Ancylostoma
Forum Guru
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if a small thrombus lodges in a pulmonary artery, what changes would you expect or the following variables in the throbus occluded unit?
PAO2 ,PACO2 , PUlMonary end capillary ph
A decrease, increase, decrease
B decrease , decreaase, increase
C increase , decrease , decrease
D increase, decrease , increase
E decrease , decrease , decrease
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| MRMAVERICK
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D
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| Palaniappan
Forum Senior
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D :-)
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| Ancylostoma
Forum Guru
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Good job guys , I dont think this questions requires explanation. Me007 posted 2 questions in the biochem forum, just in case you guys want to look at it.
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| new_n_lost
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Can u guys tell me that in Goljan he says a Perfusion without Ventilation which is an exmaple of Pulmonary Embolus. so which is true whts the logic ??/ getting confused
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| babydoc4usmle
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pulmonar embolus is example of ventilation without perfusion = dead space
bronchiolar obstruction = perfusion without ventilation = pulmonary shunt
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| Luckyall
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Babydoc, Goljan notes says viceversa Pulm Embolus is an ex. of PERFUSION without VENTILATION -----> increased dead space, thas why giving 100% O2 will increase PO2, b/c a normal ventilated lung will make up for the difference
PERFUSION probl-----> example atelectasis-----> intrapulmonary shunting and by giving 100% O2 will NOT increase PO2
Soooo ? i'll check Robbins text book by tonight
Whats your source ?
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| babydoc4usmle
Forum Guru
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common sense and uncle G
the beginning and nd of what you are saying makes sence, but in the middle of it.....
think it through
PERFUSION DEFFECT=no blood is able to flow in the vessel (thrombus), but we still have VENTILATED alveoli = DEAD SPACE in the lung
VENTILATION DEFFECT=no air is able to flow in the bronchus (obstruction), but we stl have blood coming and leaving without gas being exchanged = SHUNTING OF BLOOD through the obstructed unit
agree?
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| Luckyall
Forum Guru
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yeah... just checked physio ...
That means in Goljan notes there is an error ???
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| bangledoc
Forum Senior
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Which goljan note u r talking about? Rapid reveiw 2006 edition explains as(cell injury chapt)
1)ventilation defects---impaired Oxy delivery to alveoli------no oxy exchange in lungs that are perfused but not ventilated-----intrapulmonary shunting of blood------administration 100%oxy will not increasethe PaO2.
2)Perfusion defect-----absence of blood flow to alveoli-----no oxy exchange in lungs that are ventilated but not perfused----produces an increase in pathologic dead space---administration of 100%oxygen increases thePaO2.
Thanks guys
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| nandrolone
Forum Junior
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I dont know wht Goljan says because this is a simple concept explained in kaplan very well
According to him In case of a pulmonary embolus there is a decrease in alveolar blood flow => there is an increase in V/Q ratio => In a way the lungs are hyperventilating for that particular segment( i e there is more ventilation per unit pressure)=> when we have that
plasma pO2 goes up
plasma pCO2 goes down ie CO2 wash out
Hence there is an increase in end capillary pH.
Hope it helped. Bye
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| GoodGirl
Hanging in there
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What a query over such a logic thing ! 
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