Pulmonology Flashcards
Areas of gas exchange in the respiratory tract
Respiratory bronchiole
4 basic lung volumes
Inspiratory Reserve Volume (IRV)
Amount of air inhaled /exhaled with each normal breath
TV (~0.5L)
Amount of air remaining in the lungs after full exhalation
RV (maintains oxygenation between breaths)
Maximum amount of air that one can inhale/exhale
Vital Capacity (IRV + TV + ERV)
Anatomic dead space volume
Area with no gas exchange from nose to terminal bronchiole (~150mL)
Physiologic dead space volume
Anatomic dead space volume + alveolar dead space volume
Alveolar Ventilation per minute
Respiratory Rate x (TV - Physiologic Dead Space Volume)
Minute Respiratory Volume
TV x RR
Stimulates central chemoreceptors in the medulla
Carbon Dioxide (as CSF +)
Lung Zones
Zone 1 (no blood flow)
Increase in the following factors would cause shift to the right of the O2-Hgb dissociation curve (unloading of O2 from Hgb)
Mnemonic: CADET face RIGHT: CO2, Acidosis, 2,3-DPG, Exercise, Temperature
Increase in the following factors would cause shift to the left of the O2-Hgb dissociation curve (increased binding of O2 to Hgb)
Carbon monoxide, fetal hemoglobin
Percentage of blood that gives up oxygen as it passes through the tissue capillaries
Utilization coefficient (25% at rest, 75-85% during exercise)
Central control of inspiration; sends inspiratory ramp signals
Dorsal respiratory group (DRG) of the medulla
Central control of both inspiration and expiration; sends overdrive mechanism in exercise
Ventral respiratory group (VRG) of the medulla
Limits inspiration and increases respiratory rate
Pneumotaxic center of the pons
Stimulates the inspiration and decreases the respiratory rate
Apneustic center of the pons
Receptors in the ventral medulla that is stimulated by CSF H+ from blood CO2; adapts within 1-2 days
Central chemoreceptors
Receptors in carotid bodies (CN IX) and aortic bodies (CN X); activated when PO2 < 70 mmHg and to a lesser extent, CO2
Peripheral chemoreceptors
Reversibility in asthma (spirometry)
> 12% and 200mL increase in FEV1: 15 minutes after an inhaled short-acting B2-agonist; or
Physiologic abnormality of asthma
Airway hyperresponsiveness
Pathogenesis behind asthma
Imbalance favoring TH2 production over TH1 -> increases IL-1, IL-5 -> increased eosinophils
Putative mediators of asthma
SRS-A (made up of leukotrienes C4, D4, E4)
Whorls of shed epithelium in mucus plugs in asthma
Curschmann?s Spirals
Crystalloid made up of eosinophil membrane protein seen in both asthma & amoebiasis
Charcot-Leyden Crystals
Predominant key cell involved in asthma
None
Characteristic feature of asthmatic airways
Eosinophil infiltration
Most common triggers of acute severe asthma exacerbations
URTI: rhinovirus, respiratory syncytial virus (RSV), coronavirus
Mechanism of exercise-induced asthma (EIA)
Hyperventilation
EIA is best prevented by regular treatment with
Inhaled corticosteroids (ICS)
Confirms airflow limitation with a reduced FEV1, FEV1/FVC ratio, and PEF
Spirometry
Confirms diurnal variation in airflow obstruction
Measurements of PEF twice daily
Primary action of B2-agonists
Relax smooth-muscle cells of all airways, where they act as functional antagonists
Most common side effect of anticholinergics
Dry mouth
Most common side effects of theophylline
Nausea, vomiting, headaches
Most effective controllers for asthma
ICS
Indicates the need for regular controller therapy
Most common reason for poor control of asthma
Drugs that are safe for asthma in pregnancy
Most common pathogenesis of pneumonia
Aspiration
Most common etiology of community-acquired pneumonia
Streptococcus pneumoniae
Most common etiology of atypical pneumonia
Mycoplasma pneumonia
Most common cause of nosocomial pneumonia and pneumonia in cystic fibrosis patients
Pseudomonas aeruginosa
Most common viral cause of atypical pneumonia and bronchitis in children
Respiratory Syncytial Virus (RSV)
Main purpose of the sputum gram stain
Ensure suitability of sample for culture
To be adequate for culture, a sputum sample must have
> 25 neutrophils; and
Most frequently isolated pathogen in blood cultures of community-acquired pneumonia
Streptococcus pneumoniae
Irreversible airway dilation that involves the lung in either a diffuse or focal manner
Bronchiectasis
Most common form of bronchiectasis
Cylindrical or tubular
Most cited mechanism for infectious bronchiectasis
Vicious cycle hypothesis
Most common clinical presentation
Persistent cough with production of thick sputum
Imaging modality of choice for confirming bronchiectasis
Chest CT
First step in diagnostic approach to pleural effusion
