An alternative method for measuring total respiratory resistance during quiet breathing: a feasibility and validation study

OBJECTIVE: Determining the re-spirator y system's mechanical properties with minimal patient effort has been an important field of investigation addressing patients un-able to perform pulmonary function testing and in light of the preventive measures due to the re-cent pandemic. The current study aimed to pres-ent an alternative method for total respiratory resistance measurement during tidal breathing, compare it with airway resistance (Raw), mea-sured by body plethysmography, and validate the procedure in three groups of subjects with normal, constrictive and obstructive respiratory patterns in spirometry.PATIENTS AND METHODS: We developed an alternative method of assessing total respi-rator y resistance during quiet breathing. After manufacturing the appropriate hardware appa-ratus, we applied a steady extrinsic resistance (Delta R) for 100-200 m/s during tidal breathing. Alpha theoretical mathematical model allowed mea-surement of total respiratory resistance (Rtot) during inspiration (Rin) and expiration (Rex). To validate the method, 15 individuals were en -rolled and assigned to the normal, obstructive and restrictive groups based on their spirom-etry patterns. All groups participated in two sets of measurements, the plethysmograph-ic and novel method. Finally, respiratory resis-tance measurements were compared between groups and methods.RESULTS: The method was successfully de-veloped, and Rtot measurements were record-ed in five normal subjects and in five obstruc-tive and restrictive subjects. Mean Rin and mean Rex were 4.99 cm H2O/L/sec and 4.42 cm H2O/L/sec in the healthy, 4.87 cm H2O/L/sec, and 6.63 cm H2O/L/sec in the obstructive and 5.97 cm H2O/L/sec and 4.12 cm H2O/L/sec in the restrictive group, respectively. Rex was notably higher than Rin in the obstructive group and was positively correlated with Raw (p<0.005, r=0.47). CONCLUSIONS: This method provides the theoretical background for a plausible alterna-tive tool for accessing a mechanical parameter of the respiratory system, which is easy to per -form and requires only passive patient cooper-ation while enabling rough differentiation be-tween obstructive and restrictive disorders. The model's feasibility potential in a real-life setting was studied in a small sample, and additional implementation and validation of the method in a larger population are guaranteed.