CHAPTER 22

#### KEY POINTS

• Sedatives and analgesics used commonly in the care of critically ill patients often exhibit pharmacokinetics and pharmacodynamics that are significantly different when compared with studies of their use in other arenas, such as the operating room. Knowledge of these differences is crucial to designing a sedation protocol for the critically ill patient.

• While the administration of sedatives and analgesics to the critically ill patient is indicated for a variety of conditions ranging from relief of suffering to facilitation of lung protective strategies of mechanical ventilation, continued reassessment of the need for and means of providing sedation is necessary to prevent the prolongation of mechanical ventilation.

• Intravascular catheters, endotracheal intubation, suctioning, immobility, and underlying illnesses all may cause pain in the critically ill patient. While physical remedies always should be tried—eg, repositioning a patient to alleviate arthritic pain—most patients require intravenous narcotics at least initially. Thus adequate sedation begins with adequate analgesia.

• Regional pain control techniques, such as with epidural catheter–administered anesthetics or opiates, can be highly effective at achieving pain control in the postoperative patient. The placement and removal of such catheters require correction of any underlying coagulation abnormalities in order to reduce the risk of epidural hematoma.

• The evaluation of sedation adequacy can only be performed at the bedside and is facilitated by the use of a validated sedation scale, such as the Richmond Agitation-Sedation Scale, along with a protocol for the systematic assessment and administration of sedatives and analgesics.

• Although both continuous and intermittent bolus strategies for sedative administration have been advocated, the two strategies have not been compared directly in a large, randomized, controlled trial. Regardless of the approach used, some patients require larger doses of sedatives—often in excess of drug manufacturer guidelines. Thus the level of sedation must be reassessed continuously and a protocol for downward titration of sedation applied.

• If continuous administration is used, daily sedative interruption is recommended to prevent drug accumulation, allow the performance of a neurologic examination, and permit reassessment of the need for sedation. If resedation is required, restarting the infusion at half the previous dose, with subsequent titration as necessary, is a useful strategy for systematic downward titration.

• Prolonged (>48 hours) neuromuscular blockade should be used as a last resort owing to the high incidence of neuromuscular complications associated with this practice in critically ill patients. In particular, the administration of these agents in combination with high-dose corticosteroids is discouraged.

Administration of analgesics and sedatives is commonplace in the ICU. Unfortunately, many early studies of analgesic and sedative medications were performed in the operating room, a setting very different from the ICU. The clinician must recognize the diverse and often unpredictable effects of critical illness on the pharmacokinetics and pharmacodynamics of sedatives and analgesics. Failure to recognize these effects may lead to inadequate or excessive sedation. Sedatives and analgesics may cause prolonged alterations in mental status and may mask the development of coincident complications of critical illness. Data ...

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