Sedation and Analgesia in the Intensive Care Unit
Authors: John P. Kress, Anne S. Pohlman, Jesse B. Hall
Journal: American Journal of Respiratory and Critical Care Medicine (2002)

Critically ill patients requiring mechanical ventilation are fretives should never be given as a substitute for adequate analgesia. A strategy that strives to focus initially on assuring adequate quently treated with sedatives and analgesics. Much of what is analgesia will often reduce the need for other sedatives in many known about these medications is derived from investigations critically ill patients. Accordingly, patients should be frequently in the operating room, an environment often very different from reassessed to assure that pain is being adequately addressed. the intensive care unit (ICU). Recently, important complications Although pain is certainly a cause for anxiety in most ICU related to sedation practices in the ICU have been recognized patients, many patients suffer from anxiety even after analgesia and efforts to modify sedation practices in the ICU have begun. is addressed. It is self-evident that being critically ill and depenSedation practices vary widely between institutions, partly bedent on others for care can invoke anxiety. Accordingly, sedation cause of institutional bias and partly because requirements for strategies must recognize and respond to this problem. sedation vary greatly from patient to patient. This commentary Dyspnea is common in ICU patients and may be a source of discusses principles and goals of sedation in the ICU based on distress. Coughing is common in intubated patients, particularly data from publications on this topic. Certainly, some patients in during suctioning. Excessive coughing may contribute to patient– the ICU require little or no sedation. Nonpharmacological means ventilator dysynchrony. Opiates may alleviate coughing in intu(e.g., patient reassurance, positioning comfortably in bed) should bated patients. be attempted initially in all patients; however, this commentary Excessive oxygen consumption (Vo2) may be detrimental in focuses on patients who require mechanical ventilation and pharpatients with respiratory failure or shock. A shift of the delicate macological means of sedation. This commentary does not rebalance of oxygen delivery and consumption can be an important view individual medications for sedation and analgesia; the component of the management of these patients. Previous work reader is referred to guidelines by Jacobi and coworkers (1) for has shown that oxygen consumption can be reduced from basea review of this topic. line by an average of 15% after administration of sedatives and opiates (9). For some patients, such as those with shock or severe INDICATIONS FOR SEDATION hypoxemic respiratory failure, this reduction in oxygen consumpPain is a common experience for most ICU patients (2–4). Failtion may be important for cardiopulmonary stability. ure to recognize that pain frequently leads to agitation may Although it may seem intuitive that amnesia for the period result in excessive administration of sedatives. Accordingly, an of critical illness is desirable, data supporting this notion are aggressive approach to managing pain has been strongly recomlacking. On the contrary, it has been our experience that the mended by published consensus opinions regarding sedation in absence of memory of a period in a person’s life may be unsettling the ICU (1, 5). This can be challenging because many clinical for some, even if that period is the experience of critical illness. parameters such as changes in vital signs may be unreliable The notion that complete amnesia may be detrimental has been indicators of the presence of pain. Surgical incisions, indwelling supported by some studies (10–12). Accordingly, we believe the vascular catheters, endotracheal suctioning, and mechanical venonly circumstance in which complete amnesia is mandatory is tilation are all potential sources of pain for patients. Pain may during the administration of neuromuscular blocking agents. result in many adverse events including increased endogenous Certainly, more data are needed to improve our understanding catecholamine activity, myocardial ischemia, hypermetabolic of the impact of sedation and amnesia on long-term psychological states, and anxiety. A compelling study of mechanically ventioutcomes in critically ill patients. lated preterm neonates reported a decrease in morbidity and Some patients may demonstrate periods of disorientation mortality in those receiving morphine rather than midazolam or during which psychotic behavior occurs. At times an aggressive placebo, underlining the importance of pain control in critical type of behavior may ensue. Reasons for such behavior include illness (6). Previous studies have shown that benzodiazepines medications, sepsis, fevers, encephalopathy (hepatic or renal), may enhance the analgesic effects of opiates (7, 8), a phenomeparanoia, or withdrawal syndromes (alcohol, tobacco, or other non not seen with propofol. Indeed, we have previously noted illicit drugs). that opiate requirements are decreased in patients sedated with Work by Ely and colleagues reported an 83% incidence of delirium in a cohort of ICU patients. Delirium is characterized benzodiazepines rather than propofol (9). Nevertheless, sedaby an acutely changing or fluctuating mental status, inattention, disorganized thinking, and an altered level of consciousness that may or may not be accompanied by agitation (13). Treatment of such agitated behavior is another indication for sedation in (Received in original form April 1, 2002; accepted in final form July 16, 2002) the ICU. Such behavior often responds well to neuroleptic mediCorrespondence and requests for reprints should be addressed to John P. Kress, cations such as haloperidol (1). M.D., Section of Pulmonary and Critical Care Medicine, University of Chicago, 5841 S. Maryland Avenue, MC 6026, Chicago, IL 60637. E-mail: jkress@medicine. bsd.uchicago.edu ASSESSING ADEQUACY OF SEDATION