Evaluation of a novel hands-free cheek holder for oscillometry measurements

Objective: Accurate oscillometry requires minimizing artifacts, particularly those from cheek vibrations, which introduce a parallel (shunt) impedance pathway that distorts measurements. Standard practice includes using a nose clip and manually supporting the cheeks to reduce this effect by stiffening the tissue. This study evaluated the performance of a novel, equipment-integrated cheek holder designed to stabilize the cheeks and improve measurement accuracy without manual support, by comparing it to the current gold-standard (operator-supported cheeks). Methods: Respiratory resistance (Rrs) and reactance (Xrs) at 5 Hz were measured using a handheld oscillometer (FIRST, Restech srl) with the cheek holder and with manual support, in randomized order. Each test was performed in triplicate. Agreement was assessed using Deming regression. Equivalence was defined as the 95% confidence interval (CI) of the regression line falling within the known short-term repeatability: 17% (Rrs) and 37% (Xrs) for adults; 27% and 40% for children, respectively. Results: 55 subjects (age 5 – 75 years; height 104 – 185 cm; 56% females) were included for a broad representation of facial characteristics, with lip length ranging from 36 to 67 mm and bigonial breadth from 80 to 155 mm. The bias between methods was not clinically significant for Rrs or Xrs: the 95% confidence intervals (CI) from the Deming regression fell within the expected short-term variability for all evaluated parameters, indicating consistency between the two methods. Conclusion: The novel cheek holder produced impedance measurements comparable to manual support, simplifying oscillometry and potentially improving its reproducibility.