Give me a 10 marks answer about rapid sequence induction intubation from standard anaesthesia textbooks for AIIMS md anaesthesia exams

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Rapid Sequence Induction and Intubation (RSII)

[10 Marks - AIIMS MD Anaesthesia Level Answer]

Definition

Rapid Sequence Induction and Intubation (RSII) is a specialized method of intravenous induction of general anaesthesia designed to minimize the risk of pulmonary aspiration of gastric contents. It achieves the rapid transition from a conscious, unintubated state to a secured, cuffed endotracheal airway in the shortest possible time by the near-simultaneous administration of an induction agent and a rapid-onset neuromuscular blocking drug (NMBD), while avoiding positive-pressure mask ventilation.

Miller's Anesthesia, 10e, p. 5862

Indications

RSII is indicated whenever there is a significant risk of gastric regurgitation and pulmonary aspiration:

Full stomach - non-compliance with NPO fasting guidelines
Bowel obstruction - paralytic or mechanical
Gastro-oesophageal reflux disease (GERD) - poorly controlled
Morbid obesity - increased intra-abdominal pressure + delayed gastric emptying
Diabetic gastroparesis
Trauma patients - assumed full stomach, also pain/opioids delay gastric emptying
Pregnancy - second trimester onwards (though increasingly questioned)
Presence of a nasogastric tube (incompetent lower oesophageal sphincter)
Predicted difficult mask ventilation (e.g., edentulous, bearded patient with otherwise reassuring airway) - to avoid prolonged unprotected gas delivery
Emergency surgery - insufficient fasting

Miller's Anesthesia, 10e, pp. 5862-5863; Morgan & Mikhail's Clinical Anaesthesiology, 7e, p. 538

The "6 Ps" of RSII (Mnemonic)

Step	Timing	Action
Preparation	0-3 min	Equipment check, suction, IV access, monitors, drugs drawn up, difficult airway cart available
Preoxygenation	0-3 min	100% O2 via tight-fitting mask for 3-5 min (8 vital capacity breaths acceptable in emergency)
Premedication	3 min	Adjuncts: fentanyl, lidocaine, atropine, defasciculating agent
Paralysis (+ induction)	3.5-5.5 min	Induction agent immediately followed by NMBD
Placement	6-6.5 min	Endotracheal intubation without mask ventilation
Post-intubation management	>7.5 min	Cuff inflation, position confirmation, sedation/analgesia

Current Surgical Therapy, 14e

Step-by-Step Technique

1. Preoxygenation

The goal is to wash out nitrogen from the functional residual capacity (FRC) and replace it with oxygen, extending the safe apnoea time. Target: exhaled O2 concentration >90% or SpO2 >97%. Patients with lung disease require a full 3-5 minutes. High-flow nasal oxygen (10-15 L/min via nasal cannula) can be added to provide apnoeic oxygenation during laryngoscopy and extend safe apnoea time further.

2. Pre-treatment / Premedication (optional but important)

Fentanyl (1-3 mcg/kg): blunts sympathetic response to laryngoscopy, reduces pressor response
Lidocaine (1.5 mg/kg IV): attenuates airway reflexes, reduces ICP rise - used in head injury
Atropine (0.02 mg/kg): prevents succinylcholine-induced bradycardia, especially in children
Defasciculating dose (1/10th intubating dose of rocuronium/vecuronium): given 3 min prior to succinylcholine to reduce fasciculations, myalgia, and rise in ICP/IOP

3. Cricoid Pressure (Sellick Manoeuvre)

Applied before induction (10 N force in the awake patient, increased to 30 N after loss of consciousness)
Mechanism: the cricoid ring is a complete cartilaginous ring; pressure over it collapses the upper oesophagus beneath it
Maintained until endotracheal tube cuff is inflated and tube position is confirmed
Based on oesophageal manometry and cadaver studies

4. Induction Agent

A rapid-acting IV hypnotic is given as a bolus (not titrated):

Agent	Dose	Notes
Propofol	1.5-2.5 mg/kg	Most widely used; causes hypotension
Thiopental	3-5 mg/kg	Historical gold standard; not widely available
Etomidate	0.3 mg/kg	Haemodynamically stable; preferred in trauma/shock; adrenal suppression with single dose is controversial
Ketamine	1-2 mg/kg	Drug of choice in haemodynamic instability, bronchospasm, trauma; raises ICP (controversial)

5. Neuromuscular Blocking Drug

Administered immediately after the induction agent, even if the patient has not yet lost consciousness.

