First Aid 605-609 - Resp Flashcards
(34 cards)
Formula to find O2 content of blood?
(1.34 × Hb × Sao2) + (0.003 × Pao2)
How does O2 sat and PaO2 change with dec Hgb?
There is no change in either one, the only change is with dec O2 content in arterial blood (PAO2)
What disease cause an increase in total O2 content?
Polycythemia
In which disease will there be dec O2 sat’n but normal Hgb?
CO poisoning
Treatment for CO poisoning?
100% O2, Hyperbaric O2
Diffusion equation
Diffusion: V˙ gas = A × Dk × [(P1 – P2)/T]
A = area, T = alveolar wall thickness,
Dk(P1 – P2) ≈ difference in partial pressures:
When is area decreased? when is alveolar wall thickness inc?
Emphysema, Pulm fibrosis
Dec in pAO2 causes what in lung a/v?
VC (diff from systemic circ)
PVR formula (pulm vas resistance)
PVR =( Ppulm artery – P L atrium)/CO
When is A-a gradient normal / Inc?
Normal A-a gradient = 10-15 nmHg
A-a gradient may occur in hypoxemia; causes
include shunting, V˙/Q˙ mismatch, fibrosis
(impairs diffusion)
Causes of Hypoxia
DEC cardiac output
Hypoxemia
Anemia
CO poisoning
Causes of Hypoxemia (DEC PaO2)
Normal A-a gradient High altitude Hypoventilation (eg, opioid use) INCA-a gradient V˙/Q˙ mismatch Diffusion limitation (eg, fibrosis) Right-to-left shunt
Ischemia (loss of blood flow)
Impeded arterial flow
venous drainage
T or F Both ventilation and perfusion are greater at the
base of the lung than at the apex of the lung.
True
How does ventilation and perfusion change with exercise?
With exercise (INC cardiac output), there is
vasodilation of apical capillaries –> V˙/Q˙ ratio
approaches 1.
CO2 is transported from tissues to lungs in what forms?
HCO3− (90%).
Carbaminohemoglobin or HbCO2 (5%). CO2 bound to Hb at N-terminus of globin (not heme). CO2 binding favors taut form (O2 unloaded). Dissolved CO2 (5%).
Haldane effect explain?
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 explain?
In peripheral tissue, H+ from tissue
metabolism shifts curve to right, unloading O2
Body response to high altitude - what metabolic disturbance
atmospheric oxygen DEC (PO2) –> dec Pao2 –> INC ventilation Paco2 respiratory alkalosis –> altitude
sickness.
Other body responses to high altitude
What two things do we produce more of?
What happens in the kidney?
on a cellular level?
Inc erythropoietin –> Inc hematocrit and Hb (chronic hypoxia).
Inc 2,3-BPG (binds to Hb so that Hb releases more O2).
Cellular changes ( Inc mitochondria).
renal excretion of HCO3− to compensate for respiratory alkalosis (can augment with acetazolamide).
What happens to pH in exercise?
Dec due to lactic acid
How do gas values change in exercise? (PaO2, PaCO2, v CO2/o2 content)
No change in paO2, and PaCO2, but INC venous CO2, and dec venous O2
Most common cause of rhinosinusitis?
Most common acute cause is viral URI; may cause superimposed bacterial infection, most
commonly S pneumoniae, H influenzae, M catarrhalis.
Most common location of epistaxis? when is it dangerous?
Most commonly occurs in anterior segment of nostril (Kiesselbach plexus). Lifethreatening
hemorrhages occur in posterior segment (sphenopalatine artery, a branch of maxillary
artery).
