The Case

A 73-year-old woman with a history of carotid artery stenosis was admitted for an elective carotid endarterectomy. The procedure was initially thought to be uncomplicated, and the patient was extubated in the operating room. After extubation, the patient was safely brought back to the recovery area, but within 30 minutes she developed respiratory distress necessitating urgent reintubation. The reintubation required multiple attempts but was ultimately successful. The patient was taken back to the operating room and found to have an expanding neck hematoma, which was drained safely. She was then transferred to the intensive care unit (ICU).

The patient gradually improved and was alert with intact mental status. The ICU physician felt it was appropriate to wean the patient from the ventilator with the goal of extubation later in the day. While on rounds, the intensivist planned to ask the respiratory therapist to test for a cuff leak prior to extubation. (Testing for a cuff leak involves deflating the cuff of the endotracheal tube. Patients should have normal airflow around the endotracheal tube after the cuff is deflated. If there is no cuff leak, it suggests that laryngeal edema or another type of laryngeal injury has reduced the space between the endotracheal tube and the larynx. This places the patient at risk for breathing difficulty after extubation.) However, no formal order for a cuff leak test was placed.

After a half hour weaning trial, the patient was ready to be extubated. The respiratory therapist extubated the patient without checking the cuff leak. Within about 15 minutes, the patient developed acute shortness of breath and stridor, progressing quickly to hypoxemic respiratory failure. She required urgent reintubation, which was technically difficult because her vocal cords were edematous. Eventually, an airway was established. The patient remained intubated for 2 more days and required intravenous steroids to reduce laryngeal edema. She was eventually successfully extubated and discharged home in good condition.

The ICU medical director reviewed the case and discovered that the physician had forgotten to place an order for cuff leak and had assumed that the respiratory therapist would know to perform the test, given the patient's history of difficult intubation. The respiratory therapist was covering extra patients that day due to another staff illness, which led him to overlook the need to check for a cuff leak. The medical director also realized that the ventilator weaning process was not standardized.

The ICU decided to implement a standardized protocol for positive pressure weaning trials, which also required a cuff leak test be performed, documented, and the results communicated to the physician before extubation. One year later, the ICU had seen a significant drop in unplanned reintubations after extubation.

The Commentary

Commentary by Rommel Sagana, MD, and Robert C. Hyzy, MD

The process of reliably identifying when a patient is ready to be extubated following invasive mechanical ventilation continues to be clinically challenging. Among patients who are extubated, approximately 10%–20% require reintubation (extubation failure) within 48–72 hours.(1) The patient in this case underwent urgent reintubation twice in one day. Risk factors associated with extubation failure include positive fluid balance 24 hours prior to extubation (1), age, general disease severity, primary reason for intubation, cough efficacy, and amount of secretions.(2,3) An ineffective cough (graded in terms of strength and effectiveness at clearing secretions), a duration of mechanical ventilation greater than 7 days, and severe left ventricular systolic dysfunction (left ventricular ejection fraction ≤ 30%) have been found to be stronger predictors of extubation failure than delirium or ICU-acquired weakness. Only one-third of patients who required intubation were considered high risk for extubation failure by medical providers.(4)

The need for reintubation is an important predictor of mortality, even after accounting for the presence of comorbid conditions and severity of illness.(2) Extubation failure is associated with poor outcomes, including a mortality rate as high as 25%–50%.(4) Mortality is highest among those who fail more than 12 hours after extubation or who require reintubation for reasons unrelated to the airway (i.e., respiratory failure, heart failure, or encephalopathy instead of stridor). Several hypotheses for this finding have been suggested: (i) The act of reintubation itself may result in life-threatening complications. (ii) Failed extubation may not directly cause a poor outcome but may be an independent marker of illness severity. (iii) Significant deterioration may occur between the time of extubation and eventual reintubation.(5)

Laryngeal edema and postextubation stridor are potential consequences of endotracheal intubation. Patients with postextubation stridor are likely at increased risk of reintubation. The published frequency of this outcome has varied from zero to 80%.(6) Patients who are intubated more than 36 hours (7) have an incidence of postextubation stridor of 6%–37%.(8) Additional risk factors for postextubation stridor include traumatic intubation, large endotracheal tube, female sex, and reintubation after unplanned extubation.(6) Simultaneous assessment of both cough and cuff leak has been shown to improve prediction of postextubation stridor. Once the cuff is deflated, the endotracheal tube is occluded and the patient is instructed to cough. The absence of both an audible cough and a cuff leak indicates the patient is 10 times more likely to develop postextubation stridor.(9)

