What is the step‑by‑step management of a patient with community‑acquired pneumonia in the emergency department?

Step-by-Step Management of Community-Acquired Pneumonia in the Emergency Department

Upon arrival in the ED, immediately assess severity using clinical criteria and initiate oxygen therapy targeting SpO2 >92% and PaO2 >8 kPa, as severity assessment is the key to planning appropriate management and reducing mortality. 1

Step 1: Immediate Assessment and Severity Stratification

Assess vital signs and adverse prognostic features immediately:

• Measure respiratory rate (>30/min indicates severe disease) 2, 3
• Check blood pressure (systolic <90 mmHg or diastolic <60 mmHg indicates severe disease) 3
• Assess mental status (confusion or drowsiness indicates severe disease or hypercapnia) 1, 2
• Measure temperature (>38°C or ≤36°C supports diagnosis) 4
• Obtain pulse oximetry immediately (SpO2 <92% is an adverse prognostic feature) 1
• Check for bilateral or multilobar involvement on imaging (indicates worse prognosis) 1, 3

Obtain arterial blood gas if patient appears critically ill or has SpO2 <85%: 2

• ABG is essential for critically ill patients rather than capillary sampling 2
• Assess for hypercapnia, especially in patients with acute deterioration 2

Step 2: Oxygen Therapy and Respiratory Support

Initiate high-flow oxygen immediately:

• Use reservoir mask at 15L/min for patients with SpO2 <85% 2
• Target SpO2 94-98% (or >92% minimum) and PaO2 >8 kPa 1, 2, 5
• High concentrations of oxygen can safely be given in uncomplicated pneumonia 1

For patients with pre-existing COPD:

• Use controlled oxygen therapy guided by repeated arterial blood gas measurements to avoid hypercapnia 1, 5

Consider ICU admission if:

• Respiratory rate >30/min with bilateral involvement 3
• Oxygen requirement of 15L via non-rebreather mask (FiO2 ~80-90%) 2
• PaO2/FiO2 ratio <250 3
• Prepare for non-invasive ventilation or intubation if worsening despite maximal oxygen 2

Step 3: Diagnostic Workup

Obtain chest radiograph immediately:

• Confirm diagnosis with air space density 4
• Assess for bilateral or multilobar involvement (adverse prognostic feature) 1, 3
• Rule out complications such as pleural effusion, pneumothorax, or hemothorax 2, 3

Laboratory testing:

• Complete blood count (leukocyte count <4000/μL or >10,000/μL supports diagnosis) 4
• Basic metabolic panel to assess for metabolic acidosis and renal function 2, 3
• CRP level (useful for monitoring response to treatment) 1, 3
• Arterial blood gas if critically ill or SpO2 <85% 2

Pathogen-specific testing:

• Test for COVID-19 and influenza when these viruses are common in the community, as diagnosis affects treatment and infection prevention strategies 4
• Only 38% of hospitalized CAP patients have a pathogen identified 4

Step 4: Fluid Resuscitation and Hemodynamic Support

Assess for volume depletion and initiate IV fluids:

• All patients should be assessed for volume depletion and may require intravenous fluids 1, 5, 3
• Patients with severe sepsis require adequate fluid resuscitation 3
• Monitor for signs of septic shock requiring vasopressor support 3

Step 5: Empirical Antibiotic Therapy

For hospitalized patients without risk factors for resistant bacteria:

• Administer β-lactam/macrolide combination therapy: ceftriaxone combined with azithromycin 4
• Alternative: combined oral therapy with amoxicillin and a macrolide (erythromycin or clarithromycin) for non-severe CAP 1
• Most hospitalized patients can be adequately treated with oral antibiotics 1

For severe CAP requiring ICU admission:

• Use combination therapy with anti-pseudomonal β-lactam plus macrolide or respiratory fluoroquinolone 3, 6
• Consider adding coverage for methicillin-resistant Staphylococcus aureus or Pseudomonas only if risk factors present 6

Timing considerations:

• Administer antibiotics immediately if illness is life-threatening or delays in admission exceed 2 hours 1
• Do not change antibiotics within first 72 hours unless marked clinical deterioration occurs 3
• Minimum treatment duration is 3 days for responding patients 4

For severe CAP with systemic corticosteroids:

• Administer systemic corticosteroids within 24 hours of development of severe CAP to reduce 28-day mortality 4

Step 6: Monitoring and Reassessment

Establish continuous monitoring:

• Monitor temperature, respiratory rate, pulse, blood pressure, mental status, oxygen saturation, and inspired oxygen concentration at least twice daily 1, 5
• More frequent monitoring (every 15-30 minutes initially) for severe pneumonia or those requiring regular oxygen therapy 1, 2
• Continuous pulse oximetry targeting SpO2 94-98% 2

Reassess at 48-72 hours:

• Evaluate for clinical stability markers 3
• Remeasure CRP level in patients not progressing satisfactorily 1, 3
• Repeat chest radiograph only if not progressing satisfactorily 1

Step 7: Disposition Decision

Admit to ICU if any of the following:

• Respiratory rate >30/min with severe respiratory failure 3
• Oxygen requirement necessitating non-rebreather mask or FiO2 >80% 2
• Two or more minor criteria or one major criterion for severe CAP 3
• Bilateral involvement with hemodynamic instability 3
• High risk for intubation 2

Admit to general medical ward if:

• Requires hospitalization for clinical reasons but does not meet ICU criteria 1
• Has adverse prognostic features but is stable on supplemental oxygen 1

Common pitfalls to avoid:

• Do not delay oxygen therapy while awaiting diagnostic workup 2
• Do not withhold high-flow oxygen in uncomplicated pneumonia due to unfounded concerns 1
• Do not change antibiotics prematurely within 72 hours unless clear deterioration 3
• Do not repeat chest radiograph prior to discharge in those with satisfactory clinical recovery 1

Step 8: Nutritional Support and Adjunctive Care

Provide supportive care:

• Nutritional support should be given in prolonged illness 1, 5
• Relieve pleuritic pain using simple analgesia such as paracetamol 1
• Advise patients not to smoke, to rest, and to drink plenty of fluids 1