Respiratory Tract Flashcards
What is the leading cause of infectious death and the fifth leading cause overall?
Pneumonia
What the three ways infectious agents gain entry to the lower respiratory tract?
Aspiration of upper airway resident flora, inhalation of aerosolized material, and, less frequently, metastatic seeding of the lung from blood
What size of particle is ideal for evading anatomic barriers, yet having an impact on alveoli? What size are most bacteria?
2 to 5 microns, 0.5 to 2 microns
What host defenses are present at terminal airways and alveoli?
Humoral and cell mediated defenses but not mucociliary apparatus
Examples of mucociliary apparatus inhibitors
Smoking impairs ciliary and macrophage activity, congenital defects impair secretion clearance and promote mucus compaction (Kartagener`s syndrome and Cystic Fibrosis)
What increases one`s risk for aspiration?
Nasogastric and endotracheal tubes
What is the most useful classification of pulmonary pathogens?
Community acquired vs nosocomial
Most pulmonary infection patients with complain of some difficulty breathing, associated with cough and fever. When present with a physical exam suggesting consolidation should prompt what?
More detailed evaluation, including chest x-ray
Community acquired pnemonia (CAP) is divided into typical and atypical groups. What does typical CAP present with?
acute illness with fever, chaking chills, purulent sputum, and dense lobar infiltrate on x ray
Typical CAP is most commonly caused by:
Streptococcus pneumonia
What is Faget`s sign?
Patients with atypical CAP are more likely to have relative bradycardia or pulse/temperature deficit on physical exam
What months are most viral infections, including influenza, usually seen?
December to March
What are important nosocomial respiratory pathogens? What pathogen targets cystic fibrosis patients?
Gram negative enteric flora, S. aureus; Pseudomonas
Why is specimen collection key to recovery of Strep pneumoniae?
Streptococci have an autolytic mechanism activated when adverse conditions are encountered, older cells die to give younger cells the best chance of survival, this can greatly reduce number of streptococci in 30 mins
What are the four criteria that suggest an infectious source in hospital acquired pneumonia?
1) New or changing infiltrate on chest x-ray 2) Change in respiratory secretions 3) Change in ventilatory requirements 4) Positive culture from sterile site with same organism found in respiratory culture
Definition of sputum
bolus of respiratory secretions coughed from deep in the lung and expectorated by the patient
What is considered an adequate specimen based on PMN leukocytes and epithelial cells?
> 25 PMN leukocytes and
Rapid antigen tests have clinical utility for which organisms?
influenza A, S. Pneumoniae, Legionella
Which imaging study is an integral part of pneumonia diagnosis? Why is the test not definitive? What test has both high sensitivity and specificity?
X-ray; non-specific; CT scan
Blood cultures are prognostic of an increasing risk of what, especially in pneumococcal disease?
Morbidity
If pleural fluid is visible on chest x-ray, what should be obtained next and why?
Lateral decubitus film to see if the fluid can be drained
How is an exudative effusion classified? Transudative?
pleural fluid /serum protein ratio > 0.5, pleural fluid/serum LDH ratio > 0.6, or pleural fluid LDH >200; protein and LDH ratios less than 0.5 and 0.6 respectively
How is empyema classified?
purulent pleural fluid pH1000mg/dl)
True False: For most commonly acquired pneumonia, measurement of oxygenation is unnecessary.
True
When is assessment of pulmonary function via spirometry best performed?
When patient has recovered from the acute episode
What methods are useful to obtain an adequate specimen when the patient is unable to produce one?
Fiberoptic bronchoscopy and also bronchoalveolar lavage in immunocompromised patients
What is the criteria used to identify patients with a low risk of dying in the next 30 days? Which classes should be admitted based on the criteria?
Fine criteria; Class IV and Class V
Fifty percent of adults have antibodies against Chlamydophila pneumoniae but what is unique about these antibodies?
They are not protective against the disease
Which pneumonia gives extrapulmonary symptoms?
Legionella - GI (nausea, vomiting, diarrhea), neurologic (headache, delirium), renal, hepatic, electrolyte disturbances, and SIADH (antidiuretic hormone hypersecretion)
What causes aspiration pneumonia and what are symptoms?
Aspiration of oropharyngeal contents, can present as acute, subacute, or chronic febrile illness, productive cough, putrid sputum, hemoptysis, chest pain
In aspiration pneumonia, what bacteria are responsible for CAP, nosocomial, or diabetic and alcoholic patients?
oral anaerobic bacteria; Staphylococci, aerobic gram negatives; , aerobic gram negative rods
What viral pneumonias occur in immunosuppressed patients?
Herpes Simplex, Cytomegalovirus, and Measles
The different possible fungal pneumonias are:
Histoplasmosis, Coccidiomycosis, Cryptococcus, Blastomycosis, and Pneumocystis jiroveci
Indications for hospitalization with pneumonia:
Arterial hypoxemia, severe viral sign abnormalities (low BP, high RR), coexist medical problems requiring hospitalization, severe lab abnormalities
Additional risk factors in pneumonia patients which predicts a prolonged course:
> 65y.o., immunosuppression, comorbid illness (diabetes, etc.), Temp >38.3, high risk etiology
Therapy for pneumonia must be individualized to likely pathogens in a particular patient based on these characteristics:
Age, General health, Immune status, Community acquired vs nosocomial vs Nursing home, Exposure, Clinical presentation
