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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