anaesthesia in patients who are at risk of aspiration of gastric contents into the lungs. It involves inducing loss of consciousness whilst cricoid pressure is applied followed by placement of an endotracheal tube.

An induction agent (e.g. propofol) induces a state of immediate unresponsiveness. This is then followed by the administration of a neuromuscular blocking agent to induce paralysis. The combination of drugs ceases spontaneous ventilation in the patient and allows for better view of the vocal cords. RSI is useful in patients with an intact gag reflex, a full stomach and a life threatening injury or illness requiring immediate airway control.

There are considerable variations in medications used for induction and paralysis. In the UK, propofol and ketamine remain the two most commonly used induction agents. There is now a shift of use of paralytic agent, from suxamethonium to rocuronium. In a recent analysis of 4275 intubations performed in the ED (USA), suxamethonium and rocuronium exhibited no differences in first-pass success (87.0% versus 87.5%) or adverse events (14.7% versus 14.8%) (April MD et al). This study only examined patients receiving either suxamethonium or rocuronium.

The most common induction agents used are:

Drug How to make up Final concentration
Propofol 1% Neat into 20ml syringe 10mg/ml
Ketamine 500mg/10ml Neat into 10ml syringe 50mg/ml
Thiopentone 500mg vial Add 20ml water into 20ml syringe 25mg/ml
Etomidate 20mg/10ml Neat into 10ml syringe 2mg/ml

The most common paralysing agents used are:

Drug How to make up Final concentration
Suxamethonium 50mg/ml Neat 1 ampoule into 2ml syringe 50mg/ml
Rocuronium 50mg/5ml Neat 2 ampoules into 10ml syringe 10mg/ml
Atracurium 50mg/5ml Neat 2 ampoules into 10ml syringe 10mg/ml
Vecuronium 10 mg Add 5ml water into 5ml syringe 2mg/ml

Look Externally

Any external markers of difficult airway? Examples; Body habitus, beards, midface trauma, jaw malocclusion, short neck, large tongue.

Evaluate 3/3/2

Inter-incisor distance (assess how many fingers can be placed between superior and inferior incisors whenSoft mouth opened wide) should be at least three fingers.

Hyomental distance: At least three fingers from base of mandible (mentum) to hyoid bone

Thyromental distance: At least two fingers from hyoid bone to thyroid notch


Ask patient to open mouth and protrude tongue. Class 1-4 is awarded based on features of airway seen. 1: Complete visualisation of soft palate, fauces, uvula and pillars 2: Soft palate, fauces, portion of uvula, 3: Soft palate, base of uvula, 4: Only hard palate visible. A higher class (3/4) is a possible predictor of a more difficult intubation.
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Conditions which may compromise laryngoscopy and the passage of an ETT e.g. epiglottits, head and neck cancer, ludwig’s angina, neck haematoma, airway burn, foreign body.

Neck Mobility

Any restrictions to neck mobility e.g. degenerative/inflammatory spine pathology (OA, rheumatoid, ankylosing spondylitis), trauma (cervical collar/ manual in line stabilisation). Those with limited neck mobility are considered more difficult to intubate.

Emergency intubations are not without risk, not least due to the emergent nature of the procedure itself. A growing body of evidence suggests that the risk accompanying an invasive airway technique may even outweigh its intended benefits of protecting the airway and achieving adequate ventilation. The AIRWAYS-2 and PART studies, both published in the same 2018 issue of the Journal of the American Medical Association (JAMA), concluded that intubation is not superior to placing a supraglottic airway device (SAD) in the out-of-hospital (atraumatic) cardiac arrest setting; and that SAD may be at least as good, if not better than attempts at inserting an ETT.

