DIT X: Pulmonary Flashcards
Tracheoesophageal fistula: definition, most common type
Abn connection between esoph + trachea Most common Type C (85%): upper esoph ends in blind pouch, lower esoph connects to trachea
Rx tiotropium
Inhaled anticholinergic relaxes airway, opposes bronchospasm COPD
TE fistula: types
A: esoph atresia w/o fistulas (no connection) B: upper esoph connects C: lower esoph connects D: upper & lower both connect E: fistula but no esoph atresia (“H type”)
What type of epithelium lines trachea, and what metaplasia is seen in smokers?
Ciliated columnar epithelium –> squamous metaplasia in smokers
Kartagener syndrome: alternate name, what is the defect?
Primary ciliary dyskinesia, due to non-functional dynein
Kartagener syndrome: clinical triad, other S&S
Triad: situs inversus, bronchiectasis, chronic sinusitis Others: infections, infertility, hearing loss
4 embryologic structures making up diaphragm
Septum transversum, pleuroperitoneal membranes, dorsal mesentery of esoph, abdo wall muscles
Congenital diaphragmatic hernia: presentation and complications
Presentation: flattened abdo, cyanosis, inability to breathe, most often on L side, assoc w polyhydramnios Complications: compression of thorax –> lung hypoplasia
Hiatal hernia: types
Sliding: most common, GEJ displaced, “hourglass stomach” Paraesophageal: cardia moves into thorax, GEJ stays in place
Innervation of diaphragm, to where does pain refer?
Phrenic nerve (C3, 4, 5) –> pain refers to neck and shoulder
Conducting zone vs respiratory zone
Conducting zone: nose to terminal bronchioles, no gas exchange, anatomic dead space Respiratory zone: resp bronchioles to alveolar sacs, gas exchange
Which lung is most common location for inhaled foreign body and why?
Right lung; right mainstem bronchus wider and more vertical than left
How many bronchopulmonary segments in each lung?
10 in right: 3 RUL, 2 RML, 5 RLL 8-10 in left: 4-5 LUL, 4-5 LLL
Respiratory muscles used in quiet respiration
Inspiration: diaphragm Expiration: relaxation
Accessory muscles of inspiration and expiration
Insp: SCM, ext intercostals, scalene muscles Exp: transversus abdominus, rectus abdominus, int & ext obliques, int intercostals
Type I pneumocytes
simple squamous epith, >97% alveolar surface, gas exchange, unable to replicate
Type II pneumocytes
large cuboidal, at alveolar-septal junctions, secrete pulmonary surfactant, can replace type I pneumocytes in lung damage
Surfactant: composition and function
Dipalmitoyl phosphatidylcholine; decreases alveolar surface tension
Lecithin:Sphingomyelin Ratio
from amniotic fluid sample, used to determine if premature lung is mature enough (ratio >2.0)
How to mature premature baby’s lungs pre-delivery?
Give mom corticosteroids
Chronic sinusitis + infertility + situs inversus
Kartagener Syndrome (Primary Ciliary Dyskinesia)
Structures traversing the diaphragm, and at which vertebral levels?
T8: IVC T10: esoph + vagus nerve T12: aorta, azygos vein, thoracic duct
Anatomical dead space vs functional dead space
Anatomical: air in airways Functional: capable of gas exchange, but none occurs
Eqn: Physiologic dead space
Vd = Vt x (PaCO2 - PeCO2) / PaCO2
Eqns: Pulmonary vascular resistance
(delta)P = Q x R
Relationship between functional residual capacity and chest wall dynamics
FRC: point at which outward force of chest wall and inward force of lung is perfectly balances, differs from person to person (compliance)
Normal pulmonary artery pressure and Dx of pulm HTN
Normal: 10-15 mmHg
Pulm HTN: pulm artery pressure >25 mmHg during rest, or >35 during exercise
Pathological changes seen in pulmonary HTN + consequences
Arteriosclerosis, media hypertrophy, fibrosis of intima
Consequences: cor pulmonale, right heart failure
Causes of secondary pulmonary HTN
Chronic lung disease (COPD, pulm fibrosis), mitral stenosis, recurrent TE, autoimmune, L to R shunts (VSD), sleep apnea, high altitude
Tx for pulmonary HTN
Bosentan / ambrisentan, prostaglandin analogue, sildenafil, dihydropyridine CCB
MOA of bosentan & ambrisentan
competitively antagonize endothelin-1 receptors –> decrease pulm vasc resistance
Primary pulmonary HTN: mutation, epidemiology, 2 disease associations
- abnormalities in BMPR2 (Bone Morphogenetic Protein Receptor type II) –> excessive vasc smooth muscl prolif
- esp women, avg age 36
- assoc w HIV and Kaposi sacroma (HHV-8)
If a lung collapses, what happens to intrathoracic volume?
