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Richmond Agitation Sedation Scale Validity and Reliability in Adult Intensive Care Unit Patients

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The Richmond Agitation–Sedation Scale
Validity and Reliability in Adult Intensive Care Unit Patients
Curtis N. Sessler, Mark S. Gosnell, Mary Jo Grap, Gretchen M. Brophy, Pam V. O’Neal, Kimberly A. Keane,
Eljim P. Tesoro, and R. K. Elswick
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine; School of Nursing and Nursing Service; Department of
Pharmacy; and Department of Biostatistics, Virginia Commonwealth University Health System, Richmond, Virginia
Sedative medications are widely used in intensive care unit (ICU)
tion among caregivers (17–19), improve consistency in drug
patients. Structured assessment of sedation and agitation is useful
administration (20, 21), be used in sedation protocols (15,
to titrate sedative medications and to evaluate agitated behavior,
22), and improve precision of medication titration as patient
yet existing sedation scales have limitations. We measured inter-
needs change over time (11, 12, 23–25). The routine use of a
rater reliability and validity of a new 10-level (�4 “combative” to
sedation scale, including frequent adjustment of the sedation
�5 “unarousable”) scale, the Richmond Agitation–Sedation Scale
target as needed, is strongly endorsed in a recent evidence-
(RASS), in two phases. In phase 1, we demonstrated excellent (r �
based guideline (11). Unfortunately, surveys indicate that
0.956, lower 90% confidence limit � 0.948; � � 0.73, 95% confi-
sedation scales are underused in ICUs (1, 3, 26).
dence interval� 0.71, 0.75) inter-rater reliability among five investi-
In a recent review of sedation scoring systems, De Jonghe
gators (two physicians, two nurses, and one pharmacist) in adult
and colleagues (25) identified 25 instruments designed to
ICU patient encounters (n � 192). Robust inter-rater reliability
measure consciousness in the ICU setting; however, only
(r � 0.922–0.983) (� � 0.64–0.82) was demonstrated for patients
three had been tested for reliability and validity in adult
from medical, surgical, cardiac surgery, coronary, and neuroscience
ICUs, patients with and without mechanical ventilation, and pa- ICU patients. Furthermore, desirable features of sedation
tients with and without sedative medications. In validity testing,
instruments such asmultidisciplinary development, simplicity
RASS correlated highly (r� 0.93) with a visual analog scale anchored
and ease of use, ease of recall, precise discriminating criteria
by “combative” and “unresponsive,” including all patient subgroups
for each level, sufficient levels for sedative medication titra-
(r� 0.84–0.98). In the second phase, after implementation of RASS
tion, measurement of agitation, and rigorous testing of inter-
in our medical ICU, inter-rater reliability between a nurse educator
rater reliability and validity in relevant patient populations
and 27 RASS-trained bedside nurses in 101 patient encounters was
(1, 24, 25, 27) are lacking in many published instruments.
high (r� 0.964, lower 90% confidence limit� 0.950; �� 0.80, 95%
The Richmond Agitation–Sedation Scale (RASS) was de-
confidence interval � 0.69, 0.90) and very good for all subgroups
veloped in a collaborative effort with practitioners represent-
(r � 0.773–0.970, � � 0.66–0.89). Correlations between RASS and
ing critical care physicians, nurses, and pharmacists. RASS
the Ramsay sedation scale (r ��0.78) and the Sedation Agitation
is a 10-point scale, with four levels of anxiety or agitation
Scale (r � 0.78) confirmed validity. Our nurses described RASS as
(�1to�4 [combative]), one level to denote a calm and alert
logical, easy to administer, and readily recalled. RASS has high
state (0), and 5 levels of sedation (�1to�5) culminating inreliability and validity in medical and surgical, ventilated and non-
ventilated, and sedated and nonsedated adult ICU patients. unarousable (�5). The values and definitions for each level
of agitation and sedation are displayed in Table 1, as are
Keywords: sedation; agitation; mechanical ventilation; validation; scale
the instructions for assessment, as previously described (12).
The purpose of this investigation was to rigorously test inter-
Sedative and analgesic medications are administered to many
rater reliability and validity of RASS in a broad spectrum
patients who are critically ill in intensive care units (ICUs)
of adult ICUpatients. These studies include testing of reliabil-
throughout the world (1–3). The consequences of inadequate
ity among nurses after implementation of RASS in a medi-
sedation and analgesia can be substantial, including self-
cal ICU.
removal of important intralumenal tubes and vascular cathe-
ters, aggressive behavior by patients against care providers,
METHODSand poor patient–ventilator synchrony (4–11). Therapeutic
sedation has inherent risks, however, particularlywhen exces-
The research protocol was approved by the Virginia Commonwealth
sive or prolonged (11–16). The increasing recognition that
University Committee on the Conduct of Human Research. The re-
the use of sedative medications can have substantial impact
quirement for obtaining written informed consent was waived, as this
on duration of ICU length of stay and complications (14–16)
noninterventional study posed no added risk to subjects. Testing of
has raised the awareness of the value of structured sedation
validity and inter-rater reliability was performed in two phases at the
evaluation. Reliable sedation tools can enhance communica-
Medical College of Virginia Hospitals, the 750-bed tertiary-care urban
teaching hospital of the Virginia Commonwealth University Health
Systems. Before formal testing, investigators pilot tested RASS in ap-
proximately 20 patients, resulting in minor modifications.
(Received in original form July 25, 2001; accepted in final form August 15, 2002)
Phase 1
Correspondence and requests for reprints should be addressed to Curtis N. Sessler,
Consecutive patients from the medical respiratory ICU, neuroscience
M.D., F.C.C.P., F.C.C.M., Professor of Medicine, Pulmonary & Critical Care Medi-
ICU, coronary ICU, surgical trauma ICU, and cardiac surgery ICUwere
cine, Virginia Commonwealth University, Box 980050, Richmond, VA 23298–
evaluated. Patients with the following characteristics were excluded: (1 )
0050. E-mail: csessler@hsc.vcu.edu
concurrent neuromuscular blockade or quadriplegia, (2 ) contact or
This article has an online data supplement, which is accessible from this issue’s
airborne isolation precautions, (3 ) impaired hearing, (4 ) non-English
table of contents online at www.atsjournals.org
speaking, or (5 ) impaired visual acuity such as blindness or facial or
Am J Respir Crit Care Med Vol 166. pp 1338–1344, 2002
eye trauma. The bedside nurse was contacted regarding these and any
DOI: 10.1164/rccm.2107138
Internet address: www.atsjournals.org additional reasons for exclusion. The time of day, day of week, and

