RSI Drug Doses — Paediatric
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Rapid Sequence Intubation (RSI) in paediatrics is the technique of administering an induction agent and a neuromuscular blocking agent in rapid succession to achieve unconsciousness and motor paralysis, facilitating urgent endotracheal intubation while minimising the risk of pulmonary aspiration. Paediatric RSI differs from adult RSI in several important ways: drug doses are strictly weight-based, physiological reserve is lower (particularly respiratory), the airway anatomy is different (larger occiput, cephalad larynx, shorter trachea), and certain drugs require dose modification. The standard RSI sequence involves pre-oxygenation, preparation of equipment and drugs, administration of induction agent followed immediately by neuromuscular blockade, application of cricoid pressure (controversially), intubation during the apnoeic window, and confirmation of tube placement. Ketamine (1-2 mg/kg IV) is the preferred induction agent in haemodynamically compromised children due to its sympathomimetic properties. Succinylcholine (suxamethonium), a depolarising neuromuscular blocker, provides the most rapid onset (45-60 seconds) and shortest duration of action, making it ideal for difficult airway situations where paralysis reversal may be needed. Dosing is 2 mg/kg for children under 10 kg (infants have higher volume of distribution) and 1.5 mg/kg for older children. Rocuronium (1.2 mg/kg) is the non-depolarising alternative, particularly when succinylcholine is contraindicated (hyperkalaemia, burn injuries >24 hours, muscular dystrophy, denervation injuries). Atropine (0.02 mg/kg, minimum 0.1 mg) is recommended in infants under 1 year and when succinylcholine is used in any child to prevent the profound bradycardia that can be triggered by laryngoscopy or succinylcholine-induced muscarinic stimulation in the immature conduction system.
Ketamine: 1-2 mg/kg IV (induction); Succinylcholine: 2 mg/kg IV (<10kg) or 1.5 mg/kg (≥10kg); Rocuronium: 1.2 mg/kg IV; Atropine: 0.02 mg/kg IV (min 0.1 mg, max 0.6 mg) — give before succinylcholine in infants; all doses calculated from estimated or actual weight
- 1Estimate or confirm weight using APLS formula or Broselow tape. Calculate and draw up all RSI drugs BEFORE starting — prepare ketamine, succinylcholine or rocuronium, and atropine at the bedside with doses clearly labelled.
- 2Pre-oxygenate for 3-5 minutes with 100% oxygen via non-rebreather mask or bag-valve mask (avoid positive pressure unless child is apnoeic or desaturating). Target SpO2 ≥95% before induction.
- 3Apply monitoring: continuous SpO2, ECG, capnography, and non-invasive blood pressure. Ensure IV or IO access is patent and has adequate flow.
- 4In infants or when using succinylcholine, administer atropine 0.02 mg/kg IV (minimum 0.1 mg) to prevent bradycardia during laryngoscopy. Give 1-2 minutes before induction or simultaneously in a rapid sequence.
- 5Administer induction agent: ketamine 1-2 mg/kg IV over 30-60 seconds for haemodynamic stability; thiopental or propofol may be used in non-haemodynamically compromised patients by experienced practitioners.
- 6Immediately after induction, administer neuromuscular blocker: succinylcholine 2 mg/kg (infants) or 1.5 mg/kg (older children), or rocuronium 1.2 mg/kg IV. Succinylcholine produces fasciculations in 30-45 seconds and intubation conditions in 45-60 seconds; rocuronium at 1.2 mg/kg achieves conditions in 60-90 seconds.
- 7Intubate once jaw relaxation and vocal cord opening are confirmed. Confirm tube placement by: visualising tube passing cords, auscultation bilaterally and over epigastrium, waveform capnography (gold standard), and CXR. Secure tube and note depth at lips.
ETT size = (age/4)+4 = 3.5 mm uncuffed; depth at lips = weight/2 + 6 = 10 cm
In infants under 10 kg, succinylcholine dose is 2 mg/kg. Atropine minimum 0.1 mg applies as calculated dose (0.16 mg) is above the minimum. Use an uncuffed tube and confirm depth carefully in this age group.
Rocuronium preferred due to ICP concerns about succinylcholine-induced fasciculations raising ICP; can reverse with sugammadex 16 mg/kg if intubation fails
In head-injured patients, succinylcholine is used with caution due to transient intragastric and intracranial pressure elevation. Rocuronium at 1.2 mg/kg provides similar intubation conditions and is reversible with sugammadex.
