Cam Icu Calculator

Screen for delirium in ICU patients using the Confusion Assessment Method for ICU. Enter values for instant results with step-by-step formulas.

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Formula

CAM-ICU Positive = Feature 1 + Feature 2 + (Feature 3 OR Feature 4)

Delirium is present when both Feature 1 (acute onset or fluctuating course) AND Feature 2 (inattention) are present, PLUS either Feature 3 (altered level of consciousness, RASS not 0) OR Feature 4 (disorganized thinking). If RASS is -4 or -5, the patient is too sedated to assess.

Worked Examples

Example 1: Positive CAM-ICU in Postoperative Patient

Problem: A 70-year-old post-cardiac surgery patient, RASS -1, was previously alert and oriented but has been intermittently confused over the past 12 hours. On the letter attention test (SAVEAHAART), the patient makes 4 errors. The patient answers yes when asked if a stone floats on water.

Solution: RASS: -1 (Drowsy) - assessable for delirium\nFeature 1 (Acute onset/fluctuation): POSITIVE - was oriented, now intermittently confused\nFeature 2 (Inattention): POSITIVE - 4 errors on ASE (>2 errors)\nFeature 3 (Altered LOC): POSITIVE - RASS -1 (not zero)\nFeature 4 (Disorganized thinking): POSITIVE - incorrect answer\nCAM-ICU = Feature 1 + Feature 2 + Feature 3 = POSITIVE

Result: CAM-ICU: POSITIVE - Delirium Present | Subtype: Hypoactive (RASS -1)

Example 2: Negative CAM-ICU in Sedated Patient

Problem: A 55-year-old mechanically ventilated patient on propofol, RASS 0 (alert and calm during awakening trial). No change from baseline mental status. On the letter attention test, the patient makes 1 error. The patient correctly answers all orientation questions.

Solution: RASS: 0 (Alert and Calm) - assessable for delirium\nFeature 1 (Acute onset/fluctuation): NEGATIVE - no change from baseline\nBecause Feature 1 is negative, CAM-ICU is NEGATIVE\n(Features 2-4 do not need to be positive if Feature 1 is negative)

Result: CAM-ICU: NEGATIVE - No Delirium Detected

Frequently Asked Questions

What is the CAM-ICU and what does it screen for?

The Confusion Assessment Method for the ICU (CAM-ICU) is a validated bedside screening tool designed to detect delirium in critically ill patients, including those who are mechanically ventilated and unable to speak. Developed by Dr. Wes Ely and colleagues at Vanderbilt University in 2001, it adapts the original Confusion Assessment Method for use in the ICU setting. The CAM-ICU assesses four features: acute onset or fluctuating mental status, inattention, altered level of consciousness, and disorganized thinking. Delirium is diagnosed when Features 1 and 2 are present along with either Feature 3 or Feature 4. The tool has a sensitivity of 93 to 100 percent and specificity of 89 to 100 percent for detecting delirium when performed by trained nurses, making it highly accurate for bedside screening.

How do you assess Feature 1 of the CAM-ICU?

Feature 1 evaluates whether there has been an acute change in mental status from the patient baseline or any fluctuation in mental status over the past 24 hours. This assessment requires knowledge of the patient prior to their current illness, which may come from family members, prior medical records, or nursing assessments from previous shifts. Acute onset refers to a sudden change from the patient normal cognitive function, such as a previously alert patient becoming confused or agitated. Fluctuating course means the mental status has varied during the current illness, waxing and waning between normal and abnormal. This can be assessed by reviewing the RASS or GCS scores documented over the past 24 hours and identifying any significant variations. If either acute onset or fluctuating course is present, Feature 1 is scored as positive.

How is Feature 2 (Inattention) tested in the CAM-ICU?

Feature 2 assesses inattention using either the Attention Screening Examination (ASE) with letters or pictures. For the auditory ASE, the examiner reads a series of 10 letters (S-A-V-E-A-H-A-A-R-T) and asks the patient to squeeze their hand only when they hear the letter A. There are 4 target letters (A) and 6 non-target letters. Errors include both failing to squeeze on A and squeezing on non-A letters. If the patient makes more than 2 errors out of 10, Feature 2 is positive for inattention. For patients who cannot hear well, a visual ASE using picture recognition can be used instead, where patients are shown 5 pictures and then asked to identify which pictures are new from a mixed set. More than 2 errors on either test indicates clinically significant inattention consistent with delirium.

What are the subtypes of ICU delirium?

ICU delirium is classified into three subtypes based on the patient psychomotor activity level, which can be assessed using the RASS score in conjunction with the CAM-ICU. Hyperactive delirium (RASS +1 to +4) involves agitation, restlessness, and sometimes combativeness, and accounts for only about 1 to 2 percent of all ICU delirium cases. Hypoactive delirium (RASS -1 to -3) is characterized by decreased alertness, reduced motor activity, and withdrawal, and is the most common subtype accounting for approximately 44 to 64 percent of cases. Mixed delirium alternates between hyperactive and hypoactive phases and accounts for roughly 6 to 55 percent of cases depending on the study. Hypoactive delirium is often underdiagnosed because patients appear calm and cooperative, yet it carries the worst prognosis of all subtypes.

How often should CAM-ICU screening be performed?

The Society of Critical Care Medicine PADIS guidelines recommend screening for delirium at least once per nursing shift, which typically means every 8 to 12 hours. However, many high-performing ICUs screen more frequently, performing CAM-ICU assessments every 4 hours or even at every RASS assessment. More frequent screening increases the sensitivity for detecting delirium, particularly the hypoactive and mixed subtypes that may fluctuate throughout the day. The CAM-ICU should also be performed whenever there is a clinically significant change in mental status, after sedation interruptions or spontaneous awakening trials, and when family members report that the patient seems confused or different. Consistent screening with documented results helps track delirium duration, which is an important prognostic indicator since longer delirium duration is associated with worse cognitive outcomes at hospital discharge.

What are the risk factors for developing ICU delirium?

ICU delirium has numerous risk factors that are categorized as predisposing (baseline patient characteristics) and precipitating (ICU-specific factors). Major predisposing factors include advanced age over 65 years, pre-existing cognitive impairment or dementia, history of alcohol abuse, high severity of illness scores at admission, and vision or hearing impairment. Key precipitating factors include benzodiazepine use (the strongest modifiable medication risk factor), opioid administration, sleep deprivation, physical restraints, immobility, lack of natural light exposure, absence of familiar objects or family presence, and environmental factors like noise and frequent interruptions. Medical precipitants include sepsis, hypoxia, metabolic derangements, and major surgery. Understanding these risk factors enables implementation of preventive strategies through the ABCDEF bundle that targets modifiable risk factors.