1
T/F: The lungs you are laying on are getting the most perfusion
True
Peripheral O2 = SpO2 = % =
Hypoxic
Decreased O2 in the blood
Hypoxemic (in the blood gas)
V=Q
Ratio is 1
Ideal zone due to pulmonary vasculature at level of heart for optimal perfusion and ventilation both
Zone II (mid lungs)
- Head/neck tilt (extension vs. flexion)
- Facilitators voice/command
- Ambiance and lighting of room
Other considerations to help facilitate ventilation
- Oxygen tension in the arterial blood reflects adequacy of ventilation and perfusion matching (V/Q) in the lungs
- Overall V/Q average = 4L/min/ 5L/min = 0.8
- Arterial blood blood oxygenation is measured by blood draw (usually using radial artery) and called arterial blood gas (ABG test)
- Checks (in mmHg) PaO2 and PaCO2 as well as pH
- Calculates bicarbonate (HCO3)
- Can measure electrolytes and standard CBC blood tests as well
Principles of ventilation/perfusion
- Ventilation and perfusion both increase independently from the apex to base of the lungs
- Zone 1: top ; least amount of air
- Zone 2: middle
- Zone 3: Bottom ; most amount of air; perfusing the most
Rule #3
T/F: Perfusion increases disproportionately to ventilation, apex to base
True
V < Q
Ratio is < 1
V is high, but Q is very high (because of gravitational pressure), so V < Q
Hypoxemic; hypo ventilatory
Zone III (bases)
1. Hgb Affinity
2. Oxyhemoglobin dissociation curve
3. Intrapleural pressure
- Pressure outside lung/within pleural cavity
- Highest at base
4. Intrapulmonary pressure
- Pressure within ling/in alveoli
- Highest at base
5. Atmospheric pressure vs. PA and PP to influence ventilation
Additional rules (ventilation also depends on..)
- Ventilation and perfusion are gravity dependent
- Increased V and Q both at:
- Bases vs apices (standing upright)
- Lung down (ipsilateral) vs. lung up (sidelying)
- As well as lowest most lateral segments (each lung) in sidelye
- Posterior vs. anterior most segments (supine)
- Anterior vs. posterior most segments (prone)
Rule #1
- Ventilation and perfusion are not equally distributed
- For example, in upright sitting or standing position:
- Ventilation (air) at bases is about 2.5x greater than at apices BUT
- Perfusion (blood) at bases is 6x greater than at apices
Rule #2
Which zone of ventilation:
1.92L/minute
Reason: increase size of alveoli
Zone 1
V>Q
Ratio is > 1
V is low, but Q is almost non-existent, so V > Q
Hyperventilation
Zone 1 (apices)
Extension, eyes up and moving out of/against gravity is which breathing movement
Inhalation
Which zone of ventilation:
4L/minute
Reason: intermittent size of alveoli
Zone 2
Which zone of perfusion:
Perfusion is absent
Zone 1
Which zone of ventilation:
6/5L.minute
Reason: decrease size of alveoli
Zone 3
Zone II is at which % of V/Q ratio?
100% ***
Pulmonary vascular resistance (constriction/dilation)
Ejection timing (cardiac output)
The position of optimal physiological function:
- Upright
- Moving/staying active
Perfusion is also influenced by:
Which zone of perfusion:
Perfusion is constant
Zone 3
T/F: V/Q ratio increases from apex to base (in upright lung)
False... V/Q decreases from apex to base
Which zone of perfusion:
Perfusion is sporadic
Zone 2
Ideally, we would like to reside in equal amount of V and Q but gravity wins and average healthy person stays about ____
0.8 *** (zone III)
Flexion, eccentric or concentric contraction, eyes down and coming back into/towards gravity is which type of breathing movement
Exhalation