pneumonia

Pneumonia
**definition:defined as an acute respirotery illness associated with recently developed radiological pulmonary shadowing , may be segmantal, lobar, multilobar & bronchopneumonia.**Types:lobar pn: homogenous consolidation of one or more lung lobes often associated with pleural inflamation.Bronchopn: its more patchy alveolar consolidation associated with bronchial & bronchiolar inflamation often affecting both lower lobes. **classification:1- community-acquired pn (viral, bacterial)2- hospital-acquired pn (nosocomial)3- suppurative & aspirational pn (lung abscess)4- pn in the immunocompromised patients. 
Viral pneumonia:() causes: influenza, parainfleunza, measles, RSV, varicella, CMV.() risk factors:  *old age & children *chronic disease of the heart, lung or kidney *women in the last trimester of pregnancy.() clinical features: *dry cough, dyspnea & malaise. *unremarkable physical examination  *CXR= interstitial pattern()complication: influenza-induced necrosis of resp epithelium predisposes to bacterial colonization, like strep. Pneumonia or staph. Aureus.
() community-acquired pn (CAP):*Introduction:1- incidence varies with the age.2- accounts for one-fifth of childhood deaths3- affect 2 million of children per year under the 5 years.4- most patients managed at home, hospital admission 20-40%5- MR at home is very low < 1%, hospital death rate 5-10% & may be as high as 50% in sever cases. *Transmission:spread by droplet inhalation *Pathogenesis:when organism settles in the alveoli, an inflammatory response ensues.Two phases : congestion, red & grey hepatisation.Finally resolution with little or no scarring.
() factors predisposes to CAP:*smoking *CS therapy *HIV *alcohol *old age*recent influ infection *pre-existing lung diseases *multiple myloma*sickle cell disease *contact with sick birds & farm environment() Organisms:*strep. Pn *mycoplasma pn *chlamydia psittaci *ch pn.*legionella * H . Infleunza *staph. Aureus *coxiella burnetti*klebsialla *actinomyces israelli () Clinical features:typically presents as acute illness with fever, rigors, sweating, vomiting, anorxia & headache.Pulmonary == cough, sputum, pleuritic chest pain & confusion.O/E pyrexi, tachycardia, tachypnea, hypotension, after 2 days, the consolidation will appear with dull on percussion & bronchial breathing, whispering pectorilquy & aegophony. When resolution occur, fine crackles & then coarse which indicate liquefaction of alveolar exudates.
()Specific features of pn:**pneumococcal pneumonia: (30%) caused by strept. Pneumonia, rusty sputum, herpetic features, lobar or multilobar on CXR.**Chlamydia pn: (5-15%) pharyngitis, sinusitis, increase LFT, diagnose serologically, CXR show small segmental infilterates.**Mycoplasma pn: (9%) insidious onset, few signs on chest with systemic features complicated by myocarditis, pericarditis, meningoencephalitis, hemolytic anemia, stevens johnson syndrom, erythema nodusum & GB.CXR lobar consolidation with hilar LAP.**Legionella pneumophilia: (5%) traveler history with systemic symptoms like headache, confusion, malaise, myalgia& diarrhea. Hyponatremia, hypoalbuminemia, high LFT & CK. CXR consoli slow to resolve.**Haemophilus infleunzae: (3%) COPD, Bronchiactasis, CXR bronchopn.**Staph aureus: (2-5%) may cause osteomyelitis, endocarditis & brain abscess CXR cavitation.**Chlamydia psittaci:(<1%)contact with bird, hepatosplenomegally , CXR lower lobe consolidation.
()Investigations:1- CXR: appear within 12-18 h. 2- microbiological : *sputum for gram stain & culture*blood culture*serology for mycoplasma, chlam, legionella.3- Oximetry: 4- general blood tests: WBC, LFT, RFT, CRP.() Diff Dx: *pulmonary infarction *pul TB *pul odema *pul eosinophilia*bronchoalveolar cell ca. *cholecystitis, acute pancreatitis, subphrenic absecess, hepatic amebiasis.
() Assessement of disease severity:hospital CURB-65: *Confusion *Urea > 7 mmol/l * RR > 30/M * B Pr <90 or < 60 mmHg *65 years of ageif 0-1 treated at homeif 2 consider hospital treatmentif 3 or > for ICU admission.() features of high mortality:A- clinical: B- Lab*age>60 years, male *Pa O2<8kPa*RR > 30 min * WBC < 4000/mm3*Bpr < 90 mmHg, <90 mmHg *WBC > 20 000/mm3*confusion *BU > 7 mmol/l *multilobar on CXR * positive blood culture*underlying diseases * hypoalbuminemia
() management:1-general:2- O2: 3- Ventilation: indications for RCU: *CURB score > 3 not respond to treatment *persistent hypoxia < 8 kPa despite high conc O2 *progressive hypercapnea *severe acidosis *shock *depressed conciousness4- fluid balance:5- antibiotic treatment:*uncomplicated pn 7-10 days, but 14 days for Legionella, or Klebseilla*oral Ab are adequate unless has severe illness, impaired conc, loss swallowing reflex or malabsorption.
() in uncomplicated pn:*amoxicillin 500mg 8-h orally.*if allergic to pencillin: clarithromycin 500mg 12h orally.*if staph : flucloxacillin 1-2 g 6h IV plus clarithromycin 500mg 12h IV *if mycoplasma or legionella: clarithromycin 500mg 12h IV*if chlamydia: tetracycline or erythromycine.*if H. infleunzae: ampicillin plus 3rd generation cephalosporin.*if Klebsialla: cephalosporin plus fluoroquinolone or aminoglycoside.() in severe CAP:*Clarithromycin 500mg 12h IV Or erythromycin 500mg 6h plus either Co-amoxiclav 1.2 g 8h IV or ceftriaxone 1-2 g daily.()Complications:failure to respond to therapy may indicate:1- wrong AB 2- mixed infection 3- bronchial obstruction 4- wrong diagnosis 5- complications as follow:* para-pneumonic effusion *empyma *lobar collapse*thromboembolic disease *pneumothorax *lung abcess*ARDS, renal failure, multi-organ failure *ectopic abcess*hepatitis, pericarditis, myocarditis, meningoencephalitis
() Discharge & Follow-up:@ discharge depend on no more than one of the followings:1- RR > 24/m 2- systolic Bpr < 90 mmHg 3- Sa O2< 90%.4- inability to intake oral 5- abnormal mental state() Prevention:1- influenza vaccine: (yearly) for:elderly, chronic lung or heart diseases, DM, AIDS, health care worker, sickle cell diseases.2- polyvalent Pneumococcal poly saccharide vaccine: (5 years) for:elderly, chronic heart or lung diseases, sickle cell diseases, asplenic patients, Hodgkin disease, multiple myloma, cirrhosis, DM, AIDS.