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Department of Anesthesiology - Residents Section

Anesthesia Knowledge - Epiglottitis

Epiglottitis and its Anesthetic Management

1. Pathophysiology

a. Etiology:

  • children: almost always Hemophilus influenzae (95%) (4)
  • adults: varying bacteria: Hemophilus, Staphylococcus, Streptococcus, Canidida (in immunocompromised patient)
  • chemical epiglottitis: hot liquids, inhalation injury (burns!), crack or heroine smoking

b. Pathology:

  • cellulitis of the epiglottis and the aryepiglottic folds
  • copious, often thick and inspissated secretions
  • occasionally complicated by epiglottic abscess

2. Clinical presentation

a) Epidemiology:

Classically: children 2-6 years of age, male preponderance

  • With the introduction of Hemophilus influenzae-vaccine (in 1985 in the US) there is been a sharp decline in the incidence in children (Mayo-Smith et al reported a decrease from 38 cases 1975-77 to 1 case 1990-92 in their practice in Rhode Island (1), Felter cites a decrease from 3.47/100 000 in 1980 to 0.63/100 000 in 1990 in children (2) and epiglottitis has become a rare disease in children.
  • There are striking geographical variations, in Switzerland an incidence of 34/100 000 was reported in the pre-vaccine era.
  • vaccine failures have been reported even though their incidence is low (171 cases in 21 000 000 "child years" ( = exposure time) compared to an expected incidence of 6500 cases during the pre-vaccination area, the single most important predictor of vaccine failure was prematurity (8), it has to be kept in mind that H. influenzae infection can occur despite vaccination although often the clinical course will be milder as demonstrated by decreceased mortality (4.3% in unimmunized vs. 2.6% in vaccine failures). (8)
  • Generally rare in adults (4/100 000/year), occurring in all age groups, occasionally in immunocompromised patients.

b) Clinical Manifestation

In children the disease can progress from symptoms of a mild upper respiratory infection to severe or complete respiratory obstruction over 6-12 hours, there are no reliable indicators at presentation (stridor…) that predict the course of airway compromise in adults the onset of symptoms is often slower (24-48 hours), even though the more protracted onset is often associated with less severe forms that is not always so and severe airway compromise can be encountered even after a slow onset.

  • fever, often high
  • history of dysphagia which often progresses to the inability to swallow even saliva
  • patient is appearing lethargic and severely ill
  • patient is often sitting/standing and leaning forward, mouth open, tongue protruding
  • patient is often quiet, concentrating on slow and deep breathing as irritation and movement worsen the airway obstruction, also vigorous inspiration causes the epiglottis to act as a "ball valve" worsening the obstruction
  • stridor, is not always present and is definitely not an indicator of severity
  • "muffled voice"
  • rapid progression is possible: increased respiratory effort, paradoxical breathing, restlessness disorientiation, cyanosis
  • ashen-grey skin discoloration is a sign of impending espiratory arrest

systemic symptoms:

  • fever
  • tachycardia
  • restlessness, disorientation

There is often marked dehydration due to the inability to swallow along with fever and excessive secretions.

3. Diagnosis

Clinical diagnosis: especially the rapid onset and the typical presenting features leave little doubt about the diagnosis, in adults making a clinical diagnosis can be more difficult.

Indirect, fiberoptic laryngoscopy with visualization of the involved structures.

All manipulations have to be performed with extreme caution as irritation of the patient in general or of the larynx in particular can cause complete airway obstruction at any time, direct laryngoscopy is contraindicated in the awake patient.

X-ray: enlarged epiglottis presenting as "thumb sign" on neck-X-ray.

Because of the wide availability of fiberoptic laryngoscopes X-ray will usually not be necessary, in fact it can be counterproductive as it may delay airway management.

4. Management

a) Standard Airway management (9)

Decision to secure the airway: there is no predictor at presentation that allows to foresee the course of airway obstruction, the decision to secure the airway will usually be made (in a study in 1978 intubation, tracheostomy and medical management were compared, while tracheostomy and intubation carried a similar mortality (0.86 vs. 0.92%) with medical management there was a mortality of 6.1% (3)), the case has been made for elective tracheostomy since emergency tracheostomy in the situation of failed intubation carries a high risk for complications but given the invasive nature of tracheostomy intubation will usually be attempted, in addition tracheostomy under local anesthesia represents an irritating stimulus to the patient (especially worrisome in the pediatric population) and may in itself lead to worsening airway obstruction with the sharp decline of epiglottitis in children and a relative rise in adults the decision for medical management may be made more often considering the often less severe presentation in adults.

If the decision to intubate is made the patient has to be transported to the Operating Room where personnel capable of performing a tracheostomy have to be present and the instruments are for tracheostomy are ready for use.

Transport to the Operating Room: it is mandatory that any intervention take place in an environment where the tools and personnel for immediate tracheostomy are available, this will typically be the operating room, transport has to be as least irritating as possible (the pediatric patient should be accompanied by parents), monitors (EKG, pulseoximetry) have to be in place, personnel capable of performing an emergency intubation has to be present at all times, instruments to perform emergency laryngoscopy and cricoid- thyroidotomy have to be readily available.

