BLOOD GASES CCHM Flashcards
substance that can yield a hydrogen ion (H) or hydronium ion when dissolved in water
represents (+) charge molecules
Acids
substance that can yield hydroxyl ions (OH)
represents (-) charge molecules
Base
combination of a weak acid or weak base and its salt, is a system that resists changes in pH
Effectiveness of a buffer is determined based on:
1.
2.
Buffer
1 Ionization constant/ pKa of the
buffering system
2 pH of the environment
Function: maintain or prevent sudden
fluctuations in pH
Buffer
Major buffer system:
Plasma – bicarbonate
carbonic acid buffer system; pK of 6.1
Normal blood pH: ___, to achieve this the body uses buffers
7.35-7.45
BUFFER SYSTEMS
1 BICARBONATE-CARBONIC ACID BUFFER SYSTEM
2 PHOSPHATE BUFFER SYSTEM
3 HEMOGLOBIN-OXYHEMOGLOBIN BUFFER SYSTEM
4 PROTEIN BUFFER SYSTEM
BUFFER SYSTEMS
1 BICARBONATE-CARBONIC ACID BUFFER SYSTEM
2 PHOSPHATE BUFFER SYSTEM
3 HEMOGLOBIN-OXYHEMOGLOBIN BUFFER SYSTEM
4 PROTEIN BUFFER SYSTEM
Principal mammalian buffer system
BICARBONATE-CARBONIC ACID BUFFER SYSTEM
Acids combine with Bicarbonates in the blood
Neutral Salts (Bicarbonate Salts) –
conjugate base
Carbonic Acid (Weak Acid)
BICARBONATE-CARBONIC ACID BUFFER SYSTEM
Acids combine with Bicarbonates in the blood
Neutral Salts (Bicarbonate Salts) –
conjugate base
Carbonic Acid (Weak Acid)
Bicarbonate
Form:
Regulation:
Bicarbonate
Through Kidney renal regulation
Carbonic acid (unstable)
Form
Regulation
Changes to H2O and CO2 once it reaches the plasma.
Measurement: based on pCO2
Carbonic acid (unstable)
Form
Regulation
Changes to H2O and CO2 once it reaches the plasma.
Measurement: based on pCO2
____ unstable, changing to H2O and CO2 in fluid
H2CO3
Primary utilization is in RBCs. It is 16% of the non-bicarbonate buffer value of erythrocytes It increases the amount of ____ in ECF (more alkaline)
PHOSPHATE BUFFER SYSTEM
NaHCO3
_____ is a negatively charged molecule which makes blood pH to be more ____, but still maintaining the normal blood pH
Sodium bicarbonate (NaHCO3)
alkaline
In PHOSPHATE BUFFER SYSTEM , ____ phosphate form that acts as a buffer
2,3-diphosphoglycerate
In PHOSPHATE BUFFER SYSTEM , ____ phosphate form that acts as a buffer
2,3-diphosphoglycerate
maintains pH level (Venous and Arterial Blood)
____ is considered to be an effective buffer because it is responsible for carrying oxygen so it has the ability to off load ___ replacing it with ___
- helps in the maintenance of CO2; it facilitates its diffusion across different gradients
____ carries ____.
Each mole of Hgb binds with ____ (primarily more than 95% of Hgb binds with O2)
HEMOGLOBIN-OXYHEMOGLOBIN BUFFER SYSTEM
Hemoglobin
O2
CO2
1 gram of Hemoglobin
1.39 mL of Oxygen
1 mole of O2
Proteins can also help in maintaining the buffer due to charges present on their surfaces. Proteins are made up of ____ which has ___ and ____; consisting of (+) and (-) charge end.
Proteins can exist in 2 forms: ___, ___ > Their characteristics depend on the pH of the environment
• More (+) in _____ environment
•More (-) in ___
•Has capability to bind or release excess Hydrogen as required within blood circulation
Plasma proteins (Charges on their surface)
o pH > pI –
o pH < pI –
PROTEIN BUFFER SYSTEM
amino acids
carboxyl end
amino end
H+ protein
B Protein
acidic
basic/alkaline
(-) charge
(+) charge
second largest fraction of the anions in the plasma.
Conjugate base representative of major buffer system
Classified under electrolytes.
It includes: ___ and _____
BICARBONATE (HCO3)
ionized bicarbonate (HC03)
Bicarbonate molecules linked with amino acid:
second largest fraction of the anions in the plasma.
Conjugate base representative of major buffer system
Classified under electrolytes.
It includes: ___ and _____
BICARBONATE (HCO3)
ionized bicarbonate (HC03)
Bicarbonate molecules linked with amino acid:
measured to determine pH
ionized bicarbonate (HC03) –
measured to determine pH
ionized bicarbonate (HC03) –
carbonate and the carbamino
compounds.
