Evaluating and monitoring analgesia and sedation in the intensive care unit

Abstract

Management of analgesia and sedation in the intensive care unit requires evaluation and monitoring of key parameters in order to detect and quantify pain and agitation, and to quantify sedation. The routine use of subjective scales for pain, agitation, and sedation promotes more effective management, including patient-focused titration of medications to specific end-points. The need for frequent measurement reflects the dynamic nature of pain, agitation, and sedation, which change constantly in critically ill patients. Further, close monitoring promotes repeated evaluation of response to therapy, thus helping to avoid over-sedation and to eliminate pain and agitation. Pain assessment tools include self-report (often using a numeric pain scale) for communicative patients and pain scales that incorporate observed behaviors and physiologic measures for noncommunicative patients. Some of these tools have undergone validity testing but more work is needed. Sedation-agitation scales can be used to identify and quantify agitation, and to grade the depth of sedation. Some scales incorporate a step-wise assessment of response to increasingly noxious stimuli and a brief assessment of cognition to define levels of consciousness; these tools can often be quickly performed and easily recalled. Many of the sedation-agitation scales have been extensively tested for inter-rater reliability and validated against a variety of parameters. Objective measurement of indicators of consciousness and brain function, such as with processed electroencephalography signals, holds considerable promise, but has not achieved widespread implementation. Further clarification of the roles of these tools, particularly within the context of patient safety, is needed, as is further technology development to eliminate artifacts and investigation to demonstrate added value.

Figure 1

The jagged blue line represents display of Patient State Index (PSI) and suppression ratio (SR) is shown by the red line falling below 0, over time. Solid triangles represent stimulation of patient and stars represent onset and offset of ventricular tachycardia (VT). Ventricular tachycardia with hypotension resulted in a precipitous fall in PSI and SR, with recovery following termination of VT. Reproduced with permission from Ramsay M: Role of brain function monitoring in the critical care and perioperative settings. Semin Anesth Periop Med Pain 2005, 24:195–202. [89].

Figure 2

The jagged blue line represents display of Patient State Index (PSI) and suppression ratio (SR) is shown by the red line falling below 0, over time. Solid triangles represent stimulation of patient. Accidental mis-programming of propofol infusion rate resulted in a steady decline in PSI and SR over time. Recognition of mis-programmed rate was recognized and corrected, resulting in return of PSI and SR to baseline values. Reproduced with permission from Ramsay M: Role of brain function monitoring in the critical care and perioperative settings. Semin Anesth Periop Med Pain 2005, 24:195–202. [89].