Sessler, Gosnell, Grap, et al.: ICU Sedation Scale Validation 1339
TABLE 1. RICHMOND AGITATION–SEDATION SCALE
Score Term Description
�4 Combative Overtly combative or violent; immediate danger to staff
�3 Very agitation Pulls on or removes tube(s) or catheter(s) or has aggressive behavior
toward staff
�2 Agitated Frequent nonpurposeful movement or patient–ventilator dyssynchrony
�1 Restless Anxious or apprehensive but movements not aggressive or vigorous
0 Alert and calm
�1 Drowsy Not fully alert, but has sustained (more than 10 seconds) awakening,
with eye contact, to voice
�2 Light sedation Briefly (less than 10 seconds) awakens with eye contact to voice
�3 Moderate sedation Any movement (but no eye contact) to voice
�4 Deep sedation No response to voice, but any movement to physical stimulation
�5 Unarousable No response to voice or physical stimulation
Procedure
1. Observe patient. Is patient alert and calm (score 0)?
Does patient have behavior that is consistent with restlessness or agitation (score �1to�4 using the criteria listed above,
under DESCRIPTION)?
2. If patient is not alert, in a loud speaking voice state patient’s name and direct patient to open eyes and look at speaker. Repeat
once if necessary. Can prompt patient to continue looking at speaker.
Patient has eye opening and eye contact, which is sustained for more than 10 seconds (score �1).
Patient has eye opening and eye contact, but this is not sustained for 10 seconds (score �2).
Patient has any movement in response to voice, excluding eye contact (score �3).
3. If patient does not respond to voice, physically stimulate patient by shaking shoulder and then rubbing sternum if there is no
response to shaking shoulder.
Patient has any movement to physical stimulation (score �4).
Patient has no response to voice or physical stimulation (score �5).
sequence of ICUs were intentionally varied for testing, which was done
Statistical Analysis
on six separate occasions from May to September 1999.
RASS data are displayed with mean � SD, as well as median and
To begin RASS testing, five investigators (two physicians [C.N.S.
interquartile range. Although RASS is ordinal, it has 10 defined levels
and M.S.G.], two nurses [M.J.G. and P.V.O.], and one pharmacist
and, consequently, could be treated as continuous data. The interclass
[G.M.B.]) observed the patient’s level of alertness and presence of
correlation coefficient is used to measure the amount of agreement
agitated behavior for 30 seconds (step 1) (Table 1). If the patient did
between raters for continuous data, and the weighted � is used for
not meet criteria for levels 0 through 4, the principle investigator (PI)
ordinal or categorical data. We used both the interclass correlation
(C.N.S.) spoke loudly to the patient, instructing him or her to open his
coefficient and weighted � to test inter-rater reliability (32). Generally,
or her eyes and look at the PI, as all investigators observed closely
the interclass correlations are significantly larger than the �.A� of
(step 2). If the patient did not sustain eye contact for more than 10
more than 0.8, more than 0.6, and more than 0.4 is considered to have
seconds, this step was repeated. If no patient movement was observed,
“almost perfect,” “substantial,” and “moderate” agreement, respec-
the PI physically stimulated the patient while calling his or her name,
tively (33). The lower 90% confidence limit for interclass correlations
by gently shaking the shoulder, followed by rubbing the sternum if no
is displayed in parenthesis. The 95% confidence intervals for � values
patient movement to shaking was observed. The PI marked a 10-cm
are displayed in parenthesis. Because the RASS data are not normally
visual analog scale anchored by the terms “combative” and “unrespon-
distributed, the association between RASS and the visual analog scale,
sive.” All investigators independently recorded a RASS score.
Sedation–Agitation Scale, Ramsay sedation scale, and Glasgow Coma
Scale score is done using Spearman’s �. Comparisons of RASS values
Phase 2
for a priori identified subgroups are done using the nonparametric
This validation study evaluated inter-rater reliability after implementa-
Wilcoxon rank sum test; p� 0.05 was accepted as statistically significant.
tion of RASS into a medical ICU in December 1999. All medical
JMP version 4.0.5 and SAS version 8.02 (both from SAS Institute, Inc.,
respiratory ICU bedside nurses had previously attended in-services on
Cary, NC) statistical programs were used to perform statistical analyses.
RASS and had previously administered RASS to ICU patients while
being supervised by a nurse educator (K.A.K.). The same exclusion
RESULTS
criteria as in the first study applied, except isolation patients were
included. In consecutive medical respiratory ICU patients, the bedside
Phase 1
nurse performed RASS testing and recorded a score, whereas the nurse
A total of 246 consecutive ICU patient encounters were evalu-
educator observed and recorded a RASS score. Within 15 minutes of
RASS testing, the bedside nurse recorded a Glasgow Coma Scale score ated for enrollment, and 54 patient encounters were excluded
(28) using routine medical respiratory ICU policy, and the PI assessed
(17 medical respiratory ICU, 22 surgical trauma ICU, 12 neuro-
a Ramsay sedation scale score (29) and Sedation–Agitation Scale (30)
science ICU, 3 coronary ICU, and 0 cardiac surgery ICU pa-
score. Specific criteria for Glasgow Coma Scale, Ramsay sedation scale,
tients) for the following reasons: 42 patients had airborne or
and Sedation–Agitation Scale are displayed in the appendix and in
contact precautions, 3 had impaired vision, 4 were receiving a
recently published reviews (11, 24, 25).
neuromuscular blocking agent or were quadriplegic, and 5 were
deemed to be poor candidates in the judgment of the bedside
Data Collection
nurse. One hundred ninety-two patient encounters in 172 pa-
Clinical data, including age, gender, use of mechanical ventilation, and
tients (age 56.0 � 16.4 years, 102 men and 70 women) were
dosage and route of administration of sedative and analgesic medica-
evaluated. The characteristics of the 192 adult ICU patient en-
tions within 8 hours of RASS testing, were recorded. Clinical and
counters are displayed in Table 2. The 958 RASS scores (two
laboratory data were collected for the 24-hour period preceding each
missing values) ranged from �5to�3. Forty-three percent of
patient encounter, and an Acute Physiology and Chronic Health Evalu-
ation II severity of illness score (31) was calculated. RASS scores were in the sedation range (�5to�1); 44% were

