In an adult intubated patient on mechanical ventilation who cannot speak, how should delirium be screened, which tool should be used, how often, and what sedation level is required?

Delirium Assessment in Intubated Patients

All intubated adult ICU patients on mechanical ventilation should be screened for delirium using the CAM-ICU (Confusion Assessment Method for the ICU) at least once every 8-12 hours (every nursing shift), and the patient must be arousable to voice (RASS -3 or higher) to complete the assessment. 1, 2

Recommended Assessment Tool

The CAM-ICU is the preferred validated tool for intubated patients because it:

• Was specifically designed and validated for mechanically ventilated patients who cannot speak 3, 4
• Demonstrates excellent psychometric properties with a weighted score of 19.6 out of 20 2
• Can be completed in less than 2 minutes by bedside nurses and physicians 2
• Shows high sensitivity (78-80%) and specificity (95%) for detecting delirium 4
• Has excellent interrater reliability (kappa 0.79-0.95) when used by trained ICU staff 3

The ICDSC (Intensive Care Delirium Screening Checklist) is an acceptable alternative with a weighted score of 16.8 out of 20, though CAM-ICU remains first-choice 2.

Required Sedation Level for Assessment

Patients must be arousable to verbal stimulation (RASS score of -3 or higher) to complete a valid CAM-ICU assessment. 1

• Deeply sedated patients (RASS -4 or -5) or comatose patients should be documented as "unable to assess" (UTA) - this is an appropriate UTA designation 3, 5
• Light sedation (versus deep sedation) is recommended to facilitate delirium screening 1
• The assessment evaluates four key domains: acute onset/fluctuating course, inattention, altered level of consciousness, and disorganized thinking 2, 3

Assessment Frequency

Screen every 8-12 hours (at minimum once per nursing shift) because: 2, 6

• Mental status fluctuates substantially throughout the day 1, 6
• Delirium can develop rapidly in response to new medications, procedures, or metabolic changes 6
• Early detection enables prompt investigation and treatment of reversible causes 2

Critical Clinical Considerations

Hypoactive Delirium is Commonly Missed

• Hypoactive delirium accounts for 60-64% of all delirium cases in mechanically ventilated patients but is frequently unrecognized without structured screening 7
• This "quiet" subtype is characterized by decreased responsiveness and withdrawal rather than agitation 7
• Without validated tools, clinicians miss delirium in the majority of cases 1, 6

High-Risk Populations Requiring Mandatory Monitoring

All mechanically ventilated patients require routine screening, with particular vigilance for: 2

• History of alcoholism, cognitive impairment, or hypertension
• Severe sepsis or shock
• Receiving parenteral sedatives (especially benzodiazepines) and opioids
• Post-cardiac surgery patients
• Trauma and emergency surgery patients

Persistent Delirium After Sedation Cessation

Delirium persists for ≥4 hours after stopping sedatives in approximately 75-83% of patients, indicating that delirium is not simply medication-induced but reflects underlying brain dysfunction requiring ongoing assessment and management 8. Patients with persistent delirium have significantly longer ICU stays compared to those with rapidly reversible delirium 8.

Common Pitfalls to Avoid

• Do not skip assessments in "quiet" patients - hypoactive delirium is the most common subtype and carries the same poor prognosis as hyperactive delirium 7
• Avoid documenting "unable to assess" inappropriately - approximately 30% of UTA documentations are inappropriate when patients are actually arousable enough for assessment 5
• Do not rely on clinical gestalt alone - without structured tools, delirium detection rates drop dramatically 1, 6
• Avoid using benzodiazepines for sedation when possible, as they are strongly associated with increased delirium risk 1

Clinical Impact of Systematic Screening

Routine delirium monitoring with CAM-ICU is essential because undetected delirium independently predicts: 2, 6

• Increased in-hospital and post-discharge mortality
• Prolonged ICU and hospital length of stay
• Persistent cognitive impairment lasting months to years after discharge
• Higher healthcare costs and worse functional outcomes