Original articleReliability of the Sedation-Agitation Scale between nurses and doctors
Introduction
The management of sedation in critically ill patients has been recognised as a complex issue for intensive care units (ICUs) worldwide. Although non-pharmacological techniques (e.g. correct positioning, minimising noxious environmental stimuli, and re-establishing sleep cycles) are essential, they are often not enough to ensure patient comfort. Sedation is therefore an integral part of the management of many critically ill patients. Its use can minimise agitation, promote synchronised breathing with the ventilator, and reduce the anxiety and discomfort associated with the highly technological environment of the ICU. It has been estimated that 90% of critically ill patients require sedation and analgesia for at least part of their stay in an ICU (Devlin et al., 2001). Consequently notable complications of sedation practices, such as over sedation, have been identified (Cook et al., 1998, De Jonghe et al., 1998, Kollef et al., 1998, Kress et al., 2000, Meade et al., 1997) and systems to better manage sedation practices in ICUs are now being developed and utilised. These advances have resulted in a number of sedation scoring instruments being developed (De Jonghe et al., 2000). Many of these instruments however have not been established as reliable instruments for use clinically. This does not mean they are unreliable, only that formal reliability testing has not been carried out. One instrument which has reliability established in certain ICU contexts and with some health practitioners is the Sedation-Agitation Scale (SAS) (Brandl et al., 2001, Riker et al., 1994, Riker et al., 1999).
The SAS originated in, and has only undergone face validity and inter-rater reliability testing in the United States of America (USA) intensive care context (Brandl et al., 2001, Riker et al., 1999). Given there are differences in how ICUs are organised from those with a specialised patient group such as cardiac ICU to those catering for a generalist patient group it is unclear whether the USA reliability studies which were undertaken in specialist units are applicable to generalist units outside the USA. No published studies conducted outside the USA which confirmed its reliability were identified.
Section snippets
The Sedation-Agitation Scale
The SAS uses a seven-point scale (Table 1) to assess patient behaviour and define where the patient lies within the spectrum of sedation from unrousable to dangerously agitated. The scale is designed to be used by nursing and medical staff to inform the need for and level of sedation.
There are several potential limitations of the SAS. The SAS relies on an understanding of the English language. In the multicultural society of New Zealand it is common to come across patients with little
Method
The design was that of an inter-reliability study that distinguished between the raters by identifying them as nurses or doctors. In contrast, the earlier studies on the SAS considered how similarly people were rated without taking into account the category of the rater.
The study was undertaken in a 12-bed tertiary general ICU in New Zealand. The ICU covers most specialties including surgical, medical, paediatric, trauma, cardiothoracic, neurosurgical and renal intensive care. The study design
Samples
All staff except those who were agency and casual resource (pool) staff or who had worked in the unit for less than 6 weeks were eligible to participate in the study. All patients, except those under 16 years of age (defined in New Zealand as a child), those who were deaf or could not speak English, and those who had already had a rating assessment were eligible for the study. In addition, patients who had procedures performed on them (such as turns, airway suctioning, or line insertion) or had
Patient assessment
The nurse–doctor ratings were carried out simultaneously. There was no set pairing of nurses and doctors, the nurse–doctor pair was determined on the day by who was caring for the randomly selected patient. The raters were observed to ensure they did not communicate with each other during the ratings process and were asked not to discuss their ratings after. The rating process replicated Riker et al. (1999) (Table 2). Prior to ratings clinical data were collected from patient notes related to
Analysis
The weighted kappa statistic was used to examine inter-rater reliability. The weighted kappa estimates the proportion of staff agreement between two administrations of the SAS. Intraclass correlation (using a one-way random effects model) was undertaken to examine whether staff who completed multiple ratings biased results. Data were analysed using the Statistical Package for the Social Sciences (SPSS) versions 10 and 14 and Kw was calculated using software Analyse-it® for Microsoft Excel
Staff
Sixty percent of ICU staff, consisting of 48 nurses and seven doctors consented to participate in the study. Of these a convenient sample of 35 nursing and seven medical staff actually performed paired ratings on 69 randomly selected adult ICU patients. The study was completed over an 8-week period.
The mean number of years the nursing participants had worked in any ICU was 6.9 years (±5.0, range 1–18) and 31% had worked in any ICU for 3 years or less. Sixty-six percent said they held a
Discussion
The aim of this study was to determine whether nurses and doctors rate patients similarly using the SAS ratings. It established there was a high level of agreement that is reliability of the SAS by doctors and nurses. The study also provides confirmation of the applicability of the SAS outside the USA. In this research the weighted kappa score compares favourably with earlier studies. This study, performed in a natural setting, has reported a score of 0.82. Nurses and doctors in the general
Conclusion
For a sedation scale to be useful in guiding therapy it should be able to reliably indicate the degree of sedation or agitation within defined categories, be simple to use, be mutually understood by all relevant clinicians and to be validated to the patient group. The SAS has all these features. This research has confirmed the SAS as an appropriate instrument for use in general ICUs and nurses and doctors using the SAS do provide consistent scores and have a mutual understanding of the SAS and
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