Endgames Case Report

Acute epiglottitis

BMJ 2013; 347 doi: http://dx.doi.org/10.1136/bmj.f5235 (Published 19 September 2013) Cite this as: BMJ 2013;347:f5235
  1. Robert Charles, core trainee year 2, anaesthetics,
  2. Marc Fadden, foundation year 1 trainee,
  3. Jacqueline Brook, consultant, anaesthetics
  1. 1Anaesthetic Department, Dewsbury District Hospital, Dewsbury WF13 4HS, UK
  1. Correspondence to: R Charles robertcharles{at}nhs.net

A 30 year old man presented to the emergency department with a two day history of fever, sore throat, and progressive difficulty in swallowing. He had no allergies and had taken one dose of benzylpenicillin, prescribed by his general practitioner, earlier that day. His medical history included recurrent tonsillitis, which had been treated with antibiotics; he smoked 15 cigarettes a day.

On initial examination he had tachycardia (115 beats/min) and fever (38.5°C). The remainder of his respiratory and cardiovascular examination was normal. Oropharyngeal examination showed a swollen uvula and enlarged red tonsils without pus. There was no lip or tongue swelling and no obvious rash.

Ten minutes later he developed progressively worsening stridor. He was unable to complete sentences and was drooling. His respiratory rate was 34 breaths/min and his oxygen saturation was 89% on 15 L oxygen. A wheeze was present throughout his chest. He was still tachycardic at 120 beats/min and his blood pressure had increased to 170/100 mm Hg. Administration of adrenaline nebulisers improved the stridor slightly. Blood cultures were taken and intravenous antibiotics and steroids administered. A working diagnosis of acute epiglottitis was made; an urgent anaesthetic and ear, nose, and throat (ENT) review was requested.

Questions

  • 1 What are the causes and clinical features of acute epiglottitis?

  • 2 What other inhalational therapy could be instituted to improve oxygenation?

  • 3 How should this patient be managed further?

Answers

1 What are the causes and clinical features of acute epiglottitis?

Short answer

Acute epiglottitis can be caused by bacteria (such as Haemophilus influenzae type B), viruses (such as herpes simplex), fungi (such as Candida albicans), and non-infectious insults (such as physical trauma, chemicals, and heat). Clinical features include stridor, dyspnoea, and drooling.

Long answer

Acute epiglottitis may progress rapidly into life threatening upper airway obstruction. The incidence of epiglottitis in children in the United Kingdom has fallen considerably since the implementation of the Haemophilus influenzae type B (HIB) vaccine in 1992.1 Incidence peaks at 2-8 years and 35-39 years of age.2

The abrupt onset of oedema and inflammation of the epiglottis and surrounding tissues can progress to total airway obstruction. Clinical features of acute epiglottitis include stridor, dyspnoea, hoarseness, fever, sore throat, odynophagia, dysphagia, drooling, and cervical lymphadenopathy. General malaise and a globus sensation often precede presentation. Signs of respiratory distress or sepsis (or both) may be evident.3 It can be difficult to distinguish epiglottitis from more benign causes of sore throat and dysphagia. This may lead to delays in presentation or referral from primary care and a subsequent increase in mortality. The timing and severity of the progression should give vital clues.2

The causes of acute epiglottitis can be broadly split into two categories—infective and non-infective. The infective causes are mainly bacterial, most notably HIB. The list of other potential bacterial causes is extensive and includes β-haemolytic streptococci (groups A, B, and C), Staphylococcus aureus, and Streptococcus pneumoniae. Viruses (including herpes simplex) and fungi (Aspergillus spp and Candida albicans) should be considered. Blood cultures taken before the administration of antimicrobial therapy allow treatment to be tailored to the particular organism responsible.1. Non-infective causes are mostly associated with trauma to the upper airway, such as foreign bodies, burns (inhalation and chemical), and chemical irritation. Risk factors include absence of immunisation, an immunocompromised state, and smoking.4

2 What other inhalational therapy could be instituted to improve oxygenation?

Short answer

Owing to the physics of flow, in a partially obstructed airway, heliox should reduce the work of breathing and result in larger tidal volumes and improved gas exchange.

Long answer

Heliox is a mixture of helium and oxygen that is usually supplied in cylinders with a helium to oxygen ratio of 79:21 or 70:30. Helium is less dense than oxygen and also has a higher viscosity.5 6 7 Although not widely available, it can be useful in the management of upper airway obstruction. It is not a definitive treatment but can buy valuable time.

