Pneumonia- Prager Flashcards
Definition of Pneumonia
Definition: Inflammation of the pulmonary
parenchyma involving the terminal airways,
alveoli, bronchioles, and interstitium
6th most common cause of death in the U.S.
Final common pathway for many acute and
chronic illnesses
How do pathogens enter the lungs in pneumonia?
Inspiration of pathogens found in the air
Inspiration of flora from naso or oropharynx
• Commonest cause of bacterial pneumonia
Aspiration of oral or refluxed esophago-gastric
contents (saliva, food, etc.)
Enter starility of tracheo bronchial tree
How is the sterility of the tracheo-bronchial tree usually defended-anatomy?
Vocal cord closure in response to liquid or solid
matter
Cough: a highly effective mechanism ridding the
tracheo-bronchial tree of foreign material and of
mucous, prevents aspiration, high velocity of air expulsion
Mucociliary escalator blanket that lines the respiratory
mucosa, traps bacteria and particulate matter and
transports it rostrally by means of ciliary beating like flypaper, moves up and out (cilia hindered by smoking)
Branching of airways
How is the sterility of the tracheo-bronchial tree usually defended-humoral?
IgA: more in upper airways, antiviral
IgG: in lower airways, chemotaxis
Lymphocytes
How is the sterility of the tracheo-bronchial tree usually defended-cellular?
Alveolar macrophages (95%), dendritic cells, lymphocytes. CD4+ and CD8+ T cells. Neutrophils if recruited by smoking or other stimuli. Decreased in AIDS, steroids, and other immunosuppression.
Predisposing riskfactors to aspiration
Altered consciousness, dysphagia, neurologic disorders, mechanical disruption of usual barriers (NG tube), etc.
Besides aspiration, what risk factors are there for pneumonia?
Disturbances generating an effective couth (splinting from rib fractures, neuromuscular disease, sedatives)
Suppressed function of mucociliary escalator (alcohol, cigarettes, hyperviscious sputum-CF, immotile cilia syndrome, viral infections, bronchiectasis)
Bronchial obstruction by tumor or foreign body
What pathogens most commonly cause pneumonia?
Bacterial:
Oropharyngeal flora:
Aerobic: Pneumococcus (most common community acquired), H. Influenza, S. Aureus, Neisseria
Anaerobic: Low pathogenicity and when aspirated cause putrid lung abscess.
Atypical (don’t show up on culture, susceptible to Ab, normal WBC):
Mycoplasma low fever, children and young adults), Chlamydia (elderly, gradual onset), Legionella (can be severe, GI, headache, humid ducts) Pneumocystis carinii (untreated AIDS)
Viral:
Influenza, Adenovirus, RSV. Rarely: varicella measles, CMV
Nosocomial (usually gram negative):
Pseudomonas aerugenosa (CF), Staphylococcus aureus (MRSA), Enterobacteriaceae species, E. coli, Proteus, Panresistant: Klebsiella,Serratia, Acinetobacter
Clinical presentation of pneumonia
Signs: fever; tachycardia; tachypnea
Symptoms: Cough (dry or productive); dyspnea;
chills; pleuritic chest pain; headache; myalgias (flu-like);
diarrhea
Examination of sputum (important if immunocompromised): purulence
implies bacterial pathogen, and can be sent for
culture and sensitivity
Check for similar illness in community, clue to diagnosis;
(influenza; SARS; anthrax)
Splinting, rales, Low O2 sat proportional to increased stability, confusion, restlessness.
If normal vital signs, don’t need to hospitalize. COPD will be sicker than other pneumonia patient.
Labs and Imaging in Pneumonia
Nature of infiltrate on chest film may suggest causative agent. Lobar consolidation with air bronchogram suggest bacterial infection such as strep pneumoniae. Viral or atypical pneumonia: CXR shows patchy, diffuse consolidation with no air bronchograms.
CT scan
Gram stain and culture, may need to be invasive if not a lot of sputum: nasotracheal suction or flexible bronchoscopy. Do culture for an/aerobic, fungus, etc. and more for immunocompromised, including viral and bronchoscope. Blood culture if admitted to check sepsis. Serologic if find a spike in Igs or urine (esp for atypical).
How is viral pneumonia different from bacterial?
Usually mild in immunocompetent hosts, no
treatment needed
Can be lethal in immunocompromised patients;
requires high index of suspicion
Bronchocopy indicated for viral culture in
immune compromised patient with pneumonia
Influenza pneumonia may be complicated by
bacterial superinfection—a potentially lethal
condition
What groups are high risk for H1N1 and what are the complications?
Children younger than 2
Older than 65—less likely to get infected, at greater
risk if they do
Pregnant women
Patients with chronic illnesses such as COPD,
cardiovascular disease, cancer, renal insufficiency,
liver disease, diabetes, sickle cell disease
Immunosuppression—HIV, chemotherapy, organ
transplant anti-rejection Rx, chronic steroid Rx, etc/
Patients with trouble handling respiratory secretions—
cognitive dysfunction, neuro-muscular disorders, etc
Obese patient
Most cases self limited, but can progress to pneumonia, ARDS, multi-organ failure, death. Can be helped by extra corporeal membrane oxygenation.
What are the risk factors for nosocomial pneumonia?
Age > 70
Chronic lung disease
Depressed consciousness
Chest surgery
H-2 blocker or antacid therapy
Nasogastric tube
Ventilator/ET tube (more virulent, from GI, Ab resistant)
Post-Obstructive Pneumonia
Obstruction of a bronchus by tumor or foreign
body often leads to infection in the blocked area
of lung
Importance of obtaining follow up chest x rays in
patients at risk for lung cancer who have
pneumonia
Importance of thinking of aspirated foreign
bodies in at-risk patients (alcoholics, children, altered mental status, seizure patients).
Role of flexible bronchoscop
Complications of Pneumonia
Bacteremia, endocarditis, lung abscess
Pleural Effusion
–Parapneumonic effusion (near pleura, no bacteria)
–empyema (infection of pleural space, need chest tube, puss)
Respiratory failure–ARDS
Septic shock
Pneumonia in a child may cause
bronchiectasis—permanent bronchial
damage
