What are the indications for Intensive Care Unit (ICU) or High Care Unit (HCU) admission?

ICU and HCU Admission Indications

Patients requiring organ support for acute vital function failure or those with multiple organ dysfunction requiring close monitoring and intervention should be admitted to the ICU, while those needing enhanced monitoring without full organ support may be appropriate for HCU admission. 1

Absolute Indications for Direct ICU Admission

Major Criteria (Any One Requires ICU)

• Septic shock requiring vasopressors after adequate fluid resuscitation, defined as hypotension (SBP <90 mmHg) with clinical evidence of shock (altered consciousness, decreased urine output, end-organ dysfunction) 1, 2

• Acute respiratory failure requiring invasive mechanical ventilation, including:

  • Refractory hypoxemia (SpO2 <90% on non-rebreather mask/FiO2 >0.85) 1, 2
  • Respiratory acidosis with pH <7.2 1, 2
  • Clinical evidence of impending respiratory failure 1, 2
  • Inability to protect or maintain airway due to altered consciousness or secretions 1, 2

• Multiple organ failures (two or more acute vital organ failures) requiring pharmacological and device-related support such as hemodynamic support, respiratory assistance, or renal replacement therapy 1

Indications for ICU or High-Level Monitoring Unit

Minor Criteria (≥3 Criteria Warrant ICU/HCU Admission)

For patients meeting at least 3 of the following minor criteria, direct admission to ICU or high-level monitoring unit is recommended 1, 2:

• Respiratory rate ≥30 breaths/minute 1, 2
• PaO2/FiO2 ratio ≤250 1, 2
• Systolic blood pressure ≤90 mmHg 1, 2
• Multilobar infiltrates on imaging 1, 2
• Confusion/disorientation 1
• Blood urea nitrogen ≥20 mg/dL 1
• Leukopenia (WBC <4,000 cells/mm³) 1
• Thrombocytopenia (platelets <100,000/mm³) 1
• Hypothermia (core temperature <36°C) 1

This approach achieves 78% sensitivity and 94% specificity for predicting ICU need when using two of three specific criteria (systolic BP ≤90 mmHg, multilobar disease, PaO2/FiO2 ≤250) or one major criterion 2.

Disease-Specific ICU Admission Criteria

Acute-on-Chronic Liver Failure (ACLF)

Patients with ACLF requiring close monitoring or organ support should be admitted to the ICU 1:

• Any patient with organ failure(s) requiring active support 1
• Patients with severe comorbidities should be considered on a case-by-case basis 1
• Prognosis should be reassessed after 3-7 days of full organ support 1
• Consider withdrawal of support for patients with >4 organ failures or CLIF-C ACLF score >70 points without transplant option after 3-7 days 1

Cardiovascular Emergencies

ICU admission significantly reduces mortality in acute myocardial infarction, acute aortic dissection, and post-cardiac arrest patients compared to general ward admission 3:

• Acute myocardial infarction with hemodynamic instability 3
• Acute aortic dissection 3
• Post-cardiac arrest requiring ongoing resuscitation 3
• Acute heart failure with respiratory compromise 3

High Care Unit (HCU) Criteria

HCU is appropriate for patients requiring enhanced monitoring (Level I care) but not full organ support 1:

• Single organ dysfunction with reasonable expectation of recovery 1
• Patients at risk of deterioration requiring closer monitoring than general ward 1
• Post-operative patients requiring intensive monitoring but not mechanical ventilation or vasopressors 1
• Nurse-to-patient ratio of 1:3 with 2 FTE per bed annually 1

Exclusion Criteria from ICU Admission

The following patients generally should not be admitted to ICU, particularly during resource constraints 1:

Absolute Exclusions

• Severe trauma with TRISS predicted mortality >80% 1
• Severe burns with age >60 years AND >40% total body surface area AND inhalation injury (any two criteria) 1
• Unwitnessed cardiac arrest or cardiac arrest not responsive to electrical therapy 1
• Metastatic malignant disease 1
• End-stage organ failure (NYHA class III/IV heart failure, COPD with FEV1 <25% predicted, advanced cirrhosis without transplant option) 1
• Severe baseline cognitive impairment requiring institutionalization 1
• Advanced irreversible immunocompromised state (AIDS without treatment options) 1

Critical Pitfalls to Avoid

Do not rely solely on age or single parameters when making ICU admission decisions 2:

• Delayed ICU transfer for respiratory failure or septic shock is associated with increased mortality 1
• Approximately 45% of patients ultimately requiring ICU are initially admitted to non-ICU settings, representing missed opportunities for early intervention 1
• Early recognition and prompt triage within 3-7 days improves outcomes 1
• Severity indices may underestimate illness in certain populations, requiring clinical judgment beyond scoring systems 2

Practical Implementation

ICU admission criteria should be objective, ethical, transparent, and applied equitably 1:

• Establish clear protocols for triage decisions 1
• Reassess patients at regular intervals (48 and 120 hours) for ongoing ICU appropriateness 4
• Consider availability of high-level monitoring units as an intermediate option between ICU and general ward 1
• Document rationale for admission decisions and communicate clearly with patients and families 1