Normal range is from ___
Bicarbonate molecules linked with amino acid
21 - 28 mmol/L (21 - 28 meq/L)
carbonate and the carbamino
compounds.
Normal range is from ___
Bicarbonate molecules linked with amino acid
21 - 28 mmol/L (21 - 28 meq/L)
Weak acid representative of major buffer system
readily dissociated into ___ and ___ once it reaches the blood circulation
This fraction of blood, plasma or serum includes the ___ and ___
In blood circulation, CO2 concentration is ____ than HCO3, the symbol cdCO2 (conc. of dissolved C02) is frequently used and measured from ___
Other references: the complete solubility
coefficient is ____
Normal range: ____
CARBONIC ACID (H2CO3)
H2O
CO2
undissociated carbonic acid
physically dissolved anhydrous C02
higher
pCO2 multiplied by the solubility coefficient (0.03) of CO2.
0.0307 or 0.0306
1.05 –1.45 mmol/L.
Weak acid representative of major buffer system
readily dissociated into ___ and ___ once it reaches the blood circulation
This fraction of blood, plasma or serum includes the ___ and ___
In blood circulation, CO2 concentration is ____ than HCO3, the symbol cdCO2 (conc. of dissolved C02) is frequently used and measured from ___
Other references: the complete solubility
coefficient is ____
Normal range: ____
CARBONIC ACID (H2CO3)
H2O
CO2
undissociated carbonic acid
physically dissolved anhydrous C02
higher
pCO2 multiplied by the solubility coefficient (0.03) of CO2.
0.0307 or 0.0306
1.05 –1.45 mmol/L.
pressure or tension exerted by C02 gas
dissolved in blood
It is an index of efficiency of gas exchange in the lungs and not a direct measurement of total CO2 concentration in the blood.
Function: used to determine (H2CO3) level by multiplying it with solubility coefficient
Normal range: ____
PARTIAL PRESSURE OF C02 (PCO2)
35 - 45 mmHg.
pressure or tension exerted by C02 gas
dissolved in blood
It is an index of efficiency of gas exchange in the lungs and not a direct measurement of total CO2 concentration in the blood.
Function: used to determine (H2CO3) level by multiplying it with solubility coefficient
Normal range: ____
PARTIAL PRESSURE OF C02 (PCO2)
35 - 45 mmHg.
Amount of CO2 bound within the blood
circulation depending on the sample used
The value of the CO2 combining power Is an index of the amount of CO2 that can be bound by serum, plasma, or whole blood as HCO3 at a ____ of ___ at ____ degree celsius
Normal range: ___
CARBON DIOXIDE COMBINING POWER (CO2 COMBINING POWER)
pCO2 of 40 mmHg at 25 degrees Celcius.
24 - 30 mmol/L.
Amount of CO2 bound within the blood
circulation depending on the sample used
The value of the CO2 combining power Is an index of the amount of CO2 that can be bound by serum, plasma, or whole blood as HCO3 at a ____ of ___ at ____ degree celsius
Normal range: ___
CARBON DIOXIDE COMBINING POWER (CO2 COMBINING POWER)
pCO2 of 40 mmHg at 25 degrees Celcius.
24 - 30 mmol/L.
Formerly known as ____
Sum of major buffer system or total concentration of C02 in the blood consisting of ionized HC03, C03, carbamino compound) and unionized fraction (H2C03) and physically dissolved C02.
Normal range: ____
TOTAL CARBON DIOXIDE CONCENTRATION (ctCO2)
-C02 content
21-28 mmol/L.
The negative logarithm of hydrogen ion activity with a normal average range of 7.35-7.45
pH
MAJOR FACTORS REGULATING BLOOD PH:
in order to prevent drastic fluctuation in pH, and second line which acts when major disturbances, changes or deviations from normal pH occurs.
Primary line
1) Chemical buffers (with charges)
> bicarbonate and carbonic acid buffer
system
>proteins
>Hemoglobin
>Electrolytes (Cl and HCO3)
Second line
Second line
2) Respiratory regulatory mechanism
> increased release of CO2: thru respiration or decreasing the exhalation
> Decreased release of CO2: thru
decreasing the respiratory rate
3) Renal regulatory mechanism – kidney which regulates level of bicarbonate (HCO3)
used to measure blood pH
HENDERSON-HASSELBALCH EQUATION
ph= bicarbonate/ carbonic acid
may not be encountered by MTs anymore because there are other healthcare professionals that are responsible for this procedure
as they are capable and trained to perform.
