Management Algorithm (NICE NG138 / BTS Guidelines)

            SUSPECTED PNEUMONIA
            (Cough + Fever + Breathlessness)
                    ↓
          CONFIRM DIAGNOSIS
          - Clinical features
          - CXR (consolidation)
                    ↓
              CALCULATE CURB-65
          (Confusion, Urea>7, RR≥30, BPless than 90/60, Age≥65)
                    ↓
        ┌───────────┼───────────┐
     SCORE 0-1    SCORE 2     SCORE 3-5
      (MILD)      (MODERATE)   (SEVERE)
        ↓           ↓            ↓
    HOME CARE    HOSPITAL    ICU/HDU REVIEW
    Oral Abx     ADMISSION   URGENT
                              ↓
          ANTIBIOTIC CHOICE
          (Based on severity + local guidelines)
                    ↓
    MILD (CURB 0-1):
    - Amoxicillin 500mg TDS PO x 5 days
    - (Penicillin allergy: Doxycycline 200mg loading, 
       then 100mg OD OR Clarithromycin 500mg BD)
                    ↓
    MODERATE (CURB 2):
    - Amoxicillin 500mg-1g TDS PO/IV
    + Clarithromycin 500mg BD PO/IV x 5-7 days
    - (Penicillin allergy: Levofloxacin 500mg OD)
                    ↓
    SEVERE (CURB 3-5):
    - Co-amoxiclav 1.2g TDS IV
    + Clarithromycin 500mg BD IV x 7-10 days
    - (Penicillin allergy: Levofloxacin 500mg BD IV
       + Clarithromycin 500mg BD IV)
    - Consider adding Vancomycin/Linezolid if
      suspected MRSA (IVDU, post-flu, necrotizing)
                    ↓
          SUPPORTIVE CARE
          - Oxygen (Target SpO₂ 94-98%)
          - IV Fluids (if septic, dehydrated)
          - Analgesia (paracetamol, opiates if pleuritic pain)
          - VTE Prophylaxis (LMWH if inpatient)
                    ↓
          REVIEW AT 48-72 HOURS
          - Clinically improving? (Apyrexial, less breathless)
          - CRP trending down?
          - Switch IV → PO antibiotics (if tolerating oral)
          - Discharge if stable + CURB ≤1
                    ↓
          FAILURE TO IMPROVE?
          - Repeat CXR / CT Chest (Empyema? Abscess?)
          - Blood cultures, sputum culture
          - Consider resistant organisms, atypicals
          - Consult Respiratory / Microbiology
                    ↓
          TREATMENT COMPLETION
          - Total 5-7 days antibiotics (uncomplicated)
          - Longer if complications (empyema, abscess: 2-6 weeks)
          - Safety net advice (return if worsening)
          - Follow-up CXR at 6 weeks (if >50 years or smoker)

1. Antibiotic Therapy

Empirical Antibiotic Choice (NICE NG138 / BTS Guidelines)

Principles:

• Start antibiotics within 4 hours of hospital arrival (Sepsis 6 bundle if septic).
• Empirical therapy (covers most likely pathogens before culture results).
• De-escalate based on culture results and clinical response (antibiotic stewardship).
• Duration: 5 days usually sufficient for uncomplicated CAP (NICE NG138). Longer if severe, slow response, or complications.

Mild CAP (CURB 0-1) - Outpatient:

• Do NOT routinely add Clarithromycin to Amoxicillin in mild CAP (NICE NG138). Reserve dual therapy for moderate-severe.

Moderate CAP (CURB 2) - Hospital Admission:

• Switch IV → PO when clinically improving (apyrexial for 24h, tolerating oral, stable observations).

Severe CAP (CURB 3-5) - ICU/HDU:

Pathogen-Specific Therapy (If Identified)

Streptococcus pneumoniae:

• Penicillin-sensitive: Benzylpenicillin 1.2g QDS IV OR Amoxicillin 1g TDS PO.
• Penicillin-resistant (rare in UK): Co-amoxiclav or Ceftriaxone.

Staphylococcus aureus:

• MSSA (Methicillin-sensitive): Flucloxacillin 2g QDS IV.
• MRSA (Methicillin-resistant): Vancomycin 15-20mg/kg BD IV (target trough 15-20 mg/L) OR Linezolid 600mg BD IV/PO.

Legionella pneumophila:

• Fluoroquinolone (1st line): Levofloxacin 500mg BD IV/PO x 7-10 days.
• Alternative: Azithromycin 500mg OD IV/PO x 5-10 days.
• Severe: Add Rifampicin 600mg BD PO (synergistic).

Mycoplasma pneumoniae:

• Macrolide (1st line): Clarithromycin 500mg BD PO x 7-10 days OR Azithromycin 500mg OD x 3 days.
• Alternative: Doxycycline 100mg BD PO x 7-10 days.

Influenza:

• Oseltamivir (Tamiflu): 75mg BD PO x 5 days if less than 48h from symptom onset OR severe disease (any time). Consider in all hospitalized flu patients.

