FA Respiratory JWM

Conducting zone

Consists of nose, pharynx, trachea, bronchi, bronchioles, and terminal bronchioles. Cartilage is present only in the trachea and bronchi. Brings air in and out.

warms, humidifies, filters air.
Anatomic dead space.
Walls of conducting airways contain smooth muscle

Respiratory zone

Consists of respiratory bronchioles, alveolar ducts, and alveoli. Participates in gas exchange

Pneumocytes

Pseudostratified ciliated columnar cells that extend to the respiratory bronchioles (macrophages clear debris in alveoli); goblet cells extend only to the bronchi

Mucus secretions are swept out of the lungs toward the mouth by ciliated cells.
Two types

Type I pneumocytes

97% of alveolar surfaces. They line the alveoli. Squamous; thin for optimal gas diffusion.

Type II pneumocytes

3%. They secrete pulmonary surfactant (dipalmitoyl phosphatidylcholine), which decreases the alveolar surface tension.

Cuboidal and clustered
Serve as precursors to type I cells and other type II cells.
proliferate during lung damage

Clara cells

Another kind of pneumocyte. Nonciliated; columnar with secretory granules. Secrete component of surfactant; degrade toxins; act as reserve cells

Indication of fetal lung maturity

A lecithin-to-sphingomyelin ratio of > 2.0 in amniotic fluid

Where a peanut would go if you aspirated it(give answer for upright and supine)

While upright: lower portion of right inferior lobe (makes sense it goes to the lower portion due to gravity)
While supine: superior portion of right inferior lobe.
Right main stem bronchus is wider and more vertical than the left

Lingula

Homologue of right middle lobe.

Left lung only has 2 lobes + the lingula + space occupied by the heart
Right lung has 3 lobes

Relationship of pulmonary artery to the bronchus at each lung hilus

Remember RALS. Right is Anterior while the Left is Superior

Structures that perforate the diaphragm(give level where they do it too)

T8 = IVC
T10 = esophagus, vagus(2 trunks)
T12 = aorta, thoracic duct, and azygous vein
"I (IVC) 8 10 Eggs (Esophagus) At (Aorta) 12"

Diaphragm innervation

C3, 4, 5 keeps the diaphragm alive

Pain from the diaphragm can be referred to the shoulder

During exercise, muscles used in inspiration

External intercostals, Scalene muscles, Sternomastoids

During exercise, muscles used in expiration

Rectus abdominis, internal and external obliques, transversus abdominis, internal intercostals

Collapsing pressure

= ((2 x surface tension)/radius)

Tendency to collapse on expiration as radius decreases(law of Laplace)

5 important products of the lung

1. Surfactant (produced by type II pneumocytes)
2. Prostaglandins 3. Histamine (bronchoconstriction) 4. ACE, which both converts angio I to angio II and inactivates bradykinin(which if left activated can lead to cough and angiodema, two big problems with ACE inhibs) 5. Kallikrein, which activates bradykinin

Residual volume

Air in lung after maximal expiration; cannot be measured on spirometry

Vital capacity is everything BUT the Residual volume

Vital Capacity

TV + IRV + ERV.

Everything but the vital capacity

Expiratory reserve volume (ERV)

air that can still be breathed out after normal expiration

Tidal volume TV

Air that moves into lung with each quiet inspiration, typically 500ml

Inspiratory reserve volume (IRV)

air in excess of tidal volume that moves into lung on maximum inspiration

Functional residual capacity (FRC)

RV + ERV (volume in lungs after normal expiration)

Inspiratory Capacity(IC)

IRV + TV

Total Lung capacity

IRV + TV + ERV + RV

Determination of physiologic dead space

Vd = Vt x ((PaCO2 - PeCO2)/PaCO2)

Vd = anatomic(of lung airways) + functional dead space(mostly from apex of a healthy lung). So volume of inspired air not taking part in gas exchange
Vt = tidal volume, PaCO2 = arterial PCO2, PeCO2 = expired air PCO2

When is the inward pull of the lungs balanced by the outward pull of chest wall

At FRC(which is volume after a normal expiration)

airway and alveolar pressure are 0, and intrapleural pressure is negative(prevents pneumothorax)

Name three times when lung compliance is decreased

Pulmonary fibrosis, insufficient surfactant, and pulmonary edema

Two forms hemoglobin exists in

1. Taut = low affinity for O2
2. Relaxed = High affinity for O2. Exhibits positive cooperativity and negative allostery (accounts for sigmoid-shaped O2 dissociation curve for Hemoglobin), unlike myoglobin

think of when you are relaxed, you do your job better

Fetal hemoglobin

2 alpha and 2 gamma subunits(as opposed to beta). Has lower affinity for 2,3-BPG than adult hemoglobin (HbA) and thus has a higher affinity for O2.