BLOOD COLLECTION FOR BLOOD GAS AND PH ANALYSIS
Keep the sample at ___technique in blood collection; at least prevent its exposure to ambient air because the concentration of ___ and ___ is different in blood and in air.
anaerobic
O2 and CO2
Keep the sample at ___technique in blood collection; at least prevent its exposure to ambient air because the concentration of ___ and ___ is different in blood and in air.
anaerobic
O2 and CO2
Preferred sample:______
____ is the more preferred
specimen for blood gas analysis
because it is of more uniform
composition than venous blood. This is due to the metabolic diversity
whole blood
Arterial blood
These specimens can also be used for blood gas analysis provided that they undergo arterialization.
Venous and Capillary (Skin punctured) Blood
___ used as an alternative if arterial sample from the patient cannot be
possibly collected or if the patient
does not have arterial cannula
yet.
Arterialized capillary blood
_____ process by which
vasodilation is induced to maintain good blood flow. Sample from capillary puncture undergoing arterialization will be near arterial sample.
Arterialization
Procedure of Blood gas analysis
Warm up first the area of blood
extraction. (i.e in finger/heel stick, dip it first in water bath with ____
and leave it for at least ____
Alternative: _____
42oC temp
10mins.
use warming pad
Exceptions in Arterialization
If patients have low blood pressure: ____
Conditions which induce
_____
Patients undergoing ___
____
systolic with <95mmHg
vasoconstriction
O2 therapy
Newborns with Respiratory Distress
Ssyndrome (RDS)
______ is preferred than venous blood because it is a mixture of venous and arterial blood.
Capillary (Skin punctured) blood
_____ is a very delicate procedure because arteries are always situated next to a nerve. Incorrect procedure may damage a nerve or dangerous effects to patient may occur.
Arterial blood gas collection
Ideal syringe (but not used anymore): _____ less porous than plastic syringe so it
lessens amount of exposure and difference in amount of CO2 and O2 in ambient air.
glass syringe
Anticoagulant: ___ powdered . The use of liquid is not advisable because it causes dilution of sample.
Always follow anaerobic technique.
heparin (lyophilized/freeze dried) –
___ Method
______
Principle: Based on amperometric or
polarographic measurement of oxygen.
Gasometric analysis
Calculation from oxygen saturation, pH and temperature by means of the standard O2 dissociation curve.
pO2 partial pressure of oxygen
ISE
Clark/e p02 electrode
___ non-invasive method where patients stay in the hospital and put up with an electrode with gel casing which
maintains temperature in certain portion of skin between ____ causing arterialization of
capillaries; thus measuring O2
Transcutaneous monitoring
43o-44oC
Use of ______
Principle: Based on pH measurement of a stationary NaHCO3 solution which is in
equilibrium with the test solution and the
test via a CO2 permeable membrane.
Gasometric analysis
Use of _____ -from pH and total carbon dioxide.
From a measured pH value interpolated in the C02 equilibrium curve
partial pressure of carbon dioxide PCO2
pCO2 electrode (Severinghaus electrode)
Henderson Hasselbach equation
___
Principle: Based on polarographic
principle
____– used as
mathematical derivation for determining pH based on pCO2 and HCO3 level
Use of PH meters
Nomogram and Slide Rule
Siggard -Anderson Alignment nomogram
PH electrode
Henderson - Hasselbach equation
______
Principle: Carbon dioxide is released frontHC03 by the addition of lactic add. The C02 and other gases are extracted under a partial vacuum. The pressure difference at constant value before and after absorption of C02 by NaOH Is the amount of C02 present in the sample.
CT C02
Manometric Method Using Natelson
Microgasometer
2 Types of Gasometric Analysis
vary depending on the volume of blood
sample which will be utilized
Macrogasometric method – >1mL of sample
Microgasometric method - <1mL of sample
Gasometric Analysis
Natelson Gasometric Analysis
Van Slyke Gasometric Analysis
Chemicals are used to liberate the
different blood gases; and specific
chemicals to differentiate which is O2
and CO2
Natelson Gasometric Analysis
Principle: Involves the release of CO2 gas when the sample is added to H2S04 with subsequent monitoring of this release with a pair of pCO2 electrodes (reference and sample electrodes). The
rate of change in pH of the buffer inside the pCO2 electrodes is a measure of the concentration of its CO2 in the sample
Same methodology which involves replacement of ____ of ___ for the release
of CO2 gas.
Same with ___ which has reference and sample electrode so the measurement is also done through electrochemical analysis
ALTERNATIVE METHOD
lactic acid with sulfuric acid (H2SO4)
ISE
Conditions for Blood Gas Analysis:
- All procedures should be considered “STAT”
- Specimen must be kept at anaerobic condition
Specimen w/c cannot be analyzed immediately
must be placed in an ice slurry (done but not
advisable)
Should have short TAT; test procedure must be performed within an hour after blood extraction.
If delayed 20-30 mins: pH lowers by ___
Avoid glycolysis
All procedures should be considered “STAT”
0.01
conversion of glucose into acetyl coA, further proceeding to production of ATP
(end product together with CO2
and H2O). Since there is CO2, this
has an effect to blood gas
analysis
Glycolysis
O2 at ambient air could enter the sample which can cause a decrease.
