Module 4 Gas Exchange Flashcards
Two types of external respiration?
Pulmonary ventilation (breathing)
Pulmonary gas exchange
2 aspects of Internal transport of gases? (hint internal respiration)
Via Blood:
-Systemic tissue gas exchange
-cellular respiration
Where is O2 and CO2 exchanged?
Alveolar-capillary membrane
What is considered effective ventilation?
when the bodies needs for O2 uptake are met, AND CO2 removal.
Alternatively as well:
(low consumption of O2 and low production of CO2)
Why is ventilation not entirely efficient?
Dead space.
Dead space is a portion of inspired air wasted with each breath.
What are 3 types of deadspace?
Anatomic dead space (VDanat)
Alveolar dead space (VDalv)
Physiological dead space (VDphy)
Anatomic Dead Space
Gas left in the conducting airways; Does not patriciate in gas exchange.
(oropharynx, trachea, and airways)
Alveolar Dead Space
Alveoli that are ventilated but have no perfusion; No Gas exchange.
(alveoli are ventilated but not perfused)
Physiologic Dead Space
The sum of anatomic and alveolar dead space
How do you calculate ventilation?
Probably just understand it. Don’t worry about this one too much.
Tidal Volume
Volume of air that is inhaled/exhaled from the lungs normally (without effort)
Minute Ventilation
Total volume moving in or out of the lungs per minute
Efficiency of ventilation depends what?
The volume of fresh gas reaching the alveoli.
What factors produce alveolar ventilation?
Breathing frequency and alveolar volume per breath
Why is alveolar ventilation always less than minute ventilation?
Dead space (VDphy)
Calculate VA (add solutions later)
Worse case scenario
- check google docs for solutions.
what is “Vd.Vt”?
Ratio of physiologic dead space over tidal volume.
What could cause an increase in VdVT
-Pulmonary embolism
-thrombosis
-vascular obliteration (kinking/clamping of pulmonary artery during surgery)
Status asthmaticus: long-lasting and severe asthma
Normal Vd.VT range?
30-40%
Generally, what could you say Physiologic dead space could result from?
Shunt
Low ventilation/perfusion (V/Q)
TLDR: if minute ventilation can’t be increased
How much does dead space increase for intubated patients?
50%
Complete the reaction/path for Dead Space: for every given minute ventilation, the ____ the deadspace, the ____ the CO2 elimnation.
For any given minute ventilation, the GREATER the dead space, and the POORER the CO2 elimnation
Why does dead space increase for intubated patients?
increases in ventilated patients is due to positive pressure.
What is Vd, Va, MV, and Vd/Vt?
Vd = dead space
Va = alveolar volume
Vd/Vt = how much is going into dead space
MV = min volume/ventilation
What is a normal range for Vd/Vt?
30-40%
Do equal pressure points limit inspiration flow?
No.
(needs confirmation)
Equal pressure points only happen during expiration
What is VQ, and what is its normal range?
V/Q is the amount of air that reaches your lungs divided by the amount of blood flow in the capillaries in your lungs.
Normal Range = 0.8
What constant (number) is used for dead space?
-Important-
2.5ml/kg
You have to multiply 2.5 by IBW to get Vd
