Flow-volume curve changes in patients with obstructive sleep apnoea and brief upper airway dysfunction

Area of Science:

• Respiratory Physiology
• Pulmonary Function Testing

Background:

• Maximal flow-volume curves may show abnormalities in patients with obstructive sleep apnoea (OSA) and brief upper airway dysfunction (BUAD).
• Previous reports suggest potential links between flow-volume curve patterns and these conditions.

Purpose of the Study:

• To evaluate the predictive capability of maximal flow-volume curves for diagnosing OSA and BUAD.
• To determine if flow-volume curve analysis can differentiate between OSA, BUAD, and normal respiratory function.

Main Methods:

• Maximal flow-volume maneuvers were performed by 33 OSA patients, 16 BUAD patients, and 36 healthy controls.
• Analysis included flow-volume indices, curve variability, saw-toothing, and an algorithm based on flow ratios and curve shape.
• Statistical adjustments were made for confounding factors like BMI, age, gender, and smoking status.

Main Results:

• No significant differences in flow-volume curve indices were found between OSA patients and normal subjects after accounting for confounders.
• All BUAD patients exhibited abnormal flow-volume curves based on the developed algorithm.
• Decreased FEV1 and increased variability in PEF/PIF and FEV1/PEF were significantly associated with BUAD, even after adjusting for confounders.

Conclusions:

• Flow-volume curve indices are not valuable for predicting obstructive sleep apnoea.
• Abnormalities in flow-volume curves are observed in patients with brief upper airway dysfunction.
• A normal flow-volume curve makes the diagnosis of BUAD unlikely.