Pneumonia: Severe CAP, VAP Prevention and Aspiration

Community-acquired pneumonia (CAP) is an acute infection of the lung parenchyma. It starts in someone who was not recently in hospital. Hospital-acquired pneumonia (HAP) starts during a hospital stay. Ventilator-associated pneumonia (VAP) shows up more than 48 hours after endotracheal intubation or tracheostomy. Pneumonia within 48 hours of weaning or extubation is counted in that spectrum too (2026 VAP prevention evidence summary).

Severe CAP is defined by the ATS/IDSA 2019 guideline: one major criterion, or three or more minor criteria (see Recognition & Red Flags). The same guideline notes that as many as 5% to 15% of pneumonia hospitalizations are linked to aspiration. No definition separates aspiration pneumonia from other pneumonia.

• Mechanism: Organisms fill the alveoli and inflame them. Ventilation-perfusion mismatch and shunt cause the hypoxemia. When the host response goes systemic, it can progress to sepsis and septic shock (see Sepsis and Septic Shock).
• Aspiration pneumonitis vs aspiration pneumonia: Aspirated gastric contents cause pneumonitis. Many patients improve within 24 to 48 hours on supportive care alone, with no antibiotics. Infection that follows the aspiration is aspiration pneumonia. That one needs antibiotics.
• Who is at higher risk: Older adults, nursing-home residents, people with a depressed level of consciousness or a poor swallow, mechanically ventilated patients, and anyone with chronic heart, lung, liver or renal disease, diabetes, alcoholism, malignancy or asplenia.

Don't wait for the textbook picture. It is cough with new sputum, fever or hypothermia, shortness of breath, pleuritic chest pain and crackles, plus a new infiltrate on chest imaging. In older adults, confusion, falls, hypothermia or a sudden loss of function may be the only signs.

Red Flags

• Respiratory rate 30/min or more, or PaO₂/FiO₂ 250 or less (minor criteria)
• Hypotension that needs aggressive fluid resuscitation, or any vasopressor need (septic shock is a major criterion)
• Respiratory failure that needs mechanical ventilation (major criterion)
• Multilobar infiltrate, or SpO₂ that keeps falling despite rising oxygen
• Confusion; core temperature below 36 °C
• Systolic blood pressure below 90 mm Hg or diastolic 60 mm Hg or below (CURB-65 criteria)
• Blood urea nitrogen 20 mg/dL or higher, WBC below 4,000 cells/mm³, or platelets below 100,000/mm³ (minor criteria)

• Heart failure or fluid overload: Look for bilateral opacities, a raised BNP, an enlarged heart, or improvement with diuresis. See Acute Heart Failure.
• Pulmonary embolism: Pleuritic pain and hypoxemia, with a clear or focal film. See Pulmonary Embolism.
• Pneumothorax: Sudden pleuritic pain, absent breath sounds on one side, or a collapsed lung on imaging. See Pneumothorax and Hemothorax.
• ARDS: Diffuse bilateral opacities with no focal consolidation. See ARDS.
• Aspiration pneumonitis: Hypoxemia after a witnessed aspiration. It improves within 24 to 48 hours, and supportive care alone is often enough.

1. Scene and airway: confirm the airway is open and suction visible secretions or vomit.
2. Position: sit the patient upright if breathing is easier that way and the patient can tolerate it.
3. Oxygen: start oxygen per protocol and titrate to the target on the Oxygen page: SpO₂ 94 to 98%, or 88 to 92% when hypercapnia is a risk.
4. Inhaler: help the patient use their own prescribed inhaler for wheeze, per protocol.
5. Infection control: place a surgical mask on the patient for transport and use PPE per agency policy.
6. Report: onset time, fever, sputum, any aspiration or vomiting, antibiotics already taken, and oxygen given.
7. Transport priority: any severe criterion or any sign of sepsis sends the patient to an ICU-capable hospital with prompt transport.

