ObjectiveTo establish the validity and reliability of a new sedation scale, the Motor Activity Assessment Scale (MAAS).DesignProspective, psychometric evaluation.SettingSixteen-bed surgical intensive care unit (SICU) of a 937-bed tertiary care, university-affiliated teaching hospital.Patientsor=to12 hrs after surgery and were not receiving neuromuscular blockers.InterventionFour hundred assessments (eight per patient) were completed consecutively but independently, in pairs, at standardized times (both day and night) by two nurses who were preselected for each assessment from a pool of 32 pretrained SICU nurses.Measurements and Main ResultsTo estimate validity, paired assessments (four/patient) compared the MAAS result with the subjective assessment using a 10-cm visual analog sedation scale, the percent change in blood pressure and heart rate from the previous 4-hr baselines, and the number of recent agitation-related sequelae. To estimate reliability, paired assessments (four/patient) measured correlation between assessments of the same type (e.g., MAAS-MAAS). Generalized estimating equations, which accounted for the four repeated measures in each patient, supported MAAS validity by finding a linear trend between MAAS and the visual analog scale (p < .001), blood pressure (p < .001), heart rate (p < .001), and agitation-related sequelae (p < .001) end points. The MAAS (kappa = 0.83 [95% confidence interval, 0.72 to 0.94]) was found to be more reliable than subjective assessment using the visual analog scale (intraclass correlation coefficient = 0.32 [95% confidence interval, 0.05 to 0.55]).ConclusionsThe MAAS is a valid and reliable sedation scale for use with mechanically ventilated patients in the SICU. Further studies are warranted regarding the effect of MAAS implementation in our SICU on patient outcomes, such as quality of sedation and length of mechanical ventilation, as well as the use of the MAAS in other patient populations (e.g., medical). (Crit Care Med 1999; 27:1271-1275)