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
Top Related