It is easy to merge decisions about extubation with decisions about weaning in everyday practice. Indeed, much patient mismanagement is caused by conflating these two subjects. But the conflation is not confined to clinicians. Many researchers have also merged the two subjects, such as using weaning predictors to predict reintubation in a patient who has already tolerated a weaning trial. The result is scientific confusion.
When a patient tolerates a weaning trial without distress, a clinician feels reasonably confident that the patient will be able to sustain spontaneous ventilation after extubation. But this is not the only consideration. The clinician also has to consider whether the patient will be able to maintain a patent upper airway after extubation.
Removal of an endotracheal tube is typically performed under controlled conditions. The patient has satisfactorily tolerated a weaning trial. Enteral feeding is temporally withheld for approximately 4 hours. The patient is usually positioned in a sitting posture. The endotracheal tube, mouth, and upper airway are suctioned, paying attention to the collection of secretions above an inflated cuff. Some clinicians recommend keeping a suction catheter in place (aiming for the catheter to barely protrude from the distal end of the endotracheal tube) as the cuff is deflated; this step is taken in an attempt to capture any secretions sitting on top of an inflated cuff, which might fall into the airway after deflating the cuff. Some clinicians forcefully inflate the lungs with an Ambu Bag immediately before pulling out the endotracheal tube, hoping that the larger than usual ensuing exhalation will push secretions upward and outward. After removal of the endotracheal tube, the patient is given supplemental oxygen, titrated to oxygen saturation (SO2), being particularly cautious with a patient who is at risk of carbon dioxide retention. Patients may have impaired airway protection reflexes immediately after extubation. If speech is impaired for more than 24 hours, indirect laryngoscopy should be undertaken to assess vocal cord function. Oral intake should be delayed in patients who have been intubated for a prolonged period.
In the hours following extubation, patients are carefully monitored for ability to protect the upper airway and sustain ventilation. Most patients will display progressive improvement, allowing the discontinuation of supplemental oxygen and ultimate discharge from the intensive care unit (ICU).
Between 2%1,2 and 30%3–6 of patients experience respiratory distress in the postextubation period (Table 59-1). Many, but not all, require reinsertion of the endotracheal tube and mechanical ventilation. These patients are commonly classified as extubation failures, a term popularized by Demling et al.7 These investigators defined extubation failure as the need for reintubation within 7 days. Unfortunately, the meaning of extubation failure varies among authors, leading to scientific confusion. Even when authors employ it as a synonym for reintubation, the period under study varies—within 24, 48, or 72 hours, or as long as 7 days.