What is the management for a patient presenting with fever, headache, vomiting, hypoxemia, and altered mental status?

Management of Fever, Headache, Vomiting, Hypoxemia, and Altered Mental Status

This patient requires immediate emergency transport to hospital within one hour, aggressive fluid resuscitation, empiric broad-spectrum antibiotics (ceftriaxone 2g IV plus vancomycin 15-20 mg/kg IV), supplemental oxygen to correct hypoxemia, and urgent CT head followed by lumbar puncture—this presentation strongly suggests bacterial meningitis with sepsis, which can deteriorate rapidly and requires treatment within the first hour to prevent death. 1, 2, 3

Immediate Life-Threatening Actions (Within 1 Hour)

Oxygen and Hemodynamic Support

• Start supplemental oxygen immediately to target SpO2 >94% given the current hypoxemia at 89%. 2
• Begin aggressive IV crystalloid boluses to restore intravascular volume and correct hypotension if present, targeting normalization of heart rate, blood pressure, capillary refill time, urine output, and mental status. 2
• If hypotension persists despite fluid resuscitation, this indicates septic shock requiring ICU admission. 2, 3

Empiric Antibiotic Therapy (Do Not Delay)

• Administer ceftriaxone 2g IV PLUS vancomycin 15-20 mg/kg IV immediately after obtaining blood cultures (but do not delay antibiotics beyond a few minutes waiting for cultures). 2, 3
• This regimen covers Streptococcus pneumoniae (including resistant strains), Neisseria meningitidis, and other common bacterial pathogens. 2, 3
• Add ampicillin 2g IV every 4 hours if the patient is >50 years old, immunocompromised, or has risk factors for Listeria monocytogenes. 2, 3
• Add dexamethasone 10mg IV before or with the first antibiotic dose to reduce neurological complications if bacterial meningitis is suspected. 2

Emergency Transport

• Arrange rapid emergency ambulance transport to ensure hospital arrival within 1 hour of initial assessment, as delay significantly increases mortality. 1, 2, 3

Critical Clinical Assessment

Document These Specific Features

• Presence or absence of neck stiffness (though absence does not exclude meningitis—elderly patients and those with early disease frequently lack this finding). 1, 3
• Type and distribution of any rash, particularly petechial or purpuric rash (when present with meningitis, Neisseria meningitidis is the causative organism in 92% of cases). 3
• Signs of shock: hypotension, prolonged capillary refill time, cold extremities. 1, 2, 3
• Seizure activity (current or recent). 1, 3

Do Not Rely On These Signs

• Kernig's sign and Brudzinski's sign should not be relied upon for diagnosis—they have very poor sensitivity (5-11%) and their absence does not exclude meningitis. 1, 2, 4

Essential Diagnostic Studies (Do Not Delay Treatment)

Immediate Laboratory Testing

• Obtain at least 3 sets of blood cultures before antibiotics if possible, but do not delay treatment beyond a few minutes. 2
• CBC with differential to assess for leukopenia, thrombocytopenia, or leukocytosis. 2, 3
• Metabolic panel to assess for hyponatremia (present in ~60% of encephalitis cases), renal dysfunction, and electrolyte abnormalities. 1, 2, 3
• Lactate level—lactate >4 mmol/L indicates high risk for fatal outcome. 2, 3
• Inflammatory markers (C-reactive protein, procalcitonin) to assess severity. 2

Neuroimaging

• CT head without contrast is mandatory before lumbar puncture given the altered mental status. 2, 3
• This identifies contraindications to LP such as mass effect, obstructive hydrocephalus, or posterior fossa lesions. 2

Lumbar Puncture

• Perform LP urgently once CT clears the patient, ideally within 4 hours of starting antibiotics to maximize culture yield. 2, 3
• CSF analysis must include: cell count with differential, glucose, protein, Gram stain, bacterial culture, and viral PCR panel. 2
• In elderly or immunocompromised patients, CSF findings can be minimal despite severe infection. 3

Risk Stratification for Fatal Outcome

High-Risk Features Indicating Severe Disease

• Rapidly progressing symptoms 3
• Coma or profound altered consciousness 3
• Hypotension and shock 3
• Lactate >4 mmol/L 2, 3
• Low or normal white blood cell count (paradoxical leukopenia indicates overwhelming sepsis) 3
• Low platelets and coagulopathy 3
• Absence of meningitis with sepsis alone (worse prognosis than meningitis with sepsis) 3

Differential Diagnoses to Consider

Bacterial Meningitis (Most Likely)

• The combination of fever, headache, vomiting, and altered mental status strongly suggests meningitis. 1, 3
• The classic triad (fever, neck stiffness, altered mental status) is present in less than 50% of bacterial meningitis cases. 4
• Elderly patients are more likely to have altered consciousness and less likely to have neck stiffness or fever. 1, 3

Viral Encephalitis

• Defined as altered mental status lasting ≥24 hours plus at least 2 of: documented fever ≥38°C within 72 hours, seizures, new focal neurologic findings, CSF WBC ≥5/mm³, abnormal neuroimaging, or abnormal EEG. 3
• Patients with NMDA receptor antibody-associated encephalitis often present with headache and fever as earliest symptoms, followed by seizures, confusion, and psychosis. 1
• VGKC-complex antibody encephalitis presents with profound disorientation and confusion with seizures and amnesia, often with hyponatremia (~60%). 1

Meningococcal Sepsis

• Can deteriorate extremely rapidly even if initially appearing stable. 3
• 37% of meningococcal cases have no rash, so absence of rash does not exclude this diagnosis. 3

Tuberculosis Meningitis

• Consider in patients with subacute onset of symptoms, particularly with cranial nerve palsies (especially sixth nerve). 4
• CSF typically shows lymphocytic pleocytosis, elevated protein, and low glucose, but acid-fast bacilli smear is frequently negative. 4
• Treatment must be started based on clinical suspicion due to high mortality with delayed treatment. 4

Hospital Admission and Monitoring

ICU Admission Criteria

• Persistent hypotension despite fluid resuscitation 2
• Altered consciousness (already present in this patient) 2
• Respiratory distress or hypoxemia requiring supplemental oxygen 2

Ongoing Monitoring

• Monitor for signs of clinical deterioration—patients with meningitis can deteriorate rapidly even if initially appearing stable. 2, 3
• Frequent reassessment of vital signs, mental status, and neurological examination. 3

Critical Pitfalls to Avoid

• Never delay antibiotics waiting for lumbar puncture or neuroimaging—this significantly increases mortality. 2, 3
• Do not underestimate severity based on initial vital signs—patients with sepsis can deteriorate rapidly. 2
• Do not rely on neck stiffness to rule in or rule out meningitis—sensitivity is only 31% in adults. 4
• Do not assume absence of rash excludes meningococcal disease—37% have no rash. 3
• In elderly patients, do not expect typical presentation—they often lack fever and neck stiffness but have prominent altered consciousness. 1, 3