Abstract
Objective: To validate the Sedation-Agitation Scale (SAS) with the Visual Analog Scale (VAS) and Bispectral Index (BIS) in adult ICU patients after cardiac surgery. Design: Prospective study comparing blinded evaluations of the SAS, VAS and BIS. Setting: Forty-two-bed multidisciplinary ICU. Patients and participants: Convenience sample of 39 adults after cardiac surgery. Measurements and results: Bispectral Index 3.2 was continuously recorded using the Aspect A-1000 and evaluators were blinded to this value. The bedside nurse and a trained researcher independently rated wakefulness using a 100 mm VAS upon patient arrival on the ICU, at first awakening, when ventilator weaning was started and after extubation; the researcher also evaluated patients using SAS. Upon arrival on the ICU, the median SAS score was 2 (interquartile range =1–3), the mean VAS was 26±30 and the mean BIS was 70±16. Twenty-four patients underwent a trial of weaning from mechanical ventilation with a SAS of 4 (IQR =4), VAS of 86±12 and BIS of 87±10. SAS correlated well with VAS performed by one researcher (r=0.91, p<0.001) or by 19 different bedside nurses (r=0.43, p<0.001) and with BIS 3.2 (r=0.60, p<0.001). The correlation between SAS and BIS was reduced in patients with above average electromyogram (EMG) power. As a measure of construct validity, significant differences were noted for the BIS, SAS, VAS and EMG between ICU arrival and extubation (all p<0.001). Conclusions: Sedation-Agitation Scale and BIS are valid measures of wakefulness after cardiac surgery, but EMG interference may affect the accuracy of BIS for a small percentage of patients not receiving neuromuscular blockade.
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Final revision received: 30 January 2001
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Riker, R.R., Fraser, G.L., Simmons, L.E. et al. Validating the Sedation-Agitation Scale with the Bispectral Index and Visual Analog Scale in adult ICU patients after cardiac surgery. Intensive Care Med 27, 853–858 (2001). https://doi.org/10.1007/s001340100912
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DOI: https://doi.org/10.1007/s001340100912