Respiratory Flashcards
What is the equation for physiologic dead space?
Vd = Vt x (PaCO2 - PeCO2)/PaCO2 Vd = physiologic dead space Vt = tidal volume PaCO2 = arterial O2 pressure PeCO2 = expired air PCO2
Alveolar ventilation equation?
Va = (Vt-Vd) x RR RR = respiratory rate
Which form of hemoglobin has low affinity for O2?
T (taut) form
What causes hemoglobin to favor the taut form (5)?
Cl-, H+, CO2, 2,3-BPG, temperature
On the oxygen-hemoglobin dissociation curve, what is the significance of a shift to the right?
Decreased affinity of Hb for O2
How is diffusion assesed (calculation)?
Volume of gas = A/T x Dk (P1-P2)
A = area
T = thickness
Dk (P1-P2) = difference in partial pressure
How do emphysema and pulmonary fibrosis affect lung diffusion?
Both decrease it
Area of diffusion decreases in emphysema
Thickness increases in pulmonary fibrosis
What is pulmonary wedge pressure
Pressure in the left atrium
What is the alveolar gas equation?
PAO2 = PIO2 - (PaCO2/R) PAO2 = alveolar PO2 PIO2 = PO2 in inspired air R = Respiratory quotient (CO2 produced/O2 consumed) = usually 0.8
What can increase the A-a gradient?
V/Q mismatch (ideally should = 1)
Diffusion limitaiton
Right-to-left shunt
What is the function of the BMPR2 gene and what happens when it is mutated?
BMPR2 gene functions to inhibit vascular smooth muscle proliferation - mutation results in primary pulmonary hypertension
What are the activating metastases for adenocarcinoma of the lung?
Where is adenocarcinoma located?
How does it appear on histology?
What are the activating metastases for adenocarcinoma of the lung?: k-ras, EGFR, ALK
Where is adenocarcinoma located?: peripheral lung
How does it appear on histology?: grows along alveolar septa (thickening of alveolar walls)
What is Lambert Eaton myasthenic syndrome
Autoimmune disorder that is characterized by muscle weakness of the limbs. It is the result of an autoimmune reaction in which antibodies are formed against presynaptic voltage-gated calcium channels - These antibodies can be produced by small cell carcinoma of the lung
What can small cell carcinoma of the lung produce?
ACTH, ADH, Antibodies against calcium channels
What are the organisms associated with Lobar pneumonia?
S. pneumoniae (most frequent); Legionella, Klebsiella
What organisms are associated with Bronchopneumonia
S. Pneumoniae; S. Aureus; H. Influenzae; Klebsiella
What organisms are associated with interstitial pneumonia?
Viruses (influenza, RSV, adenoviruses), Mycoplasma, Legionella, Chlamydia
What are causes of transudate pleural effusion (decreased protein content)?
CHF, nephrotic syndrome, hepatic cirrhosis
What are causes of exudate pleural effusion (increased protein content, cloudy)?
Malignancy, pneumonia, collagen vascular disease, trauma - must be drained
Where is the least airway resistance in the conducting zone of the lung?
terminal bronchioles (large numbers in parallel)
What is the cell distribution throughout the lung passages?
Conducting zone: Cartilage and goblet cells extend to end of bronchi; Pseudostratified ciliated columnar cells extend to beginning of terminal bronchioles
Respiratory zone: At terminal bronchioles, PCCC cells transition to ciliated cuboidal cells up through respiratory bronchioles; simple squamous up to alveoli
What is the function of club (clara) cells?
Secrete component of surfactant
Degrade toxins
Act as reserve cells
What is the function of Type II pneumocytes?
Secrete pulmonary surfactant
Serve as precursors to type I cells and other type II cells
Proliferate during lung damage
Structures perforating diaphragm and T-level?
“I ate ten eggs at twelve”
IVC: T8
Esophagus: T10
Aorta: T12
At FRC, what is happening to the following measures?
airway and alveolar pressure:
intrapleural pressure:
Pulmonary vascular resistance:
airway and alveolar pressure: zero
intrapleural pressure: negative
Pulmonary vascular resistance: at a minimum
Which type of hemoglobin has higher affinity for cyanide?
How is this used to treat cyanide poisoning?
Methemoglobin (Fe3+)
To treat cyanide poisoning, use nitrites to oxidize Hb to methemoglobin which binds cyanide. Use thiosulfate to bind this cyanide, forming thiocyanate, which is renally excreted
How do you calculate peripheral vascular resistance?
PVR = (Pressure in pulm artery - pressure in left atrium)/CO R = (viscosity of blood x length)/(radius^4)
What is the V/Q at…
Zone 1 (apex):
Zone 2:
Zone 3 (base):
Zone 1 (apex): V/Q > 1 (Q decreases more than V decreases) Zone 2: V/Q = 1 Zone 3 (base): V/Q
What is the haldane effect?
What is the Bohr effect?
Haldane effect: Oxygenation of Hb promotes dissociation of H+ from Hb which shifts the equilibrium toward CO2 formation (carbonic anhydrase); therefore CO2 is released from RBCs
Bohr effect: In peripheral tissue, increased H+ from metabolism shifts curve to right, unloading O2
The majority of CO2 is carried as _______
HCO3- in the plasma
What does Cl- decrease in peripheral tissue?
