Respiratory Flashcards
What intracellular signal is affected by beta adrenergic agonists?
Smooth muscle relaxes (from B2 stim) from increased cAMP
Cause of hypoxemia with a normal A-a difference?
alveolar hypoventilation
OR
high altitude (less O2 in the air)
trachea deviates toward normal lung
Pulmonary effusion
Trachea deviates away from normal lung
atelectasis (collapsed lung)
kerley B lines tell you
edema of interlobular septa
flattened diaphragm on Xray
COPD
ARDS causes
pneumonia
trauma
aspiration
sepsis
Acute rejection of lung affects
pulmonary and bronchial circulation
Chronic rejection of lungs affects
Small airways
In healthy individuals, respiration is perfusion rather than diffusion limited (exercise, pulmonary embolism, etc).
Which is more affected in diffusion limitation, CO2 or O2 levels?
O2 levels. CO2 levels have a much higher diffusion capacity across the respiratory membrane. If you see VERY low pCO2 at the alveoli, this indicates a perfusion not a diffusion limitation
How do you measure fetal lung maturity?
Lecithin/Sphingomyelin ratio. They are equal until 3rd trimester, when Type II pneumocytes start secreting surfactant
Eggshell calcifications of hilar nodes and birefringent silica particles surrounded by fibrous tissue
silicosis
fusiform rods seen with iron protein (prussian blue stain)
pulmonary asbestos. Will see an interstitial pattern on Xray
Chloride shift in RBCs caused by
Carbonic anhydrase
- -CO2 carried in bicarb form predominantly
- -when bicarb leaves the RBC to dissolve in plasma, chloride enters the cell to maintain charge neutrality
how does hemoglobin carry CO2
15% as carbamate Hb-NH-CO2
85% as HCO3 (carbonic anhydrase
Which cancer causes SVC syndrome
small cell lung cancer. Causes headache, facial/upper extremity edema, and dilated veins
- -hoarseness: recurrent laryngeal
- -dysphagea: esoph. compression
Sx of phrenic nerve irritation
- hiccups, SOB, elevation of hemidiaphragm on X ray
Small airways
bronchioles and terminal bronchioles
–Large bronchi are part of the large airways
What cells do you find in bronchi
cartilage
goblet cells
glands
What do you find in the terminal bronchioles
pseudostratified ciliated columnar cells
–smooth muscles of airway walls(disappear after terminal bronchioles
type of cell in respiratory bronchioles
cuboidal cells without cilia
What secretes elastase
neutrophils and macrophages
Where is there mixing of blood normally?
bronchial veins mix in
Collapsing pressure=
2*T/R. This is the PRESSURE YOU NEED INSIDE THE BALLOON TO KEEP IT OPEN
what indicates fetal lung maturity?
lecithin: sphingomyelin ratio of 2
when are mature levels of pulmonary surfactant achieved?
Week 35. synthesis starts at week 26
When do alveoli tend to collapse
when radius is small (with expiration)
Which is the MOST important component of surfactant
dipalmitoylphosphatidylcholine
type II cells
cuboidal clustered cells that secrete pulmonary surfactant
clara cells
columnar cells that secrete component of surfactant and degrade toxins
Relation of pulmonary artery to bronchus
RALS
- Right PA anterior to bronchus
- Light PA superior to bronchus
Which lung are you more likely to inhale a foreign body into?
Right lung
What enters the diaphragm at T12?
Aorta
thoracic duct
azygous vein
Where should you do a thoracentesis?
MCL: 5-7th rib
Mid axillay: 7-9th rib
paravertebral: 9th-11th rib
Muscles of inspiration during exercise
scalene
sternocleidomastoids
external intercostals
IRV
amount of air that can still be breathed in after normal inspiration
FRC+IC
TLC
Inspiratory capacity
IRV+TV
how much more can you breathe in after a normal breath
FRC
ERV+RV
TLC-IC
how much more can you breathe out after a normal breath
TLC
IRV+TV+ERV+RV
Dead space calcuation
Vt x (Paco2-Peco2)/Paco2
Which part of the lungs is the biggest contributor to functional dead space?
apex of lungs
Taut vs relaxed forms of hemoglobin (2alpha + 2beta)
Taut: low affinity for O2
Relaxed: high affinity for O2
What factors cause taut form to dominate?
increased chloride, 2,3 BPG, H+, and CO2
how do you treat methemoglobinemia?
methylene blue
How do nitrites cause poisoning?
