Acute epiglottitis
Acute epiglottitis is an acute inflammatory condition of the epiglottis, arytenoids, and aryepiglottic folds, with gross swelling and oedema of the structures at the laryngeal inlet, resulting in an acute upper airway obstruction. The onset and progression of symptoms are rapid and can lead to complete upper airway occlusion, hypoxaemia, and death. Acute epiglottitis is a medical emergency and requires prompt recognition and management.
The anatomy of the paediatric airway is different to adults. The tongue and arytenoid structures are relatively large, and the infant nares are small. The larynx and epiglottis have a higher position in the infant which descends with age. The epiglottis shape is longer, softer, and omega-shaped and changes to a more adult configuration as the larynx descends. These differences mean any reduction in the calibre of the airway has a greater effect on airflow than in adults.
Acute epiglottitis is caused by infectious agents, including Haemophilus influenzae type B, group A Streptococcus pneumoniae, Haemophilus parainfluenzae, Staphylococcus aureus, and β-haemolytic streptococci. The principal agent was Haemophilus influenzae type B, but, since the introduction of the H. influenzae B (HiB) vaccine in 1992, the incidence of acute epiglottitis has fallen dramatically, and many trainees may never have seen a case.
1 Recognize the signs and symptoms of life-threatening airway pathology
2 Discuss appropriate preoperative interventions
3 Plan a safe induction technique for a child with upper airway compromise.
1C01; 2A01
A healthy 2-year-old boy has developed a cough, sore throat, and rhinorrhoea, with a low-grade temperature over the last 5 days. This morning, the child’s temperature was 37.4°C, and a barking cough with a loud inspiratory stridor was noticed. The parents were concerned with this new noise, and they presented with the child to the ED. The child is swallowing fluids and is able to lie down but has suprasternal retractions, nasal flaring, oxygen saturations of 93% on air, and a RR of 26 breaths/min.
A healthy 3-year-old girl was entirely well until the last 12 hours when she developed a high temperature of 38.9°C, and severe throat pain, and she is now unable to swallow. The parents have brought the child to the ED. She is distressed, sitting upright, with inspiratory and expiratory stridor. Oxygen saturations are 88% on air, and there is significant nasal flaring and suprasternal and intercostal retractions, with a RR of 38 breaths/min.
In children, acute epiglottitis typically occurs at age 2–5 years old. The main differential diagnosis is croup, which occurs in younger children aged 6 months to 3 years, has a more gradual onset over a number of days, and rarely appears toxic.
The 2-year-old boy has croup (laryngotracheobronchitis). Croup is an acute viral URTI, in which there is inflammation, with swelling and oedema in the larynx and trachea, reducing airflow and producing the characteristic barking cough. There is a gradual onset of symptoms with low-grade fever, sore throat, and URTI over a number of days preceding to a loud barking cough, hoarseness, and inspiratory stridor. Swallowing is normal with no drooling, and children are usually able to lie down. Treatment depends on the severity of the respiratory distress at presentation. Initial therapy in early cases involves humidification therapy to limit airway drying, steroids therapy to reduce inflammation, and nebulized adrenaline to reduce mucosal oedema quickly. Occasionally, children with croup can present with severe respiratory distress and need urgent intubation.
The 3-year-old girl has acute epiglottitis with its typical presentation of sudden onset in a previously well child. A sore throat, abrupt onset of fever, dysphagia, drooling, open mouth, muffled voice, inspiratory and expiratory stridor, and severe respiratory distress are characteristic. The child will often assume the tripod position, sitting upright with their hands outstretched and still, with the neck extended and head held forward in an attempt to improve the mechanical advantage of the respiratory muscles. These children are toxic, distressed, and anxious. Prompt diagnosis and urgent intervention is required.
An assessment of the severity of the respiratory distress guides the diagnosis and future management in children with upper airway obstruction. Inspiratory stridor is classically a sign of supraglottic upper airway obstruction, and expiratory stridor is a feature of intrathoracic airway obstruction. With severe upper airway obstruction, both inspiratory and expiratory stridor can be present. The presence of stridor is always a worrying sign, but its absence or reduction in volume may suggest the child is becoming tired and may soon be unable to maintain the airway.
The RR, body position, chest wall and abdominal movements, retractions with the use of accessory muscles, air entry, and cyanosis all indicate the severity of respiratory distress. The level of consciousness will be affected with a normal child becoming anxious, restless, and eventually lethargic with a depressed level of consciousness. With reduced air entry, hypoxaemia and cyanosis develop, with hypercarbia and resultant cardiovascular system compromise and tachycardia. With exhaustion, the RR can fall, and air entry diminishes dramatically.