Agent	Dose	Onset	Duration	Notes
Succinylcholine	1-1.5 mg/kg	45-60 sec	8-10 min	Gold standard; only depolarising NMBD
Rocuronium	1.0-1.2 mg/kg	60-90 sec	30-60 min	Preferred when succinylcholine is contraindicated; reversible with sugammadex
Vecuronium	0.3 mg/kg	<90 sec	Prolonged	Rarely used now

6. Intubation

No bag-mask ventilation is performed (avoids gastric insufflation and risk of vomiting/aspiration)
Wait until there is no response to peripheral nerve stimulation
Intubate rapidly; confirm with capnography and auscultation
Cricoid pressure released only after cuff is inflated and tube position confirmed

Contraindications to Succinylcholine (Use Rocuronium Instead)

Known or suspected myopathy / muscular dystrophy (risk of rhabdomyolysis and hyperkalaemic cardiac arrest)
Burns >24-48 hours old
Crush injuries / denervation injuries (upregulation of extrajunctional receptors - dangerous hyperkalaemia)
Malignant hyperthermia (MH) susceptibility or personal/family history
Severe hyperkalaemia (serum K+ >5.5 mEq/L)
Penetrating eye injury (raises IOP) - relative, often ROC preferred
History of pseudocholinesterase deficiency

Barash Clinical Anaesthesia, 9e; Miller's Anesthesia, 10e

Controversies in RSI

Cricoid Pressure - Arguments For and Against

For:

Properly applied cricoid pressure effectively prevents passive regurgitation from reaching the pharynx
MRI studies show the force displaces soft tissue and can occlude the oesophageal lumen when correctly applied

Against:

MRI studies show the oesophagus is often laterally displaced rather than compressed
Cricoid pressure reduces lower oesophageal sphincter tone (paradoxically may increase reflux risk)
Worsens laryngoscopic view by up to one Cormack-Lehane grade
Can cause subglottic airway occlusion, making mask ventilation or intubation difficult
The landmark IRIS RCT (2019, published in JAMA Surgery) showed that cricoid pressure compared with a sham procedure did not reduce aspiration - this directly questioned its routine use
Miller's Anesthesia, 10e, pp. 5862-5863; Current Surgical Therapy, 14e

Modified RSI

The term "modified RSI" refers to allowing gentle positive pressure ventilation (inspiratory pressure <20 cmH2O) in conjunction with cricoid pressure, particularly in:

Obese and pregnant patients (reduced FRC, rapid desaturation)
Critically ill patients
Paediatric patients (especially neonates/infants with high O2 consumption and low FRC)

No universally accepted definition exists; in the US, it most commonly refers to mask ventilation + cricoid pressure.

RSI vs. Awake Intubation

When intubation is predicted to be difficult in a patient with a full stomach, a difficult choice arises between RSI (with risk of cannot-intubate-cannot-oxygenate) and awake fibreoptic intubation. In general:

RSI is preferred when intubation is predicted difficult but mask ventilation is easy
Awake intubation is the safer choice when both intubation AND ventilation are predicted to be difficult
Failed RSI: maintain cricoid pressure, ventilate gently with O2, retry; if still failing, allow spontaneous ventilation to return (or give sugammadex to reverse rocuronium), and proceed with awake technique

Failed RSI and Rescue

If intubation fails: do NOT release cricoid pressure; gently ventilate with O2 at low pressure
Reassess and re-attempt with video laryngoscopy or bougie
If still unsuccessful: allow return of spontaneous ventilation
Sugammadex (16 mg/kg) can immediately reverse even large-dose rocuronium (1.2 mg/kg), restoring spontaneous ventilation within ~3 minutes - this is the major advantage of rocuronium + sugammadex over succinylcholine for RSI in cannot-intubate scenarios

Paediatric Considerations

Neonates/infants desaturate rapidly due to higher O2 consumption and lower FRC
Succinylcholine dose is higher: 2 mg/kg in infants vs. 1-1.5 mg/kg in adults
Rocuronium: 1.2 mg/kg
Atropine should be available (succinylcholine-induced bradycardia is more common)
Modified RSI (gentle mask ventilation) is often safer in infants than classical RSI
Barash Clinical Anaesthesia, 9e, p. 3749

Key Summary Points for Exam

Feature	Classical RSI
Preoxygenation	3-5 min, 100% O2
Mask ventilation	Avoided
Cricoid pressure	10 N awake, 30 N after LOC (Sellick)
Induction agent	Propofol / Etomidate / Ketamine
NMBD of choice	Succinylcholine 1.5 mg/kg OR Rocuronium 1.2 mg/kg
No response to NS required?	Yes, before intubation
Cricoid pressure released when?	After cuff inflated + tube confirmed
Modification allowing gentle PPV	Modified RSI (<20 cmH2O)
Reversal of rocuronium	Sugammadex 16 mg/kg
Historical first description	1970

Sources: Miller's Anesthesia, 10e (pp. 5862-5864) | Morgan & Mikhail's Clinical Anaesthesiology, 7e (pp. 537-538) | Barash, Cullen & Stoelting's Clinical Anaesthesia, 9e (pp. 3748-3749) | Current Surgical Therapy, 14e

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