Factors that favor Hemoglobin in Taut form

Increased Cl-, H+, CO2, 2,3BPG and temperature.

So all shift dissociation curve to right, leading to increased O2 unloading)

Tx for methemoglobinemia

Methylene blue

Methemoglobin, and treatment of cyanide poisoning

Oxidized form of hemoglobin (ferric, Fe3+ when it is normally Fe2+), that does not bind O2 as readily, but has increased affinity for CN-.

to treat CN- poisoning, use nitrites to oxidize hemoglobin to methemoglobin, which binds cyanide, allowing cytochrome oxidase to function. Use thiosulfate to bind this cyanide, forming thiocyanate, which is renally excreted

Carboxyhemoglobin

Form of hemoglobin bound to CO in place of O2. Causes decreased oxygen-binding capacity with a left shift in the oxygen-hemoglobin dissociation curve. Decreased oxygen unloading in tissues

CO has 200x greater affinity than O2 for hemoglobin.

Right shift

Decreased affinity of Hb for O2 (facilitates unloading of O2 to tissue). An increase in all factors (except pH) causes a right shift.

These factors are CO2, 2,3BPG, Exercise, Acid/Altitude, Temp

Increased affinity for oxygen, Increased pH: decreased acidity/ [H+], Decreased temperature, Decreased DPG (exercise)

Fetal Hb(right or left shift)

Has a higher affinity for O2 than adult Hb, so its dissociation curve is shifted left

Perfusion limited

O2(normal health), CO2, N2O.

Gas equilibrates early along the length of the capillary. Diffusion can be increased only if blood flow increases

Diffusion limited

O2(emphysema, fibrosis), CO

Gas does not equilibrate by the time blood reaches the end of the capillary
In emphysema it is due to decreased Area
In pulmonary fibrosis it is due to increased Thickness

Diffusion(eqtn for it)

Vgas = A/T x (Dk(P1-P2) where A = area, T = thickness, and Dk(P1-P2) = difference in partial pressures

A is decreased in emphysema
T is increased in pulm fibrosis

Hypoxic Vasoconstriction

What the pulmonary circulation does when it senses a decrease in PAO2. It shifts blood away from poorly ventilated regions of lung to well-ventilated regions of lung

opposite of what happens in rest of body with hypoxia

Pulm. circulation(resistance and compliance)

Low-resistance and high-compliance(when healthy)

Pulmonary Htn

>25mmHg or >35mmHg during exercise.

results in atherosclerosis, medial hypertrophy, and intimal fibrosis of pulmonary arteries
primary and secondary types

Primary Pulmonary Htn

Due to an inactivating mutation in the BMPR2 gene(which normally functions to inhibit vascular smooth muscle proliferation); poor prognosis

Secondary Pulmonary Htn

Due to COPD(destruction of lung parenchyma); mitral stenosis (increased resistance leads to increased pressure); recurrent thromboemboli; autoimmune dz; left-to-right shunt(increased shear stress leads to endothelial injury); sleep apnea or living at high altitude(hypoxic vasoconstriction

Pulmonary Vascular Resitance(PVR)

PVR = (Ppulm artery - Pl.atrium)/(Cardiac Output)

O2 content of blood

= (O2 binding capacity x % saturation) + dissolved O2

and O2 delivery to tissue is O2 content of blood x CO

Alveolar Gas Eqtn

PAO2 = PIO2 - (PaCO2/R)

R = resp quotient, PIO2 = PO2 in inspired air
Can normally be approximated: PAO2 = 150 - PaCO2/0.8
Normal A-a gradient = 10-15mmHg, medically significant when >30mmHg

Times when A-a gradient is elevated during tissue hypoxia

3main causes of tissue hypoxia = ischemia, hypoxemia, and Hb-related problems

A-a gradient is elevated only in times of hypoxemia(defined as decrease in PaO2 < 40mmHg) when there is a ventilation, perfusion or diffusion defect.
The two types of hypoxemia where A-a gradient are normal are decreased inspired PO2(high altitude) or respiratory acidosis(hypoventilation

V/Q mismatch in lung zones

1. Apex of lung has V/Q = 3, so wasted ventilation.
2. Base of the lung has V/Q = 0.6, so wasted perfusion

both ventilation and perfusion are greater at the base of the lung than at the apex of the lung

V/Q = infinity

blood flow obstruction(physiologic dead space). Assuming <100% dead space, 100% O2 improves PO2.

