The NBRC RPFT registry examination evaluates advanced respiratory therapists on the precise execution and interpretation of pulmonary function testing modalities. Candidates demonstrate mastery in spirometry, lung volume determination via plethysmography or helium dilution, and single-breath diffusing capacity measurement. Technical proficiency encompasses gas analysis instrumentation, calibration protocols, and quality control maintenance for diagnostic hardware. Practitioners must analyze flow-volume loops and pressure-volume curves while integrating physiological data with clinical diagnostics. Evaluation criteria include standardized testing techniques, interpretation of restrictive and obstructive patterns, and procedural troubleshooting within cardiopulmonary laboratories. This credential validates the advanced technical competency required to perform complex physiological assessments and manage data accuracy.