What are the anaesthetic considerations in paediatric anaesthesia?

Anaesthetic Considerations in Paediatric Anaesthesia

Induction Techniques

Inhalational induction with sevoflurane is the preferred method for most paediatric patients, as children typically resist intravenous access when awake and mask induction avoids the distress of needle insertion. 1, 2, 3

• Sevoflurane has replaced halothane as the gold standard induction agent due to its non-pungent odor, rapid onset, lack of airway irritation, and superior cardiovascular safety profile compared to halothane 1, 4, 2
• Sevoflurane allows rapid and smooth induction with better patient acceptability than halothane, though it requires higher maintenance concentrations in pediatric patients 1, 2
• Intravenous induction with propofol (1-2 mg/kg) or ketamine (1-2 mg/kg) is appropriate when venous access is already established or in older cooperative children 1
• Ketamine maintains systemic vascular resistance and provides analgesia, making it particularly useful in hemodynamically unstable patients 1

Critical Pitfall in Down Syndrome Patients

• Episodes of severe bradycardia and cardiac arrest have been reported during sevoflurane induction in pediatric patients with Down syndrome, unrelated to congenital heart disease 4
• Incrementally increase inspired sevoflurane concentration rather than using high initial concentrations 4
• Have anticholinergic agents and epinephrine immediately available, and closely monitor heart rate throughout induction 4

Airway Management Strategy

The choice between facemask, laryngeal mask airway (LMA), and endotracheal intubation depends on aspiration risk, surgical requirements, and presence of upper respiratory infection. 5

• Sevoflurane provides faster time to LMA insertion than halothane, with similar conditions for tracheal intubation 2
• In children with upper respiratory infections (URI), facemask ventilation is associated with fewer perioperative respiratory adverse events than supraglottic airways or endotracheal tubes 5
• When facemask is not feasible in URI patients, no clear superiority exists between LMA and endotracheal intubation for preventing severe respiratory complications 5
• Administer inhaled salbutamol 30 minutes before induction in children under 6 years with URI, as this reduces perioperative cough and bronchospasm by approximately 50% 5

Neuromuscular Blockade and Reversal

• Non-depolarizing agents (rocuronium, vecuronium, cisatracurium) are preferred for intubation and muscle relaxation 1
• Succinylcholine should be avoided in patients with myopathies due to risk of hyperkalemia 1, 4
• Ensure complete reversal with train-of-four ratio ≥0.9 before extubation to prevent residual neuromuscular blockade 1
• Sugammadex shortens time to achieve TOF 0.9 compared to neostigmine, though anaphylaxis risk is not negligible 5

Perioperative Hyperkalemia Risk

• Inhaled anesthetic agents combined with succinylcholine have caused rare but fatal hyperkalemic cardiac arrests in pediatric patients, particularly those with latent neuromuscular disease including Duchenne muscular dystrophy 4
• These patients exhibit elevated creatine kinase and myoglobinuria without typical malignant hyperthermia signs 4
• Early aggressive treatment of hyperkalemia and resistant arrhythmias is mandatory, followed by evaluation for latent neuromuscular disease 4

Extubation Considerations

No evidence definitively supports either deep extubation or awake extubation as safer in uncomplicated pediatric cases without aspiration risk. 5

Deep Extubation Criteria

• Effective spontaneous breathing (tidal volume ≥5 mL/kg, age-appropriate respiratory rate) 5
• Small central pupils on eye examination 5
• Maintain at least 1 MAC of volatile agent during extubation, then discontinue 5
• Risk: postoperative apnea (mainly obstructive) 5

Awake Extubation Criteria

• Age-appropriate tidal volume (5-8 mL/kg) and respiratory rate (12-25 breaths/min) 5
• Grimacing, cough with open mouth, or eye opening 5
• Full decurarisation with purposeful movements 5
• SpO₂ ≥95% with FiO₂ ≤50% 5
• Risk: increased cough, agitation, postoperative sore throat, and potential surgical site bleeding 5

Sedation for Procedures

For procedures like flexible bronchoscopy, conscious sedation preserving spontaneous ventilation is preferred to assess dynamic airway compression and vocal cord movement. 5

Conscious Sedation Protocol

• No single agent provides adequate anxiolysis, analgesia, and amnesia; drug combinations are necessary 5
• Midazolam 75-300 mcg/kg IV for anxiolysis/amnesia (onset 1-5 min, duration 90 min, reversible with flumazenil 0.01 mg/kg) 5
• Meperidine for analgesia (onset 5 min, duration 180-240 min, reversible with naloxone 0.01 mg/kg) 5
• Drug combinations increase likelihood of adverse outcomes; administer in small incremental doses until desired effect observed 5
• Nitrous oxide 50% in oxygen via facemask provides anxiolysis and analgesia 5