Succinylcholine is CONTRAINDICATED in hyperkalaemia — causes further acute K+ release, risking cardiac arrest
Succinylcholine causes transient hyperkalaemia of approximately 0.5 mmol/L in normal patients and can precipitate fatal cardiac arrest in those with pre-existing hyperkalaemia, rhabdomyolysis, crush injury, or denervation.
Push-dose epinephrine (10 mcg/kg) at bedside before intubation; ketamine chosen for vasopressor effect
Ketamine is the ideal induction agent in haemodynamic compromise because it stimulates catecholamine release, supporting blood pressure. It should be used at lower dose (1 mg/kg) in profound shock to avoid catecholamine depletion causing hypotension.
Paediatric emergency department: RSI for respiratory failure from bronchiolitis, croup, anaphylaxis, or airway foreign body., where accurate rsi pediatric dose analysis through the Rsi Pediatric Dose supports evidence-based decision-making and quantitative rigor in professional workflows
PICU: RSI for mechanical ventilation initiation in septic shock, ARDS, or severe metabolic encephalopathy., where accurate rsi pediatric dose analysis through the Rsi Pediatric Dose supports evidence-based decision-making and quantitative rigor in professional workflows
Trauma: RSI for airway control in head-injured children with GCS ≤8 or impending airway compromise., where accurate rsi pediatric dose analysis through the Rsi Pediatric Dose supports evidence-based decision-making and quantitative rigor in professional workflows
Transport medicine: critical care transport teams using RSI to secure the airway of an unstable child before inter-hospital transfer., where accurate rsi pediatric dose analysis through the Rsi Pediatric Dose supports evidence-based decision-making and quantitative rigor in professional workflows
Simulation training: paediatric RSI scenarios are a core component of APLS and PALS simulation programmes, rehearsing drug calculation and airway management under pressure.
Anticipated Difficult Airway
If the airway is anticipated to be difficult (syndromic child, micrognathia, trismus, trauma), do not use succinylcholine as the sole paralytic without a failed intubation plan. Prefer rocuronium 1.2 mg/kg with sugammadex available at the bedside for immediate reversal (16 mg/kg). Have a surgical airway kit (needle cricothyrotomy) immediately accessible.
Neuromuscular Disease
Children with Duchenne muscular dystrophy, spinal muscular atrophy, or other myopathies should never receive succinylcholine. Succinylcholine can trigger acute life-threatening hyperkalaemia and rhabdomyolysis in these patients. Rocuronium is the paralytic of choice. Also avoid potent volatile anaesthetic agents due to malignant hyperthermia risk in some myopathies.
Head Injury and Raised ICP
In children with head injury and suspected raised intracranial pressure, succinylcholine-induced fasciculations may transiently raise ICP. Rocuronium 1.2 mg/kg is therefore often preferred. Lidocaine 1.5 mg/kg pre-treatment to blunt the laryngoscopy-associated ICP spike has been used historically but has limited evidence. Ketamine's effect on ICP is no longer considered a major contraindication.
Neonatal Emergency Intubation
Neonatal RSI uses the same principles but with different dose considerations. Atropine (0.02 mg/kg, min 0.1 mg) is universally recommended. Morphine or fentanyl pretreatment (2-4 mcg/kg) is used for elective intubations. Succinylcholine is rarely used in neonates; atracurium or vecuronium are alternatives. ETT sizes: 2.5 mm for <1 kg, 3.0 mm for 1-2 kg, 3.5 mm for 2-3.5 kg.
| Drug | Dose | Route | Onset | Special Notes |
|---|---|---|---|---|
| Atropine | 0.02 mg/kg (min 0.1 mg, max 0.6 mg) | IV | 1-2 min | Give before succinylcholine in infants |
| Ketamine | 1-2 mg/kg | IV | 30-60 sec | Preferred in haemodynamic instability |
| Succinylcholine | 2 mg/kg (<10 kg) / 1.5 mg/kg (≥10 kg) | IV | 45-60 sec | Contraindicated in hyperkalaemia/myopathies |
| Rocuronium | 1.2 mg/kg | IV | 60-90 sec | Reversible with sugammadex 16 mg/kg |
| Sugammadex (reversal) | 16 mg/kg (immediate reversal) | IV | 3 min | Reverses rocuronium only, not succinylcholine |
| Thiopental | 3-5 mg/kg | IV | 20-30 sec | For raised ICP; causes hypotension — avoid in shock |
Why is the succinylcholine dose higher in infants than older children?
Infants have a larger volume of distribution relative to adults and older children because their extracellular fluid volume (where succinylcholine distributes) is proportionally much larger. As a result, a higher mg/kg dose is required to achieve the same plasma concentration. The recommended dose is 2 mg/kg for infants/children under 10 kg and 1.5 mg/kg for those over 10 kg.
