Hypoxemia, Hypercapnia, Acid Base Physiology
Write out the carbonic acid equation.
CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3−
What classic sputum color is associated with Streptococcus pneumoniae?
What classic sputum color is associated with Streptococcus pneumoniae?
What is the most common cause of death in COPD patients?
Respiratory failure
High CO2 leads to CNS depression combined with RHF and infection pushes patients to ARDS and multi-organ failure
Which oxygen delivery device provides low-flow oxygen (1–6 L/min) with variable FiO₂ and is commonly used for mild hypoxemia?
Nasal cannula
Most common cause of CAP overall?
Streptococcus pneumoniae
Gram-positive diplococci, lancet-shaped, alpha-hemolytic, optochin sensitive
What is the most common cause of hypoxemia in pneumonia?
V/Q mismatch
What hematologic change occurs due to chronic hypoxia?
Secondary polycythemia
What is the primary mechanism that leads to cor pulmonale in COPD patients?
Chronic hypoxic pulmonary vasoconstriction → pulmonary hypertension
What are the 3 main causes of atypical pneumonia?
Mycoplasma pneumoniae
Chlamydophila pneumoniae
Legionella pneumophila
Which organism causes “walking pneumonia”?
Mycoplasma pneumoniae
What electrolyte abnormality is commonly seen in chronic CO₂ retainers?
Elevated bicarbonate
What lung sound is most associated with alveolar fluid accumulation?
Crackles (rales)
What echocardiogram finding supports cor pulmonale in COPD patients?
Right ventricular hypertrophy and elevated pulmonary artery pressure
What is the mechanism of action of azithromycin?
Binds 50S ribosomal subunit → inhibits protein synthesis
*good for atypical pneumonias
Which organism is gram-negative coccobacillus that produces IgA protease and commonly causes pneumonia in COPD patients
Haemophilus influenzae
What happens to CO₂ in severe COPD exacerbation?
Hypercapnia (respiratory acidosis)
What lab findings suggest bacterial pneumonia rather than viral?
Elevated procalcitonin + neutrophilia
Q: What type of heart failure is caused by chronic lung disease such as COPD?
Cor pulmonale
What is the MOA of amoxicillin and ceftriaxone?
Both are beta lactam antibiotics: inhibits cell wall synthesis by binding penicillin binding proteins thereby blocking peptidoglycan cross linking + leading to bacterial lysis
Gram-positive cocci in clusters, catalase positive, causes post-influenza pneumonia
Staphylococcus aureus
What phenomenon explains increased CO₂ after oxygen administration in COPD?
Reversal of hypoxic pulmonary vasoconstriction (V/Q mismatch)
Haldane Effect
Decreased respiratory drive
Myeloperoxidase!
(this is the last enzyme in the generation of ROS (specifically hypochlorite) in neutrophils. It contains a heme-containing pigment which gives the yellow green color
What are examples of triggers for acute RHF exacerbation in a patient with COPD?
Pneumonia (RLL infiltrate, fever, sputum) and Hypoxemia (PaO₂ 52, sat 83%) causes:
leads to decompensated RHF
Which oxygen device delivers a fixed FiO₂ and is preferred in COPD patients to avoid CO₂ retention?
Venturi mask
Which bacterial organism can be discovered as the cause of a patient's community acquired pneumonia by putting a blood vial in an ice box?
Mycoplasma pneumonia