Utilization of a Risk Stratification Tool and Volume-Based Cuff Leak Test to Assess Post-Extubation Stridor

Background: Post-extubation stridor (PES) is an imminently life-threatening event. Maximizing patient safety requires a systematic approach to screen patients for PES risk factors and a standardized test to evaluate that risk. This retrospective study of adult subjects was based on quality assurance data including standardized surveillance screening criteria and a volume-based cuff leak test (CLT) to evaluate PES risk among predominantly surgical-trauma and neurotrauma subjects. Data characterizing PES subjects also were collected.

Methods: Data were collected between May 2010 and December 2017 for all intubated subjects in our surgical-trauma, neurotrauma and medical ICUs. Respiratory therapists were trained in performing both PES risk assessment surveillance and a volume-based CLT. A pre-hoc cut-off leak volume of < 110 mL defined a true positive test result when associated with PES and a leak ≥ 110 mL defined a true negative test if PES was absent. Multiple comparisons were analyzed by Kruskal-Wallis tests and dichotomous variables assessed by Fisher exact tests. Alpha was set at 0.05.

Results: In 681 pre-extubation CLTs ∼85% produced true negative results and 15% consisted of: true positive (∼4%), false negative (∼5%), and false positive (∼6%) results. Positive and negative predictive values were 0.42 (0.32-0.54) and 0.94 (0.92-0.96) respectively. The PES likelihood ratio was 7.0 and correct classification was 89%. Of the 115 PES incidences occurring in 112 PES cases 67% were female and 53% had suffered acute brain injury.

Conclusion: Among predominantly surgical-trauma and neurotrauma subjects a CLT leak volume of ≥ 110 mL was associated with a PES risk of ∼6% whereas the risk of PES is 7 times greater when the leak volume is < 110 mL.