Assessments and exercises of cough strength in critically ill patients: a literature review

Airway clearance is essential for maintaining patency in critically ill patients and relies on the mucociliary escalator, expiratory flow, and cough strength. A weak cough significantly increases the risk of therapy failure in patients receiving noninvasive ventilation (NIV) or high-flow nasal cannula (HFNC). This review aims to summarize current practices for assessing and exercising cough strength in critically ill patients. A comprehensive literature search was conducted in PubMed, Embase, and ScienceDirect using specific keywords related to cough assessment and exercises. A total of 281 articles on cough assessment and 1,407 on cough exercises were identified, with 26 and 73 studies included in the review, respectively. By collecting literature related to cough efficacy, this narrative review describes methods for assessing cough ability and strategies for improving it. The assessment methods for cough ability include quantitative, semi-quantitative, and qualitative evaluations, each targeting different populations and having its own advantages and disadvantages. For patients whose cough ability has diminished, it is essential to implement cough training. Cough exercises focus on increasing inhaled volume, enhancing expiratory flow, and utilizing oscillation techniques to improve cough effectiveness. Choosing the appropriate training method for the patients can lead to significantly better outcomes. Weak cough in critically ill patients correlates with increased risks of extubation failure and prolonged hospitalization. Employing appropriate assessment methods and individualized cough exercises is critical for improving patient outcomes in the intensive care unit (ICU) setting. Further research is needed to optimize training methods and enhance patient cooperation.