Pneumonia Treatment

1. Classification of Pneumonia

2. Common Pathogens

• Goldman-Cecil Medicine, International Edition

3. Severity Assessment

Pneumonia Severity Index (PSI)

• Classes I-III (score ≤90): Outpatient management is generally safe
• Higher scores warrant hospital admission, ICU for scores >130

CURB-65 Score (simpler alternative)

• Score 0-1: Outpatient
• Score 2: Short-stay admission
• Score ≥3: ICU consideration

4. Antibiotic Treatment by Setting

Outpatient CAP (Mild, No Comorbidities)

• Monotherapy for 5 days with:
  • Amoxicillin (first-line beta-lactam)
  • Doxycycline
  • Azithromycin (where macrolide resistance rates are low)

Outpatient CAP (With Comorbidities / Risk for Drug-Resistant Organisms)

• Monotherapy with a respiratory fluoroquinolone (levofloxacin, moxifloxacin), OR
• Combination: one of amoxicillin/clavulanate, cefpodoxime, or cefuroxime PLUS azithromycin, clarithromycin, or doxycycline

Inpatient CAP (Non-Severe, No MRSA/Pseudomonas Risk)

• Monotherapy: respiratory fluoroquinolone, OR
• Combination: beta-lactam + macrolide
• 3 days of IV beta-lactam therapy may be adequate if clinically stable

Inpatient CAP (Severe)

• Dual therapy: beta-lactam + macrolide OR beta-lactam + respiratory fluoroquinolone
• Cover for MRSA if: prior parenteral antibiotics in last 90 days, prior MRSA infection; use vancomycin or linezolid
• Cover for Pseudomonas if similar risk factors - use antipseudomonal beta-lactam
• Anaerobic coverage (clindamycin) only if lung abscess or empyema suspected

Duration

• Minimum 5 days for most patients
• 7 days for suspected MRSA or Pseudomonas
• Extend until clinical stability (resolution of vital sign abnormalities, tolerating oral intake, normal mentation)
• Goldman-Cecil Medicine, International Edition

5. Special Pathogens

• Fishman's Pulmonary Diseases and Disorders

6. Pediatric Pneumonia

• Neonates: Target group B streptococci and gram-negative organisms (e.g., E. coli) - use ampicillin + gentamicin
• Children <5 years: Cover H. influenzae and S. pneumoniae (amoxicillin)
• Children >5 years: Add macrolide coverage for M. pneumoniae
• Oral antibiotics are adequate for most mild-to-moderate cases; IV therapy for severe disease or inability to tolerate oral intake
• Textbook of Family Medicine 9e

7. HAP / VAP Treatment

• Guided by local antibiograms and MDR risk factors
• MDR risk factors include: prior IV antibiotics, prior hospitalization >5 days, septic shock at time of VAP, ARDS, renal replacement therapy
• Empirical broad-spectrum coverage: antipseudomonal beta-lactam + antipseudomonal fluoroquinolone or aminoglycoside; add vancomycin/linezolid if MRSA risk
• Short-course antibiotic therapy (minimum effective duration) is recommended when clinically applicable

8. Adjunctive / Supportive Therapy

• Corticosteroids: Generally NOT recommended for routine CAP; may be used in refractory septic shock (e.g., hydrocortisone 200 mg for 4-8 days)
• Oxygen therapy: Target SpO2 ≥95%
• Fluids: Correct dehydration; aggressive IV fluids if septic
• Antiviral agents: Oseltamivir for influenza-positive patients, regardless of duration of illness before diagnosis
• Switch from IV to oral: Early de-escalation from IV to oral antibiotics (once stable) reduces hospital stay without compromising outcomes

9. Hospitalization Indications

• Failure to respond or tolerate oral antibiotics
• Significant hypoxia (low PaO2, wide A-a gradient)
• More than one lobe involved, empyema, abscess
• Immunosuppression, significant comorbidities (cardiac, pulmonary disease)
• Age extremes (infants <2 months, frail elderly)
• High-risk PSI score or CURB-65 ≥2-3

10. Prevention

• Annual influenza vaccine for everyone >6 months; especially those >50 years, chronic lung disease, diabetes, immunosuppression
• Pneumococcal vaccine (PCV13 or PPSV23): all children <5 years, adults ≥65 years, high-risk younger adults
• Revaccinate after 10 years if first dose was given before age 65
• Approximately half of adult pneumonia cases can be prevented through vaccination
• Textbook of Family Medicine 9e

Recent Evidence (2025)

Note: Drug dosing should always be verified against current formulary references before prescribing. This overview is based on Goldman-Cecil Medicine, Fishman's Pulmonary Diseases and Disorders, and Textbook of Family Medicine.

