paco2 equation n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
PaCO2 equation PowerPoint Presentation
Download Presentation
PaCO2 equation

Loading in 2 Seconds...

play fullscreen
1 / 18

PaCO2 equation - PowerPoint PPT Presentation


  • 334 Views
  • Uploaded on

PaCO2 equation. Alveolar Ventilation www.mecriticalcare.net. The Key to Blood Gas Interpretation: Four Equations, Three Physiologic Processes. Equation Physiologic Process 1) PaCO2 equation Alveolar ventilation 2) Alveolar gas equation Oxygenation

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'PaCO2 equation' - onofre


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
paco2 equation

PaCO2 equation

Alveolar Ventilation

www.mecriticalcare.net

the key to blood gas interpretation four equations three physiologic processes
The Key to Blood Gas Interpretation:Four Equations, Three Physiologic Processes

EquationPhysiologic Process

1) PaCO2 equation Alveolar ventilation

2) Alveolar gas equation Oxygenation

3) Oxygen content equation Oxygenation

4) Henderson-Hasselbalch equation Acid-base balance

These four equations, crucial to understanding and interpreting arterial blood gas data.

paco2 equation paco2 reflects ratio of metabolic co2 production to alveolar ventilation
PaCO2 Equation: PaCO2 reflects ratio of metabolic CO2 production to alveolar ventilation

VCO2 x 0.863

PaCO2= ----------------------------

VA = VE – VD

VCO2 = CO2 production

VE = minute (total) ventilation = resp. rate x tidal volume

VD = dead space ventilation = resp. rate x dead space volume

0.863 converts VCO2 and VA units to mm Hg

dead space
Dead Space

High PEEP

Alveolus

VDA

Alveolus

Alveoli

High PEEP

Airways

ETT

VDequip

VDanat

paco3 equation
PaCO3 Equation

Low Production

High Production

  • Hypothermia
  • Hyporthyroidism
  • Underfeeding
  • Neuromuscular blockade
  • High fatty acid substrate
  • Sepsis/inflammation
  • Hyperthermia
  • Hyperthyroidism
  • High carbohydrates
  • Seizure and agitation

Cell Metabolism

.

VCO2

PaCO2=

VE

* (1- VD/VT)

VDequip

HME

Respiratory Rate

Tidal Volume

VDanat

VDA

PEEP

Low BP

hypercapnia
Hypercapnia

↑VCO2

↑PaCO2

= -----------------------

↔VA = VE – VD

  • Increased CO2 production but not able to hyperventilate:
    • Fever
    • Sepsis
    • Hyperthyroidism
    • Overfeeding with carbohydrates
    • Agitation
hypercapnia1
Hypercapnia

↔VCO2

↑PaCO2

= -----------------------

↓VA = ↓VE – VD

  • Decreased Alveolar Ventilation due to Decreased Minute Ventilation (VE= ↓VT X ↓RR)
    • Sedative drug overdose
    • Respiratory muscle paralysis
    • Central hypoventilation
hypercapnia2
Hypercapnia

↔VCO2

↑PaCO2

= -----------------------

↓VA = VE– ↑VD

  • Decreased Alveolar Ventilation due to Increased Dead Space Ventilation (VD= Dead Space Volume X RR)
    • Pulmonary embolism
    • High PEEP
    • Pulmonary hypertension
    • Chronic obstructive pulmonary disease
hypocapnia
Hypocapnia

↓VCO2

↓PaCO2

= -----------------------

↔VA = VE – VD

  • Decreased CO2 production but same minute ventilation:
    • Hypothermia
    • Paralysis
    • Hypothyroidism
    • Underfeeding with carbohydrates
    • Sedation
hypocapnia1
Hypocapnia

↔VCO2

↓PaCO2

= -----------------------

↑VA = ↑VE – VD

  • Increased Alveolar Ventilation due to Increased Minute Ventilation (VE= ↑ VT X ↑RR)
    • CNS stimulants
    • Agitation
    • Central hyperventilation
eucapnia
Eucapnia

↑VCO2

↔PaCO2

= -----------------------

↑VA = ↑VE – VD

  • Increased CO2 production and Increased Alveolar Ventilation:
    • Fever and sepsis
    • Hyperthyroidism
    • Agitation
eucapnia1
Eucapnia

↓VCO2

↔PaCO2

= -----------------------

↓VA = ↓VE – VD

  • Decreased CO2 production and decreased Alveolar Ventilation
    • Hypothermia
    • Hypothyroidism
pco2 vs alveolar ventilation
PCO2 vs. Alveolar Ventilation

The relationship is shown for metabolic carbon dioxide production rates of 200 ml/min and 300 ml/min (curved lines). A fixed decrease in alveolar ventilation (x-axis) in the hypercapnic patient will result in a greater rise in PaCO2 (y-axis) than the same VA change when PaCO2 is low or normal. This graph also shows that if alveolar ventilation is fixed, an increase in carbon dioxide production will result in an increase in PaCO2.

paco2 and alveolar ventilation test your understanding
PaCO2 and Alveolar Ventilation: Test Your Understanding

VCO2 X 0.863

VCO2=300 X .863

VCO2=259

PaCO2

= -----------------------

PaCO2=71.9

VA = VE – VD

VA = 3.6

VA = VE (7.2) – VD (3.6)

VA = VE (300X24) – VD (150 X 24)

What is the PaCO2 of a patient with respiratory rate 24/min, tidal volume 300 ml, dead space volume 150 ml, CO2 production 300 ml/min? The patient shows some evidence of respiratory distress.

paco2 and alveolar ventilation test your understanding1
PaCO2 and Alveolar Ventilation: Test Your Understanding

VCO2 X 0.863

VCO2=200 X .863

VCO2=173

PaCO2

= -----------------------

PaCO2=38.4

VA = VE – VD

VA = 4.5

VA = VE (6) – VD (1.5)

VA = VE (600X10) – VD (150 X 10)

What is the PaCO2 of a patient with respiratory rate 10/min, tidal volume 600 ml, dead space volume 150 ml, CO2 production 200 ml/min? The patient shows some evidence of respiratory distress

paco2 and alveolar ventilation test your understanding2
PaCO2 and Alveolar Ventilation: Test Your Understanding

↑300X 0.863

200X 0.863

VCO2 X 0.863

PaCO2

= -----------------------

PaCO2=59.9

PaCO2=40

VA = 4.32 L/min

VA = VE – VD

A man with severe chronic obstructive pulmonary disease exercises on a treadmill at 3 miles/hr. His rate of CO2 production increases by 50% but he is unable to augment alveolar ventilation. If his resting PaCO2 is 40 mm Hg and resting VCO2 is 200 ml/min, what will be his exercise PaCO2?

effective ventilation
Effective Ventilation

Alveolus

VDA

Alveolus

Alveoli

Airways

ETT

VDequip

VDanat

VT= 500

RR= 10

VDequip= 50

VDanat= 125

VDA= 25

VTe= 300

VT= 250

RR= 20

VDequip= 50

VDanat= 125

VDA= 25

VTe= 50

VE= 5 L/min