Intubation is an acute respiratory intervention to ensure continued airflow through the upper airways and into the lungs. However, removal of the tube, also known as extubation, comes with an increased risk of airway obstruction. Partial obstruction, or stridor, can be supraglottic or glottic and is typically indicated by increased respiratory noise and struggle. Complete obstruction which can occur in the form of post-extubation airway obstruction typically points to a more extreme underlying condition and can be life-threatening.
There are many risk factors which contribute to post-extubation airway obstruction. For example, one study performed by Tanaka et al. found that frequent endotracheal suctioning was correlated with increased incidence of stridor.1 Other risk factors include being female, prolonged intubation, and emergency intubation (as opposed to intubation in a controlled setting).2 These findings suggest that the structure of the laryngeal airway as well as the level of intubation-associated trauma contribute to the risk of post-extubation airway obstruction.
Typically, conditions which involve a decrease in the airway lumen are associated with a higher risk of post-extubation airway obstruction. Laryngeal edema is commonly the underlying cause of partial or complete airway obstruction following extubation.3 In cases of extreme laryngeal edema, re-intubation may be necessary to re-establish respiratory flow. However, this is option is avoided if possible: re-intubation is often associated with a myriad of other complications, contributing to overall increased morbidity and mortality.4 Other types of lumen trauma, including ulcers and vocal cord damage, have also been found to be associated with post-extubation airway obstruction.3
Although some instances of post-extubation airway obstruction are unpredictable, certain diagnostic tests can be performed prior to extubation to anticipate the integrity of the laryngeal airway. The gold standard for the past few decades has been the cuff leak test, which assesses the leak around the endotracheal tube when the cuff is deflated.5 The current threshold for a CLT is 110 mL of absolute volume. However, as authors Tokunaga et al. point out, there are a few issues with the current standard of CLT: for one, there is no way of validating the measurement, and no evaluation criteria have been established.6 Moreover, performing a CLT test increases the risk of patient-ventilator asynchrony.7 As an alternative, Tokunaga et. al report in their 2022 publication that measuring pressure above the cuff may serve as a less invasive alternative to the cuff link test to evaluate the risk of post-extubation airway obstruction.6
The relative prevalence of post-extubation airway obstruction is not well known. Studies have estimated incidence rates of extubation-related stridor ranging from as low as 1.5 to as high as 26.3 percent.8 Similarly, studies have estimated the incidence of extubation-related laryngeal edema to be between five and 55 percent.5 This wide range points towards possible inconsistencies in the diagnosis and prevention of extubation-related stridor and laryngeal edema.
Post-extubation airway obstruction is one of many complications associated with intubation. Although intubation is a commonly practiced intervention in emergency or hospital settings, it remains an invasive procedure associated with considerable discomfort. For that reason, risk assessments should be performed prior to any intubation, and then again prior to extubation. Tests such as the cuff leak test (or potentially the less invasive above-the-cuff pressure test) are critical to anticipating and avoiding life-threatening respiratory distress.
References
1 Tanaka, A., Uchiyama, A., Horiguchi, Y., Higeno, R., Sakaguchi, R., Koyama, Y., Ebishima, H., Yoshida, T., Matsumoto, A., Sakai, K., Hiramatsu, D., Iguchi, N., Ohta, N., & Fujino, Y. (2021). Predictors of post-extubation stridor in patients on mechanical ventilation: a prospective observational study. Scientific reports, 11(1), 19993. DOI: 10.1038/s41598-021-99501-8
2 Shinohara, M., Iwashita, M., Abe, T., & Takeuchi, I. (2020). Risk factors associated with symptoms of post-extubation upper airway obstruction in the emergency setting. The Journal of international medical research, 48(5), 300060520926367. DOI: 10.1177/0300060520926367
3 Colice, G. L., Stukel, T. A., & Dain, B. (1989). Laryngeal complications of prolonged intubation. Chest, 96(4), 877–884. DOI: 10.1378/chest.96.4.877
4 Epstein, S. K., & Ciubotaru, R. L. (1998). Independent effects of etiology of failure and time to reintubation on outcome for patients failing extubation. American journal of respiratory and critical care medicine, 158(2), 489–493. DOI: 10.1164/ajrccm.158.2.9711045
5 Zhou, T., Zhang, H. P., Chen, W. W., Xiong, Z. Y., Fan, T., Fu, J. J., Wang, L., & Wang, G. (2011). Cuff-leak test for predicting postextubation airway complications: a systematic review. Journal of evidence-based medicine, 4(4), 242–254. DOI: 10.1111/j.1756-5391.2011.01160.x
6 Tokunaga, K., Ejima, T., Nakashima, T., Kuwahara, M., Narimatsu, N., Sagishima, K., Mizumoto, T., Sakagami, T., & Yamamoto, T. (2022). A novel technique for assessment of post-extubation airway obstruction can successfully replace the conventional cuff leak test: a pilot study. BMC anesthesiology, 22(1), 38. DOI: 10.1186/s12871-022-01576-x
7 Sassoon C. (2011). Triggering of the ventilator in patient-ventilator interactions. Respiratory care, 56(1), 39–51. DOI: 10.4187/respcare.01006
8 Pluijms, W. A., van Mook, W. N., Wittekamp, B. H., & Bergmans, D. C. (2015). Postextubation laryngeal edema and stridor resulting in respiratory failure in critically ill adult patients: updated review. Critical care (London, England), 19(1), 295. DOI: 10.1186/s13054-015-1018-2
