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• PULMONARY EDUCATION
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• Arterial Blood Gases
• Cardiopulmonary Exercise Testing
• Mechanical Ventilation
• Pulmonary Function Testing
• Pleural Effusion
• Radiology

Mechanical Ventilation

Case 9 Answers

A 30 year-old woman has been intubated for 2 days following a motor vehicle accident. On morning rounds, she passed her spontaneous breathing trial and a decision was made to extubate her. The respiratory therapist removes the endotracheal tube and shortly afterwards, she is noted to have stridor. You are called to the room and find her struggling to breathe. She has audible stridor and suprasternal retractions on exam. Her oxygen saturation on 4L oxygen by nasal cannula is 94%.

What is the differential diagnosis for her problem?

This patient has developed post-extubation stridor. This is most likely due to laryngeal edema related to her volume overload but could also be due to laryngospasm, dislocation of the arytenoid structures or, in rare cases, bilateral vocal cord paralysis. Stridor is usually apparent immediately upon extubation but, in some cases, may develop over a period of hours following extubation.

How should you manage the patient? Does she need to be reintubated?

Management of the problem is guided by the patient’s clinical appearance. Patients who appear to be in extremis or have other signs of severe respiratory distress should be reintubated immediately, although you should be aware that reintubation may be challenging due to the airway edema. Patients who appear more clinically stable can be managed with a different approach. They are often given dexamethasone and racemic epinephrine to help decrease the airway edema, although you must recognize that the data supporting these practices is poor and largely derived from the pediatric patient population. In addition, patients can be placed on a mixture of helium and oxygen (heliox) administered through a face mask. For a similar inspired oxygen concentration, a mixture of helium and oxygen is less dense than a mixture of nitrogen and oxygen and, as a result, has better flow properties through the edematous, narrowed airway. Administering this gas mixture can significantly decrease the patient’s work of breathing until the airway edema resolves. Heliox cannot be used, however, in patients who require high inspired oxygen concentrations (F_IO₂ > 0.4) because the density of such gas mixtures is increased and the favorable flow properties of the gas mixture are eliminated. Laryngeal edema will typically resolve over 24 to 48 hours. If the patient has stridor on subsequent attempts at extubation or clinical suspicion for the other possible causes is high enough, Otolaryngology should be consulted to evaluate the laryngeal structures for evidence of the other problems noted above.

In cases where you suspect prior to extubation that a patient may have laryngeal edema and post-extubation stridor, what can you do to minimize the risk of this problem?

There is some evidence to suggest that if you suspect a patient may have laryngeal edema following extubation, you can decrease the risk of this problem by administering several doses of corticosteroids prior to extubation. Consensus does not exist regarding this practice, however and it is not uniformly done across institutions. There are also problems associated with correctly identifying which patients will require this intervention, a not insignificant issue in light of the desire to avoid unnecessary use of corticosteroids.

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