General Anaesthesia for Procedures

• Propofol, ketamine, sufentanil, or remifentanil intravenously, or sevoflurane by inhalation, alone or in combination 5
• Propofol: intermittent bolus 0.5-1 mg/kg or continuous infusion 100 mcg/kg/min 5
• Remifentanil: IV 0.1-0.25 mcg/kg (onset 2-5 min, duration 2-3 min) or continuous infusion 0.05 mcg/kg/min 5

Topical Anaesthesia

• Lidocaine 2-5% applied to nose and larynx, 0.5-1% below larynx 5
• Total dose must not exceed 5-7 mg/kg 5
• Examine larynx before applying topical anaesthetic, as it can falsely create appearances of laryngomalacia (arytenoid collapse, epiglottal folding) 5
• Insufficient topical anaesthesia causes pain, cough, laryngospasm, or bronchospasm from vagal stimulation 5

Oxygen Supplementation

• Mandatory in young infants and children, especially those with poor respiratory status 5
• Deliver via nasopharyngeal prong through one nostril with bronchoscope in the other, or facemask over nose and mouth 5
• Oxygen supplementation delays detection of reduced ventilation; monitor closely with capnography where appropriate 5

Monitoring and Safety Standards

Children undergoing sedation for procedures must receive the same standard of care as those undergoing general anaesthesia. 5

• Continuous monitoring including pulse oximetry throughout procedure and recovery 6
• Minimum of one qualified nurse trained in techniques and dedicated solely to patient care during entire procedure 6
• All resuscitation equipment must be immediately available and regularly reviewed 6
• Patient remains in recovery until cardiovascular and respiratory stability assured and patient awake and oriented 5
• After topical anaesthetic to airway, laryngeal reflexes may be depressed for up to one hour; children should not drink during this period due to aspiration risk 5

High-Risk Factors for Adverse Events

• Weight <10 kg 5
• Upper airway pathology 5
• Persistent radiographic changes 5
• Oxygen dependency 5
• Younger infants experience more frequent oxygen desaturation 5

Most Common Complications

• Respiratory depression is the most concerning adverse effect of sedation 5
• Partial or total airway obstruction by equipment and depression of respiratory drive are most frequent causes of desaturation 5
• Most life-threatening adverse events involve drug overdose, inadequate monitoring, or inappropriate sedation 5
• Falls in oxygen saturation are common particularly when equipment is in mid-trachea, even with oxygen supplementation 5

Multimodal Analgesia

Combine non-opioid analgesics (NSAIDs, paracetamol, metamizole where available) to reduce opioid requirements and associated respiratory depression. 5

Basic Analgesic Regimen

• Rectal or intravenous NSAIDs and/or paracetamol during entire postoperative period 5
• Intravenous fentanyl in PACU for breakthrough pain 5
• Oral/rectal/intravenous tramadol or morphine as rescue with adequate monitoring (pulse oximetry) 5

Regional Anaesthesia Adjuncts

• Ultrasound guidance should be used for all abdominal wall blocks; landmark-based techniques should not be performed without ultrasound 5
• Add clonidine as adjunct to long-acting local anaesthetics in peripheral blocks 5
• Consider intraoperative ketamine as co-analgesic drug 5
• Methylprednisolone or dexamethasone reduces postoperative swelling 5

Neurotoxicity Concerns

Published animal studies show anesthetic and sedation drugs blocking NMDA receptors and/or potentiating GABA activity increase neuronal apoptosis in developing brain when used >3 hours, with potential long-term cognitive deficits. 4

• Window of vulnerability correlates with third trimester gestation through first several months of life, possibly extending to approximately 3 years of age 4
• Some pediatric studies suggest repeated or prolonged exposures may cause adverse cognitive or behavioral effects, though studies have substantial limitations 4
• No specific medications have been shown safer than others; decisions regarding elective procedures should weigh benefits against potential risks 4
• Anesthetic and sedation drugs are necessary for children needing surgery or procedures that cannot be delayed 4

Environmental Considerations

• Sevoflurane is preferred over desflurane or isoflurane due to lower environmental impact 1
• Minimize nitrous oxide use due to environmental concerns and increased postoperative nausea/vomiting 1
• Employ low fresh gas flow techniques when using inhaled anesthetics 1

Postoperative Recovery

• Performance of activities requiring mental alertness (driving, operating machinery) may be impaired after sevoflurane anaesthesia 4
• Rapid emergence from sevoflurane lessens time under anaesthesia but may result in more intense and earlier postoperative pain than gradual emergence 2
• Sevoflurane may cause less postoperative nausea and vomiting than halothane 2
• Pattern and incidence of emergence agitation/excitement is similar between sevoflurane and halothane, though this remains an area requiring clarification 2, 3