Para-pneumonic effusion and Empyema

-Patho-physiology:

Capillary Leak/ Exaudate stage	Bacterial Invasion/ Fibrinolytic stage	Organization/ Empyema stage
Mechanism: Micro-organisms à PMNs à O2 free radicals + products à endothelial injury à ñ capillary permeability à ñ interstitial/pleural pressure gradient (subpleural) à effusion	Mechanism: ññ endothelial injury with bacterial multiplication over whelming lymphatics, MQ, neutrophils	Mechanism: Continuous fibroblastic migration from visceral, parietal pl. à coagulable pleural matrix (inelastic membrane or pleural peel) à thick cavity 'e thick yellowish white opaque viscous pus
Fluid ccc: · Ipsilateral,Small, Free · Sterile (-ve gram and culture) · Predominant PNLs · PH > 7.2, exaudate · Glucose > 60 mg · LDH > 500 IU/L · Appears in 2-5 ds of pneumonia onset	Fluid ccc: · Cloudy fluid · +ve gram and culture for bacteria · ññ PNLs, debris · PH between 7-7.2 · Glucose < 40 mg/dl · LDH > 1000 (lysis) · In 5-10 ds of pneumonia onset	Fluid ccc: · Pus ± foul smelling · G-ve (30%), staph (10-25%), strept. malleri, anaerobes (bacteroids, peptost), mixed infection, or sterile pus in 1/3 cases · Staph, H.I. in children · In 2-3 weeks of pn.

-Classification:

I. Non significant parapneumonic effusion:

II. Typical exaudative effusion (uncomplicated):

III. Borderline complicated effusion:

IV. Simple complicated (Fibrinolytic):

V. Complex complicated effusion:

VI. Simple empyema:

VII. Complex empyema:

-Differential Diagnosis:

	Empyema	Abscess
CXR	-Displaces bronchial, vascular markings -Cross major fissures -Unequal width of air-fluid level in P/A and lateral views	-No displacement -Follows anatomical rules -Equal width in both
CT	-Smooth rounded outline -Acute angle between empyema and pleural margin -Compresses lung -Pleural split sign à walls of visceral & parietal pleurae are separate (2 contrasts)	-Oval irregular outline -Obtuse angle -No compression -No pleural split sign

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