1340 AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE VOL 166 2002
TABLE 2. PHASE 1 STUDY RICHMOND AGITATION–SEDATION SCALE SCORES, INTER-RATER RELIABILITY TESTING, AND
VALIDITY TESTING ACROSS PATIENT ENCOUNTER SUBGROUPS
RASS Inter-rater Reliability
Correlation of
Population Number Mean � SD Median IQR ICC* �

RASS and VAS

All 192 �0.96 1.67 �0.1 �1.8, 0 0.956 (0.948) 0.73 (0.71, 0.75) 0.93
Age, yr
� 40 36 �1.04 1.92 0 �2.7, 0 0.973 (0.960) 0.74 (0.69, 0.79) 0.94
40–64 91 �0.98 1.59 �0.2 �1.4, 0 0.963 (0.952) 0.76 (0.73, 0.80) 0.97
� 64 65 �0.88 1.65 0 �1.9, 0.1 0.937 (0.914) 0.67 (0.63, 0.71) 0.95
Sex
Male 114 �1.06 1.84 �0.1 �1.2, 0 0.970 (0.962) 0.76 (0.73, 0.78) 0.97
Female 78 �0.81 1.40 �0.1 �2.2, 0 0.922 (0.898) 0.68 (0.65, 0.72) 0.91
APACHE II (14.7 � 7.0)
§
� 10 47 �0.38 1.25 0 �1, 0 0.962 (0.946) 0.78 (0.73, 0.84) 0.84
10–14 51 �0.77 1.38 �0.2 �1.2, 0 0.950 (0.929) 0.74 (0.69, 0.78) 0.89
15–18 44 �0.86 1.58 �0.4 �1.7, 0 0.950 (0.929) 0.70 (0.65, 0.74) 0.97
� 18 50 �1.77 2.06 �1.6 �4, 0 0.951 (0.931) 0.67 (0.63, 0.71) 0.98
Intensive Care Unit

MRICU 39 �1.31 1.75 �1 �2, 0 0.976 (0.965) 0.81 (0.76, 0.86) 0.96
NSICU 51 �1.54 1.94 �1.2 �3.6, 0 0.943 (0.921) 0.64 (0.60, 0.68) 0.97
STICU 23 �0.33 1.45 0 �1, 0.2 0.952 (0.922) 0.76 (0.69, 0.82) 0.97
CSICU 28 �1.11 1.65 �0.2 �2.5, 0 0.951 (0.924) 0.67 (0.61, 0.73) 0.97
CICU 51 �0.30 1.07 0 �0.4, 0 0.937 (0.913) 0.73 (0.67, 0.78) 0.84
Service
Surgical 81 �1.07 1.75 �0.6 �2.4, 0 0.956 (0.943) 0.76 (0.73, 0.78) 0.94
Nonsurgical 111 �0.87 1.67 0 �1.8, 0 0.956 (0.945) 0.69 (0.66, 0.72) 0.93
Mechanical ventilation

Present 67 �1.67 1.89 �1.8 �3.6, 0 0.955 (0.940) 0.68 (0.65, 0.71) 0.97
Absent 125 �0.58 1.41 0 �1, 0 0.949 (0.937) 0.74 (0.71, 0.77) 0.89
Sedative or analgesic medication
Administered 91 �1.07 1.80 �0.4 �2.2, 0 0.970 (0.961) 0.76 (0.73, 0.79) 0.94
Not given 101 �0.86 1.55 0 �1.2, 0 0.940 (0.924) 0.69 (0.66, 0.72) 0.92
Sedative or analgesic infusion

Administered 25 �2.25 2.20 �3 �4, �0.5 0.983 (0.972) 0.82 (0.77, 0.88) 0.97
Not given 166 �0.77 1.50 0 �1.2, 0 0.943 (0.931) 0.70 (0.68, 0.73) 0.96
Definition of abbreviations: CICU � coronary ICU; CSICU � cardiac surgery ICU; ICC � intraclass correlation coefficient; MRICU � medical respiratory ICU; NSICU �
neuroscience ICU; RASS � Richmond Agitation–Sedation Scale; STICU � surgical trauma ICU; VAS � Visual Analogue Scale.
One hundred nineth-two patient encounters in 172 patients.
* Interclass correlation coefficient with lower 90% confidence limits in parentheses.

Weighted � with upper and lower 95% confidence intervals in parentheses.

Spearman’s rank sum (p � 0.0001 for all comparisons).
§
p � 0.05, Wilcoxon rank sum test.

p � 0.001, Wilcoxon rank sum test.

