Difficulty: Intermediate | Prerequisites: Parts 1 and 2 (nerve preservation, middle ear procedures, N₂O), basic paediatric anaesthesia principles
Tags: myringotomy, grommet insertion, tympanostomy tubes, tonsillectomy, adenoidectomy, paediatric anesthesia, OSA, obstructive sleep apnea, airway obstruction, sevoflurane, CRNA, nurse anesthesia, recurrent otitis media, URI
Myringotomy with tube insertion and tonsillectomy/adenoidectomy are among the most common paediatric surgical procedures. Both present anaesthetic challenges that are distinct from adult ENT surgery. Myringotomy is ultra-short, often performed without IV access, and is the one middle ear procedure where N₂O is safe to use. Tonsillectomy and adenoidectomy, by contrast, carry significant airway obstruction risk, and patients with severe obstructive sleep apnoea may need awake intubation before induction. Understanding when the "normal rules" (such as avoiding N₂O in middle ear surgery) do and do not apply is exactly the kind of reasoning these exams test.
Myringotomy is short, low-risk and uses mask induction with sevoflurane, O₂ and N₂O. N₂O is safe here because the tube vents pressure, so no closed space develops. Tonsillectomy/adenoidectomy patients have a higher incidence of airway obstruction; severe adult OSA may require awake intubation. Smooth emergence matters in both, but for different reasons: preventing bleeding and avoiding airway compromise.
Myringotomy
A small incision in the tympanic membrane to relieve pressure or drain fluid from the middle ear. In simple terms, the surgeon cuts a tiny hole in the eardrum.
Tympanostomy tube (grommet)
A small tube inserted through the myringotomy incision to keep the opening patent and allow ongoing pressure equalisation and drainage. Think of it as a tiny ventilation pipe through the eardrum.
Chronic serous otitis media
Persistent fluid in the middle ear space without acute infection. The main indication for grommet insertion in children.
Recurrent otitis media
Defined as three or more acute middle ear infections in six months, or four or more episodes in one year. A common paediatric disorder and a frequent indication for myringotomy with tubes.
URI (upper respiratory infection)
Children with chronic otitis frequently have accompanying recurrent URIs with brief intervals between episodes. This creates a scheduling dilemma for surgery.
OSA (obstructive sleep apnoea)
A condition in which the upper airway repeatedly collapses during sleep. Relevant here because patients presenting for tonsillectomy/adenoidectomy often have hypertrophied tissues causing chronic obstruction, and severe adult OSA may require awake intubation before induction of general anaesthesia.
Sevoflurane
A volatile anaesthetic agent commonly used for mask induction in paediatric cases. It has a relatively pleasant smell, low blood-gas solubility (allowing rapid induction and emergence), and minimal airway irritation.
Tube leak test
A test to assess whether post-extubation airway oedema may cause obstruction. The lumen of the ETT is occluded for one or two breaths during inspiration and expiration while listening for air movement around the tube. If no air escapes around the ETT, significant oedema is suspected and postoperative sedation and ventilation may be considered.
Racemic epinephrine
An inhaled medication used to treat post-extubation stridor and airway oedema. One of the supportive measures available for postoperative airway complications alongside bronchodilators and steroids.
Simple tubes with a lumen (grommets) are placed through the tympanic membrane to equalise pressure in the middle ear. The usual indications are chronic serous otitis media and recurrent otitis media.
Chronic otitis media manifests as fluid in the middle ear.
Recurrent otitis media is defined as three or more acute infections in six months, or four or more episodes in one year.
Untreated otitis media may lead to permanent middle ear damage and hearing loss.
Children with chronic otitis frequently have accompanying recurrent URIs with brief intervals between them, and are often on antibiotics. Scheduling surgery in an infection-free window is often impractical. The key clinical point: because eradicating the middle ear fluid frequently resolves the URI, surgery should not be delayed to wait for an infection-free window.
Most patients are young and healthy. The procedure is very short, so sedative premedications may outlast the procedure and are usually not necessary.
Induction: Mask induction with sevoflurane, oxygen and N₂O.
Maintenance: Oxygen, N₂O and a volatile agent such as sevoflurane.
IV access is usually not necessary unless another procedure is being performed at the same time. If established, it is typically placed after mask induction.
Intubation is performed only if airway difficulties are anticipated or encountered, but airway equipment is always prepared and available.
