The ABCs of Rapid Sequence Induction

Rapid Sequence Induction

Definition: a technique to safely secure the airway with an endotracheal tube. Used in patients who are at risk of regurgitation and aspiration of gastric contents on induction of anaesthesia.

Regurgitation: passive movement of gastric contents into the pharynx. This is normally prevented by the upper and lower oesophageal sphincters.

The lower oesophageal sphincter is formed by the lowest 2-4 cm of the oesophagus. The major component of the upper oesophageal sphincter is the cricopharyngeus muscle.
Protective laryngeal reflexes are also lost during GA.

Aspiration: regurgitation occurs and gastric contents then enter the trachea and lungs.

Indications 1. Full stomach or conditions considered as full stomach     eg: stress, delayed gastric emptying,       emergency cases 2. Obese 3. Pregnant 4. History of hiatal hernia 5. Intestinal obstruction

Checklist 1. Anaesthetic machine and breathing circuit 2. Routine patient monitoring applied 3. Airway equipment 4. Tipping trolley 5. Suction switched on and immediately to hand 6. Drugs – including emergency drugs 7. A trained assistant

Technique

1.     Preparation and echking of equipment, tilting trolley and suction

2.     Pre-oxygenation – delayed onset of muscle relaxant, avoid face mask ventilation

3.     Administration of intravenous pre-calculated dose of induction agent

4.     Administration of suxamethonium – depolarizing muscle relaxant onset faster 30s compared to non-depolarising muscle relaxant onset 2-3 minutes*

5.     Cricoid pressure (Sellick’s manoeuevre) – cricoid cartilage at level C6

6.     Intubate and confirm ETT placement

7.     Remove cricoid pressure

* bag mask technique during 2-3 minute period may insufflate the stomach and increase intra-gastric pressure and regurgitation

Pre-oxygenation

- high flow oxygen for 3 minutes of tidal breathing or four vital capacity breaths, target 85% O₂

- tight fitting face mask, ensure no leakage

Cricoid pressure

The cricoid cartilage is the only complete ring of cartilage in the larynx. Pressure on the cricoid cartilage compresses the oesophagus against the cervical vertebrae, thus preventing the passage of gastric and oesophageal contents, should passive regurgitation occur.

Light cricoid pressure (10 Newtons [N]) is applied before intravenous induction. The force is increased (30 N) after loss of consciousness. It is the responsibility of the anaesthetist to ensure that cricoid pressure has been applied. The direction of the force is posterior. A force of 30 N is approximately equal to a 3 kg weight.

Two-finger technique – the index finger and thumb are placed on each side of the cricoid arch, with force applied by both.

Three-finger technique – the thumb and middle finger are placed on each side of the cricoid arch with force applied by the index finger in the midline.

A two-handed technique is used if a cervical spine fracture is suspected. The second hand is placed behind the neck to prevent posterior displacement of the spine on applying cricoid pressure. Manual in-line stabilization of the neck must also be used.

Muscle relaxant (Suxamethonium)

- Fast onset of action providing paralysis in approximately 30-45 s

- Short duration of action of 5-8 min

- dosage: 1.5mg/kg

- post-administration, face mask remained applied with airway held open until fasciculations ceased and jaw relaxed.

Contraindications to Suxamethonium

1. anaphylaxis

2. malignant hyperthermia

3. major burns

Gastric Aspiration

Tilt the trolley head down, suction the oropharynx, intubate immediately and inflate the cuff. Pass a suction catheter down the endotracheal tube (ETT) to clear any aspirate before starting ventilation with 100 % oxygen (to prevent contamination of the distal airways).

A higher FiO2, Positive End-Expiratory Pressure (PEEP) or bronchodilators may be needed to maintain oxygenation.

If significant pulmonary aspiration has occurred the patient should be transferred to a high dependency area post-operatively.

Mendelson Syndrome

syndrome of pneumonitis following aspiration of gastric contents was originally described by Mendelson in obstetric patients. Features include hypoxia, bronchospasm and pulmonary oedema. Treatment is mainly supportive including oxygen, bronchodilators, physiotherapy and assisted ventilation if required.

sourced from: RCoA and AAGBI