p � 0.0001, Wilcoxon rank sum test.
zero, and 10% were in the agitation range (�1to�3). The
distribution of the RASS scores from 192 patient encounters is
displayed in Figure 1. RASS scores are displayed for important
subgroups of adult ICU patients in Table 2. RASS scores were
lower for mechanically ventilated than nonventilated patients
(p� 0.0001) and for patients receiving continuous infusion seda-
tive or analgesic medication (p � 0.001). Lower RASS scores
were found as Acute Physiology and Chronic Health Evaluation
II scores increased (p � 0.05). RASS scores varied among ICUs
(p � 0.001). There was no difference for RASS scores based on
age, gender, clinical service, or use of any sedative or analgesic
medication.
Excellent inter-rater reliability was demonstrated for RASS
among the entire adult ICU population (intraclass correlation�
0.956 [0.948]) (��0.73 [0.71, 0.75]). Similarly, inter-rater reliabil-
Figure 1. Investigator agreement in RASS scoring for 192 patient en-
ity was high (r � 0.922–0.983) (��0.64–0.82) for all subgroups
counters. RASS score is displayed as the median value of the five investi-
(Table 2). Inter-rater reliability was high for all pair-wise com-
gators’ scores for each individual patient encounter. Shaded stacked
parisons between investigators (r� 0.944–0.973) (��0.65–0.80)
columns correspond to number of caseswith the stated level of investiga-
(Table E1). All five investigators selected the same score in
tor agreement for the same RASS score (box with white fill � five of five
60.4% of cases, four of five investigators in 21.4%, and three of
investigators, light gray fill � four of five investigators, dark gray fill �
five investigators in 15.1%; thus, there was agreement among
three of five investigators, and black fill � two of five investigators).
the majority of investigators in 97% of cases (Figure 1). All five Total columnheight corresponds to the total number of patient encoun-
ters with the specified median RASS score.investigator scores were within one RASS point in 95% of the

Sessler, Gosnell, Grap, et al.: ICU Sedation Scale Validation 1341
TABLE 3. PHASE 2 RICHMOND AGITATION-SEDATION SCALE SCORES AND INTER-RATER RELIABILITY TESTING AFTER
RICHMOND AGITATION-SEDATION SCALE IMPLEMENTATION IN A MEDICAL INTENSIVE CARE UNIT
RASS Inter-rater Reliability
Population Number Mean � SD Median IQR ICC* �

All 101 �1.18 1.69 �0.5 �2, 0 0.964 (0.950) 0.80 (0.69, 0.90)
Age

� 40 29 �0.45 1.17 0 �1, 0 0.910 (0.827) 0.75 (0.55, 0.96)
40–64 45 �1.51 1.74 �0.5 �3.75, 0 0.972 (0.953) 0.76 (0.60, 0.91)
� 64 27 �1.35 1.83 0 �4, 0 0.975 (0.948) 0.89 (0.68, 1.00)
Sex
Male 48 �0.88 1.53 0 �1, 0 0.941 (0.904) 0.76 (0.60, 0.91)
Female 53 �1.42 1.77 �0.5 �3.25, 0 0.980 (0.967) 0.82 (0.69, 0.96)
APACHE II
§
(16.0 � 6.2)
� 12 24 �0.29 0.99 0 �0.75, 0 0.886 (0.773) 0.78 (0.53, 1.00)
12–15 26 �0.33 1.03 0 �0.625, 0 0.916 (0.837) 0.69 (0.48, 0.89)
16–20 29 �1.41 1.57 �1 �2.5, 0 0.948 (0.900) 0.77 (0.59, 0.96)
� 20 22 �2.77 1.78 �4 �4, �0.875 0.987 (0.970) 0.85 (0.60, 1.00)
Mechanical ventilation
§
Present 63 �1.74 1.80 �1.5 �4, 0 0.965 (0.946) 0.82 (0.60, 0.94)
Absent 38 �0.21 0.79 0 �0.5, 0 0.883 (0.801) 0.66 (0.44, 0.88)
Sedative or analgesic medication

Administered 46 �1.63 1.61 �1 �3, 0 0.960 (0.934) 0.81 (0.67, 0.95)
Not given 55 �0.77 1.63 0 �1, 0 0.965 (0.943) 0.76 (0.60, 0.92)
Sedative or analgesic infusion

Administered 42 �1.64 1.62 �1.25 �3, 0 0.957 (0.927) 0.79 (0.65, 0.94)
Not given 59 �0.82 1.63 0 �1, 0 0.967 (0.947) 0.78 (0.63, 0.94)
Definition of abbreviations: APACHE II � acute physiology and chronic health evaluation; ICC � intraclass correlation coefficient; IQR � interquartile range; RASS �
Richmond Agitation–Sedation Scale.
One hundred one patient encounters in 30 patients.
* Correlation between RASS scores by nurse educator and bedside nurses (n� 27) by intraclass correlation coefficient with lower 90% confidence limits in parentheses.

