Inter-rater reliability of the measurement of diaphragmatic excursion and fraction of diaphragmatic thickening by ultrasonography in healthy volunteers.

BACKGROUND AND OBJECTIVE: To determine the inter-rater reliability in the ultrasonographic (US) measurement of the diaphragmatic excursion (DE) and the diaphragm thickness fraction (DTF) performed by non-medical health professionals in healthy people. PARTICIPANTS AND METHODS: Prospective observational study in a third level hospital in Cali, Colombia. Measurements were made to 30 healthy volunteers chosen by convenience sampling, without a history of lung diseases, with ages between 18-60 years. A pilot test was previously carried out with 8 healthy volunteers. US measurements of DE, and DTF were based on previously published protocols. Each assessor independently observed several cycles of normal quiet breathing for 3min to establish a baseline. The Intraclass Correlation Index (ICC) was used to evaluate the inter-rater reliability in the measurements of DE and DTF, with 95% confidence intervals and a p<0.05. RESULTS: Substantial agreement was identified in the measurement of DE in the splenic and hepatic windows because the ICC was greater than 0.6 (p<0.05). The measurement of the DTF in the hepatic window showed slight agreement in both 2D and M modes (p>0.05). In the splenic window, the measurement of the DTF in the 2D mode was found to be moderate agreement and for the M mode a slight agreement was found (p>0.05). CONCLUSIONS: The diaphragmatic US constitutes a reproducible method with acceptable inter-rater reliability for the measurement of inspiratory/expiratory thickness, and with little reliability for the measurement of DTF.