The 4thNational Audit Project of the Royal College of Anaesthetists and Difficult Airway Society (NAP4) was designed, in part, to look at airway management in ED and highlight any deficiencies that have or could have led to serious harm. Analysis of cases highlighted the following gaps in care:

  • Poor or delayed recognition of at-risk or deteriorating patients
  • Inadequate preparation
  • Insufficiently trained staff
  • Inadequate equipment

Steps in RSI

  1. Verbalise time out
  2. Ensure designation of roles intubator, drug delivery, managing equipment, monitoring patients vital signs
  3. Check drugs, equipment
  4. Ensure plan discussed
  5. Give induction agent
  6. Give paralytic agent
  7. Wait 45-60 seconds after paralytic agent
  8. Pass endotracheal tube
  9. Move to plans B, C or D as needed
  10. Confirm end-tidal CO2, lung sounds, chest rise and misting of tube

The Difficult Airway Society, Intensive Care Society, FICM and the Royal College of Anaesthetists published a 2018 guideline on the management of tracheal intubations in critically ill adults.

As a minimum, the following personnel should be present during an intubation:

In the event of a failed or difficult airway, the following steps should be followed:

An unanticipated difficult RSI can occur for a number of reasons:

  • Rapidly deteriorating patient/ haemodynamic instability – make attempts to optimise haemodynamic parameters prior to intubation and ensure team aware of, and plan for deterioration.
  • Uncooperative or combative patients – consider cause of agitation or aggression – can this be managed/treated prior to RSI? Is the use of delayed sequence intubation (DSI) required [Modified RSI where ketamine is used to provide a dissociative state, allowing pre-oxygenation to occur. RSI can then proceed in a safe controlled fashion.9
  • Structural airway problems (e.g. short neck, immobilised neck in trauma) – experienced airway operator (s) present? Use of video laryngoscope considered?
  • Full Stomach (increased risk of regurgitation, vomiting, aspiration), secretions, vomitus, blood present – tilting trolley in use? Suction and back up suction available, team briefed on plan for vomiting?
  • Difficult ventilation – ensure airway adjuncts available and sized pre-procedure (NPA, OPA, LMA), two-person BVM technique. Significant facial hair such as prominent beards can make mask ventilation challenging. Some suggested management steps include using a tegaderm/defibrillator pad over the entire mouth and hair with a hole cut in the middle for ventilation. Removal can be another solution (however care needs to be exercised around facial hair in cultural and religious circumstances and where possible consent should be obtained prior to its removal. Another suggested route would be to if first laryngoscopy attempt is unsuccessful to bypass NPA/OPA/ Mask ventilation and proceed directly to LMA prior to second attempt at laryngoscopy.10

Always ensure that the following medications are within reach:

Drug Use How to make up Final concentration Suggested initial dose
Atropine Bradycardia Neat from pre-filed syringe  






Neat into 2ml syringe 600mcg/ml 600mcg
Glycopyrronium Bradycardia Neat into 5ml syringe 200mcg/ml 200mcg
Metaraminol 10mg Hypotension 1 vial Add N Saline to make 20ml 0.5mg/ml 0.5mg
Ephedrine 30mg Hypotension 1 vial Add N Saline to make 10ml 3mg/ml 6-9mg
Sugamaddex 500mg/5ml Reversal of NMB Neat into 5ml syringe 100mg/ml 16mg/kg (immediate reversal)

If the patient suddenly develops post intubation hypoxia use the acronym ‘DOPES’ to help troubleshoot the problem.

D: Dislodgement of the tube – check depth of tube against recorded depth at intubation. Is ETCO2 still connected and recording?

O: Obstruction – can a suction catheter be passed?

P: Pneumothorax – consider clinical examination, Point of Care Ultrasound (POCUS) or portable Chest X-ray

E: Equipment failure – disconnect ventilator and return to manual BVM.

S: Stacked breaths – especially auto-PEEP in COPD/asthma. Disconnect from ventilator. If reconnecting to ventilator consider decreasing RR, decreasing I:E ratio (to increase expiratory time) and ensure optimal sedation.

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