� with upper and lower 95% confidence intervals in parentheses.

p � 0.05, Wilcoxon rank sum test.
§
p � 0.0001, Wilcoxon rank sum test.

p � 0.01, Wilcoxon rank sum test.
cases. As a measure of validity, the mean RASS score recorded in Figure 2. Validity of RASS after implementation is demon-
strated by strong correlations between RASS and the Sedation–
for four investigators correlated highly (r � 0.93, p � 0.0001)
Agitation Scale score (30) (r � 0.78, p � 0.0001), Ramsay seda-
with a sedation–agitation visual analog scale score measured by
tion scale score (29) (r��0.78, p� 0.0001), and Glasgow Coma
thePI. Strong correlations (r� 0.84–0.98, all p� 0.0001) between
Scale score (28) (r� 0.79, p� 0.0001). Individual data for paired
investigator RASS and visual analog scale score confirmed valid-
observations of RASS with the Sedation–Agitation Scale score
ity of RASS for all ICU subgroups (Table 2). RASS scores
and Ramsay sedation scale score in medical ICU patient encoun-
recorded by individual physician, nurse, and pharmacist investi-
ters (n � 101) are displayed in Figures E1 and E2.
gators correlated highly with the PI’s visual analog scale score
(r � 0.91–0.93, all p � 0.0001) (Table E1).
DISCUSSION
Phase 2
Our goals in the multidisciplinary development and validation
The characteristics of 101 medical respiratory ICU patient en-
of RASS were to establish a clinically useful tool to assess the
counters are displayed in Table 3. Thirty patients (age 52 � 15
level of consciousness and agitated behavior in ICU patients
years, 18 men and 12 women) were studied. Mean RASS mea-
that might guide sedation therapy and improve communication
sured by the nurse educator was�1.18� 1.69 and by the bedside among healthcare providers. We placed emphasis on ease of use
nurses was �1.14 � 1.69. The averages of the RASS scores
recorded by the nurse educator and bedside nurse are displayed
for subgroups inTable 3. LowerRASS scoreswere demonstrated
for patients receivingmechanical ventilation (p� 0.0001), receiv-
Figure 2. Display of con-
comitant RASS scores by a
ing sedative or analgesic medication (p � 0.01), with higher
nurse educator and by
Acute Physiology and Chronic Health Evaluation II scores (p�
bedside nurses (n � 27) in
0.0001), and with an age of more than 40 years (p � 0.05). As
medical ICU patient en-
ameasure of inter-rater reliability after implementation ofRASS
counters (n � 101). Open
into clinical practice within the medical respiratory ICU, the
circles represent each indi-
correlation between the nurse educator and the trained bedside
vidual patient encounter.
nurses (n � 27) was 0.964 (0.950) (��0.80 [0.69, 0.90]). The
The number within large
agreement was high for all subgroups tested, ranging from 0.883
open circles represents the
to 0.987 (��0.69–0.90) (Table 3). Data for RASS performed
total number of observa-
by the nurse educator and RASS performed by the bedside
tions when greater than 20
observations are present.nurses (n � 27) in patient encounters (n � 101) are displayed