The patient's head must be held still, particularly when the myringotomy knife is in use. The procedure carries little risk of bleeding.
This is the high-yield exception to the "avoid N₂O in middle ear surgery" rule. In myringotomy, the effects of N₂O on middle ear pressure are not relevant for two reasons:
The procedure is short.
A tube is placed through the tympanic membrane to relieve pressure, so no closed pressurised space develops.
N₂O is continued until completion of the surgery.
For bilateral procedures:
The inhalation (volatile) anaesthetic is discontinued during the second myringotomy to facilitate prompt emergence.
N₂O is continued until the surgery is complete.
The patient is supine with the head turned to expose the ear to the microscope. An ear speculum is inserted, cerumen is removed, and an incision is made in the tympanic membrane. Fluid may be suctioned from the middle ear. A tympanostomy tube is inserted through the incision, straddling the tympanic membrane. Antibiotic and steroid eardrops are instilled. Pain medications are given rectally, orally, intranasally or intravenously. The surgeon then moves to the other side, repositions the microscope, turns the head, and repeats the procedure.
Patients undergoing tonsillectomy and/or adenoidectomy have a higher incidence of airway obstruction because of hypertrophied tissues. Chronic obstruction and infection can produce systemic involvement with additional cardiac and respiratory anomalies.
The clinician must choose wisely among:
Routine IV induction
Inhalation induction
Awake intubation
Fibreoptic-assisted intubation
Adult patients with severe OSA may require awake intubation before induction of general anaesthesia. This is a safety-first decision: losing the airway in a patient with severe tonsillar hypertrophy can be very difficult to recover from.
Several techniques exist, including coblation, cold steel, snare, monopolar cautery and hot knife. They differ in operative times, intraoperative blood loss, postoperative pain scores, and time to resumption of oral intake. The anaesthetic considerations are broadly similar across techniques.
Induction is most commonly by mask with sevoflurane, oxygen and N₂O, depending on the child's age and IV access.
Some institutions allow parental presence in the operating room during induction to prevent separation anxiety.
Both LMA and ETT (endotracheal tube) may be used, depending on the experience of the operating team.
When checking for an airway/tube leak, the lumen of the ETT is occluded for one or two breaths during inspiration and expiration while listening for air movement around the tube. If no air escapes around the ETT, postoperative sedation and ventilation might be considered.
Postoperative care includes:
Close observation and humidified oxygen during recovery
Supportive measures for complications: racemic epinephrine, bronchodilators, and steroids
The myringotomy anaesthetic is one of the shortest general anaesthetics in all of surgery. In practice, the entire case may last five to ten minutes per side. The anaesthetist often has no IV line, no intubation and no muscle relaxant on board. Understanding why this is safe (short case, healthy child, minimal bleeding risk, pressure-venting tube negates N₂O concerns) is the clinical reasoning that underpins the exam answers.
For tonsillectomy, the real-world stakes are higher. Post-tonsillectomy bleeding is a surgical emergency, and an obstructed airway in a child with massive tonsillar hypertrophy is one of the more stressful scenarios in paediatric anaesthesia. The decision tree for induction technique (IV vs. inhalation vs. awake intubation) is one that CRNAs face regularly.
The most common error is applying the "avoid N₂O" rule to myringotomy. Students who memorise "N₂O is bad for middle ear surgery" without understanding the mechanism will get this wrong. The rule exists because of pressure in a closed space. Myringotomy creates an open vent, so the rule does not apply.
Students sometimes think IV access is always required for any general anaesthetic. In paediatric myringotomy, IV access is usually not established unless another procedure is being performed simultaneously.
The URI scheduling dilemma trips students up. The instinct is to postpone surgery until the child is well, but the correct answer is that surgery should not be delayed, because clearing the middle ear fluid often resolves the URI itself.
Students may underestimate the airway risk in tonsillectomy patients. These patients have hypertrophied tissues by definition, and the chronic obstruction can produce systemic cardiac and respiratory effects that complicate anaesthesia further.
⚠️ "Why is N₂O acceptable during myringotomy but not during tympanoplasty?" is a frequently tested comparison question. The answer hinges on whether a closed pressurised space exists.
⚠️ The definition of recurrent otitis media (three or more infections in six months, or four or more in one year) is a testable number.