2. Supportive Care

Oxygen Therapy

• Target SpO₂: 94-98% in non-COPD patients. 88-92% if COPD (avoid hypercapnia).
• Delivery:
  • Nasal cannula: 1-4 L/min (24-40% FiO₂).
  • Simple face mask: 5-10 L/min (40-60% FiO₂).
  • Non-rebreather mask + reservoir: 15 L/min (60-90% FiO₂).
  • High-flow nasal oxygen (HFNO): 30-60 L/min, warmed, humidified. For severe hypoxia.
• Monitor: SpO₂ continuously (if severe), ABG (if SpO₂ less than 94% or deteriorating).

Fluid Resuscitation (If Sepsis)

• Sepsis 6 Bundle (within 1 hour):
  1. Give high-flow oxygen (target SpO₂ 94-98%).
  2. Take blood cultures.
  3. Give IV antibiotics (broad-spectrum).
  4. Measure lactate and full blood count.
  5. Give IV fluid challenge (500mL crystalloid over 15 min if hypotensive or lactate >2 mmol/L).
  6. Measure urine output (catheterize if anuric).
• Fluid choice: 0.9% Saline or Hartmann's (crystalloid). Avoid starches (ARDS risk).
• Target: MAP ≥65 mmHg, Urine output >0.5 mL/kg/h, Lactate clearance.
• Caution: Avoid fluid overload in elderly/heart failure (pulmonary edema). Reassess frequently.

Analgesia

• Paracetamol: 1g QDS PO/IV (fever, mild-moderate pain).
• Opiates: Morphine 2.5-10mg IV PRN or Oxycodone 5-10mg PO PRN (severe pleuritic pain). Caution: respiratory depression.
• NSAIDs: Generally avoid (AKI risk in sepsis, GI bleeding).

VTE Prophylaxis

• All hospitalized patients should receive LMWH (enoxaparin 40mg SC OD or dalteparin 5000 units SC OD) unless contraindicated (active bleeding, platelets less than 50).
• Mechanical: TED stockings, intermittent pneumatic compression (if LMWH contraindicated).

Nutrition

• Maintain oral intake if possible. High-calorie, high-protein diet.
• NG feeding if unable to swallow safely (dysphagia, reduced GCS).
• IV fluids: Maintenance (25-30 mL/kg/day) if NBM.

3. Escalation of Care (Severe CAP / Deteriorating Patients)

Criteria for ICU/HDU Admission (CURB 3-5 OR)

• Respiratory Failure: SpO₂ less than 90% despite high-flow O₂. PaO₂ less than 8 kPa. RR >30.
• Septic Shock: Hypotension (SBP less than 90) requiring vasopressors (Noradrenaline).
• Multi-organ Failure: AKI (oliguria, Cr >300), confusion (encephalopathy), coagulopathy.
• Need for Invasive Ventilation or Non-Invasive Ventilation (NIV).

Non-Invasive Ventilation (NIV) - CPAP/BiPAP

• Indication: Type 1 Respiratory Failure (hypoxia) refractory to high-flow O₂. COPD with Type 2 Failure (hypercapnia).
• Contraindications: Vomiting, facial trauma, reduced GCS (less than 8), pneumothorax (untreated).

Invasive Mechanical Ventilation

• Indication: Severe hypoxia refractory to HFNO/NIV. Exhaustion. Airway protection (GCS less than 8).
• Complications: Ventilator-associated pneumonia (VAP), barotrauma, prolonged weaning.

Vasopressors (Septic Shock)

• Noradrenaline: 1st line. Target MAP ≥65 mmHg.
• Fluid Resuscitation first (30 mL/kg crystalloid bolus), then vasopressors if still hypotensive.

4. Monitoring and Review

Daily:

• Observations: Temp, HR, BP, RR, SpO₂. NEWS2 score (early warning score).
• Clinical: Cough improving? Sputum clearing? Breathlessness easing?
• Bloods: FBC (WCC trending down?), CRP (should ↓50% by Day 3-4), U&Es (AKI?).

48-72 Hour Review:

• Switch IV → PO antibiotics if:
  • Apyrexial for 24h.
  • Hemodynamically stable (BP, HR normal).
  • Tolerating oral intake.
  • Oxygen requirement stable/improving.
• Discharge planning if CURB ≤1 and stable.

Failure to Improve:

• Definition: Persistent fever (>48h), worsening breathlessness, rising CRP, new/worsening CXR changes.
• Actions:
  1. Repeat CXR or CT Chest (empyema, abscess, underlying malignancy).
  2. Repeat blood cultures, send sputum.
  3. Consider resistant organisms (MRSA, Pseudomonas), atypicals (Legionella - check urinary antigen).
  4. Broadening antibiotics (add Clarithromycin if not already on it, add antipseudomonal - Piperacillin-Tazobactam).
  5. Consult Respiratory / Microbiology.