Patients admitted to the intensive care unit (ICU) often require sedation and analgesia as part of their medical care. Sedation involves administering medications to induce a calm or sleepy state in order to manage pain, anxiety, agitation, and other symptoms. The goals of sedation in the ICU include improving patient comfort and tolerance of mechanical ventilation and other interventions, as well as reducing metabolic demands during critical illness. However, determining optimal sedation strategies in the ICU remains a complex issue given the need to balance adequate symptom control with avoiding over-sedation and related complications.
Reasons for Sedation in the ICU
There are several common reasons patients in the ICU may require sedation:
- Mechanical ventilation – Sedation facilitates tolerance of endotracheal intubation and mechanical ventilation. Being intubated and on a ventilator can provoke anxiety, discomfort, and the gag reflex.
- Invasive procedures – Sedatives help patients undergo invasive and potentially painful procedures (e.g. central line placement, wound care, etc.) while minimizing discomfort and adverse physiologic responses.
- Management of other symptoms – Sedation alleviates pain, anxiety, agitation, delirium, and other issues commonly experienced during critical illness.
- Reduce metabolic demands – Sedation may be used in certain situations to reduce oxygen consumption and metabolic needs (e.g. severe respiratory failure).
- Reduce intracranial pressure – In traumatic brain injury or other neurological conditions, sedation can lower intracranial pressure.
The need for sedation depends on the patient’s medical issues, with mechanical ventilation being the most common indication. However, the decision to use sedation also depends on managing patient comfort and safety while avoiding over-sedation.
Risks of Over-Sedation
While sedation has clear roles in the ICU, over-sedation has been associated with a number of adverse effects:
- Increased time on mechanical ventilation
- Longer ICU and hospital length of stay
- Increased risk of delirium
- Greater long-term cognitive dysfunction
- Higher rates of ICU-acquired weakness
- Increased mortality
These risks have driven initiatives to minimize sedation exposure. Lighter levels of sedation are now commonly targeted to balance patient comfort and safety with avoiding complications of over-sedation.
Sedation Assessment
Given the risks of both under and over-sedation, protocols exist for systematically assessing sedation needs and response. The Richmond Agitation-Sedation Scale (RASS) is one commonly used scale in ICUs. It rates patients on a 10-point scale:
| Score | Term | Description |
|---|---|---|
| +4 | Combative | Overtly combative, violent, immediate danger to staff |
| +3 | Very agitated | Pulls or removes tubes or catheters; aggressive |
| +2 | Agitated | Frequent non-purposeful movement, fights ventilator |
| +1 | Restless | Anxious but movements not aggressive/vigorous |
| 0 | Alert and calm | |
| -1 | Drowsy | Not fully alert, but has sustained awakening (eye-opening/eye contact) to voice (>10 seconds) |
| -2 | Light sedation | Briefly awakens to voice (eye opening/eye contact < 10 seconds) |
| -3 | Moderate sedation | Movement or eye opening to voice (but 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 |
Frequent assessment with a tool like the RASS guides titration of sedatives and analgesics to achieve a light level of sedation whenever appropriate. Target RASS scores are typically 0 to -2 for most mechanically ventilated patients.
Medications for Sedation
There are several medication classes used for sedation in ICU settings:
Propofol
Propofol is a sedative hypnotic in the class of IV anesthetics. It has a rapid onset and short duration of action. Propofol is commonly used for continuous sedation infusions in the ICU, often in combination with opioids. Benefits include reliable sedation and antiemetic effects. However, propofol infusions can be difficult to titrate and often require additional medications to manage pain and agitation. It can also cause hypotension.
Benzodiazepines
Benzodiazepines like midazolam and lorazepam provide sedation, anxiolysis, amnesia, and muscle relaxation. However, they lack analgesic properties so opioids are often co-administered. Benzodiazepines also carry risks like over-sedation, tolerance, withdrawal, and delirium. Their long-acting nature makes them less ideal for continuous infusions. Intermittent dosing may be preferred when shorter acting medications are ineffective.