Doses vary by protocol; follow local protocols and medical direction.

• Monitoring: continuous SpO₂ and ECG, blood pressure at protocol intervals, and EtCO₂ when capnography is available (Paramedic/RN/CCT).
• Access: IV or IO access; place two lines when hypotension is present. See IO Access.
• Sepsis trigger: for probable sepsis with hypotension when in-hospital evaluation is expected after more than 60 minutes, give the first antibiotic dose in the ambulance or aircraft per SSC 2026. See Sepsis and Septic Shock.
• Antibiotic (Paramedic/RN/CCT, per local protocol): ceftriaxone 1–2 g IV every 24 hr, with azithromycin 500 mg daily as the inpatient macrolide partner. Screen for beta-lactam allergy and document the reaction type before the first dose. Do not give ceftriaxone to neonates (28 days or younger) who require or are expected to require IV calcium. Do not infuse it with calcium-containing solutions such as lactated Ringer's; flush between drugs per label. See Ceftriaxone.
• Fluid: crystalloid bolus with reassessment after each bolus. Do not give a fixed volume without reassessment. Volume targets are on the Sepsis page. Give boluses through a line separate from ceftriaxone, or flush between drugs, because lactated Ringer's must not run with ceftriaxone.
• Airway and breathing: high-flow nasal oxygen or noninvasive support where protocol allows, since high-flow nasal oxygen is preferred over conventional oxygen and noninvasive ventilation in sepsis-related hypoxemic respiratory failure per SSC 2026; hypercapnic COPD with acidosis is an NIV indication. Intubate with a planned approach. See Rapid Sequence Intubation.
• After intubation: tidal volume 6 to 8 mL/kg ideal body weight when ARDS is absent (2026 secondary summary of SSC; primary text not verified). Use the ARDS page if ARDS is present.
• Wheeze: nebulized albuterol per protocol.

Don't wait for culture results. Start empiric antibiotics now. De-escalate when cultures and susceptibilities return.

Empiric antibiotics by setting and risk

• Outpatient, nonsevere: amoxicillin 1 g orally three times daily, or doxycycline 100 mg orally twice daily. A macrolide is used only where local pneumococcal macrolide resistance is below 25%. With comorbidities: amoxicillin-clavulanate or a cephalosporin plus a macrolide or doxycycline.
• Inpatient, nonsevere: a β-lactam plus a macrolide (ampicillin-sulbactam 1.5–3 g IV every 6 hr, cefotaxime 1–2 g every 8 hr, ceftriaxone 1–2 g daily, or ceftaroline 600 mg every 12 hr; plus azithromycin 500 mg daily or clarithromycin 500 mg twice daily). Alternative: respiratory fluoroquinolone alone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily).
• Inpatient, severe: a β-lactam plus a macrolide, or a β-lactam plus a respiratory fluoroquinolone.
• MRSA coverage (ATS/IDSA 2019): add vancomycin (AUC-guided dosing) or linezolid 600 mg every 12 hr for prior respiratory isolation of MRSA. In severe CAP, also add it after hospitalization with parenteral antibiotics in the last 90 days; send cultures and nasal MRSA PCR and de-escalate on the results. In nonsevere CAP, add it only with locally validated risk factors plus recent hospitalization and IV antibiotics; withhold anti-MRSA therapy unless cultures are positive, and a negative nasal MRSA PCR supports withholding it.
• Antipseudomonal coverage (ATS/IDSA 2019): add for prior respiratory isolation of P. aeruginosa. In severe CAP, also add it after hospitalization with parenteral antibiotics in the last 90 days, with cultures. In nonsevere CAP, add it only with locally validated risk factors plus recent hospitalization and IV antibiotics. Agents: piperacillin-tazobactam 4.5 g every 6 hr, cefepime 2 g every 8 hr, ceftazidime 2 g every 8 hr, aztreonam 2 g every 8 hr, meropenem 1 g every 8 hr, or imipenem 500 mg every 6 hr.
• Duration: ATS/IDSA 2019 advises a minimum of 5 days with clinical stability. The shorter ATS 2025/26 durations (nonsevere CAP under 5 days once stable, minimum 3 days; severe CAP 5 days or more) come from a secondary summary and are not yet checked against the primary. For MRSA or Pseudomonas CAP, the 2019 guideline's expert opinion is 7 days.
• Anaerobic coverage: not routinely added for suspected aspiration unless lung abscess or empyema is suspected (conditional, ATS/IDSA 2019). SSC 2026 advises anaerobic coverage for sepsis at high risk of anaerobic infection; follow local protocol where the two differ.

