Upper airway obstruction assessment: Peak inspiratory flow and clinical COPD Questionnaire

Objectives: Spirometric evaluation of upper airway obstruction (UAO) is not commonly performed by Otolaryngologists. In addition, functional evaluation of UAO by flow-volume loops (FVL) is not available in all clinical settings. More recently, peak inspiratory flow (PIF) has proven to be a useful tool to monitor UAO at the patient's bedside. The aim of this work is to assess the role of PIF measured with a simple flow metre (In-Check method) as a standardised, simple, non-invasive tool in quantifying chronic and subacute UAO in a routine clinical practice. In addition, a Clinical COPD Questionnaire (CCQ), previously validated to assess the psychophysical status in patients with laryngotracheal stenosis, was utilised to evaluate respiratory function in UAO.

Design: Prospective cohort study.

Settings: University teaching hospital.

Participants: Seventy 2 subjects, an UAO group of 26 patients and a control group of 46 healthy subjects.

Main outcome measures: The ability of PIF values to discriminate between the UAO group and the control group was assessed using a ROC curve. A Spearman rank correlation was used to test the relationship between PIF measurements and the global CCQ score. Additionally, an analysis of CCQ at domain and items levels was performed.

Results: Peak inspiratory flow values were accurate, with an area under the ROC curve (AUC) of 0.98 (P < .05) for differentiating the control group from the UAO group. A threshold PIF value of 170 L/min was found for diagnosing UAO. An inconclusive negative trend was found (r = -.19; P = .35) between PIF values and CCQ global score. Concerning CCQ, the symptoms domain was the most affected by UAO, higher than mental domains (P < .001) as well as functional domains (P < .01). Exertional dyspnoea and cough were the items that obtained the highest disturbed scores.

Conclusions: Peak inspiratory flow is a non-invasive, quantitative parameter to evaluate the severity of UAO. Testing can be easily performed in a routine clinical setting, with a non-expensive hand-held device, and could help medical follow-up programmes and prevent emergency situations. However, FVL may be necessary for further assessment of UAO diseases. The CCQ confirms that exertional dyspnoea is the main symptom of UAO, but cough remains a common symptom.