Assessing Sedation Need

Critically ill patients requiring mechanical ventilation often experience distress and agitation. Common causes include anxiety, pain, delirium, and dyspnea. Before initiating pharmacologic sedation, the underlying cause(s) should be identified and managed.

Causes of Agitation

• Anxiety – Fear, loss of control, inability to communicate effectively
• Pain – From procedures, immobility, tubes, monitoring devices
• Delirium – Acute change in mental status, inattention, disorganized thinking
• Dyspnea – Air hunger, feeling of suffocation, respiratory distress

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Non-Pharmacological Management

First-line management of agitation should focus on non-pharmacological strategies:

• Identify and treat underlying causes (e.g. hypoxemia, ventilator asynchrony)
• Reorient and reassure through communication
• Address physical needs (e.g. thirst, hunger)
• Promote sleep hygiene
• Relaxation techniques (music therapy, guided imagery)
• Family involvement
• Safe mobilization

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Sedation Scales

The Richmond Agitation-Sedation Scale (RASS)

The RASS is a 10-point scale developed to assess level of sedation and agitation in ICU patients. It ranges from +4 (combative) to -5 (unresponsive). Patients are assigned a score based on observed behaviors such as restlessness, agitation, and response to verbal and tactile stimulus.

To administer the RASS, providers first establish if the patient is alert and calm. If not, they proceed to observe behavior and assess response to verbal and physical stimulus. For example, a combative patient pulling at tubes would score +4. A patient who briefly awakens and makes eye contact to voice would score -2.

The RASS has been validated for inter-rater reliability in multiple studies. One evaluation found excellent inter-rater reliability between nurses and research staff assigning RASS scores in over 10,000 paired observations. Another study confirmed the RASS has excellent inter-rater reliability and criterion validity when tested by clinical staff in an ICU.

The RASS offers several advantages over other sedation scales:

• Assesses level of agitation and sedation on a single scale
• Quantifies level of agitation separately from sedation
• Good inter-rater reliability between different providers
• Validated in broad spectrum of ICU patients
• Predicts outcomes like duration of mechanical ventilation and delirium

Due to these favorable properties, the RASS is recommended in clinical practice guidelines for ICU sedation assessment. It allows standardized communication between team members about sedation goals and response to interventions. The RASS is easy to implement, requires minimal training, and can improve sedation management.

The Riker Sedation-Agitation Scale (SAS)

The SAS is a 7-point scale developed to assess depth of sedation in mechanically ventilated ICU patients.29 Patients are assigned a score based on observed behaviors ranging from dangerous agitation (7) to unarousable (1).

To administer the SAS, providers assess the patient’s agitation behaviors, ability to be calmed by verbal instructions, and response to physical stimulation. For example, a patient whose agitation subsides with verbal instructions would score 5. A patient unarousable to voice or physical stimulus would score 1.

Like the RASS, the SAS demonstrates good inter-rater reliability when used by bedside nurses and other ICU staff. One study found an inter-rater reliability of 0.92 when research staff applied the SAS in 102 mechanically ventilated patients.

The SAS is best suited for assessing heavily sedated patients and for evaluating sedative effects. It does not assess agitation well, lacking gradations for mild to moderate agitation. For this reason, the RASS may be better for titrating sedation and detecting early agitation. However, the SAS remains a valid and reliable sedation scale, particularly in deeply sedated patients.

Delirium Assessment

The Confusion Assessment Method for ICU (CAM-ICU) and Intensive Care Delirium Screening Checklist (ICDSC) allow regular delirium assessment in critically ill patients. Both assess features such as acute mental status changes, inattention, disorganized thinking, and level of consciousness. The CAM-ICU has excellent sensitivity and specificity for delirium diagnosis. The ICDSC correlates well with other delirium assessment tools.

Bispectral Index Monitoring

Bispectral index (BIS) monitoring uses EEG data to generate an index from 0-100 reflecting depth of sedation. Values of 40-60 generally indicate adequate anesthesia. BIS may help assess sedation in pharmacologically paralyzed patients. However, use in ICU patients remains controversial due to issues like artifact from electromyographic activity. Current guidelines state there is insufficient evidence to recommend routine BIS monitoring in ICU sedation management.