Safety cautions for empiric agents

• Macrolides (azithromycin, clarithromycin): QT prolongation and torsades. Check the ECG QTc, potassium and magnesium, and review other QT-prolonging drugs.
• Fluoroquinolones (levofloxacin, moxifloxacin): The same QT caution applies. The FDA boxed warning covers tendinitis and tendon rupture, peripheral neuropathy, CNS effects, and exacerbation of myasthenia gravis. Avoid them in myasthenia gravis.
• Linezolid: Serotonin syndrome with serotonergic drugs. Myelosuppression with prolonged courses, so check the CBC weekly.
• Doxycycline: Photosensitivity and esophageal irritation are the risks. Give it with water, and keep the patient upright.
• Beta-lactam allergy: In nonsevere CAP, the respiratory fluoroquinolone alone is the alternative to a beta-lactam regimen. In severe CAP, pharmacy and ID choose the regimen. Document the reaction type.

Corticosteroids

• Severe CAP in the ICU: hydrocortisone 200 mg/24 hr IV (50 mg every 6 hr or continuous infusion) for 4 days, or 7 days if not improved by day 4, then a taper (CAPE COD; total 8 or 14 days). CAPE COD excluded PCR-positive influenza: do not start steroids in influenza-related pneumonia without ICU or ID direction. Monitor glucose for steroid hyperglycemia, and watch for infection and delirium. CAPE COD 28-day mortality was 6.2% with hydrocortisone and 11.9% with placebo. SCCM 2024 gives a strong recommendation for corticosteroids in hospitalized patients with severe CAP and names no molecule or dose.
• Nonsevere CAP: steroids are not used routinely (strong, ATS/IDSA 2019). ATS 2025/26 also advises against them here.
• Contested: REMAP-CAP tested a fixed 7-day course of hydrocortisone 50 mg every 6 hr. Enrollment stopped for futility. Possible harm was not excluded. See Clinical Pearls.

Oxygen, ventilation and escalation

• Oxygen: titrate to SpO₂ 94 to 98%, or 88 to 92% when hypercapnia is a risk. See Oxygen.
• Acute hypoxemic failure: High-flow nasal oxygen over conventional oxygen and noninvasive ventilation, per SSC 2026. That applies to hypoxemic failure only. Hypercapnic COPD with acidosis is an NIV indication. For patients not intubated, a trial of awake proning is suggested (2026 secondary summary of SSC; primary text not verified). See Noninvasive Ventilation.
• ICU admission: Hypotension that needs vasopressors, or respiratory failure that needs mechanical ventilation, goes straight to ICU (strong, ATS/IDSA 2019). See Mechanical Ventilation.
• ARDS: if ARDS develops, use the lung-protective strategy on the ARDS page.
• Influenza: antiviral treatment for inpatients with influenza (strong, ATS/IDSA 2019).

Prevention of VAP in the ICU

• Elevate the head of the bed to 30° to 45° when there is no contraindication.
• Oral care every 6 to 8 hours with toothbrushing and rinsing. Chlorhexidine should not be used routinely.
• Keep cuff pressure at 25 to 30 cmH₂O. Use subglottic secretion drainage when intubation is expected to exceed 72 hours.
• Assess daily whether mechanical ventilation is still needed, and assess sedation daily for reduction or discontinuation.
• Do not use selective digestive decontamination, or routine systemic or topical respiratory antibiotics, for prevention.

