Extubation Criteria and Failure
Extubation most commonly refers to removal of an endotracheal tube (ETT) to transition a patient back to spontaneous respiration; however, when is it appropriate to do so? How do we know the patient is ready and won’t require reintubation?
The truth is we never know for sure. Depending on what observational or randomized controlled study you read, the rate of reintubation runs between 5% and 30%. UpToDate says that 12-14% of planned extubations (ie, the patient was deemed ready) will ultimately require reintubation.
In general, I go back to an A-B-C-D-E mnemonic for extubation criteria:
- A/B – Airway and Breathing
- Passed a spontaneous breathing trial (SBT) with minimal settings – pressure support of 5 cm H2O, positive end-expiratory pressure (PEEP) of 5 cm H2O, no more than 40% oxygen
- Assess appropriate gas exchange (ie, PaO2 > 60 mmHg)
- A chest x-ray (CXR) that’s either stable or improving. Remember that CXRs sometimes take many weeks to show significant radiographic changes.
- Peak expiratory flow of > 60 liters/minute with coughing
- Thin secretions requiring suctioning no more than every 2-3 hours
- C – Circulation
- Hemodynamic stability with minimal pressor support (MAP > 60 mmHg)
- No evidence of myocardial ischemia
- Controlled dysrhythmia/tachycardia
- D – Disability
- Follows commands: eye opening and tracking, sustained hand squeeze, head raise, tongue protrusion
- Neuromuscular blockade has been fully reversed.
- Appropriate analgesic regimen. Sometimes I’ll extubate patients on a combination of dexmedetomidine and/or fentanyl drips, transition to a PCA, and ultimately initiate a multimodal IV/PO regimen
- E – Everything Else
- Acid-base status is acceptable
- Electrolytes have been corrected
- Place an NG tube if you foresee that the patient will have difficulty swallowing
What makes people most nervous are the minutes immediately following extubation. Will the patient fatigue and become hypercarbic/hypoxemic? Will they have significant post-extubation laryngeal edema leading to stridor? Risk factors for stridor following extubation include a traumatic intubation, female gender, presence of an NG or OG tube, aspiration history, reactive airway disease, age over 80, and a large ETT (> 8 mm in men, > 7 mm in women). Post-extubation stridor occurs in roughly 10% of critically ill patients and portends a higher risk for reintubation, prolonged mechanical ventilation, and overall longer ICU stay. Some studies support using steroids in people who are deemed high risk, so I’ll give 40 mg of methylprednisolone roughly 4 hours before attempting extubation.
Some respiratory therapists will perform a “cuff leak” to assess for laryngeal edema. Deflating the ETT’s cuff should create an air leak if there’s no significant laryngeal edema. We can assess this leak qualitatively by auscultating the upper trachea and quantitatively by comparing the ventilator’s preset tidal volume to what was actually delivered. For example, if I set the ventilator to deliver 500 cc tidal volumes at a rate of 12 breaths per minute, and I deflate the ETT cuff, the leak will allow some of the inspired tidal volume to escape. The ventilator might only receive back ~75% of its original delivered breath. With this in mind, I’m not a fan of cuff leaks as they are very nonspecific.
Overall, I think we can do our best to assess the aforementioned parameters in our patients, but sometimes clinical acumen makes us “just take a chance” and try extubation. Whenever we do this, we have to make sure we take the patient’s initial airway exam into consideration. If they were a difficult intubation, we better make sure we have airway experts immediately available to intervene if the patient requires immediate reintubation. If I’m really concerned about a difficult airway, I’ll extubate over a Cook exchange catheter and leave it in place for about 30 minutes just in case I need a conduit to intubate over.
What experiences do you have with extubation? Any words of wisdom or things you’ve learned? Drop me a comment below! 🙂