Dead Space vs Shunting

true (absolute) dead space

ventilation, no perfusion

clinical example of true deadspace

pulmonary embolism and low cardiac output

anatomic deadspace

no gas exchange (conducting airway)

clinical example of of anatomic deadspace

shallow breathing

relative deadspace

more ventilation than perfusion

clinical example of relative deadspace

mechanical ventilatilator and copd

formula for physiologic deadspace

paco2 - pEco2 / paco2 = %

normal spontaenously breathing

< 40%

normal mechanical breathing

< 60%

external respiration

the exchange of o2 and co2 between the alveoli and pulmonary capillaries

o2 transport

transport of o2 from pulmonary capillaries to the cellular destination

internal respiration

diffusion of o2 from small systemic capillaries for metabolic needs

ventilation

the movement of air into and out of the lungs

v/q normal value

0.8

which lung segments have greater ventilation than perfusion

apicoles

which lung segments have greater perfusion than ventilation

base

which lung segment have the greatest amount of perfusion

base

which lung segments have the greatest amount of ventilation?

base

is there a greater amount of perfusion or ventilation in the bases

perfusion

does o2 help v/q mismatch

yes

clinical

FRC definition

volume of gas remaining in the lungs following a normal exhalation

cardiac output

the volume of blood ejected by the heart each minute

CO normal range

4-8 LPMal

alveolar minute ventilation abbreviation

VA

VA defintion

the volume of fresh gas reaching the alveoli each minute

VA equation

(VT - VD) X RR

PVR definition

pulmonary vascular resistance (right sided heart problem)

the pulmonary vessels are the only blood vessels in

the body that react to low o2 levels by constricting rather than dilating

PVR are caused by

hypoxemia, acidemia, pulmonary fibrosis

mechanical deadspace

remaining exhaled gas when connected to some type of appliance

physiologic deadspace

the sum of alveolar and anatomic deadspace

when ventilation is excessive and the paco2 remains high or normal

increased physiologic deadspace should be suspected

Petco2

end tital partial pressure of co2

pEco2

mean expired gas sample

how to determine PECO2

douglas bag

silent unit

no ventilation and no perfusion

As the patient increases their minute ventilation, what should happen to the PaCO2 value

Get lower

If my patient's minute ventilation is 20 L/min (they are very tachypneic) and I obtain an ABG (arterial blood gas), and the results show a PaCO2 value that is normal or high. What should the respiratory therapist suspect?

Physiologic Deadspace

Normal Anatomic Shunting is approximately what percent of the cardiac output?

2%

True or False- Deadspace results in hypoxemia?

False

True or False- Shunting tends to cause primary hypoxemia

true

What are the units for CaO2, CvO2, and CcO2?

vol%

What's the normal shut value?

10%

What's the normal difference between the CaO2 and CvO2?

5 vol%

Congenital heart defects can cause?

Anatomic Shunting

The largest volume of oxygen is carried in the blood how?

Combined with hemoglobin

The volume of fresh gas reaching the alveoli each minute is called?

Alveolar Minute Ventilation

The volume of gas remaining in the lungs after a normal exhalation is called?

Functional Residual Capacity (FRC)

What is the normal range for Cardiac Output?

4-8 L/min

The diffusion of oxygen from small systemic capillaries in response to cellular metabolic needs is called?

Internal Respiration

The exchange of oxygen and carbon dioxide between the alveoli and the pulmonary capillaries is called?

External Respiration

What's the normal Hb level for a woman?

13-14 g%

What's the normal hemoglobin for a male?

15 g%

What's the normal Hct (hematocrit) for a woman?

42%

What's the normal Hct (hematocrit) for a male?

47%

Define ventilation

The movement of air in and out of the lungs.

Which arterial blood gas value (ABG) assesses the adequacy of ventilation?

PaCO2

Define PaO2

Partial pressure of oxygen in the arterial blood

What's the normal PaO2 range?

80-100 mm Hg

Define the term PaCO2

Partial pressure of carbon dioxide in the arterial blood

normal PaCO2 value

35-45mmhg

What's the normal SvO2 value?

75%

What's the normal range for PvO2?

35-45 mm Hg

What's the formula for Alveolar Minute Ventilation?

Respiratory Rate x (Tidal Volume - Deadspace Volume)

What are the units for alveolar minute ventilation?

L/min

What's the normal V/Q ratio?

0.8

What's the normal V/Q range?

0.6-3.3

Which lung segments have a higher V/Q ratio?

Apical segments

Which lung segments have a lower V/Q ratio?

Bases

Which lung segments have greater ventilation; apical or bases?

Bases

Which lung segments have greater perfusion; apical or bases?

Bases

Is there more VENTILATION or PERFUSION in the lung bases?

Perfusion

When you have ventilation but NO perfusion

True Deadspace

When you have both perfusion and ventilation but there is more ventilation than perfusion.

Relative Deadspace

Which type of Deadspace is in the purely conducting airways?

Anatomic Deadspace

Give a clinical example that has a low V/Q ratio

Atelectasis

Give a clinical example that has a high V/Q ratio

Pulmonary Embolism

What does PVR stand for?

Pulmonary Vascular Resistance

This is when there is low oxygen in the bloodstream

Hypoxemia

This is when there is low amount of oxygen getting to cells or tissues

Hypoxia

Name the type of Deadspace where you combine both Anatomical and Alveolar Deadspace?

Physiological Deadspace

The normal Physiologic Deadspace value for a spontaneous breathing patient is?

less than 40%

What's the formula for Physiological Deadspace?

PaCO2-PECO2/PaCO2

What does PECO2 stand for?

Mean expired CO2

How do you collect PECO2?

With the Douglas Bag on the expiratory side of the vent circuit.

What's the Physiologic Deadspace value for a patient on a mechanical ventilator?

less than 60%

The normal difference between the PaCO2 and PetCO2 value is?

1-3 mm Hg

When comparing the PaCO2 and PetCO2 value, which value is always higher?

PaCO2

Clinical situations such as hypotension, decrease in cardiac output and PE are examples of?

Absolute Deadspace

Name a clinical situation that would be an example of Anatomic Deadspace?

Rapid Shallow Breathing

Clinical situations in which there is both perfusion and ventilation but there is more ventilation than perfusion is an example of?

Relative Deadspace

COPD, Mechanical Ventilation are examples of?

Relative Deadspace

This is when you have perfusion but no ventilation.

Absolute Shunting

This is when you have perfusion and ventilation, but you have more perfusion than ventilation.

Relative Shunting

ARDS, Pleural Effusion, Pneumonia, CHF are examples of?

True or Absolute Shunting

Normal range for CaO2

16-20 vol%

Normal range for CcO2

Depends on FiO2 and Hb levels

Normal range for CvO2

12-15 vol%

What's the formula for CcO2?

(Hb x 1.34x SaO2) + (PAO2 x 0.003)