Multivariable analysis of sedation, activity, and agitation in critically ill patients using the Riker scale ECG, blood pressure, and respiratory rate

Patients that are over-sedated or dangerously agitated in the Intensive Care Unit (ICU) have longer lengths of stays, and poorer outcomes in the ICU. The authors have evaluated heart rate (HR), blood pressure (BP) and respiratory rate (RR) in 2938 patients with 124,591 separate Riker (agitation/sedation) class scores over a three year period. The mean and standard deviation for HR, BP and RR in each Riker class were calculated together with inter-class F- and t-tests. Although there was a statistically significant difference in HR, BP and RR between each class except class 6 and class 7, empirical estimates of the joint probability density functions demonstrate that class overlap is overwhelming. This overlap essentially prevents individual Riker classification using HR, BP and RR. In order to improve this classification, an ECG-derived noise metric was evaluated on sections of an ECG corresponding to Riker values of 1, 4 and 7, with promising results