Pneumonia 101

Armaan Khalid

What the...

Definition of Pneumonia

An acute or chronic disease marked by inflammation of the lung parenchyma, that causes consolidation of inflammatory exudatesMain causes

BacteriaVirusFungal & etc

Classification

Anatomical/RadiologicalLobarMulti-focal/lobular (bronchopneumonia)Interstitial (focal diffuse)

Location of ContractionCommunityInstitutional (nursing home)Nosocomial (hospital)

Precipitating Factors

Smoking (Smokers in household)Previous lung pathology (COPD, CF)EToH abuseImmunosuppresionRecent hospital admissionIVDU (S Aureus haematogenous spread)Recent exposure to pneumonia ptsPreceding viral infectionHIV

Causative Organisms

Atypical Pneumonia

Assoc w a milder form of pneumoniaWalking pneumonia

Considered atypical becauseInability to detect on gram stainInability to be cultivated in normal media

ExamplesMycoplasma Chlamydophila speciesLegionella Coxiella burnetii (Q fever)Bordetella pertussis (Whooping cough)

Clinical Presentation

Preceding Hx of viral illnessOn Hx/Ex

Febrile/Pleuritic Pain/Dry coughSputum productionMalaise/Rigors/ChillsTachypnoea/cardia↓ chest movements

Use of accessory chest musclesSg of consolidation +/- pleural rub

History Taking

Impt to review pt’s:Potential exposure

Envt/Work/Social factorsAspiration risks

Seizure/EToH/GORDHost factors

COPD/IVDU/Smoking/HIV

Sputum Characteristics

S PneumoniaeRust coloured sputum

Pseudomonas/Haemophilus & Pneumococcal

Green sputumKlebsiella species

Red currant jelly sputumAnaerobic species

Foul smelling/Bad tasting sputum

Risk Stratification

How do you make the decision to Rx the pt in a out/in-patient setting?CURB-65 criteriaPneumonia Severity Index (PSI)

PSI calculator onlinehttp://pda.ahrq.gov/clinic/psi/psicalc.asp

CURB-65 criteria

C – ConfusionU – Uraemia, BUN > 20 mg/dLR – Respiratory Rate > 30 bpmB – Blood pressure < 90/60 mm Hg65 – Age > 65 years old

Score 0-1: Outpatient treatmentScore 2: Admit to the wardsScore 3-4: Admit to ICU

PSI Calculator

Differential Diagnosis

AsthmaAtelectasisBronchiectasisCOPDLung AbscessViral infectionInfluenza

Workup

FBE/UNE/BUN/LFT/CRP/ESRBlood cultures

Impt to get them before initiating empirical therapy

Sputum (microscopy & culture)ABG? Pleural fluid tapCXR (frontal & lateral)

Further Workup

Pneumococcal antigenCounter-immunoelectrophoresis of sputum, urine & serum

Mycoplasma antibodiesLegionella & Chlamydia antibodies

Immunoflurorescent testsLegionella antigen

Urinary antigen test

Radiological Findings

General CharacteristicsAffected tissue will appear denserMay contain air bronchogram(s)

Visibility of air in the bronchiSign of airway disease, not pathognomonic for pneumonia

Airspace pneumonia appears fluffy & their margins are indistinct

If it abuts a pleural surface, there will be a sharp demarcation of the margins

Patterns of Appearance

LobarSegmental (Bronchopneumonia)InterstitialRoundCavitary

I Spy With My Little Eye

Lobar Pneumonia

Patterns on CXR

Lobar PneumoniaCommon organism: S PneumoniaeHomogenous consolidation w air bronchogramSilhouette sign present when in contact with the heart, aorta or diaphragm

Segmental Pneumonia

Patterns on CXR

Segmental (Bronchopneumonia)Common organisms: S Aureus & gram-negative bacteriaAffects the walls of the bronchiolesSpread centrifugally via tracheobronchial tree to many foci @ the same timeMargins are fluffy & indistinctProduces exudate that fills the bronchi

No air bronchograms presentMay be assoc w atelectasis

Interstitial Pneumonia

Patterns on CXR

Interstitial PneumoniaCommon organisms: Mycoplasma, viral pneumonia & PCPReticular interstitial disease w diffuse spread throughout lungs in early disease processFrequently progresses to airspace disease

Round Pneumonia

Patterns on CXR

Round PneumoniaCommon organisms: H influenzae, Strep & PneumococcusSpherical pneumonia usually seen in the lower lobes of childrenMay resemble a mass

Clinical presentation does not match w that of a mass

Cavitary Pneumonia

Patterns on CXR

Cavitary PneumoniaCommon organism: M tuberculosisPrimary TB < Reactivation TBPrimary TB

Upper lobes > lower lobesAssoc w ipsilateral hilar adenopathy & large unilateral pleural effusions

Reactivation TBCavities are thin-walled, smooth inner margin & usually no air-fluid level

Localised Lower Lobe Pathology

Spine Sign

On Lateral CXR, thoracic spine vertebra are darker in diaphragm than in shoulder girdle

CXR needs to penetrate more tissue in the shoulder girdle than in diaphragmWith interstitial/airspace disease in posterior lower lobe, vertebra would be more opaque (brighter) than usual

Spine Sign!

Silhouette Sign

If 2 objects of the same radiographic density touch each other, then their edges disappear

Silhouette SignValuable in localising lung pathology

Silhouette Sign Helpful Hints

Structure That Isn’t Visible Disease LocationAscending Aorta Right Upper Lobe

Right Heart Border Right Middle Lobe

Right Hemidiaphragm Right Lower Lobe

Descending Aorta Left Upper/Lower Lobe

Left Heart Border Lingula of Left Upper Lobe

Left Hemidiaphragm Left Lower Lobe

Management

Respiratory SupportO2 +/- bronchodilators

Fluid resuscitationEmpiric Abx Rx

Empiric Rx should initially be broadEach hospital has it’s own guidelines

Empirical Rx of Pneumonia

Supportive Measures

Analgesia & anti-pyreticsChest physiotherapyIV fluids or diureticsPositioning of patient (Aspiration risk)Suctioning & bronchial hygiene

Clinical Resolution

Clinical response to Abx RxImprovement seen in 48-72 hrs

Abx shouldn’t be changed w/in 72hrsTime required for Abx to actChange if marked deterioration

Radiological resolution takes longer than clinical resolution

Clinical Resolution (or lack thereof)

No resolutionResistant to Abx2° to complications (empyema/abscess)Non-infectious cause (CHF/malignancy)Viral aetiology

ConsiderCT/MRIBronchoscopyLung biopsyConsult ID physician

Viral Pneumonia

Common in children & the elderlyPrevalent in the immunosuppressedUncommon in adults

13-50% of all CAPInfluenza virus main offender (>50%)

Clinical findings similar to bacteriaMay predispose & superimpose on a bacterial pneumonia

Common during winterRx

Supportive RxAntiviralImmunisations

References

Kumar & Clark, Clinical Medicine, 6th edn, Chapter 14, Pneumonia, pp 922-929W Herring, Learning Radiology: Recognizing The Basics, 1st edn, Chapter 8 Recognizing Pneumonia, pp 60-67Longmore et al, OHCM, 7th edn , Chapter 5, Chest Medicine, pp 152-153