Anaesthetic Considerations in Tonsillectomy Surgery

1. Preoperative Assessment

Indications (relevant to anaesthetic planning)

• Recurrent tonsillitis (Paradise criteria: ≥7 episodes/year or ≥5 for 2 years)
• Obstructive sleep apnoea (OSA) / sleep-disordered breathing - the most common indication in paediatric practice
• Peritonsillar abscess (quinsy tonsillectomy)

Key Preoperative Questions

Premedication

• Anxiolytics (e.g. midazolam) may be useful in anxious children but should be avoided or used with extreme caution in severe OSA patients due to respiratory depression risk.
• Preoperative analgesia: paracetamol 20 mg/kg orally at premedication reduces subsequent requirement.

2. Airway Management - Central Challenge

Choice of Airway Device

• Oral preformed (oral RAE) or reinforced/armoured tube preferred - lies in midline and reduces risk of kinking when the gag is placed
• Tube must be secured centrally in the midline - the gag can laterally displace it
• Cuffed ETT in children is increasingly preferred to allow a sealed airway against blood and secretions
• Provides definitive airway protection from blood and secretions

• Reinforced/flexible LMA is used by many anaesthetists and is an accepted option
• A 2024 systematic review and meta-analysis (Khoury et al., 2024, PMID 38899617) examined the safety of LMA in adenotonsillectomy and found it to be a viable alternative in carefully selected patients
• Advantages: avoids muscle relaxants, less post-operative sore throat, smoother emergence
• Disadvantages: less protection against aspiration of blood, may be displaced by surgical gag
• Contraindicated if there is active bleeding, difficult airway anticipated, or full stomach

Inhalational Induction

• Sevoflurane in oxygen is standard for paediatric induction without IV access
• Note: inhalational induction can be challenging when large adenoids obstruct the nasopharynx - the anaesthetist must apply CPAP and manage obstruction actively
• Once unconscious, establish IV access

Intravenous Induction

• Propofol 1.5-2.5 mg/kg or thiopentone 2-7 mg/kg (where available)
• Total intravenous anaesthesia (TIVA) with propofol + remifentanil is widely used - propofol provides antiemetic benefit and rapid wake-up; remifentanil allows dose titration around surgical stimulation - Scott-Brown's ORL HNS, Vol 2
• TIVA leads to faster wake-up and reduced PONV compared with volatile agents
• A 2024 SAMBA position statement notes that IV induction may reduce perioperative respiratory adverse events (PRAEs) such as laryngospasm and desaturation compared with inhalational induction in high-risk children (those with URI or OSA)

Muscle Relaxants

• Short-acting agents preferred given short procedure duration
• Suxamethonium 0.5-2 mg/kg - depolarising, rapid onset/offset, useful for rapid sequence or failed intubation
• Mivacurium 0.1-0.2 mg/kg - short-acting non-depolarising agent, allows spontaneous ventilation recovery
• Avoiding muscle relaxants altogether by deep inhalational induction is also practiced - speeds up reversal and avoids residual neuromuscular blockade

Ventilation Strategy

• Spontaneous ventilation or controlled ventilation both used - depends on technique
• Controlled ventilation with muscle relaxation gives a still surgical field

3. Positioning

• Patient supine with neck extended (shoulder roll placed) to open the oropharynx for surgical access
• The operating table is typically turned 90° or 180° away from the anaesthetist after induction - all connections (ETT, IV, monitoring) must be secured and extended before the table is turned
• ETT must be re-checked after gag insertion

4. Intraoperative Management

Monitoring

• Standard: SpO2, ETCO2, ECG, NIBP, temperature (paediatric)
• Ensure ongoing vigilance for tube displacement when the surgeon applies the Boyle-Davis gag

FiO2 Considerations

• If diathermy or laser is used on the tonsil bed, FiO2 should be reduced (target <30% if tolerated) to minimise airway fire risk
• Nitrous oxide is contraindicated if laser is in use (supports combustion)
• Avoid flammable material near the airway during electrocautery

Airway Fire Protocol (if applicable)

1. Stop ventilation - remove tracheal tube immediately
2. Disconnect circuit - turn off O2
3. Submerge tube in water
4. Ventilate with face mask and reintubate
5. Assess airway damage with bronchoscopy, serial CXR, ABG
6. Consider bronchial lavage and steroids - Morgan & Mikhail's Clinical Anesthesiology, 7e

Throat Pack

• A pharyngeal pack (throat pack) may be placed by the surgeon to absorb blood and prevent soiling of the larynx and trachea
• This is a significant risk item - the pack MUST be documented and removed before extubation; failure to do so has caused deaths
• A tail should be visible outside the mouth; a dedicated checklist/count system is used in most units

Blood Loss

• Usually modest but can be significant, especially in quinsy cases or with diathermy techniques
• Topical vasoconstriction (adrenaline-soaked swabs) used by surgeon reduces blood loss

