Ami D. Patel, Hayden D. Kopp, Justin M. Oh, Kristin M. Mendez, Kevin K. McCully, FACSM. University of Georgia, Athens, GA.

BACKGROUND: The diaphragm is the main inspiratory muscle of the body and plays a critical role in breathing. A short explosive inhalation (sniff) has been proposed as a measure of inspiratory strength. This study measured the reproducibility and validity of the sniff test compared to other measures of respiratory function: forced expiratory volume in one second (FEV1), forced inspiratory volume in one second (FIV1), and diaphragm endurance (EIdpm). METHODS: Young, healthy individuals (n=11, age=19±1.08) were tested on two separate days. The sniff test consisted of two maximal explosive inhalations, with acceleration magnitudes measured by a tri-axial accelerometer on the abdomen. FEV1 and FIV1 were measured according to clinical and manufacturer recommendations using a commercial spirometer (Easy-On PC Spirometer, NDD, Zurich, Switzerland). Diaphragm endurance was measured by electrically stimulating the phrenic nerve for 5 minutes at 5 hertz and using a tri-axial accelerometer placed on the abdomen to record declines in acceleration magnitude. RESULTS: Sniff acceleration was 0.93+0.45 g on day one and 0.96+0.37 g on day two. Day one and day two averages were not different for each of the respiratory measurements (p > 0.05). The ICC for the sniff test was 0.627, for the FEV1 test 0.992, and for the FIV1 test 0.915. All were significant (p < 0.05). We were unable to calculate an ICC for the EIdpm. When compared to gold standard spirometry tests, the sniff was negligibly correlated to FEV1 (r=0.20) and FIV1 (r=0.21). CONCLUSION: There was no order effect between days for the sniff test; however, the sniff test exhibited lower reproducibility and lacked validity compared to standard spirometry tests. We recommend using FIV1 as a measure of inspiratory strength rather than the sniff test.

This document is currently not available here.