Reliability Study of the Sedation-Agitation Scale in an Intensive Care Unit

The management of sedation in critically ill patients is a complex issue for Intensive Care Units (ICU) worldwide. Notable complications of sedation practices have been identified and efforts to modify these practices in ICUs have begun. While sedation-scoring tools have been introduced into clinical practice in intensive care few have been tested for validity and reliability. One tool which has reliability and validity established is the Sedation-Agitation Scale (SAS). This study is an extension of a previous study by Riker, Picard and Fraser (1999) to determine whether doctors and nurses rate patients similarly using the SAS in a natural ICU setting. It is essential to establish whether these different professionals provide consistent scores and have a mutual understanding of the SAS and its constituent levels. This will help ensure that clinical decisions relating to sedation-needs can be made appropriately and consistently. This quasi-experimental reliability study was set in a 12-bed tertiary general ICU in New Zealand. The SAS had recently been introduced into this unit and a convenience sample of 42 nursing and medical staff performed paired ratings on 69 randomly selected adult ICU patients over an eight week time frame. The mean patient age was 58 years, and 79% of patients were on continuous infusions of Propofol. Intubated patients made up 91% of the sample. 74% of patients were given the same SAS score by the doctor-nurse pair. The weighted kappa score for inter-rater agreement was 0.82 indicating very good agreement. Of the 26% of scores where there was a difference, the two readings were only one score apart. Most of the difference occurred around SAS scores of 1-2 and 3-4. Further analysis found no staff or patient variables to be statistically significant in impacting on the ratings. The SAS was found to be a reliable sedation-scoring tool in a general ICU when used by nurses and doctors of varying experience. The implementation of the SAS should improve the quality of sedation management in critically ill patients, facilitate communication between nurses and medical staff with regard to the effectiveness of sedation regimes, and assist with the development of optimal sedation and analgesia guidelines for ICU patients.