15 Sedation
Abstract
Patients admitted to the neuroscience intensive care unit (neuro-ICU) may be one of the more complicated ICU populations to manage in regards to sedation, with respect to preservation and frequent assessment of the neurological examination. Providing adequate sedation to the patients in the neuro-ICU depends on determination of proper objective driven goals for sedation and the appropriate choice of agent based on the patient’s physiology. Propofol and benzodiazepines are the most commonly used drugs to treat sedation in this population; however, dexmedetomidine has proven to be a noninferior agent of choice. Fentanyl is primarily an analgesic but has some sedative properties and is also often used as an option in the neuro-ICU. This chapter focuses on sedation in the neuro-ICU population and discusses advantages and disadvantages of the previously mentioned medications.
Keywords: neuro-ICU, intensive care unit, sedation, propofol, midazolam, dexmedetomidine, fentanyl
15.1 Introduction
Proper attention to sedation is an essential component of the care of critically ill patients in the intensive care unit (ICU). Patients admitted to the neuroscience ICU (neuro-ICU) may be one of the more complicated ICU populations to manage in regards to sedation, with respect to preservation and frequent assessment of the neurological examination.
• Sedation reduces the stress response, provides anxiolysis, improves tolerance of ventilatory support, decreases the cerebral metabolic rate of oxygen, and facilitates nursing care.
• Prolonged use of sedatives may result in drug accumulation, oversedation, delayed extubation, and lengthened ICU stay.
• Identifying underlying causes of agitation, such as pain, delirium, hypoxemia, hypoglycemia, hypotension, or withdrawal from alcohol and drugs, are important and treatment should be initiated prior to introducing sedatives.1,2
15.2 Indications for Sedation
• Neurologic injury: Traumatic brain injury (TBI), severe intracranial hypertension, status epilepticus, paroxysmal sympathetic hyperactivity, and withdrawal/intoxication from alcohol or drugs are a few common disease states which often require sedation.
• Patient safety: Cognitive dysfunction (dementia) and brain injury can cause agitation, restlessness, or combativeness prompting the use of sedation for the safety of the patient and staff.
• Patient comfort: Procedures such as intracranial pressure monitors, intravascular catheters, or targeted temperature management require the use of a short-acting sedative. Note that analgesia should be addressed before initiating sedation.
15.3 Complications of Sedation
• All sedation has risks. It is important to weight the risks and benefits before initiating sedatives in patients with a neurologic injury.
• Sedation can compromise a patient’s neurologic examination which may be critical in patient populations like subarachnoid hemorrhage, stroke, or TBI.
• Sedation can also compromise normal physiology
◦ Cardiac: Bradycardia, hypotension
◦ Pulmonary: Respiratory depression, CO2 retention
◦ Cerebral: Low cerebral perfusion, decreased seizure threshold
• Duration of sedation may be prolonged in patients who have chronic disease states like kidney failure, heart failure, or hepatic failure. Sedation may also be prolonged in morbid obesity or when therapeutic temperature management is implemented.
15.4 Assessment of Sedation
• Sedation regimens must be individualized to account for differences in drug pharmacokinetic and pharmacodynamic properties.
◦ Objective, goal-directed sedation is the recommended standard to avoid oversedation and when applicable promote earlier extubation.
◦ In patients with neurologic injury, short-acting agents are preferred.
• Reliable assessment tools for sedation such as the Richmond Agitation Sedation Scale (RASS) have made titration of drugs more precise and cost effective. Details regarding the RASS Scale can be found in Chapter 1.
◦ The RASS is a 10-point scale, validated and reliable in adult neuro-ICU patients, with four levels of anxiety or agitation (+ 1 to + 4), one level to denote a calm and alert state (0), and five levels of sedation (−1 to −5) culminating in unarousable (−5).3,4,5(▶ Table 15.1)
Table 15.1 Richmond Agitation Sedation Scale (RASS)
Score | Description | |
+ 4 | Combative | Violent, danger to staff |
+ 3 | Very agitated | Pulls or removes tube(s) or catheters; aggressive |
+ 2 | Agitated | Frequent nonpurposeful movement, fights ventilator |
+ 1 | Restless | Anxious, apprehensive, but not aggressive |
0 | Alert & calm |
|
−1 | Drowsy | Awakens to voice (eye opening/contact) > 10 sec |
−2 | Light sedation | Briefly awakens to voice (eye opening/contact) < 10 sec |
−3 | Moderate sedation | Movement or eye opening to voice. No eye contact |
−4 | Deep sedation | No response to voice, but movement or eye opening to physical stimulation |
−5 | Unarousable | No response to voice or physical stimulation |
Note: From Sessler et al.3 | ||
15.5 Choice of Sedative
• Propofol and benzodiazepines are among the most commonly used agents.
◦ These drugs have both sedative and anterograde amnestic properties but often lack analgesic properties.2
• Dexmedetomidine has sedative, analgesic, anesthetic, and anxiolytic properties.
• Fentanyl is primarily an analgesic but has some sedative properties and is often used due to its short-acting duration in the neuro-ICU.
• A continuous infusion of these agents provides a more constant level of sedation and improved patients’ comfort. It has been associated with prolonged mechanical ventilation and a longer ICU stay.
◦ Thus, intermittent dosing along with daily interruption of sedatives allowing patients to “wake up” may improve outcomes.6
• ▶ Table 15.2 summarizes some of the pharmacological properties of some of the more commonly use sedative agents in the neuro-ICU.
• ▶ Table 15.3 provides studies of the agents being used for sedation in critically ill patients.