Intrathoracic vol increases (chest wall expands)
What gene mutation causes primary pulmonary HTN?
BMPR2 (Bone Morphogenetic Protein Receptor Type II)
HbA: composition and 2 forms
- 2 alpha globins + 2 beta globins + 4 heme
- T form (taut): low affinity for O2, favours tissues
- R form (relaxed): high affinity for O2
How is fetal Hb different from adult Hb?
- 2 alpha globins + 2 gamma globins
- lower affinity for 2,3-DPG = higher affinity for O2
Normally, Hb has which form of iron?
Ferrous (Fe 2+)
Methemoglobin has which form of iron?
Oxidized –> ferric
Clinical use of methemoglobin
Higher affinity for cyanide, can use in cyanide poisoning (give nitrates to oxidize Hb)
Tx for cyanide poisoning
- amyl nitrite, sodium nitrite: to oxidize Hb to methemoglobin –> pick up cyanide
- thiosulfate: binds cyanide to be excreted renally
What is carboxyhemoglobin, and what effect does it have on the oxygen dissoc curve?
- Hb bound to CO
- Left shift
Substances causing methemoglobinemia
- nitrates & nitrites
- antimalarial drugs (eg chloroquine, primaquine)
- dapsone
- sulfonamides
- local anaesthetics (eg lidocaine)
- metoclopramide
Tx for methemoglobinemia
- methylene blue
- vit C
- cimetidine (H2 blocker)
Eqn: total blood O2 content
Total Blood O2 content = dissolved O2 + (Hb binding capacity x O2 sat)
How does anemia affect O2 sats and arterial PaO2?
Does not change either
How does exercise change arterial and venous O2 content?
no change in arterial O2, decreased venous O2 (due to increased O2 demand)
Alveolar gas equation
PAO2 = 150 - PaCO2/0.8
(See DIT p. 386)
A-a gradient: normal value, what would increase it?
- Normally small (10-15)
- Increase: shunting or V/Q mismatch, pulm fibrosis, increased FiO2, age
PaO2 : FiO2 ratio; normal and abnormal values
- normal: 300-500 mmHg
- <300: gas exchange deficit
- <200: severe hypoxia
V/Q ratios in lung apex vs lung base
- apex: V/Q > 1 , decreased perfusion
- base: V/Q < 1 (shunting), decreased ventilation
How is CO2 transportedd from tissues to lungs? (3 ways)
- as bicarb
- bound to N-terminal of Hb (as carbaminoHb)
- dissolved in blood
V/Q in airway obstruction vs in blood flow obstruction
- Airway obstruction: V/Q –> 0
- Blood flow obstruction: V/Q –> infinity
Acute mountain sickness: S&S
headache, fatigue, acute cerebral edema, acute pulm edema
Compensatory mechs for hypoxia at high altitude
- increased ventilation, EPO, 2,3-DPG, mitochondria, O2 efficiency, renal excr of bicarb
How much does the Hb & hematocrit change in a person that has acclimatized to a hypoxic environment for weeks?
- Hb: 15 gL –> 20
- hematocrit: 40-45 –> 65
At what positive G-force does visual blackout occur and why?
4-6 Gs; blood pools in abdo and legs, lack of flow to brain
What G force is ahceived during spacecraft liftoff?
8-9 Gs
Nitrogen narcosis
Nitrogen dissolves into neural memb –> reduced neuronal excitability
Becomes jovial / careless, drowsy, loss of strenght & coord, like EtOH intoxication
Pathophys of decompression sickness
Nitrogen bubbling out of solution
Decompression sickness: S&S, Tx
- pain in joints and muscles of arms & legs, neurologic problems (dizziness, paralysis, syncope), “chokes” (bubbles cuase SOB, pulm edema, death)
- Tx: hyperbaric therapy
By what mechanism does acute mountain sickness cause cerebral edama and acute pulmonary edema?