5. Extubation and Emergence

Timing of Extubation

• Surgeon must confirm complete haemostasis before the anaesthetist proceeds to emergence
• Two main strategies practiced:

• Removal of airway device while still deeply anaesthetised (level 3 plane)
• Advantages: smooth, minimal coughing and straining - reduces risk of haemorrhage from increased venous pressure
• Disadvantages: patient may obstruct airway post-extubation before protective reflexes return; requires skilled recovery staff
• Prefer lateral ("tonsil") position after deep extubation

• Removal once airway reflexes fully returned
• Advantages: safer in terms of airway protection
• Disadvantages: coughing/straining may increase bleeding risk
• Standard recommendation is awake extubation in most guidelines, particularly if there is any concern about a difficult airway or full stomach

Recovery Position

• Lateral ("tonsil") position - patient placed on their side with head down slightly
• Allows blood and secretions to drain out of the mouth rather than into the airway
• Standard recovery position after tonsillectomy

Laryngospasm

• Increased incidence after tonsillectomy, particularly in children with URI or OSA
• Blood and secretions in the pharynx are a potent trigger
• Prevention: meticulous suctioning of oropharynx under direct vision before extubation; smooth emergence; adequate depth before stimulation
• Treatment: positive pressure oxygen via mask, jaw thrust; if persistent - IV suxamethonium 0.1-0.2 mg/kg ("laryngospasm notch" pressure); escalate to full-dose suxamethonium and reintubation if needed

6. Analgesia

7. Antiemesis (PONV Prophylaxis)

• Dexamethasone 0.1 mg/kg IV at induction - most effective single agent
• Ondansetron 0.1 mg/kg IV - 5-HT3 antagonist, second-line
• Propofol TIVA has antiemetic properties and reduces baseline PONV risk vs. volatile agents
• Avoid opioids where possible (potent PONV trigger)
• Combined multimodal antiemesis is standard in high-risk cases (paediatric, OSA, history of PONV)

8. OSA and Special Populations

• Increased sensitivity to opioids and sedatives - respiratory depression risk
• Higher incidence of post-operative respiratory events (desaturation, apnoea, laryngospasm)
• Overnight admission indicated for: age <3 years, severe OSA on PSG (AHI >10 or SpO2 nadir <80%), obesity, cardiac complications of OSA, craniofacial abnormalities, ASA III or above
• Post-operative oxygen supplementation and SpO2 monitoring overnight
• Continuous pulse oximetry in recovery; consider HDU
• Avoid midazolam premedication; avoid long-acting opioids
• Obesity reduces the effectiveness of adenotonsillectomy for OSA

9. Post-Tonsillectomy Haemorrhage - Anaesthetic Emergency

Classification

• Primary haemorrhage: within 24 hours of surgery - usually from vessels in the tonsil bed
• Secondary haemorrhage: 24 hours to 14 days post-op - usually from premature separation of the eschar; associated with infection (Streptococcus)

Anaesthetic Challenges

1. Aspiration risk - stomach contains swallowed blood (full stomach protocol essential)
2. Hypovolaemia / anaemia - blood loss may be underestimated (much swallowed)
3. Difficult airway - active bleeding, oedema, and clots obscure the view
4. Cardiovascular instability
5. Anxious/uncooperative patient - often in significant distress

Management

• Resuscitation first - IV access × 2; crystalloid bolus 20 mL/kg; group and crossmatch; FBC, coag
• Rapid sequence induction (RSI) is standard - full stomach precautions
  • Preoxygenate thoroughly
  • Cricoid pressure
  • IV induction: ketamine (haemodynamically stable, maintains airway tone) or modified RSI with propofol if haemodynamically stable
  • Suxamethonium for rapid sequence intubation
• Have suction immediately available and switched on before induction - the pharynx must be cleared of blood and clot
• Senior/experienced anaesthetist should lead - this is a case for the most experienced person available
• Surgical haemostasis cannot proceed until the airway is secured

10. Day-Case Tonsillectomy

• Evidence supports same-day discharge for low-risk patients (no severe OSA, no coagulopathy, no young age <3)
• Main reasons for overnight admission: bleeding risk, pain, PONV, and OSA
• Adenotonsillectomy for mild OSA in children has been demonstrated safe as day-case in tertiary units - Scott-Brown's ORL HNS, Vol 2

Summary of Key Anaesthetic Points

• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Vol 2 - Anaesthesia and analgesia / Peri-operative management sections
• Morgan & Mikhail's Clinical Anesthesiology, 7e - Chapter 37: Anaesthesia for Otolaryngology
• Bailey and Love's Short Practice of Surgery, 28e - Tonsillectomy
• Khoury et al. (2024) - LMA safety in adenotonsillectomy meta-analysis (PMID 38899617)
• SAMBA 2024 Position Statement: Care of the Paediatric Patient for Ambulatory Tonsillectomy