The purpose of this descriptive study was to evaluate, through clinical testing, the interrater reliability and concurrent validity of the Interchange of Gases Assessment Tool (IGAST) for monitoring the respiratory status of patients in the Postanesthesia Care Unit. The IGAST was used to assess the respiratory status of 20 patients over three time periods (60 data samples). Findings indicated that interrater reliability of the IGAST was acceptable for clinical use in the PACU. The IGAST received a mean interrater reliability rating of 98% in the PACU setting. Results of the mean dimension scores supported the patients' readiness for discharge. Chart audit revealed that the IGAST had concurrent validity since charted information and rated IGAST items were congruent. Further findings suggested that nurses using the IGAST document the respiratory status of patients more completely and more consistently than nurses using narrative documentation.