⚠️ The URI scheduling dilemma: surgery should not be delayed. This is counter-intuitive and therefore commonly examined.
⚠️ Awake intubation for severe adult OSA before tonsillectomy is a safety-critical decision that appears in scenario-based questions.
⚠️ The tube leak test procedure and its implications (no air leak suggests significant oedema, consider postoperative sedation and ventilation) is testable.
⚠️ Know the bilateral myringotomy sequence: discontinue volatile during the second ear, continue N₂O until the end.
True or false: IV access is always required for paediatric myringotomy.
Fill in the blank: Recurrent otitis media is defined as _____ or more acute infections in 6 months, or _____ or more episodes in 1 year.
True or false: Surgery for otitis media should be postponed if the child has a concurrent URI.
Fill in the blank: In bilateral myringotomy, the volatile anaesthetic is discontinued during the _____ ear to facilitate prompt emergence.
True or false: Adult patients with severe OSA presenting for tonsillectomy may require awake intubation before induction of general anaesthesia.
Answers: 1. False (usually not necessary unless another procedure is performed simultaneously). 2. Three; four. 3. False (surgery should not be delayed; eradicating the middle ear fluid frequently resolves the URI). 4. Second. 5. True.
Q: Why is N₂O acceptable during myringotomy but contraindicated during tympanoplasty?
A: In tympanoplasty, the middle ear becomes a closed space once the graft is placed, and N₂O builds positive pressure that can displace the graft, followed by negative pressure on washout that can dislodge it. In myringotomy, a tube is placed through the tympanic membrane that vents any pressure, so no closed pressurised space develops. The procedure is also short, limiting N₂O exposure time.
Q: Describe the typical anaesthetic technique for paediatric myringotomy.
A: Mask induction with sevoflurane, oxygen and N₂O. Maintenance with oxygen, N₂O and sevoflurane. IV access is usually not established unless another procedure is planned. Intubation is performed only if airway difficulties are anticipated or encountered. No sedative premedication (the procedure is too short). For bilateral cases, the volatile agent is discontinued during the second ear while N₂O continues until completion.
Q: A child with chronic otitis media is scheduled for myringotomy with grommets but currently has a URI. Should surgery be postponed?
A: No. Children with chronic otitis frequently have recurrent URIs with brief intervals between them, making an infection-free window impractical. Eradicating the middle ear fluid often resolves the URI, so surgery should not be delayed.
Q: What induction options should be considered for a tonsillectomy patient with suspected airway obstruction?
A: The clinician should choose among routine IV induction, inhalation induction, awake intubation, or fibreoptic-assisted intubation. Adult patients with severe OSA may require awake intubation before induction of general anaesthesia. The choice depends on the degree of obstruction and the clinical assessment of whether the airway can be maintained after induction.
Q: Describe the tube leak test and explain what a negative result (no air leak) suggests.
A: The lumen of the ETT is occluded for one or two breaths during inspiration and expiration while listening for air movement around the tube. If no air escapes around the ETT, this suggests significant airway oedema. Postoperative sedation and ventilation might be considered. Close observation, humidified oxygen, and availability of racemic epinephrine, bronchodilators, and steroids are recommended.
This material connects back to the N₂O and middle ear pressure content in Part 2, where the mechanism of N₂O in closed air spaces is explained in detail. The myringotomy exception only makes sense once you understand the underlying physics. The paediatric airway management content in tonsillectomy connects to broader topics in paediatric anaesthesia, including mask induction techniques, OSA assessment and management, and post-extubation stridor. The URI scheduling dilemma links to preoperative assessment principles and the question of when to proceed vs. postpone surgery in paediatric patients.
myringotomy, tympanostomy tube, grommet insertion, tympanic membrane, otitis media, chronic serous otitis media, recurrent otitis media, URI, upper respiratory infection, tonsillectomy, adenoidectomy, T&A, paediatric anesthesia, pediatric anesthesia, airway obstruction, OSA, obstructive sleep apnea, awake intubation, fibreoptic intubation, sevoflurane, mask induction, N₂O exception, bilateral myringotomy, tube leak test, racemic epinephrine, post-extubation stridor, humidified oxygen, bronchodilators, steroids, LMA, ETT, endotracheal tube, deep extubation, CRNA, nurse anesthetist, paediatric ENT, coblation tonsillectomy