• Destination: the nearest hospital with ICU care for severe CAP, sepsis or respiratory failure. Prenotify severity, the antibiotic time, and the steroid decision.
• Monitoring: continuous SpO₂, ECG and EtCO₂ if intubated. Recheck respiratory rate, work of breathing and blood pressure after every move and every oxygen change.
• Altitude: Lower cabin pressure lowers PaO₂, so reassess oxygenation early in any flight. See Flight Transport Physiology.
• Antibiotics: document the time of the first dose and the next due time, and give scheduled doses on time during transport.
• Airway and support: keep suction ready. Continue high-flow or noninvasive support if tolerated; prepare for intubation with a planned approach if support fails.
• Infection control: mask the patient and use PPE and cleaning per agency policy.

• Pediatrics: children are managed by age and weight under pediatric protocols; this page does not restate pediatric antibiotic regimens. The ceftriaxone label gives a total daily dose of 50 to 75 mg/kg, once daily or in equally divided doses every 12 hours, for serious infection, with a total of no more than 2 g/day. Ceftriaxone is contraindicated in neonates (28 days or younger) who require or are expected to require IV calcium, and must not be given with calcium-containing solutions (see Ceftriaxone). Use weight-based dosing for every weight-based dose, and the Respiratory Distress and Failure and Sepsis pages for severity.
• Pregnancy: Treat pneumonia promptly. Pick regimens with obstetrics and infectious diseases. Doxycycline and fluoroquinolones are generally avoided where alternatives exist. Keep SpO₂ at 95% or above. Steroid and ICU decisions are made with the obstetric team. One premixed vancomycin product carries a boxed warning against use in the first and second trimesters (see Vancomycin).
• Older Adults: Confusion, falls or hypothermia may stand in for fever. Aspiration risk runs higher. No specific dose adjustment is established for these regimens.
• Renal Impairment: Vancomycin dosing is AUC-guided, and it shifts with renal function (see Vancomycin). For other agents, follow each medication page.
• Hepatic Impairment: No specific adjustment is established for these regimens. Follow each medication page.
• Obesity: Dose vancomycin maintenance by actual body weight, and monitor with levels or AUC (see Vancomycin).
• Immunocompromised: Broader coverage and extra testing are set with infectious diseases input. This page does not cover them.
• Patients on Anticoagulants: Thoracentesis, central access and bronchoscopy raise bleeding risk. Check the anticoagulant plan before any procedure.

• Error: broadening coverage to MRSA or Pseudomonas without a documented risk factor. Prior respiratory isolation of either organism is an indication on its own. Other risk factors need local validation first. The ATS/IDSA 2019 guideline recommends dropping the healthcare-associated pneumonia category when you choose extended coverage.
• Error: giving ceftriaxone without a beta-lactam allergy check, to a neonate who requires IV calcium, or in the same line as lactated Ringer's. Screen for allergy and write down the reaction type first. Keep ceftriaxone away from calcium-containing fluids, and flush between drugs per label.
• Error: holding antibiotics for a low procalcitonin or a clear early film. Start empiric treatment whatever the procalcitonin says.
• Error: giving steroids for nonsevere CAP. Run the severity criteria first. Steroids belong to severe CAP in the ICU.
• Error: treating the steroid question as settled. CAPE COD and REMAP-CAP disagree, and the guideline bodies rate it differently. Follow the ICU protocol.
• Error: adding anaerobic coverage to every aspirating patient. Add it when lung abscess or empyema is suspected, unless local protocol says otherwise.
• Error: routine chlorhexidine oral care for VAP prevention. Brush and rinse every 6 to 8 hours instead.
• Error: sizing tidal volume to actual weight. Size it to ideal or predicted body weight, not actual weight (see ARDS).