Induction of General Anesthesia and intubation: the patient is placed on the operating table, often the sitting position will be preferred as this facilitates respiration, if it is necessary to calm the pediatric patient one parent should be allowed to accompany the child to the OR, monitors are placed, amongst the standard monitors precordial stethoscope and properly functioning pulseoximetry and capnography are absolute necessities, ENT service has to be present in the operating room (scrubbed) and instruments for tracheostomy have to be open ready for use, ideally the anterior aspect of the patient's neck is surgically prepped.

Inhalational induction is performed with Sevoflurane or Halothane: "breathing down" often has to be performed with the patient in a sitting position: the goal is to achieve a sufficient depth of anesthesia without inducing apnea, reportedly Sevoflurane has a greater respiratory depressant effect than Halothane and the use of Sevoflurane has been discouraged by some authors or a combination of both has been used (initial rapid induction with Sevoflurane and early switch to Halothane to avoid respiratory depression) (4), others have suggested that the rapid onset of anesthesia with Sevoflurane is indeed an advantage over Halothane and the risk of apnea does not pose a significant risk (5,6), once anesthesia is achieved the patient can be lowered into the supine position.

If IV access has not yet been obtained it has to be secured after a sufficient depth of anesthesia is achieved, again premature irritation can cause worsening of airway obstruction or loss of airway Direct laryngoscopy is then performed and placement of an endotracheal tube attempted, Size of the ETT should be at least 0.5 smaller than appropriate size for the patient, smaller tubes should be readily available, if anatomy can not be identified (which is not an unlikely situation due to excessive inflammation and swelling) one should look for air bubbles during exhalation of the patient or an assistant can be asked to compress the chest of the patient while the intubator is looking for the emergence of an air bubble from the larynx, if air can indeed be observed it is likely that an ETT can be placed in that location (reportedly this technique is quite successful also in other situations where anatomy is obscured).

Inhalational induction has been questioned for airway management in adults with epiglottitis because of the prolonged induction as compared to children, prolonged induction includes a prolonged excitement phase which represents a risk for worsening of airway obstruction, therefore alternative ways of adult epiglottitis have been suggested (see below). (7)

The use of muscle relaxants is contraindicated at any time before the ETT has been successfully placed, if intubation fails their use would leave no other choice but tracheostomy, in addition - as in other difficult airway situations - the use of muscle relaxants may alter airway anatomy for the worse.

Positive pressure ventilation with a mask will frequently worsen the symptoms or may be impossible in the first place since the swollen epiglottis can function as ball valve and thus obstruct the airway, therefore this mode of ventilation has to be avoided.

b) Alternative ways of airway management

Inhalational induction and fiberoptic intubation: inhalational induction in the same way as described above, instead of direct laryngoscopy fiberoptic intubation is performed.

  • advantages: less traumatic, in case of failure airway obstruction from manipulation less likely visualizing the glottis underneath a swollen and rather immobile epiglottis more likely in some instances
  • disadvantages: very skilled anesthesiologist necessary to identify altered anatomy fiber- optically view likely to be impaired by secretions using an air bubble as guidance (see above) unlikely

Awake nasal fiberoptic intubation under sedation

  • advantages: less traumatic/better visualization of glottis (see above) nasal ETT offers more security in terms of self-extubation
  • disadvantages: see above use of local anesthetic spray not sufficient due to widespread edema and inflammation - nerve blocks need to be performed which represent a stimulus especially to the pediatric patient and may result in complete airway obstruction

Rapid sequence induction with cricothyroidotomy if intubation fails, if cricothyroidotomy has to be performed subsequent tracheostomy is necessary as cricothyroidotomy is only a temporary measure. This technique is described very infrequently and is certainly not the standard of care. However, there are case reports (7) where loss of airway during the prolonged excitement phase in an adult was reported. It remains to be seen if with the relative increase of adult epiglottitis more of those reports emerge and a different management of adult epiglottitis will develop

c) Post-intubation management

  • mechanical ventilation and sedation
  • humidification of inspired air to loosen secretions
  • Antibiotic therapy: antibiotics effective against H. influenzae (Ampicillin, Cefotaxim), in an adult good grampositive coverage should be included
  • Steroids to decrease edema

d) Extubation

Antibiotic treatment will usually lead to sufficient resolution of airway obstruction within 48 to 72 hours. Extubation will be performed when fiberoptic exam shows sufficient decrease of inflammatory changes and a leak around the ETT can be observed when the cuff is deflated.



    References
  1. Mayo-Smith et al. Acute epiglottitis: an 18 year experience in RI, Chest 1995, 108: 1640-7
  2. Felter, Epiglottitis, Review, emedicine, 8/02
  3. Cantrell, Acute Epiglottitis, Intubation vs. tracheostomy, Laryngoscope 1978, 88:994ff in Ballenger: Diseases of the Nose, Throat, Ear, Head and Neck, Lea and Febiger, 1991
  4. Sobolev, Plunkett, Barker, Anaesthesia, Letter,2001, 56, page 807
  5. Youngs, Anaesthesia, Letter 1999, 54, page 301
  6. Fenlon, Pearce, Anaesthesia, Letter, 1997, 52, page 285
  7. Ames et al., Adult epiglottitis: an under-recognized, life-threatening condition, British J of Anaesthesia, 2000, 85 (5) 795-797
  8. Heath, McVernon, The UK Hib vaccine experience, Archives of Disease in Childhood, 86 (6) 396-399, 2002 June
  9. Barash, Cullen, Stoelting, Clinical Anesthesia, 4th Edition 1997