Determine whether the effusion is an exudate or a transudate
Leading causes of transudative pleural effusion
LV failure and cirrhosis
Leading causes of exudative pleural effusion
Bacterial pneumonia, malignancy, viral infection, pulmonary embolism
Most common cause of chylous pleural effusion
Malignancy
Three tumors that cause ~75% of all pleural effusions
Lung carcimona, breast carcimona, lymphoma
Benign ovarian tumors producing ascites and pleural effusion
Meigs’ Syndrome
The only symptom that can be attributed to the malignant pleural effusion itself
Dyspnea
Condition most commonly overlooked in the differential diagnosis of a patient with undiagnosed effusion
Pulmonary embolism
Most common cause of chylothorax
Trauma (most frequently, thoracic surgery)
Treatment choice for most cases of chylothorax
Insertion of a chest tube plus administration of octreotide
Population at risk for spontaneous pneumothorax
Tall, thin men 20-40 y/o, smoker
Ipsilateral tracheal deviation
Tracheal deviation in spontaneous pneumothorax
Contralateral tracheal deviation
Tracheal deviation in tension pneumothorax
Coexistence of unexplained excessive daytime sleepiness with at least five obstructed breathing events (apnea or hypopnea) per hour of sleep
Obstructive sleep apnea
Breathing pauses lasting >10 seconds
Apnea
> 10 second events where ventilation is reduced by at least 50% from the previous baseline
Hypopnea
First step in evaluating a mediastinal mass
Place it in one of the three mediastinal components
Most common lesions in anterior mediastinum
Mnemonic: Terrible T?s!
Most common lesions in middle mediastinum
Vascular masses, Lymphadenopathy from metastases or granulomatous disease, Pleuropericardial and bronchogenic cysts
Most common masses in the posterior mediastinum
Neurogenic tumors, Meningocoelesm Meningomyelocoeles, Gastroenteric cysts, Esophageal diverticula
First step in evaluating a mediastinal mass
Place it in one of the three mediastinal components
Most common lesions in anterior mediastinum
Mnemonic: Terrible T?s!
Most common lesions in middle mediastinum
Vascular masses, Lymphadenopathy from metastases or granulomatous disease, Pleuropericardial and bronchogenic cysts
Most common masses in the posterior mediastinum
Neurogenic tumors, Meningocoelesm Meningomyelocoeles, Gastroenteric cysts, Esophageal diverticula
One of the three major cardiovascular causes of death, along with MI and stroke
Venous thromboembolism
Causes of pulmonary embolism
Fat, foreign body, air, DVT, bone marrow, ambiotic fluid, tumor
Population at risk for pulmonary embolism
Patients with preexisting heart/lung disease (occurs in lower lobes)
Usual cause of death from pulmonary embolism
Progressive right HF
Most frequent history in DVT
Cramp in the lower calf that persists and worsens for several days
Most frequent history in PE
Unexplained breathlessness
Classic signs of PE
Tachycardia, low-grade fever, neck vein distension
Most frequent symptom of PE
Dyspnea
Most frequent sign of PE
Tachypnea
Useful rule-out test: >95% of patients with normal levels (<500 ng/ml) do not have PE
Quantitative plasma D-dimer ELISA
Most frequently cited ECG abnormality in PE (in addition to sinus tachycardia)
S1 Q3 T3 Sign (specific but insensitive)
Most common ECG abnormality in PE
T-wave inversion leads V1 to V4
Principal imaging test for the diagnosis of PE
Chest CT scan with IV contrast
Second-line diagnostic test for PE, used mostly for patients who cannot tolerate IV contrast
Lung scanning
Best known indirect sign of PE on transthoracic echo
McConnell’s sign: hypokinesis of the RV free wall with normal motion of RV apex
Definite diagnostic test for PE, used mostly for patients who cannot tolerate IV contrast PE which visualizes an intraluminal filling defect in more than one projection
Lung scanning
Foundation for successful treatment of DVT and PE
Anticoagulation
Massive pulmonary embolism
Systemic arterial hypotension with usually anatomically widespread thromboembolism
Moderate to large pulmonary embolism
RV hypokinesis with normal systemic arterial pressure
Small to moderate pulmonary embolism
Normal RV function and normal systemic arterial pressure (excellent prognosis with adequate anticoagulation)
Definition of ARDS
Acute onset (<24 hours), Bilateral patchy airspace disease, Absence of of left atrial hypertension (PCWP < 18 mmHg), Profound shunt physiology
Top 3 causes of ARDS
Gram-negative sepsis, gastric aspiration, severe trauma
Short-term morphology of ARDS
Waxy hyaline membranes
Long-term morphology of ARDS
Intra-alveolar fibrosis
Histologic manifestation of ARDS
Diffuse alveolar damage