CO2 in the RBC is converted to HCO3- by carbonic anhydrase and this is released into the plasma in exchange for Cl- uptake by the RBC
What is the body’s response to high altitude? (acute and chronic)
High altitude:
1) Decreased atmospheric oxygen → decreased arterial O2 pressure → hyperventilation → decreased arterial CO2 pressure
2) Chronic increased ventilation → increased erythropoietin; increased hematocrit/Hb; increased 2,3 BPG (more O2 release); Increased mitochondria → Increased HCO3- exretion to compensate for respiratory alkalosis
What is the body’s response to exercise?
*bonus: what happens to arterial blood gas levels
Increased CO2 production → Increased O2 consumption → Increased ventilation to meet O2 demand → V/Q at apex approaches 1 → Increased pulmonary blood flow (increased CO) → Decreased pH (lactic acidosis)
- no change in PaO2 and PaCO2 but increasd in venous CO2 and decrease in venous O2 content
What superimposed bacterial infections occur after rhinosinusitis?
S. pneumoniae; H. influenzae; M. catarrhalis
Pulmonary embolism leads to respiratory _______
alkalosis (secondary to hypoxemia)
Obstructive lung disease general findings:
Air trapping in the lungs
Increased RV
Decreased FEV1/FVC
Requirements for chronic bronchitis are a productive cough for > _ months per year for > _ years
3;2
Which obstructive lung disease presents with increased compliance?
Which obstructive lung disease presents with crackles?
Which presents with pulsus paradoxus?
Which presents with permanently dilated airways?
Increased compliance: Ephysema
Crackles: Chronic bronchitis
Pulsus paradoxus: Asthma
Dilated airways: Bronchiectasis
What are charcot-leyden crystals associated with? What are they made from?
Asthma; formed from breakdown of eosinophils in sputum
What lung disease is associated with allergic bronchopulmonary aspergillosis?
Bronchiectasis
What restrictive lung disease are due to…
Poor muscular effort:
Poor structural apparatus:
Poor muscular effort: polio, myasthenia gravis
Poor structural apparatus: Scoliosis, morbid obesity
What drugs can cause restrictive lung disease?
Bleomycin, busulfan, amiodarone, methotrexate
Hypersensitivity pneumonitis is due to what type of hypersensitivity reaction?
Type III/IV reaction to environmental antigen
What is caplan syndrome?
Rheumatoid arthritis, ad pneumoconiosis with intrapulmonary nodules
Which type of pneumoconiosis is associated with increased incidence of both bronchogenic carcinoma and mesothelioma?
What histology finding is associated with mesothelioma?
Asbestosis (lower lobes)
Mesothelioma - psammoma bodies
Which pneumoconioses increases the risk of TB and how?
Sillicosis - Sillica may disrupt phagolysosomes and impair macrophages (which produce the fibrosis in this disease), increasing susceptibility to TB
Why does maternal diabetes lead to neonatal respiratory distress syndrome?
Increase in fetal insulin due to maternal hyperglycemia can cause decreased surfactant production
What is released in ARDS that causes damage (besides the formation of the intra-alveolar hyaline membrane)?
Damage due to release of neutrophilic substances toxic to alveolar wall, activation of coagulation cascade, and oxygen derived, free radicals
Pulmonary hypertension > __ at rest results in arteriosclerosis, medial hypertrophy, and intimal fibrosis of pulmonary arteries
25 mmHg
Most common lung cancer in non-smokers?
Adenocarcinoma
Which lung carcinoma can secrete PTHrP? How is it identified on biopsy?
Squamous cell carcinoma; Keratin pearls and intercellular bridges
What two lung carcinomas are of neuroendocrine origin? What positive stain is associated with neuroendocrine tumors?
Small cell cacrinoma and Bronchial carcinoid tumor; Chromogranin A positive
Which lung carcinoma is not treated with surgery?
Which has the best prognosis?
No surgery: Small cell carcinoma
Best prognosis: Bronchiol carcinoid tumor
What is Superior vena cava syndrome? (what causes it?)
An obstruction of SVC that impairs blood drainage from the head, neck and upper extremities (commonly caused by malignancy and thrombosis from indwelling catheters)
What are the common causes of lung abscess due to aspiration?
S. aureus (or anaerobes), bacterioides, fusobacterium, peptostreptococcus
Where is air accumulation in spontaneous pneumothorax:
What is the most frequent demographic:
What is the most frequent cause:
Air accumulation in the pleural space
Tall thin young males
Rupture of apical blebs
What is a hamartoma? What is a lung hamartoma?
A hamartoma is an excessive growth of a tissue type native to the organ of involvement
The lung is the most common location - lung hamartomas often contain islands of mature hyaline cartilage, fat, smooth muscle and clefts lined by respiratory epithelium
Which cancer of the lung arises from clara cells and grows along preexisting bronchioles and alveoli?
Bronchioloalveolar carcinoma