1342 AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE VOL 166 2002
and clarity. RASS has a single-item numerical structure, avoiding patient behavior and has important implications for care of such
patients. Documentation of agitated behavior can help guidethe complexity of summing multiple subscale scores (28, 34,
35). In contrast to some scales, no intervention that requires evaluation for treatable causes of agitation and delirium (38,
39), as well as assess response to therapy (10, 11).equipment, such as tracheal suctioning, is done (35–37). RASS
can be administered in 30–60 seconds, using three sequential We performed rigorous testing of inter-rater reliability and
validity in nearly 300 patient encounters with more than 1,100steps: observation, response to auditory stimulation, and re-
sponse to physical stimulation. Although two different condi- RASS measurements. Good inter-rater reliability has also been
demonstrated in adult ICU patients for the Ramsay sedationtions, sedation and agitation, are evaluated in a single scale, the
sequential approach establishes a single score by first assessing scale (30), the Sedation–Agitation Scale (30, 40–42), the Motor
Activity Assessment Scale (19, 43), and the New Sheffield Seda-agitation and then assessing sedation. Furthermore, the use of
positive numbers for agitation and negative numbers for sedation tion Scale (44). In contrast to most other studies that used two
raters, we demonstrated reliability among five investigators, in-offers a logical approach to enhance recall while permitting a
robust 10 levels for evaluation of response. cluding critical care physician, nurse, and pharmacist investiga-
tors, illustrating the multidisciplinary applicability of RASS.RASS was designed to have precise, unambiguous definitions
for levels of sedation that rely on an assessment of arousal, Inter-rater reliability ofRASSwas very good for all important
subgroups of adult ICU patients tested, including patients fromcognition, and sustainability using common responses (eye open-
ing, eye contact, physical movement) to common stimuli (spoken medical, surgical, cardiac surgery, coronary, and neuroscience
ICUs. We demonstrated very good reliability for mechanicallyvoice, physical stimulation) presented in a logical progression.
This approach is patterned in part after Ramsay (29) sedation ventilated patients and patients breathing without ventilatory
support, answering criticisms of validation testing of other toolsscale testing in which the response to voice or physical stimula-
tion (light glabellar tap) is subjectively assessed (brisk, sluggish, (27). Furthermore, RASS has high inter-rater reliability for pa-
tients who received sedative medications, including by infusion,no response). This is in contrast to the Sedation–Agitation Scale
and the Motor Activity Assessment Scale tools (19, 30) in which and for nontherapeutically sedated patients. Thus, RASS has
high inter-rater reliability for virtually all categories of adulteach sedation level requires a combination of several responses
and/or the selection of one criterion from asmany as four criteria. ICU patients. Although the Sedation–Agitation Scale has also
been tested in multiple ICU populations, most other sedationThe use ofmultiple or compound criteria increases the likelihood
that patient behavior satisfies multiple levels (23). scales have been validated in only mechanically ventilated pa-
tients in a medical or surgical ICU (19, 40–43, 45). In our phaseAn important goal of RASS development has been to estab-
lish sufficient levels of sedation to permit more precise medica- 2 study, we extended our evaluation of reliability to include
bedside nurses after implementation of RASS in our medicaltion titration. Recent successful sedation management protocols
have used specific sedation targets, that is, Ramsay � 3 or 4 ICU. These findings are confirmed by Ely and colleagues who
in preliminary studies demonstrated high inter-rater reliability(22) and Ramsay � 3 (15) for all patients. Newer guidelines