Case 1 has mild/moderate respiratory distress, with retractions, nasal flaring, oxygen saturations of 93% on air, and a RR of 26 breaths/min. Simple humidification may be the only treatment required, with careful assessment of the respiratory distress and the addition of steroids and nebulized adrenaline
Case 2 describes a child with severe respiratory distress, sitting upright with inspiratory and expiratory stridor. Oxygen saturations are 88% on air, and there is significant nasal flaring and suprasternal and intercostal retractions, with a RR of 38 breaths/min. Immediate intervention is required.
The diagnosis is made on the history and examination, with the least possible disturbance of the child. Keep the child in whatever position she feels is most comfortable, with the examination working around this position. The child may prefer to stay in the parent’s arms. Very gentle examination without disturbing the child will provide information on the degree of respiratory distress, and a gently placed pulse oximeter will provide information on oxygen saturation readings. The child may tolerate a gently placed oxygen mask held near to the face by the parents; if this appears to be unsettling the child, it should be moved further away or removed.
Both the child and parents should be kept calm and an explanation of the proposed management given to the parents. Preparation for a difficult intubation and an emergency tracheostomy should be made.
In this example, indirect laryngoscopy, placement of IV lines, oropharyngeal examination, IM injections, and lateral neck radiographs should not be undertaken, because further distress may precipitate a complete airway obstruction.
In a cooperative adult with acute epiglottitis, very careful flexible fibreoptic laryngoscopy, IV lines, and a careful oropharyngeal examination by experienced personnel can be performed.
Senior experienced anaesthetic and surgical staff should be involved as early as possible, and intubation should be delayed until they arrive. Operating room staff should be informed early and equipment assembled and prepared. Equipment for an emergency surgical airway, emergency cricothyrotomy, jet ventilation, various sizes of oral and nasal tracheal tubes, a flexible fibrescope, and a rigid bronchoscope may be needed. The child should be transferred with the parents and emergency equipment to the operating room, with minimal disruption and distress, accompanied by senior staff.
In the operating room, an inhalational induction with sevoflurane or halothane in oxygen is commenced, with the child usually sitting or in the preferred position. Nitrous oxide is not used. An experienced surgeon able to perform a tracheostomy should be scrubbed and ready.
Inhalational induction with sevoflurane 8% in oxygen can be a long process, taking between 5 and 10 min, because alveolar ventilation is very slow with acute airway obstruction.
Further monitoring and IV access are established as anaesthesia deepens. IV fluids and atropine may be administered to reduce the likelihood of bradycardia associated with intubation. The child may be positioned into a supine position to aid laryngoscopy and the parents asked to leave. On laryngoscopy, the epiglottis and aryepiglottic folds are swollen, and the classic ‘cherry-red’ epiglottis may be seen. Often, the glottic opening is not seen, and the only clue may be a small mucous bubble during spontaneous ventilation or by gentle pressure on the child’s chest.
A tracheal tube, usually 1–3 mm smaller than normal, is placed. Initially, this is an oral tube, and, once the child is stable, this is replaced to a nasal tube which is less likely to become dislodged during the subsequent ventilation on a paediatric ICU. Great care must be taken to prevent dislodgement of the nasal tracheal tube.
In adults with a compromised airway, inhalational induction is often unfamiliar, difficult, and slow, and the depth of anaesthesia can be hard to assess. The patient may become more hypoxic and hypercarbic with long periods of instability, arrhythmias, and apnoea. The traditional view is that the technique is safe, because, if the patient obstructs, the volatile agent will no longer be taken up and the patient will lighten and wake up. This frequently does not happen, and the technique is often not reliable. Some centres therefore use an IV induction technique in adults with epiglottitis, with a backup plan of a surgical airway, and, in some cooperative patients, the surgical airway may be placed before induction under local anaesthetic.
A post-intubation CXR should be taken to ensure optimal tube placement and to assess for LRTIs. Throat and blood cultures are taken, antibiotic therapy (usually a third- or fourth-generation cephalosporin) commenced, and the child transferred to a paediatric ICU, with the appropriate sedation and muscle relaxation to allow controlled ventilation. Extubation is normally possible within 48 hours, with rapidly resolving swelling and oedema of the epiglottis.
Summary
Acute epiglottitis is a medical emergency with a rapid onset and progression of symptoms which can lead to complete upper airway obstruction and death. In children, the main differential diagnosis is croup which occurs in younger children, has a more gradual onset over a number of days, and rarely appears toxic. The diagnosis of acute epiglottitis is made on the history and examination with a sudden onset in a previously well child of sore throat, fever, dysphagia, drooling, open mouth, muffled voice, inspiratory and expiratory stridor, and severe respiratory distress. Senior experienced anaesthetic and surgical staff should be involved as early as possible, and intubation should be delayed until they arrive. Equipment for difficult airway management and emergency surgical airway must be immediately available.