Monitoring sedation status over time in ICU patients: reliability and validity of the Richmond Agitation-Sedation Scale (RASS).
BACKGROUND
Goal-directed delivery of sedative and analgesic medications is recommended as standard care in intensive care units (ICUs) because of the impact these medications have on ventilator weaning and ICU length of stay, but few of the available sedation scales have been appropriately tested for reliability and validity.


OBJECTIVE
To test the reliability and validity of the Richmond Agitation-Sedation Scale (RASS).


METHODS
Prospective cohort study.


METHODS
Adult medical and coronary ICUs of a university-based medical center.


METHODS
Thirty-eight medical ICU patients enrolled for reliability testing (46% receiving mechanical ventilation) from July 21, 1999, to September 7, 1999, and an independent cohort of 275 patients receiving mechanical ventilation were enrolled for validity testing from February 1, 2000, to May 3, 2001.


METHODS
Interrater reliability of the RASS, Glasgow Coma Scale (GCS), and Ramsay Scale (RS); validity of the RASS correlated with reference standard ratings, assessments of content of consciousness, GCS scores, doses of sedatives and analgesics, and bispectral electroencephalography.


RESULTS
In 290-paired observations by nurses, results of both the RASS and RS demonstrated excellent interrater reliability (weighted kappa, 0.91 and 0.94, respectively), which were both superior to the GCS (weighted kappa, 0.64; P<.001 for both comparisons). Criterion validity was tested in 411-paired observations in the first 96 patients of the validation cohort, in whom the RASS showed significant differences between levels of consciousness (P<.001 for all) and correctly identified fluctuations within patients over time (P<.001). In addition, 5 methods were used to test the construct validity of the RASS, including correlation with an attention screening examination (r = 0.78, P<.001), GCS scores (r = 0.91, P<.001), quantity of different psychoactive medication dosages 8 hours prior to assessment (eg, lorazepam: r = - 0.31, P<.001), successful extubation (P =.07), and bispectral electroencephalography (r = 0.63, P<.001). Face validity was demonstrated via a survey of 26 critical care nurses, which the results showed that 92% agreed or strongly agreed with the RASS scoring scheme, and 81% agreed or strongly agreed that the instrument provided a consensus for goal-directed delivery of medications.


CONCLUSIONS
The RASS demonstrated excellent interrater reliability and criterion, construct, and face validity. This is the first sedation scale to be validated for its ability to detect changes in sedation status over consecutive days of ICU care, against constructs of level of consciousness and delirium, and correlated with the administered dose of sedative and analgesic medications.
Ely
E Wesley
EW
Department of Medicine, Center for Health Services Research, Vanderbilt University School of Medicine, Tennessee Valley Veteran's Affairs Healthcare System, Geriatric Research Education and Clinical Center, Nashville 37232, USA. wes.ely@vanderbilt.edu
Truman
Brenda
B
Shintani
Ayumi
A
Thomason
Jason W W
JW
Wheeler
Arthur P
AP
Gordon
Sharon
S
Francis
Joseph
J
Speroff
Theodore
T
Gautam
Shiva
S
Margolin
Richard
R
Sessler
Curtis N
CN
Dittus
Robert S
RS
Bernard
Gordon R
GR
D000368:Aged; D000700:Analgesics / Q000008:administration & dosage; D016292:Procedural Sedation / Q000592:standards / Q000706:statistics & numerical data; D003243:Consciousness; D003422:Critical Care / Q000592:standards / Q000706:statistics & numerical data; D004569:Electroencephalography; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D007362:Intensive Care Units / Q000592:standards / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000592:standards / Q000706:statistics & numerical data; D009483:Neuropsychological Tests; D015203:Reproducibility of Results; D012121:Respiration, Artificial
D000700:Analgesics; D006993:Hypnotics and Sedatives