How do I perform a CAM‑ICU (Confusion Assessment Method for the Intensive Care Unit) assessment on a 70‑year‑old postoperative coronary artery bypass graft (CABG) patient?

CAM-ICU Assessment in Postoperative CABG Patients

The CAM-ICU (Confusion Assessment Method for the Intensive Care Unit) is a validated, rapid delirium screening tool that should be performed twice daily for at least 4 days postoperatively in your 70-year-old CABG patient, with assessments ideally conducted in both morning and afternoon to maximize detection sensitivity. 1, 2

Why Perform CAM-ICU Assessment

• Delirium is extremely common after CABG surgery, occurring in 50-83% of patients, making routine monitoring essential for early detection and management 3, 4
• The CAM-ICU demonstrates excellent validity and reliability with sensitivity of 93-100% and specificity of 89-100% when used by trained ICU nurses and physicians 5, 4
• Delirium monitoring is strongly recommended for ICU patients at moderate to high risk, which includes all postoperative CABG patients on mechanical ventilation or receiving sedatives 1

How to Perform the CAM-ICU Assessment

The CAM-ICU evaluates four key features in sequence:

Feature 1: Acute Change or Fluctuation in Mental Status

• Assess whether there is an acute change from baseline mental status 5
• Determine if the patient's mental status has fluctuated during the past 24 hours 1
• This feature must be present to proceed with assessment 5

Feature 2: Inattention

• Use standardized attention tests (e.g., Attention Screening Examination with visual or auditory components) 5
• Ask the patient to squeeze your hand only when you say the letter "A" in a series of letters 4
• This feature must be present for delirium diagnosis 1
• Note: This feature has lower sensitivity (37%) in non-ICU settings and may require assessment over longer periods 6

Feature 3: Altered Level of Consciousness

• Assess using the Richmond Agitation-Sedation Scale (RASS) 5
• Any RASS score other than "0" (alert and calm) indicates altered consciousness 4
• Exclude comatose patients (RASS -4 or -5) as they cannot be assessed for delirium features 5

Feature 4: Disorganized Thinking

• Ask a series of yes/no questions and simple commands 5
• Examples: "Will a stone float on water?" "Are there fish in the sea?" 4
• Command: "Hold up this many fingers" (while holding up two fingers) 4
• This feature has the highest sensitivity (60%) for detecting delirium 6

Diagnostic Criteria

Standard CAM-ICU: Delirium is present when Features 1 AND 2 are present, PLUS either Feature 3 OR Feature 4 1, 5

Important caveat: In non-ICU ward settings after transfer from ICU, a modified approach using any two of Features 1,3, or 4 may improve sensitivity to 80% while maintaining reasonable specificity of 82% 6

Assessment Timing and Duration

• Perform assessments twice daily (morning and afternoon) as delirium is detected more frequently in morning assessments (10% vs 7% in evenings) 2
• Continue for at least 4 days postoperatively, which detects 97% of delirium cases with 20% fewer assessments than 5 days 2
• 65% of delirium cases are identified by the end of postoperative day 1, emphasizing the importance of early screening 2
• The assessment takes approximately 2 minutes to complete 4

Risk Factors Specific to Your CABG Patient

Your 70-year-old patient has several baseline risk factors to consider:

• Age: While controversial in ICU settings, older age remains a significant risk factor 1, 3
• History of hypertension, diabetes, or alcoholism significantly increases delirium risk 1, 3
• Prolonged surgical duration (each additional hour increases risk) 3
• Postoperative complications within the first 24 hours increase risk 2.5-fold 3
• Elevated serum cortisol levels on postoperative day 1 are independently associated with 3-fold increased delirium risk 3

Clinical Implications

• Patients who develop delirium have worse outcomes including higher complication rates, prolonged ICU stays, and longer hospital stays 3
• Continuous cardiac monitoring should be maintained for at least 48 hours postoperatively to detect arrhythmias, which commonly occur alongside delirium 7
• Early detection allows for prompt intervention including cognitive behavioral therapy or collaborative care, which can reduce depression and improve outcomes 8, 7

Common Pitfalls to Avoid

• Do not skip assessments in apparently "alert" patients: Delirium occurs in 39.5% of alert or easily aroused patients 4
• Do not rely on clinical gestalt alone: Without validated tools, clinicians have high "miss rates" for delirium detection 1
• Do not assess comatose patients (RASS -4 or -5) as they lack the interactive capacity needed for CAM-ICU evaluation 5, 4
• Ensure proper training: Both nurses and physicians require training to achieve optimal interrater reliability (kappa 0.79-0.96) 5, 4