When is succinylcholine contraindicated in children?
Contraindications include: hyperkalaemia (K+ >5.5 mmol/L or risk of acute elevation); personal or family history of malignant hyperthermia; myopathies (especially Duchenne muscular dystrophy — risk of fatal rhabdomyolysis and hyperkalaemia); denervation injuries; burns more than 24-48 hours old; and spinal cord injury with paralysis. In these cases, rocuronium 1.2 mg/kg is the alternative.
Why is atropine used before intubation in infants?
Infants and young children are prone to profound vagally mediated bradycardia during laryngoscopy and succinylcholine administration. The immature conduction system is more dependent on rate for cardiac output. Atropine pre-treatment (0.02 mg/kg, min 0.1 mg) attenuates this response. It is recommended in all infants under 1 year and in older children receiving succinylcholine by many guidelines.
Can sugammadex reverse succinylcholine?
No. Sugammadex only reverses rocuronium and vecuronium (non-depolarising agents) by encapsulating the drug molecule. Succinylcholine is a depolarising agent that is reversed by plasma cholinesterase metabolism — there is no pharmacological reversal agent. This is one reason to prefer rocuronium in anticipated difficult airway situations, where sugammadex reversal may be life-saving.
What is the ETT size formula for children?
For cuffed ETTs (now preferred even in older children): ETT internal diameter (mm) = (age in years / 4) + 3.5. For uncuffed ETTs: (age / 4) + 4. For neonates: use 3.0-3.5 mm. Confirm depth at lips: for oral intubation approximately 3 × ETT diameter in mm (e.g., 4.5 mm tube = 13.5 cm at lips) or weight/2 + 6 cm in infants.
What is the role of ketamine in paediatric RSI?
Ketamine is the most commonly used induction agent in paediatric RSI for several reasons: it preserves airway reflexes partially and maintains respiratory drive better than other agents at standard doses; it provides analgesia; and its sympathomimetic properties support blood pressure in haemodynamically compromised children. Concerns about intracranial pressure elevation with ketamine have been largely refuted in recent literature.
What is the minimum atropine dose and why?
The minimum atropine dose is 0.1 mg. This is because paradoxical bradycardia can occur with very low doses of atropine due to a central vagomimetic effect. Using less than 0.1 mg may worsen bradycardia rather than prevent it. The maximum dose is 0.6 mg regardless of weight. This is particularly important in the context of rsi pediatric dose calculations, where accuracy directly impacts decision-making. Professionals across multiple industries rely on precise rsi pediatric dose computations to validate assumptions, optimize processes, and ensure compliance with applicable standards. Understanding the underlying methodology helps users interpret results correctly and identify when additional analysis may be warranted.
How do I confirm ETT placement in children?
The gold standard is continuous waveform capnography (CO2 detection). Additional confirmation includes: bilateral equal breath sounds on auscultation, absence of sounds over the epigastrium, visible chest rise bilaterally, condensation in the tube, and stable or improving SpO2. Chest X-ray confirms final tube position and depth. Oesophageal intubation must be excluded immediately.
专业提示
Before any paediatric RSI, use the SOAPME mnemonic: Suction (size-appropriate, on and working), Oxygen (pre-oxygenation in progress), Airway equipment (ETT sizes × 3, laryngoscope, stylet, bag-mask), Pharmacy (drugs drawn up and labelled), Monitors (SpO2, ECG, ETCO2), and Equipment (backup airway — LMA, surgical airway kit). Never proceed without SOAPME complete.
你知道吗？
Succinylcholine (suxamethonium) was first synthesised in 1906 but its neuromuscular blocking properties were not discovered until 1949 by Daniel Bovet, who won the 1957 Nobel Prize in Physiology or Medicine partly for this work. The drug's unique depolarising mechanism — mimicking acetylcholine to cause simultaneous activation and fatigue of all neuromuscular junctions — means it remains unmatched in speed of onset among clinically used neuromuscular blockers, nearly 80 years after its introduction into anaesthesia.
参考资料
- ›Advanced Paediatric Life Support (APLS) 6th Edition — ALSG
- ›PALS Provider Manual 2020 — American Heart Association
- ›Kerrey BT et al. Rapid sequence intubation for pediatric emergency patients: higher frequency of failed attempts and adverse effects found by video review. Ann Emerg Med 2012.
- ›Zelicof-Paul A et al. Controversies in rapid sequence intubation in children. Curr Opin Pediatr 2005.