Current guidelines suggest performing a cuff leak test in mechanically ventilated adults who meet extubation criteria and are deemed high risk for postextubation stridor. In the case provided, the patient was at risk for reintubation given she is a woman who had a history of a failed extubation attempt. Evaluating for a cough and a cuff leak would have been recommended prior to the second extubation attempt. Lack of an effective cough or absence of a cuff leak would have prompted the ICU team to initiate treatment prior to extubation. For patients with a failed cuff leak test who are deemed high risk for postextubation stridor, the recommended treatment is glucocorticoids at least 4 hours prior to extubation. Methylprednisolone (20 mg) administered every 4 hours for a total of 4 doses prior to extubation or a single dose of 40 mg of methylprednisolone administered 4 hours prior to extubation have been trialed.(6,10) When comparing steroid regimens, both were effective but only when given to patients who were deemed at high risk for developing laryngeal edema. In one study, this was defined as a cuff leak percentage less than 24% of tidal volume received.(10) There was no benefit when steroids were given to patients without a high risk of laryngeal edema.(11)

The decision to extubate in the ICU should be preceded by daily assessments of readiness to wean, followed by a successful spontaneous breathing trial (SBT). The optimal length of time on an SBT has been debated. Prior studies in large heterogeneous populations requiring invasive mechanical ventilation have found equivalence between 30-minute and 120-minute SBTs.(12,13) These trials included few patients mechanically ventilated for more than 10 days. Thus, it is unknown if 30 minutes is an adequate test for patients who have failed their first SBT or for those who are mechanically ventilated for more prolonged periods.

There is currently no consensus on optimal therapies to prevent extubation failure. Extubation to noninvasive ventilation in order to decrease reintubation rates showed promise. Recent European/American clinical practice guidelines have suggested that noninvasive ventilation be used to prevent postextubation respiratory failure in patients at high risk, defined as older than 65 years or patients with underlying cardiac or respiratory disease.(13) High-flow nasal cannula (HFNC) has also been introduced as a therapy to reduce extubation failure. An alternative device for oxygenation, HFNC improves gas exchange and reduces the work of breathing. In a large-scale randomized controlled trial, HFNC was equivalent to noninvasive ventilation in patients at high risk of extubation failure.(14) The key element in preventing extubation failure is to recognize vulnerable patients using previously identified risk factors such as female sex, lack of an effective cough, or absence of a cuff leak. In our institution, we have a multidisciplinary process involving respiratory technicians, nurses, and physicians to assess if a patient who is ready to be extubated is at high risk for laryngeal edema. Once those patients have been identified, we use a combination of steroid treatment along with extubation to noninvasive ventilation or HFNC in order to reduce the likelihood of reintubation. In the case described, once she had received a course of corticosteroids, assuming lack of a cuff leak, she would have been extubated to noninvasive ventilation or HFNC.

In summary, reintubation 48–72 hours after extubation is associated with increased mortality. Various conditions help identify patients at higher risk for reintubation. Addressing those issues prior to extubation may help decrease reintubation rates. Patients identified as being high risk for postextubation stridor with a failed cuff leak test will benefit from steroid administration prior to extubation. Extubating to noninvasive ventilation and HFNC are additional techniques that have also been shown to help successfully liberate patients from mechanical ventilation.

Take-Home Points

• A spontaneous breathing trial of 30 minutes has been shown to be as effective as a 120-minute trial in certain patient populations.
• Of patients who are extubated after passing a spontaneous breathing trial, 10%–20% require reintubation.
• A cuff leak test can help identify patients who are at risk for developing laryngeal edema and postextubation stridor. For those who fail, the recommended treatment is methylprednisolone at least 4 hours prior to extubation.
• Patients who fail extubation have increased mortality even when accounting for comorbid conditions and general severity of illness.
• Reliably identifying when a patient is ready to be extubated remains clinically challenging. Extubation to noninvasive ventilation and high-flow nasal cannula has shown promise in reducing rates of reintubation.

Rommel Sagana, MD
Associate Professor
Division of Pulmonary/Critical Care
Department of Internal Medicine
University of Michigan
Ann Arbor, MI

Robert C. Hyzy, MD
Professor
Division of Pulmonary/Critical Care
Department of Internal Medicine
University of Michigan
Ann Arbor, MI

References

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