Pneumonia 101 Armaan Khalid. What the... Definition of Pneumonia An acute or chronic disease marked...

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 exudates

Main causesBacteria

Virus

Fungal & etc

Classification

Anatomical/RadiologicalLobar

Multi-focal/lobular (bronchopneumonia)

Interstitial (focal diffuse)

Location of ContractionCommunity

Institutional (nursing home)

Nosocomial (hospital)

Precipitating Factors

Smoking (Smokers in household)

Previous lung pathology (COPD, CF)

EToH abuse

Immunosuppresion

Recent hospital admission

IVDU (S Aureus haematogenous spread)

Recent exposure to pneumonia pts

Preceding viral infection

HIV

Causative Organisms

Atypical Pneumonia

Assoc w a milder form of pneumoniaWalking pneumonia

Considered atypical becauseInability to detect on gram stain

Inability to be cultivated in normal media

ExamplesMycoplasma

Chlamydophila species

Legionella

Coxiella burnetii (Q fever)

Bordetella pertussis (Whooping cough)

Clinical Presentation

Preceding Hx of viral illness

On Hx/ExFebrile/Pleuritic Pain/Dry cough

Sputum production

Malaise/Rigors/Chills

Tachypnoea/cardia

↓ chest movementsUse of accessory chest muscles

Sg of consolidation +/- pleural rub

History Taking

Impt to review pt’s:Potential exposure

Envt/Work/Social factors

Aspiration risksSeizure/EToH/GORD

Host factorsCOPD/IVDU/Smoking/HIV

Sputum Characteristics

S PneumoniaeRust coloured sputum

Pseudomonas/Haemophilus & Pneumococcal

Green sputum

Klebsiella speciesRed currant jelly sputum

Anaerobic speciesFoul smelling/Bad tasting sputum

Risk Stratification

How do you make the decision to Rx the pt in a out/in-patient setting?

CURB-65 criteria

Pneumonia Severity Index (PSI)PSI calculator online

http://pda.ahrq.gov/clinic/psi/psicalc.asp

CURB-65 criteria

C – Confusion

U – Uraemia, BUN > 20 mg/dL

R – Respiratory Rate > 30 bpm

B – Blood pressure < 90/60 mm Hg

65 – Age > 65 years oldScore 0-1: Outpatient treatment

Score 2: Admit to the wards

Score 3-4: Admit to ICU

PSI Calculator

Differential Diagnosis

Asthma

Atelectasis

Bronchiectasis

COPD

Lung Abscess

Viral infection

Influenza

Workup

FBE/UNE/BUN/LFT/CRP/ESR

Blood culturesImpt to get them before initiating empirical therapy

Sputum (microscopy & culture)

ABG

? Pleural fluid tap

CXR (frontal & lateral)

Further Workup

Pneumococcal antigenCounter-immunoelectrophoresis of sputum, urine & serum

Mycoplasma antibodies

Legionella & Chlamydia antibodiesImmunoflurorescent tests

Legionella antigenUrinary antigen test

Radiological Findings

General CharacteristicsAffected tissue will appear denser

May contain air bronchogram(s)Visibility of air in the bronchi

Sign 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

Lobar

Segmental (Bronchopneumonia)

Interstitial

Round

Cavitary

I Spy With My Little Eye

Lobar Pneumonia

Patterns on CXR

Lobar PneumoniaCommon organism: S Pneumoniae

Homogenous consolidation w air bronchogram

Silhouette sign present when in contact with the heart, aorta or diaphragm

Segmental Pneumonia

Patterns on CXR

Segmental (Bronchopneumonia)Common organisms: S Aureus & gram-negative bacteria

Affects the walls of the bronchioles

Spread centrifugally via tracheobronchial tree to many foci @ the same time

Margins are fluffy & indistinct

Produces exudate that fills the bronchiNo air bronchograms present

May be assoc w atelectasis

Interstitial Pneumonia

Patterns on CXR

Interstitial PneumoniaCommon organisms: Mycoplasma, viral pneumonia & PCP

Reticular interstitial disease w diffuse spread throughout lungs in early disease process

Frequently progresses to airspace disease

Round Pneumonia

Patterns on CXR

Round PneumoniaCommon organisms: H influenzae, Strep & Pneumococcus

Spherical pneumonia usually seen in the lower lobes of children

May resemble a massClinical presentation does not match w that of a mass

Cavitary Pneumonia

Patterns on CXR

Cavitary PneumoniaCommon organism: M tuberculosis

Primary TB < Reactivation TB

Primary TBUpper lobes > lower lobes

Assoc 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 diaphragm

With 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 Location

Ascending 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 resuscitation

Empiric Abx RxEmpiric Rx should initially be broad

Each hospital has it’s own guidelines

Empirical Rx of Pneumonia

Supportive Measures

Analgesia & anti-pyretics

Chest physiotherapy

IV fluids or diuretics

Positioning 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 act

Change if marked deterioration

Radiological resolution takes longer than clinical resolution

Clinical Resolution (or lack thereof)

No resolutionResistant to Abx

2° to complications (empyema/abscess)

Non-infectious cause (CHF/malignancy)

Viral aetiology

ConsiderCT/MRI

Bronchoscopy

Lung biopsy

Consult 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 winter

RxSupportive RxAntiviralImmunisations

References

Kumar & Clark, Clinical Medicine, 6th edn, Chapter 14, Pneumonia, pp 922-929

W Herring, Learning Radiology: Recognizing The Basics, 1st edn, Chapter 8 Recognizing Pneumonia, pp 60-67

Longmore et al, OHCM, 7th edn , Chapter 5, Chest Medicine, pp 152-153