3 forms in which CO2 is transported from tissues to the lungs

1. Bicarbonate(90%)
2. Bound to hemoglobin at N terminus of globin(not heme) as carbaminohemoglobin(5%). CO2 binding favors taut form(O2 unloaded)
3. Dissolved CO2(5%)

Haldane Effect

In lungs, oxygenation of Hb promotes dissociation of H+ from Hb. This shifts equilibrium toward CO2 formation; therefore, CO2 is released from RBCs

Bohr effect

In peripheral tissue, increased H+ from tissue metabolism shifts curve to right, unloading O2

Response to high altitude

chronic incr vent leads to incr epo. Result = increased hct, and hgb
Incr 2,3BPG. Incr mitochondria in cells
Increased renal secretion of bicarb
Chronic hypoxic pulm. vasoconstriction results in RVH

Response to exercise

1. incr. CO2 production 2. Incr O2 consumption 3. Incr. ventilation rate to meet O2 demand 4. V/Q ratio from apex to base becomes more uniform 5. Incr. pulmonary blood flow due to incr. CO 6. Decr. pH during hard exercise(secondary lactic acidosis) 7. No change in PaO2 and PaCO2, but incr in venous CO2 content

Types of emboli

Fat, air, thrombus, bacteria, amniotic fluid, tumor.

95% from deep leg veins
Helical CT is imaging test of choice for a PE
Long bone fractures and liposuction = fat emboli
Amniotic fluid emboli can lead to DIC, especially postpartum

Virchow's triad

1. Stasis
2. Hypercoagulability (e.g. defect in coagulative cascade proteins)
3. Endothelial damage (exposed collagen triggers clotting cascade)

Related to risk of DVT

Homans' sign

pain in calf with passive dorsiflexion of the foot

DVT tx

Prevent and tx with heparin

COPD, general definition of obstructive lung dz and PFT values

Obstruction of air flow resulting in air trapping in the lungs. Airways close prematurely at high lung volumes, resulting in increased Residual Volume and decreased FVC.

PFTs: very decreased FEV1, decreased FVC and this leads to the hallmark which is the decreased FEV1/FVC ratio. Also see V/Q mismatch

Chronic Bronchitis

Blue Bloater. Productive cough for > 3 consecutive months in at least 2yrs. Dz of small airways.

findings = wheezing, crackles, cyanosis(early-onset hypoxemia due to shunting), late-onset dyspnea

Path of chronic bronchitis

Hypertrophy of mucus-secreting glands in the bronchioles leads to Reid index = gland depth/total thickness of bronchial wall; in COPD,

Reid index >50%

Emphysema

'pink puffer,' barrel-shaped chest

Increased elastase activity, and increased lung compliance due to loss of elastic fibers. Exhalation through pursed lips to increase airway pressure and prevent airway collapse during respiration

Path of Emphysema

Enlargement of air spaces and increased recoil resulting from destruction of alveolar walls. Increased compliance

Asthma

Path = bronchial hyperresponsiveness causes reversible bronchoconstriction. Smooth muscle hypertrophy and Curschmann's spirals (shed epithelium from mucous plugs)

Can be triggered by viral URIs, allergens, and stress. Test with methacholine challenge,
Findings: cough, wheezing, tachypnea, dyspnea, hypoxemia, decreased I/E ratio, pulsus paradoxus, mucus plugging

Bronchiectasis

Path = Chronic necrotizing infection of bronchi leads to permanently dilated airways, purulent sputum, recurrent infections, hemoptysis

Associated with bronchial obstruction, poor ciliary motility (smoking), Kartagener's syndrome. Can lead to aspergillosis.

General premise of restrictive lung dzs

Restricted lung expansion causes decreased lung volumes (decreased FVC and TLC).