recommend that the benefit of protocols might be enhanced by of RASS (r � 0.96) for medical ICU nurses (46). Similar results
after implementation are reported for the Sedation–Agitationusing patient-specific sedation targets, as the relative need for
sedation can vary widely among patients as well as over time Scale (40).
Because no reference standard exists for sedation, validationfor an individual patient (11, 12). RASS has five levels of sedation
in addition to level 0 that corresponds to a calm, alert state. The of RASS was performed by correlating it with a visual analog
scale anchored by “combative” and “unresponsive” and withRamsay sedation scale (29) has three “asleep” levels and three
“awake” levels, whereas the Sedation–Agitation Scale (30) and previously published instruments to measure level of conscious-
ness in ICU patients. The correlation between RASS and thethe Motor Activity Assessment Scale (19) have three sedation
levels plus one level for a calm state. Because a target of light visual analog scale was excellent for all investigators. The corre-
lation between RASS and the visual analog scale was high forto moderate sedation is common for mechanically ventilated
patients (15, 22), RASS was designed to offer multiple levels (0 patients from all ICUs, patients whowere ventilated and nonven-
tilated, and patients who were sedated and nonsedated. Whento �3) within this range. This important range of responses is
condensed into one or two sedation levels in other scales (19, tested in 101 medical ICU patients, RASS correlated highly with
the Ramsay sedation scale, the Sedation–Agitation Scale, and29, 30). Although RASS correlated well with Ramsay score, the
39 patients who had a Ramsay score of three (“patient responds the Glasgow Coma Scale scores offering additional support for
construct validity of RASS. In work published in abstract form,to commands only”) had six different RASS scores ranging from
�1to�4 (Figure E1). Similarly, despite the good correlation Ely and colleagues also demonstrated a strong correlation be-
tween RASS and the Glasgow Coma Scale (r � 0.93) as wellbetween RASS and the Sedation–Agitation Scale, the patients
who had a Sedation–Agitation Scale score of three (sedated, as modified bispectral array electroencephalography (r � 0.70)
(46, 47). The Sedation–Agitation Scale has also been validated“difficult to arouse, awakens to verbal stimuli or gentle shaking
but drifts off again, follows simple commands”) received RASS against visual analogue scale (40), the Ramsay sedation scale
and the Harris scale (41), and with bispectral array electroen-scores ranging from �1to�4 (Figure E2). Thus, RASS offers
broader discrimination in the commonly used mild-to-moderate cephalography (48). TheMotorActivityAssessment Scale corre-
lated significantly with the visual analog scale as well as changessedation range.
A perceived limitation of the widely used Ramsay sedation in blood pressure and heart rate and agitation events (19).
There are several potential limitations of RASS and our vali-scale (29) is the lack of sufficient measure of agitation (24).
Similar to recently developed scales (19, 30), RASS contains dation studies. First, RASS relies on patient auditory and visual
acuity and is not suitable for patients with severe impairments.several levels of agitation. RASS has a logical progression from
“restlessness” (�1), which has no immediate impact on patient Second, some patients may be sleeping or sedated but respond
to auditory or physical stimulation violently. Although such pa-outcome, to “agitated” (�2), which includes patient–ventilator
dyssynchrony, to “very agitated” (�3), with immediate risk to tients would receive a RASS score in the sedation range, our
nurses also note the excessive response and consider it in theirpatient or staff through tube or catheter removal or aggressive
behavior. The highest agitation level is “combative” (�4), which medication titration. In validation testing, we recognize that
there were relative few patient encounters for which agitationalthough rare denotes immediate danger for staff from violent