Dexmedetomidine
Dexmedetomidine is a parenteral alpha-2 adrenergic agonist with sedative, sympatholytic, and analgesic effects without significant respiratory depression. It can provide light sedation while allowing patients to be easily aroused. Dexmedetomidine may help reduce the duration of mechanical ventilation and delirium compared to benzodiazepines. Hypotension and bradycardia are potential side effects.
Opioids
Medications like fentanyl and hydromorphone are powerful analgesics that also provide sedation. Opioids are often administered with other agents like propofol or benzodiazepines to provide combined analgesia and deeper levels of sedation. Adverse effects include hypotension, constipation, tolerance, and withdrawal.
Ketamine
In low doses, ketamine provides analgesia and sedation without compromising respiratory drive or blood pressure. It may be useful for sedation-difficult cases, but psychedelic side effects can limit its use. Ketamine is also used for procedural sedation in the ICU.
Non-Pharmacologic Interventions
While medications comprise the foundation of sedation in the ICU, non-pharmacologic interventions play an important complementary role. Examples include:
- Communication explanations of care/procedures
- Reorientation to place and time
- Noise reduction
- Music therapy
- Relaxation techniques
- Changes in positioning
Such interventions focus on modifying factors contributing to anxiety, agitation, and delirium. This can subsequently minimize sedative medication requirements.
Guidelines for ICU Sedation
Multiple clinical practice guidelines exist to guide best practices for sedation management in critically ill patients:
Society of Critical Care Medicine Guidelines
Key SCCM guideline recommendations:
- Target light levels of sedation whenever appropriate
- Use validated sedation scales (e.g. RASS) to systematically assess depth of sedation
- Interrupt/decrease continuous sedative infusions daily to assess neurological status
- Avoid benzodiazepines in elderly and delirious patients
- Coordinate sedation with spontaneous breathing trials and early mobility
PADIS Guidelines
The PADIS guidelines provide an algorithmic approach to analysing causes of agitation and choosing appropriate medications based on goals of care. This guideline also advocates targeting light sedation and managing pain first before escalating sedative medications.
ABCDEF Bundle
The ABCDEF bundle provides a multimodal framework for optimizing care of ICU patients at risk of delirium and other adverse outcomes linked to sedation. Key components relate to choice of sedative agents, depth of sedation, delirium monitoring, and early mobility.
Nursing Considerations
Nurses play a crucial role in the administration and monitoring of sedation in ICU patients. Key nursing responsibilities include:
- Frequent assessment of sedation levels using a validated scale
- Titrating sedative infusions to target sedation levels
- Monitoring for under-sedation or over-sedation
- Collaborating on daily sedative interruption protocols
- Communicating sedation needs and responses during rounds
- Incorporating non-pharmacologic approaches to manage anxiety/agitation
- Educating patients and families on the goals/processes of sedation
Careful nursing assessment and input guides optimal sedation management per patient needs.
Summary
– Sedative medications are commonly used in the ICU to manage issues like anxiety, agitation, ventilator dyssynchrony, and pain. However, over-sedation can result in harm, while under-sedation also poses risks.
– Light sedation targeting a RASS of 0 to -2 is now widely recommended to balance adequate symptom control with avoiding complications.
– Medications like propofol, benzodiazepines, and opioids each have different properties, benefits, and risks. Multimodal approaches help optimize sedation.
– Non-pharmacologic interventions complement medication use. Systematic sedation assessment also facilitates appropriate titration.
– ICU sedation guidelines emphasize strategies like lighter sedation targets, daily sedation interruption, analgesia-first approaches, and reducing benzodiazepine use.
– Nursing plays a key role in sedative administration, monitoring, titration, and optimizing use with non-pharmacologic approaches.
Conclusion
The majority of ICU patients require some degree of sedation to improve comfort, manage adverse symptoms, and tolerate interventions during critical illness. However, sedation strategies have evolved to use lighter levels and shorter-acting agents as much as possible to avoid complications linked to over-sedation like prolonged ventilation, delirium, and weakness. Regular formal sedation assessment, daily sedative interruption, multimodal analgesia-first approaches, reduced benzodiazepine use, and incorporation of non-pharmacologic adjuncts now represent best practices for sedation in the ICU based on clinical practice guidelines. With careful titration and monitoring, most critically ill patients can have symptoms managed effectively with lighter sedation, thereby improving outcomes.