Convert Fe2+ to Fe3+
fetal hemoglobin has a lower affinity for
2,3-BPG
How do you treat cyanide poisoning?
Nitrites–make methemoglobin which can bind cyanide.
Also give thiosulfate to bind cyanideq
how does CO shift the oxygen hemoblogin curve?
LEFT shift. Decreased maximum bound and loss of sigmoidal shape
Increased affinity for O2, less unloading
When hemoglobin curve shifts to the right
decreased affinity for O2 (more unloading, at tissue level)
Causes of right shift
C-BEAT CO2 BPG Exercise Acid/altitude Temperature
Pulmonary vascular resistance is lowest at
FRC
–increased lung volume: compresses alveolar vessels, but less resistance in extra-alveolar vessels
are you perfusion or diffusion limited during exercise?
perfusion limited. Still able to reach normal PA at the end of the capillary
When might you be diffusion limited?
Emphysema (decreased surface area)
Fibrosis (increased thickness)
Normal pulmonary artery pressure
10-14 mmHg
Cause of primary pulmonary HTN
BMPR2
Cause of secondary pulmonary HTN
COPD Mitral stenosis Recurrent emboli autoimmune dz like systemic sclerosis sleep apnea high altitude
How do you calculated pulmonary vascular resistance?
PVR= (Ppa-Pla)/CO
Resistance=deltaP/Q
Diffusion calculation
Vgas=A/T x Dk(P1-P2)
PAO2=
150-PaCo2/0.8
When do you see an increased Aa gradient
Shunting
V/Q mismatch
Fibrosis
cause of hypoxemia with a normal Aa gradient
high altitude
hypoventilation
V/Q ratio at apex of lung
3 (wasted ventilation)
V/Q ratio at the base of lung
0.6 (wasted perfusion)
are ventilation/perfusion greater at the lung base or apex?
both are greater at the base than the apex
VQ ratio during exercise
1–>apical arteries expand
V/Q=0
SHUNT. Lots of blood flow, no ventilation. Airway obstruction!
V/Q=infinity
DEAD SPACE. Lots of airflow, no blood. pulmonary embolism
Who would benefit from high flow 100% O2?
Person with Deadspace. We assume there are some areas of the lung that are still getting blood.
Shunt does NOT improve with 100% oxygen because the air is not even reaching the blood!
Most of CO2 is transported in what form?
bicarbonate in the plasma
Haldane effect
oxygenation of Hb promotes dissociation of H+ from Hb within the RBC
–H+ binds HCO3 and forms free CO2 with carbonic anhydrase
How else is CO2 transported?
- carbaminohemoglobin (CO2 bound to the N terminus of hemoglobin)
- dissolve CO2
Bohr effect
H+ in peripheral tissues causes shift to the right=unloading O2
Changes at high altitude
Increased 2,3-BPG Increased mitochondria Decreased PO2 and PCO2 Increased renal excretion of bicarbonate (increase this with acetazolamide) -->Watch out for cor pulmonale
Changes in the lungs with exercise
V/Q ratio –>1
decreased pH
No change in PaO2 and PaCO2!!
Increase in venous CO2 content and decrease in venous O2 content
dorsiflexion of foot causes calf pain
Homan’s sign, think DVT
Treatment for acute DVT
heparin
Treatment for long-term prevention of DVT
warfarin
hypoxemia
neuro changes
petechial rash
Think pulmonary emboli!
What is bronchiolitis obliterans pneumonia?
Formation of granulation tissue with pneumonia. Causes obstruction of airways
How od you treat bronchiolitis obliterans pneumonia?
Corticosteroids
How do you tell whether a patient died because of a pulmonary embolism or if the thromboembolism formed after death?
Lines of Zahn
Reid index
Tells you thickness of glandular layer compared to bronchial wall
–Over 50% in patients with bronchitis