Current Concepts in Intensive Care Unit Sedation
Current Concepts in Intensive Care Unit Sedation
Moderate sedation is an important aspect of critical care medicine, and its use is almost ubiquitous among medical and surgical intensive care unit (ICU) patients. Adequate sedation attenuates sympathetic nervous system stimulation and can reduce anxiety, agitation, motor activity, and work of breathing. It also facilitates patient comfort and sleep, which in turn modulate stress responses, decrease metabolic demands, improve hemodynamics, and increase tolerance of mechanical ventilation and invasive procedures. In contrast, inadequate sedation can lead to ventilator dyssynchrony, anxiety, pain, discomfort, and depression. Posttraumatic stress disorders may also develop following a course of ICU care, particularly among patients receiving mechanical ventilation. The benefits of sedation must be balanced with the risk for oversedation, which can lead to increases in ICU length of stay, ventilator days, ventilator-associated pneumonia, venous thromboembolic events, and pressure ulcerations. As such, the balance between patient comfort and the risk for these complications is crucial, and the strategy for sedation should be carefully chosen.
A structured approach to sedation has been shown to reduce medication complications, ICU length of stay, and overall healthcare costs. However, achieving the optimum balance between adequate sedation and toxicity can be complex, as the appropriate agent or therapeutic response may be highly variable and is significantly influenced by several patient factors, particularly organ function. The 2002 Society of Critical Care Medicine clinical practice guidelines for sedatives and analgesics outlines an evidence-based approach to moderate sedation. However, several more recent trials have introduced the benefits of newer agents and strategies for analgesia and sedation among ICU patients.
Sedatives may be given intermittently or by continuous infusion. To avoid the risk for oversedation and accumulation of drug in the blood, intermittent strategies are preferred. However, when intermittent strategies are inadequate to achieve the desired effect, continuous infusion should be initiated. If continuous infusion is used, scheduled daily interruptions should be performed. Daily interruption has been shown to reduce the duration of mechanical ventilation, length of ICU stay, ICU complications, and posttraumatic stress disorder. While beneficial, interrupted sedation may produce a catecholamine surge, and caution should be taken in patients with hypertensive crises, traumatic brain injuries, alcohol withdrawal, or unstable coronary artery disease. However, adverse cardiovascular effects are rare, even among high-risk patients.
Regardless of the chosen method of sedation, titration to the desired effect is critical. This remains the most challenging aspect of sedation, and its implementation remains controversial. Numerous scales to assess the level of consciousness exist. These scales are simple in concept but are utilized by fewer than 50% of clinicians in fewer than 50% of ICUs. Sedation scales are intended to regulate medication dosing and duration and minimize the incidence of oversedation. As such, they are recommended to standardize the level of comfort among ICU patients. Regardless of the scale, patients should be able to maintain a level of wakeful, quiet comfort; have adequate control over pain and agitation; and be able to tolerate mechanical ventilation.
Introduction
Moderate sedation is an important aspect of critical care medicine, and its use is almost ubiquitous among medical and surgical intensive care unit (ICU) patients. Adequate sedation attenuates sympathetic nervous system stimulation and can reduce anxiety, agitation, motor activity, and work of breathing. It also facilitates patient comfort and sleep, which in turn modulate stress responses, decrease metabolic demands, improve hemodynamics, and increase tolerance of mechanical ventilation and invasive procedures. In contrast, inadequate sedation can lead to ventilator dyssynchrony, anxiety, pain, discomfort, and depression. Posttraumatic stress disorders may also develop following a course of ICU care, particularly among patients receiving mechanical ventilation. The benefits of sedation must be balanced with the risk for oversedation, which can lead to increases in ICU length of stay, ventilator days, ventilator-associated pneumonia, venous thromboembolic events, and pressure ulcerations. As such, the balance between patient comfort and the risk for these complications is crucial, and the strategy for sedation should be carefully chosen.
A structured approach to sedation has been shown to reduce medication complications, ICU length of stay, and overall healthcare costs. However, achieving the optimum balance between adequate sedation and toxicity can be complex, as the appropriate agent or therapeutic response may be highly variable and is significantly influenced by several patient factors, particularly organ function. The 2002 Society of Critical Care Medicine clinical practice guidelines for sedatives and analgesics outlines an evidence-based approach to moderate sedation. However, several more recent trials have introduced the benefits of newer agents and strategies for analgesia and sedation among ICU patients.
Dosing Strategies
Sedatives may be given intermittently or by continuous infusion. To avoid the risk for oversedation and accumulation of drug in the blood, intermittent strategies are preferred. However, when intermittent strategies are inadequate to achieve the desired effect, continuous infusion should be initiated. If continuous infusion is used, scheduled daily interruptions should be performed. Daily interruption has been shown to reduce the duration of mechanical ventilation, length of ICU stay, ICU complications, and posttraumatic stress disorder. While beneficial, interrupted sedation may produce a catecholamine surge, and caution should be taken in patients with hypertensive crises, traumatic brain injuries, alcohol withdrawal, or unstable coronary artery disease. However, adverse cardiovascular effects are rare, even among high-risk patients.
Regardless of the chosen method of sedation, titration to the desired effect is critical. This remains the most challenging aspect of sedation, and its implementation remains controversial. Numerous scales to assess the level of consciousness exist. These scales are simple in concept but are utilized by fewer than 50% of clinicians in fewer than 50% of ICUs. Sedation scales are intended to regulate medication dosing and duration and minimize the incidence of oversedation. As such, they are recommended to standardize the level of comfort among ICU patients. Regardless of the scale, patients should be able to maintain a level of wakeful, quiet comfort; have adequate control over pain and agitation; and be able to tolerate mechanical ventilation.