PFTs: FEV1/FVC ratio >80%

Restrictive lung dzs due to poor breathing mechanics

1. Poor muscular effort: polio, myasthenia gravis
2. Poor structural apparatus: scoliosis, morbid obesity

both of these 2 types are extrapulmonary, peripheral hypoventilation

Restrictive lung dzs due to interstitial lung dzs

All these types are pulmonary, lowered diffusing capacity.
1. ARDS 2. hyaline membrane dz 3. Pneumovonioses 4. Sarcoidosis 5. Idiopathic pulm. fibrosis 6. Goodpastures' 7. Wegener's syndrome 7. Eosinophilic granuloma 8. Drug toxicity

Sarcoidosis

Bilateral hilar lymphadenopathy, noncaseating granuloma; increased ACE and Calcium

Idiopathic pulmonary fibrosis

Repeated cycles of lung injury and wound healing with increased collagen

Eosinophilic granuloma

Also called histiocytosis X

Drug toxicity, which drugs(that cause interstitial lung dz)

bleomycin, busulfan, amiodarone

Coal miner's lung

A type of pneumoconioses that affects upper lobes.

Associated with coal mines. Can result in cor pulmonale, Caplan's syndrome (rheumatoid arthritis involvement)

Silicosis

A type of pneumoconioses that affects upper lobes. "Eggshell calcification of hilar lymph nodes

Associated with foundries, sandblasting, and mines. Macrophages respond to silica and release fibrogenic factors, leading to fibrosis. It is thought that silica may disrupt phagolysosomes and impair macrophages, increasing susceptibility to TB

Asbestosis

A type of pneumovonioses that affects lower lobes. Asbestos bodies are golden-brown fusiform rods resembling dumbbells, located inside macrophages.

Associated with shipbuilding, roofing, and plumbing. Results in "ivory white," calcified pleural plaques. Associated with an increased incidence of bronchogenic carcinoma and mesothelioma.

Neonatal resp. distress syndrome

Surfactant deficiency resulting in alveolar collapse.

risk factors: prematurity, maternal diabetes(due to elevated insulin), cesarean delivery (decreased release of fetal glucocorticoids bc baby not 'stressed' as much)
Tx = maternal steroids before birth, artificial surfactant for infant, thyroxine can also be used

Ratio of lecithin-to-sphingomyelin (L:S) ratio you usually see neonatal resp. distress syndrome

Usually >1.5

Surfactant made by type II pneumocytes most abundantly after 35th week of gestation

Other risks with neonatal resp distress syndrome

persistently low O2 tension can lead to PDA.

therapeutic supplemental O2 can result in retinopathy of prematurity

causes of ARDS

May be caused by trauma, sepsis, shock, gastric aspiration, uremia, acute pancreatitis, or amniotic fluid embolism

diffuse alveolar damage leads to increased alveolar capillary permeability leading to protein-rich leakage into alveoli
Results in formation of intra-alveolar hyaline membrane. Initial damage due to release of neutrophilic substances toxic to alveolar wall, activation of coag cascade, and O2-derived free radicals

Sleep apnea, definition, types and tx

person stops breathing for at least 10 secs repeatedly during sleep.

Central sleep apnea = no resp effort
Obstructive sleep apnea = resp effort against airway obstruction
Tx = wt. loss, CPAP, surgery

Sleep apnea, associations and complications

Hypoxia leads to incr. EPO release which leads to erythrocytosis.

individuals may become chronically tired
Associated with obesity, loud snoring, systemic/pulmonary htn, arrhythmias, and possibly sudden death

Bronchial obstruction

absent/decreased breath sounds over affected area
decreased resonance and fremitus
Tracheal deviation toward side of lesion

Pleural effusion

decreased breath sounds over effusion
Dullness with resonance.
Decreased fremitus

Pneumonia(lobar)

may have bronchial breath sounds over lesion
Dullness with resonance
Increased fremitus

Tension pneumothorax

Decreased breath sounds
Hyperresonant
Absent fremitus
Tracheal deviation away from side of lesion

Spontaneous pneumothorax

Decreased breath sounds
Hyperresonant
Decreased fremitus
Tracheal deviation toward side of lesion

Complications(and mnemonic) of lung cancer

SPHERE

S = superiorvena cava syndrome, P = Pancoasttumor, H = Horner’s syndrome, E = Endocrine (paraneoplastic), R = Recurrent laryngeal symptoms(hoarsness), E = Effusions (pleuralor pericardial)

Lung cancer presentation, and mets

cough, hemoptysis, bronchial obstruction, wheezing, pneumonic 'coin' lesion on x-ray film or noncalcified nodule on CT

Mets to lung is most common, often from breast, colon, prostate, and bladder cancer
Sites of mets from lungs = adrenals, brain(epilepsy), bone (pathologic fracture), liver (jaundice, hepatomegaly)

Location = central

Undifferentiated, very aggressive; often associated with ectopic production of ACTH or ADH; may lead to Lambert-Eaton syndrome (autoantibodies against Ca++ channels). Responsive to chemo. Inoperable
Histo = neoplasm of neuroendocrine Kulchitsky cells which are small dark blue cells

Adenocarcinoma

Location = peripheral

2 types = bronchial and bronchioloalveolar.
Histo of both types = Clara cells which are type II pneumocytes; multiple densities on x-ray of chest

Bronchial adenocarcinoma

Peripheral location. Develops in site of prior pulmonary inflammation or injury(most common lung cancer in nonsmokers and females)

Bronchioloalveolar adenocarcinoma

Location = peripheral.

