What are the admission criteria for patients with influenza (flu)?

Hospital Admission Criteria for Influenza

Patients with influenza should be admitted to the hospital if they exhibit signs of respiratory distress, cyanosis, severe dehydration, altered consciousness, complicated seizures, or signs of septicemia, as these indicators predict significant morbidity and mortality. 1

Adult Admission Criteria

Severity Assessment Using CURB-65

• Patients with a CURB-65 score of 3 or more are at high risk of death and require immediate hospital admission for management of severe pneumonia 1
• Patients with a CURB-65 score of 2 are at increased risk of death and should be considered for short-stay inpatient treatment or hospital-supervised outpatient treatment based on clinical judgment 1
• Patients with bilateral lung infiltrates on chest radiography consistent with primary viral pneumonia should be managed as having severe pneumonia regardless of CURB-65 score 1

Clinical Indicators for Admission

• Severe dehydration represents substantial fluid deficit that may worsen rapidly and is an explicit criterion for hospital admission, particularly in obese patients where "mild" dehydration may represent significant volume loss 2
• Increased weakness or altered functional status suggests potential early sepsis or influenza-associated complications requiring monitoring 2
• Inability to maintain adequate oral hydration due to breathlessness, fatigue, or gastroenteritis necessitates hospital-level fluid therapy 1
• Oxygen saturation ≤92% on room air requires hospital admission for oxygen therapy 1

Community Referral Criteria

• Patients with bilateral chest signs or CRB-65 score of 3 or more should be urgently referred to hospital from the community 1
• GPs should consider administering antibiotics immediately for life-threatening illness or when admission delays exceed two hours 1

Pediatric Admission Criteria

Primary Indicators for Hospital Admission

• Signs of respiratory distress including markedly raised respiratory rate, grunting, intercostal recession, or breathlessness with chest signs 1
• Cyanosis 1
• Severe dehydration 1
• Altered conscious level 1
• Complicated or prolonged seizure 1
• Signs of septicemia including extreme pallor, hypotension, or floppy infant 1

Additional High-Risk Features Requiring Evaluation

Children with high fever (>38.5°C) plus cough or influenza-like symptoms and any of the following should be seen by a GP or in A&E for potential admission 1:

• Breathing difficulties 1
• Severe earache 1
• Vomiting >24 hours 1
• Drowsiness 1
• Chronic co-morbid disease 1

Age-Specific Considerations

• Children aged <1 year with fever and respiratory symptoms should be seen by a GP with a low threshold for hospital admission 1
• Most children admitted to hospital with influenza require oxygen therapy and/or intravenous support as well as antibiotics and oseltamivir 1

ICU/HDU Transfer Criteria

Adult Patients

Transfer to high dependency or intensive care should occur when patients meet specific physiologic thresholds indicating impending respiratory failure or shock 1

Pediatric Patients

Indications for transfer to high dependency or intensive care include 1:

• Failure to maintain SaO2 >92% in FiO2 >60% 1
• Shock 1
• Severe respiratory distress with raised PaCO2 (>6.5 kPa) 1
• Rising respiratory rate and pulse rate with clinical evidence of severe respiratory distress with or without raised PaCO2 1
• Recurrent apnea or slow irregular breathing 1
• Evidence of encephalopathy 1

Common Pitfalls to Avoid

• Do not rely on rapid antigen tests alone in critically ill patients as they have lower sensitivity; negative results should not guide clinical decisions, and molecular assays should be performed 3
• Do not delay antiviral treatment while awaiting test results in patients meeting admission criteria, as earlier initiation is associated with greatest clinical benefit 3
• In critically ill patients with lower respiratory tract disease, test endotracheal aspirate or bronchoalveolar lavage fluid (not just upper respiratory specimens) as viral clearance may differ between upper and lower respiratory tracts 3
• When PICU beds are unavailable, triage children based on severity of acute and co-existing disease and likelihood of achieving full recovery 1