Sessler, Gosnell, Grap, et al.: ICU Sedation Scale Validation 1343
16. Kollef MH, Levy NT, Ahrens TS, Schaiff R, Prentice D, Sherman G.
was demonstrated. Nevertheless, there was majority agreement
The use of continuous i.v. sedation is associated with prolongation of
among five investigators for all 19 phase 1 cases and complete
mechanical ventilation. Chest 1998;114:541–548.
agreement for the 5 phase 2 cases in which median RASS was
17. Slomka J, Hoffman-Hogg L, Mion LC, Bair N, Bobek MB, Arroliga
�1to�3. We a priori treated each patient encounter as an
AC. Influence of clinicians’ values and perceptions on use of clinical
independent observation, but recognize thatmeasures of associa-
practice guidelines for sedation and neuromuscular blockade in pa-
tion (interclass correlation, �, Spearman’s �) could be upwardly
tients receiving mechanical ventilation.Am JCrit Care 2000;9:412–418.
18. Bair N, Bobek MB, Hoffman-Hogg L, Mion LC, Slomka J, Arroliga AC.
biased by using repeated observations of some patients. How-
Introduction of sedative, analgesic, and neuromuscular blocking agent
ever, when recalculated using only each patient’s first encounter
guidelines in a medical intensive care unit: physician and nurse adher-
(n � 172 in phase 1, n � 30 in phase 2), these measures of
ence. Crit Care Med 2000;28:707–713.
association were essentially unchanged from the full data set.
19. Devlin JW, Boleski G, Mlynarek M, Nerenz DR, Peterson E, Jankowski
Finally, responsiveness, or the extent to which an instrument
M, Horst HM, Zarowitz BJ. Motor activity assessment scale: a valid
can detect important changes in sedation (25), was not tested.
and reliable sedation scale for use with mechanically ventilated pa-
Responsiveness has not, to our knowledge, been tested for any tients in an adult surgical intensive care unit. Crit Care Med 1999;
27:1271–1275.
sedation scale in an ICU population (25).
20. Costa J, Cabre L, Molina R, Carrasco G. Cost of ICU sedation. Clin
In summary, RASS is an instrument to assess sedation and
Intensive Care 1994;5:17–21.
agitation of adult ICU patients that is simple to use and has
21. Devlin JW, Holbrook AM, Fuller HD. The effect of ICU sedation guide-
discrete criteria and sufficient levels for sedative medication
lines and pharmacist interventions on clinical outcomes and drug cost.
titration and agitation evaluation. We have demonstrated very
Ann Pharmacother 1997;31:689–695.
good inter-rater reliability and validity across a broad spectrum
22. Kress JP, Pohlman AS, O’Connor MF, Hall JB. Daily interruption of
sedative infusions in critically ill patients undergoing mechanical venti-of adult ICU patients, including after implementation of RASS.
lation. NEnglJMed2000;342:1471–1477.
Our multidisciplinary approach to development and validation
23. Hansen-Flaschen J, Cowen J, Polomano RC. Beyond the Ramsay scale:
should enhance acceptance by ICU physicians, nurses, and phar-
need for a validated measure of sedating drug efficacy in the intensive
macists.
care unit. Crit Care Med 1994;22:732–733.
24. Riker RR, Fraser GL. Monitoring sedation, agitation, analgesia, neuro-
Acknowledgment : The authors are grateful for the enthusiastic support of the
muscular blockade, and delirium in adult ICU patients. Semin Respir
staff nurses of the medical respiratory ICU at the Virginia Commonwealth Univer-
Crit Care Med 2001;22:189–198.
sity Health System.
25. De Jonghe B, Cook D, Appere-De-Vecchi C, Guyatt G, MeadeM, Outin
H. Using and understanding sedation scoring systems: a systematic
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