- cerebral edema: hypoxia-induced vasodilation
- pulmonary edema: hypoxia-induced vasoconstriction
Primary spontanous pneumothorax: epidemiology and etiology
- tall, thin young males
- due to rupture of apical blebs
Dx of pneumothorax
decreased breath sounds on affected side, CXR, CT
Virchow’s triad
Stasis + hypercoagulability + endothelial damage
Homan’s sign
- pain with ankle dorsiflexion
- may indicate DVT but not specific
DVT: S&S
unilateral swollen foot/ankle, +/- pain, +/- Homan’s sign, +/- palpable cord
Dx of DVT
D-dimer, compression U/S
D-dimer: what is it, how is it used?
- fibrin degradation product, used in Dx of DVT but not very specific
- if -ve: DVT ruled out
- if +ve: follow with compression U/S
How to prevent DVT
subcut heparin bid-tid, SCDs / compression stockings
Tx of DVT
heparin until warfarin (coumadin) therapeutic
PE: S&S
pleuritic chest pain, SOB, hemoptysis (rare), fever, tachypnea, tachycardia, altered mental status (AMS), confusion
Classic ECG changes in PE
- S1Q3T3 (only in 20% cases)
- wide S in Lead I
- large Q & inverted T in Lead III
Dx of PE: gold std and others
- Gold std: pulmonary angiogram
- Others: D-dimer, DVT in lower extremity, large Aa grad, ECG changes, CT, V/Q scan
Tx of PE
- heparin / warfarin
- consider thrombolysis if massive PE
Causes of emboli
- fat, amniotic fluid, tumour, bacterial, air, thrombus
FEV1/FVC in normal vs obstructive vs restrictive lung disease
- normal: ~0.8
- obstructive: < 0.8
- restrictive: normal/increased
Curshmann’s spirals
spiral-shaped mucus plugs & desquamated epithelium, found in asthma
Charcot-Leyden crystals
assoc w eosinophilic inflamm, found in asthma
Asthma: 2 histological findings
Curschmann’s spirals, Charcot-Leyden crystals
DDx for eosinophilia
- “DNAAACP”
- Drugs
- Neoplasm
- Atopic diseases: allergy, asthma, Churg-Strauss
- Addison disease
- Acute interstitial nephritis
- Collagen vascular disease
- Parasites
Reid Index
- thickness of glands making up lung wall
- >0.5 in chronic bronchitis
Chronic bronchitis: definition and Dx
- hyperplasia of goblet cells and submuscosal glands
- Dx: daily productive cough for >3 mths, for at least 2 consecutive years
“Blue bloaters”: which disease and why?
- Chronic bronchitis
- cyanosis and periph edema, from poor oxygenation and pulm HTN
Emphysema: CXR findings
barrel-chest, flattening of diaphragm, blunting of costophrenic angles
Types of emphysema, locations, and causes (2)
- Centriacinar: smoking, upper lobes & superior segments of lower lobes
- Panacinar: alpha 1-antitrypsin deficiency, lower lobes
“Pink puffers”: which disease?
Emphysema; due to dyspnea and hyperventilation
Name 2 causes of bronchiectasis
CF, Kartagener syndrome
Function of alpha 1-antitrypsin
Protects against elastase
Most common cause of pulmonary HTN
COPD
N-acetylcysteine: uses (3)
- acetaminophen OD
- mucolytic
- prevents contrast-induced nephropathy
Inhaled Tx of choice for chronic asthma
inhaled steroid
Inhaled Tx of choice for acute exacerbations of asthma
b2 agonist (albuterol, levalbuterol)
Asthma drug: narrow therapeutic index, drug of last resort
Theophylline (methylxanthine)
Asthma drug: blocks conversion of arachidonic acid to leukotriene
Zileuton
Asthma med: inhibits mast cell release of mediators, used for prophylaxis only
Cromolyn
Asthma med: inhaled Tx that blocks muscarinic receptors
Muscarinic antagonists (eg ipotropium, tiotropium)
Asthma: inhaled long-acting b2 agonist
Salmeterol
Asthma med: blocks leukotriene receptors
Zafirlukast, montelukast
What meds if taken long term can result in rebound nasal congestion?
alpha agonists (nasal decongestants), eg psuedoephedrine & phenylephrine
