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30 Cards in this Set

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  • Back
________ ________ ______ is known as a compensatory mechanism to divert blood from the deflated lung to areas of better ventilation and oxygenation.
Hypoxic Pulmonary Vasoconstriction
A shunt is known as ________ without ________.
perfusion, ventilation
HPV is a intrapulmonary fedback mechanism to improve _______ _______ and _________ _________.
gas exchange, arterial oxygenation
Decreased O2 in systemic circulation leads to ________.
vasodilation
Decreased O2 in pulmonary circulation leads to ________.
vasoconstriction
The purpose of HPV is to _________ shunt flow.
decrease
Response to systemic hypoxia mediated by stimulation of _________ and ________ chemoreceptors in CNS.
peripheral, central
Response to HPV is localized.
True or False
True
HPV onset and resolution are very fast following changes in tissue ____.
PaO2
HPV is triggered by arterial hypoxemia.
True or False
False, it is triggered by alveolar hypoxia.
In general, HPV causes vasoconstriction in all but very proximal ________ _______.
pulmonary arteries
HPV may be inhibited by(anesthetic agents/meds):
NTG, nipride, volatile anesthetics > 1.5 MAC (vasodilators), Ca++ channel blockers.
Volatile anesthetics inhibit HPV in a dose related manner.
True or False
True
HPV is increased by:
hypercarbia and hyperthermia
The greatest stimulus for HPV is:
decreased O2 tension in alveolar gas.
The cellular mechanism for HPV involves a redox-based oxygen sensor in _________ ________ cell of the pulmonary arteries.
smooth muscle
Activated oxygen species (AOS) production are reduced by hypoxemia, therefore, these AOS cannot act as 2nd messengers and this leads to inhibition of voltage-dependent _______ ________.
Potassium channels.
Inhibition of voltage-gated potassium channels leads to influx of extracellular _________, which causes _________.
Calcium, vasoconstriction.
HPV during OLV causes a decrease in the CO to the nonventilated lung by ______ percentage.
20-25%
HPV can decrease the shunt fraction during OLV by ____%
50%
What is the optimal amount of hypoxic lung during OLV in order for HPV to be most effective?
between 20-80%
If the amount of hypoxic lung is more than 80%, HPV increases PVR and the amount of well-perfused lung is not sufficient to accept shunt flow to maintain arterial oxygenation. This can lead to _____ ______ ________.
right ventricular failure
What conditions can override HPV?
hypervolemia and high cardiac output; shunt fraction <20% or > 80%; hypocapnia, acidosis, volatile agents > 1.5 MAC, vasoactive medications; hypovolemia; or hypothermia; COPD.
Fluid and ventilator management of OLV should include:
normal fluid volume, moderate TV (6-7 ml/kg); PIP < 25; adjust rate to maintain PaCO2 at 35 +/- 3; and excessive peep should be avoided.
Which volatile agent should be avoided with HPV due to its tendency to increase PVR?
Nitrous oxide; use 100% O2 instead.
In atelectatic lung areas, what is the greatest stimulus for HPV?
PvO2
Anything that increases PAP decreases efficiency of HPV.
True or False
True
Which antihypertensive drug has no effect of HPV?
Hydralazine
How is placement of the OLV tube checked?
fiber optic visualization
How can hypoxia during OLV be treated?
CPAP to nondependent lung, PEP to dependent lung, intermittent two-lung ventilation