Not linked to smoking; grows along airways; can present like pneumonia. Can result in hypertrophic osteoarthropathy

Squamous cell carcinoma

Location = Central

Hilar mass arising from bronchus; Cavitation; Clearly linked to smoking; parathyroid-like activity caused by PTHrP
Histo = keratin pearls and intercellular bridges

Large cell carcinoma

Location = peripheral

Highly anaplastic undifferentiated tumor; poor prognosis; less responsive to chemo. Removed surgically.

Histo = pleomorphic giant cells with leukocyte fragments in cytoplasm

Carcinoid tumor

Secretes serotonin, can cause carcinoid syndrome (rule of 1/3s and BFDR (bronchospasm, flushing, diarrhea, right-sided valvular dz).

Fibrous deposits in right heart valves may lead to tricuspid insufficiency, pulmonary stenosis, and right heart failure

Mesothelioma

Location = pleural

Malignancy of the pleura associated with asbestosis. Results in hemorrhagic pleural effusions and pleural thickening
Histo = psammoma bodies

Pancoast tumor

Carcinoma that occurs in apex of lung and may affect cervical sympathetic plexus, causing Horner's syndrome.

Horner's syndrome = ptosis, miosis, anhidrosis

Superior vena cava syndrome

An obstruction of the SVC that impairs blood drainage from the head ('facial plethora'), neck (JVD), and upper extremities (edema). Most commonly caused by neoplasms and thromboses. Can raise intracranial pressure (if obstruction severe), which presents with headaches and dizziness and can increase risk of aneurysm/rupture of cranial arteries.

Lobar pneumonia

organism = most often Pneumococcus, sometimes Klebsiella
Characteristics = intra-alveolar exudate leading to consolidation; may involve entire lung

Bronchopneumonia

S. aureus, H. flue, Klebsiella, S. pyogenes

Acute inflammatory infiltrates from bronchioles into adjacent alveoli.
Patchy distribution involving at least 1 lobe

Interstitial (atypical) pneumonia

Viruses (RSV, adenoviruses), Mycoplasma, Legionella, Chlamydia

Diffuse patchy inflammation localized to interstitial areas at alveolar walls; distribution involving at least 1 lobes.
Generally follows a more indolent course than bronchopneumonia

Lung abscess

Localized collection of pus within parenchyma. Caused by: bronchial obstruction (e.g., cancer), aspiration of oropharyngeal contents (especially in pts predisposed to loss of consciousness like alcoholics/epileptics)

air-fluid levels often seen on CXR. Often due to S. aureus or anaerobes (Bacteroides, Fusobacterium, Peptostreptococcus)

Hypersensitivity pneumonitis

Mixed type III/IV hypersensitivity reaction to environmental antigen leads to dyspnea, cough, chest tightness, headache.

often seen in farmers and those exposed to birds

Transudate

Decreased protein content. Due to CHF, nephrotic syndrome, or hepatic cirrhosis

this definition applies to when a transudate comes from a pleural effusion

Pleural effusion, Exudate

Increased protein content, cloudy. Due to malignancy, pneumonia, collagen vascular dz, trauma (occurs in states of increased vascular permeability).

must be drained in light of risk of infection

Pleural effusion, Lymphatic

Also known as chylothorax. Milky-appearing fluid; increased triglycerides

Pneumothorax, general findings

Unilateral chest pain and dyspnea, unilateral chest expansion, decreased tactile fremitus, hyperresonance, diminished breath sounds

Spontaneous pneumothorax

Accumulation of air in the pleural space. Occurs most frequently in tall, thin, young males because of rupture of apical blebs.

Trachea deviates toward affected lung

IMAGE: COLLAPSED LEFT LUNG. Note the hyperlucent left lung field with lower diaphragm and rightward mediastinal shift
Usually occurs in setting of trauma or lung infection. Air is capable of entering pleural space but not exiting. Trachea deviates Away from affected lung

FA Respiratory JWM

Medicine Step1 with Mr.boards at University of Chapel Hill

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