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Department of Anesthesiology - Residents SectionAnesthesia Knowledge - EpiglottitisEpiglottitis and its Anesthetic Management1. Pathophysiologya. Etiology:
b. Pathology:
2. Clinical presentationa) Epidemiology: Classically: children 2-6 years of age, male preponderance
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.
systemic symptoms:
There is often marked dehydration due to the inability to swallow along with fever and excessive secretions. 3. DiagnosisClinical 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. Managementa) 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.
Awake nasal fiberoptic intubation under sedation
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
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.
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