What Drugs Are Used in Rapid Sequence Intubation?

Rapid sequence intubation (RSI) is the administration of a strong anesthetic agent followed by a rapidly acting paralytic agent (all within one minute) to make the patient unconscious. It is performed when the patient may not be fasting and is therefore at a high risk of aspiration (entry of gastric contents into the airways). 

The goal of the technique is intubation without difficulty. Maintaining oxygenation throughout the process is mandatory.

Rapid sequence intubation (RSI) is the fastest and most effective means of controlling the emergency airway. RSI is particularly useful in life-threatening situations or illnesses requiring immediate airway control. Below are common conditions in which the RSI technique is used: 

• Patients who have difficulty maintaining the airway due to upper airway swelling, infection, life-threatening injury, or anaphylaxis (allergy that causes breathing problems)
• Patients who have decreased consciousness
• Patients who have loss of airway reflexes and are at risk of aspirating gastric contents
• Patients who need intubation but are difficult to intubate due to weakness and severe respiratory diseases such as asthma or lung diseases
• Patients whose breathing mechanism is malfunctioned (air or fluid in the lungs, respiratory distress situations, or cyanide poisoning)
• Patients who have deteriorated medical conditions (such as uncooperative patients, patients with a stab wound to the neck with severe bleeding, patients who are in shock, patients with fracture of the spine, etc.)

Rapid sequence intubation (RSI) is usually performed in critical conditions. Below are common steps:

• During RSI, the patient may be positioned appropriately depending on their condition for pre-oxygenation and intubation. Usually, the supine position is adopted (lying face upwards). 
• Preoxygenation is done (100% oxygen is administered via a mask for three minutes).
• Preoxygenation is immediately followed by the anesthesia-inducing drug and paralytic drug.
• Once the drugs take effect, the patient is immediately intubated. Proper intubation is confirmed by the ET-CO2 monitor.
• Chest X-ray is often obtained when prolonged intubation is anticipated (for example, in the intensive care unit following an intubation for head injury). Ongoing sedation may be provided, and if required, a long-acting muscle relaxant may be administered.

Drugs used in rapid sequence intubation (RSI) are as follows:

• Potent anesthetic agent
• Muscle relaxants or paralytic agents
• Pharmacological adjuncts

Potent anesthetic agents include the following: 

• Propofol: It is used for patients who have unstable vital signs.
• Ketamine: It is used in prehospital settings and in unstable patients.
• Etomidate: It is used to suppress adrenaline effects on patients. 
• Thiopentone: It has the most rapid onset of action.
• Midazolam: It is most suitable in patients who are already having decreased consciousness.

Muscle relaxants or paralytic agents include the following: 

• Suxamethonium (succinylcholine): It is the most common muscle relaxant used in RSI.
• Rocuronium: It takes effect within 45-60 seconds. 
• Pharmacological adjuncts include the following:
• Fentanyl
• Alfentanil
• Remifentanil
• Lidocaine (lignocaine)

In patients who are under shock, no adjuncts may be required. However, in systemically well patients or patients at a risk of severe hypertension during induction, pharmacological adjuncts are used.