ECG Reading - A Systematic Guide

The 12-Lead ECG Layout

• Limb leads: I, II, III (bipolar) + aVR, aVL, aVF (augmented unipolar) - view the frontal plane
• Precordial leads: V1-V6 - view the horizontal plane

ECG Paper Calibration

• Horizontal axis (time): 1 small box = 0.04 sec; 1 large box (5 small) = 0.2 sec; 5 large boxes = 1.0 sec
• Vertical axis (voltage): 1 small box = 0.1 mV; standard calibration = 10 mm/mV
• Medical Physiology (Boron & Boulpaep)

The ECG Waveforms

Normal Interval Values

• Harrison's Principles of Internal Medicine, 22e

Step-by-Step ECG Reading Approach

Step 1 - Heart Rate

• 1 large box = 300 bpm | 2 = 150 | 3 = 100 | 4 = 75 | 5 = 60 | 6 = 50

Step 2 - Rhythm

• Normal sinus rhythm: Rate 60-100, regular P before each QRS, P upright in II and inverted in aVR
• Sinus tachycardia: Rate >100, same pattern
• Sinus bradycardia: Rate <60, same pattern
• Atrial fibrillation: No discrete P waves, irregularly irregular R-R intervals
• Atrial flutter: Sawtooth flutter waves at ~300/min, typically 2:1 or 4:1 block

Step 3 - P Wave

• Normal: upright in I, II, aVF, V4-V6; inverted in aVR
• Right atrial overload ("P pulmonale"): Tall peaked P ≥2.5 mm
• Left atrial abnormality ("P mitrale"): Broad notched P ≥120 ms in limb leads; biphasic P in V1 with prominent negative terminal component

Step 4 - PR Interval

• Short PR (<120 ms): Pre-excitation (WPW syndrome) - look for delta wave
• Long PR (>200 ms): 1st-degree AV block
• Progressive lengthening then dropped QRS: 2nd-degree Mobitz I (Wenckebach)
• Constant PR then dropped QRS: 2nd-degree Mobitz II
• No relationship between P and QRS: 3rd-degree (complete) AV block

Step 5 - QRS Complex

• Normal duration <120 ms - narrow complex
• QRS ≥120 ms: Bundle branch block, ventricular rhythm, or pre-excitation
  • Right Bundle Branch Block (RBBB): rSR' ("rabbit ears") in V1, wide S wave in V6, T wave inversion in V1-V3
  • Left Bundle Branch Block (LBBB): Broad QS or rS in V1, tall broad R in V6, T wave inversion in lateral leads

• Harrison's Principles of Internal Medicine, 22e

Step 6 - Axis

Step 7 - ST Segment

• STEMI: Convex (domed) upward ST elevation in contiguous leads
  • Anterior: V1-V4 (LAD territory)
  • Inferior: II, III, aVF (RCA or LCx territory)
  • Lateral: I, aVL, V5-V6 (LCx territory)
• Pericarditis: Diffuse concave (saddle-shaped) ST elevation in all leads except aVR; PR depression in inferior leads and V6; PR elevation in aVR
• Benign early repolarization: Concave ST elevation V2-V5, notching at J point, stable over time, common in young adults
• LBBB or LVH: Secondary ST changes - can mimic STEMI

• Subendocardial ischemia / NSTEMI
• Posterior MI (V1-V4 depression = reciprocal change; confirm with posterior leads V7-V9)
• Digoxin effect ("reverse tick" or scoop-shaped)
• Reciprocal changes in non-infarcted leads

Transmural ischemia: severe acute ischemia lowers resting membrane potential and shortens action potential duration, creating a voltage gradient between normal and ischemic zones - this manifests as ST elevation. Subendocardial ischemia shifts the ST vector toward the endocardium, producing precordial ST depression.

• Harrison's Principles of Internal Medicine, 22e

Step 8 - T Wave

• Normal: Positive in I, II, V3-V6; inverted in aVR; variable in III, V1, V2
• T wave inversion: Ischemia, LVH, RVH ("strain"), bundle branch blocks, pulmonary embolism
• Hyperacute T waves: Tall, broad, symmetric - earliest sign of STEMI
• Peaked narrow T waves: Hyperkalemia

Step 9 - QT Interval

• Always correct for heart rate: QTc = QT / √(R-R interval in seconds) (Bazett formula)
• Prolonged QTc: Risk of Torsades de Pointes - causes include hypokalemia, hypomagnesemia, drugs (antiarrhythmics, antibiotics, antipsychotics), congenital long QT syndrome
• Short QT: Hypercalcemia, digoxin toxicity

Lead Territories for MI Localization

• Rosen's Emergency Medicine

Common Arrhythmia Patterns at a Glance

Quick Memory Checklist (RRATES)

Note: ECG interpretation must always be integrated with the clinical picture. A single finding rarely makes a diagnosis in isolation. Drug effects, electrolyte abnormalities, and technical issues (lead placement, electrical interference) can all alter the ECG.