What is the management plan for a 10-year-old male with influenza, high fever, and inability to walk?

Differential Diagnosis and Management for a 10-Year-Old Male with Influenza, High Fever, and Inability to Walk

This child requires immediate hospital admission for assessment of serious influenza complications, particularly myositis, encephalopathy, or sepsis—the inability to walk is a red flag indicating severe disease beyond uncomplicated influenza. 1

Critical Red Flags Present

This patient meets multiple criteria for hospital admission based on British Infection Society guidelines: 1

• Altered functional status (inability to walk represents significant neurological or musculoskeletal impairment) 1
• High fever >38.5°C in the context of inability to ambulate suggests severe systemic illness 1

Differential Diagnosis for Inability to Walk in Influenza

Primary Considerations:

1. Influenza-Associated Myositis 2, 3

• Presents with severe muscle pain, weakness, and refusal to walk 2, 3
• Can progress to myoglobinuria and acute renal failure 2, 3
• More common in children with influenza A 3
• Check: CK levels (markedly elevated), myoglobin in urine, renal function 2, 3

2. Influenza-Associated Encephalopathy 1

• Altered conscious level is an explicit admission criterion 1
• Assess: Glasgow Coma Scale, focal neurological signs, seizure activity 1
• Can present with confusion, ataxia, or inability to coordinate movement 2, 3

3. Secondary Bacterial Sepsis/Septic Arthritis 1, 3

• Signs include extreme pallor, hypotension, "floppy" appearance 1
• Staphylococcus aureus (including MRSA) is a critical pathogen in influenza complications 3
• Examine joints for warmth, swelling, effusion 3

4. Guillain-Barré Syndrome 2

• Rare neurological complication of influenza 2
• Presents with ascending weakness, areflexia 2
• Requires urgent neurological assessment 2

Immediate Management Algorithm

Step 1: Urgent Hospital Assessment 1

Vital Signs and Physical Examination: 1

• Respiratory rate (tachypnea suggests respiratory distress) 1
• Oxygen saturation (hypoxia <92% requires oxygen therapy) 4
• Blood pressure and perfusion (hypotension indicates shock) 1
• Neurological examination (conscious level, focal deficits, meningismus) 1
• Musculoskeletal examination (muscle tenderness, joint examination, ability to bear weight) 2, 3

Step 2: Laboratory Investigations 1

Mandatory blood tests: 1

• Full blood count with differential (leukopenia common in influenza A; WBC <4 in 27% of children) 1
• Creatine kinase (markedly elevated in myositis) 2, 3
• Urea, creatinine, electrolytes (assess renal function and hydration) 1
• Liver enzymes (elevated in 27% of influenza patients) 1
• Blood culture (before antibiotics) 1, 4
• Myoglobin if CK elevated (indicates rhabdomyolysis risk) 2, 3

Additional testing based on presentation: 1

• Chest radiograph if hypoxic, severe illness, or respiratory signs 1, 4
• Lumbar puncture if encephalopathy or meningismus present 2, 3

Step 3: Immediate Pharmacological Treatment 1, 4

Antiviral Therapy: 1, 4, 5

• Oseltamivir 30-75 mg orally twice daily for 5 days (weight-based dosing: 15-23 kg = 45 mg; 23-40 kg = 60 mg; >40 kg = 75 mg) 1, 4, 5
• Start immediately—do not wait for laboratory confirmation 1, 4, 5
• Can be given even if >48 hours from symptom onset in severely ill hospitalized children 1, 5

Antibiotic Coverage: 1, 4

• Co-amoxiclav IV (covers S. pneumoniae, S. aureus, H. influenzae) 1, 4
• This child meets high-risk criteria requiring antibiotics (inability to walk represents severe systemic illness) 1
• If penicillin allergic: cefuroxime IV or clarithromycin IV 1, 4
• Consider adding clarithromycin or cefuroxime as second agent if severely ill with pneumonia 1, 4

Supportive Care: 1, 4

• Antipyretics (acetaminophen or ibuprofen—never aspirin in children <16 years) 1
• IV fluids at 80% basal levels if on oxygen therapy (prevent SIADH complications) 1, 4
• Monitor serum electrolytes if receiving IV fluids 1, 4

Step 4: Monitoring and Escalation Criteria 1, 4

Continuous monitoring required: 1, 4

• Heart rate, respiratory rate, oxygen saturation, neurological status 1, 4
• Four-hourly assessments minimum if on oxygen 1, 4

Transfer to HDU/PICU if: 1

• Failing to maintain SpO2 >92% despite FiO2 >60% 1, 4
• Evidence of shock 1
• Severe respiratory distress with PaCO2 >6.5 kPa 1
• Evidence of encephalopathy 1
• Recurrent apnea or irregular breathing 1

Critical Pitfalls to Avoid

Do not manage this child at home. 1 The inability to walk in the context of influenza represents severe disease requiring hospital assessment—this is not simple myalgia from uncomplicated influenza. 1, 2, 3

Do not delay antibiotics. 1, 4 Secondary bacterial infection, particularly with S. aureus, carries high mortality in influenza patients and must be covered empirically. 3

Do not withhold oseltamivir based on symptom duration. 1, 5 In severely ill hospitalized children, oseltamivir should be given regardless of time from symptom onset. 1, 5

Do not miss rhabdomyolysis. 2, 3 Check CK and myoglobin urgently—myositis can progress to acute renal failure requiring aggressive fluid resuscitation. 2, 3

Do not use aspirin for fever control. 1 Aspirin is contraindicated in children under 16 years due to Reye's syndrome risk. 1