Heliox has been used since the 1930s for respiratory conditions, including upper airway obstruction, asthma, chronic obstructive pulmonary disease, and croup. Its benefits may include decreased work of breathing owing to decreased negative pressure requirements to initiate inspiration, increased tidal volumes, and improved gas exchange.5 6 7

The benefits of heliox are explained by the physics of flow. Flow of a gas is laminar, transitional, or turbulent. Laminar flow is the most efficient; it is more likely to occur at low flow rates and is viscosity dependent.5 It is described by the Hagen-Poiseuille formula:

Q = ∆Pπr4/8ηl

Where, flow (Q) in a tube is proportional to the pressure difference (∆P) and the fourth power of the radius (r); and inversely proportional to the viscosity (η) and length (l).

The Reynolds number (Re) determines the type of flow that is likely to occur at any given point. It is a dimensionless value and is determined by the following equation:

Re = ρvd/η

Where, Re is proportional to the density (ρ), velocity (v) and diameter (d); and inversely proportional to the viscosity (η).

A value less than 2000 indicates laminar flow and a value greater than 4000 indicates turbulent flow. Between these values there is a mixture of laminar and turbulent flow, called transitional flow. The ratio of viscosity to density, the kinetic viscosity, is greater for heliox than for air or oxygen.5 6 This means that heliox will produce a lower Re and is more likely to produce laminar flow for a given velocity and tube diameter than air or oxygen. Heliox is more efficacious at higher helium concentrations and for very tight constrictions.6 7

Epiglottitis produces an upper airway obstruction resulting in turbulent flow and therefore increased work of breathing. The use of heliox should make laminar flow more likely and reduce the work of breathing.7

Heliox should be delivered through a high flow system including a tight fitting mask. This ensures sufficient flow to meet the patient’s requirements and avoids air entrainment. Supplemental oxygen can be delivered via a nasal cannula, although hypoxia is likely to be a sign of imminent airway obstruction. Entrained air or supplemental oxygen will increase the density of the heliox mix and reduce its beneficial effects.6 7 8

3 How should this patient be managed further?

Short answer

Actual or impending airway obstruction requires an immediate definitive airway, which needs to be carefully planned. The procedure should occur in a safe place, such as the operating theatre, with the appropriate senior staff, equipment, and skill sets. In less severe cases, patients may be managed conservatively.

Long answer

It was decided that this patient had impending airway obstruction and required an immediate definitive airway, either as an endotracheal tube or a tracheostomy, ideally performed in the operating theatre. Management of milder airway obstruction is open to debate but may be managed conservatively with success.4 Management options must be carefully considered because rapid complete airway obstruction is a possibility.

There are no definitive predictors of sudden airway obstruction in epiglottitis, although symptoms such as stridor indicate a degree of airway compromise.2 4 9 It could be argued that elective intubation in a controlled environment is the safest option.2 However, this is not without serious risk and may be associated with prolonged hospital stay and greater morbidity.7 Conservative management and observation in a place of safety, such as a critical care unit, carries the risk of sudden complete airway obstruction.2 4

If a definitive airway is required, the patient should be considered to have a difficult airway. The airway procedure should be planned and subsequent backup plans included. This should ideally take place in the operating theatre, where senior anaesthetic, surgical, and nursing staff are present and the appropriate equipment is available.4 10 11 12 Fibreoptic flexible nasendoscopy should be considered to facilitate diagnosis and assess the degree of obstruction.2 10

The relative merits of awake intubation versus intubation after induction of general anaesthesia should be considered. Awake fibreoptic intubation may be preferred but requires a cooperative patient and skilled personnel.2 10 Risks associated with this procedure include failure, inadequate topical anaesthesia, over sedation (if used), complete occlusion of an already narrowed airway, and damage to surrounding inflamed structures.2 4 If the decision is made to intubate during general anaesthesia, inhalational induction may be preferable to intravenous induction, with the patient breathing spontaneously.2 This allows rapid reversal if difficulty arises. The risks associated with this include a comparatively long excitement phase during which the patient may develop laryngospasm or aspirate.4 9 Rapid sequence induction has been performed in patients with epiglottitis. This may be associated with multiple or prolonged attempts at direct laryngoscopy, with an increased risk of morbidity and mortality.10 11 Tracheostomy under local anaesthetic may be a safer option.10

Any of these strategies may fail, so an alternative plan should be available. In all cases, if oxygenation and ventilation are compromised, the Difficult Airway Society guidelines for a “can’t intubate, can’t ventilate” situation should be followed.11 This may necessitate a surgical tracheostomy.2 10

Patient outcome

As predicted, the patient had a difficult airway. He was taken to theatre for inhalational induction with ENT support on standby. In spite of poor views with the fibreoptic scope and laryngoscope, the airway was successfully secured with an endotracheal tube. He was transferred to intensive care, where he continued to receive antibiotics and steroids. He was successfully extubated after 48 hours. Discharge was arranged with ENT follow-up four days after the initial presentation.

Notes

Cite this as: BMJ 2013;347:f5235

Footnotes

  • Competing interests: We have read and understood the BMJ Group policy on declaration of interests and have no relevant interests to declare.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Patient consent obtained.

References