If the sample is exposed to O2, blood will take up O2 and will ↓ pCO2 = ↓ H2CO3 = ↑ pH or
making the pH level of sample to have higher than normal pH
Use plastic syringe (but POCT is still preferred)
Winged blood collection set is not advisable to use.
Specimen must be kept at anaerobic condition
ACID-BASE DISTURBANCES:
Acidosis ( <7.35)
Alkalosis ( >7.45)
General term applied for the any condition where the pH of the blood and the bicarbonate concentration of the blood are below normal.
Acidosis ( <7.35)
General term applied for any condition with an increase in blood pH (above normal range) characterized by an elevation in the H+ ion accepting buffer of the plasma (UC03) and a reduction in the H+ ion substances (H2CO3)
Alkalosis ( >7.45)
Metabolic affects HCO3
Metabolic Alkalosis ↑
Metabolic Acidosis ↓
Respiratory affects H2CO3
Respiratory Alkalosis ↑
Respiratory Acidosis ↓
– either excretion or reabsorption
Metabolic
either retention by decreasing or
increasing exhalation of CO2 which is affected
based on the rate of respiration__ AND ___
Respiratory
Hyperventilation
Hypoventilation
caused by bicarbonate (HCO3) deficiency
Production of increased amount of acid ___,_____,_____,_____
Compensation: ____
Metabolic Acidosis
diabetic ketoacidosis, lactic acidosis (alcoholism), renal failure and diarrhea
Hyperventilation
compensated by respiratory
Metabolic
compensated by alkalosis
To induce alkalosis, decrease the
carbonic acid, therefore pCO2 must be
decreased by ensuring that there is
greater exhalation of CO2 thru
hyperventilation
↑ respiratory rate = ↑ release of CO2 thru respiration = ↓ CO2 conc. in blood circulation.
Acidosis
____ and ____ as the body’s
response to increased positively charged
molecules. If you’re increasing bicarbonate (anion), it must be replaced with Cl molecule causing hyperchloremia (except in ____ which has normal Cl level)
In _____, there is an ↑ H+ ions.
Metabolic Acidosis
Hyperkalemia
hyperchloremia
diabetic ketoacidosis
acidosis
caused by bicarbonate excess
Conditions: Vomiting with the loss of ____ from the stomach
If there’s a decrease of chloride, there
must be a replacement of same charge
which is reabsorption of bicarbonate
Compensation: _____
Metabolic → compensated by respiratory
Alkalosis → compensated by acidosis
To induce acidosis, increase the
carbonic acid by increasing pCO2
by decreasing exhalation/
respiratory rate through
hypoventilation
(+) hypokalemia, hypochloremia
For every 10 meq/L rise in bicarbonates, the pCO2
rises by 6 mmHg
Metabolic Alkalosis
chloride
Hypoventilation
caused by bicarbonate excess
Conditions: Vomiting with the loss of ____ from the stomach
If there’s a decrease of chloride, there
must be a replacement of same charge
which is reabsorption of bicarbonate
Compensation: _____
Metabolic → compensated by ___
Alkalosis → compensated by ____
>To induce it, increase the
carbonic acid by increasing pCO2
by decreasing exhalation/ respiratory rate through its compensation.
(+) ___ and _____
For every ___ rise in bicarbonates, the pCO2 rises by____
Metabolic Alkalosis
chloride
Hypoventilation
respiratory
acidosis
hypokalemia
hypochloremia
10 meq/L
6 mmHg
Excessive CO2 accumulation
Conditions: ____, ___,____,_____
overdose ____,____,___
pneumonia
>Common to these conditions are the
lowered effectiveness of lungs in terms of releasing CO2 thru respiration
Compensation: retention of ____
>Induce metabolic alkalosis: to induce, increase bicarbonate by reabsorption/ retention
Bicarbonate rises ___ for each ____rise in
pCO2
Respiratory Acidosis
Chronic obstructive pulmonic disease
(COPD), myasthenia gravis, CNS disease, drug
morphine, barbiturates and opiates
bicarbonates
1 meq/L
10 mmHg
Due to excessive carbon dioxide loss
Conditions (which causes ____):
Anxiety, severe pain, aspirin overdose, hepatic cirrhosis, during blood extraction
Compensation: _____
>Induce metabolic acidosis: to induce,
decrease bicarbonate by excreting more
thru kidney function
(+) ____ – potassium is excreted together with bicarbonate, leading to reabsorption of Na and Cl molecule
Bicarbonate falls ___ for each ___ fall in pCO2
Respiratory Alkalosis
hyperventilation
decreased reabsorption
Hypokalemia
2 meq/L
10 mmHg
Due to excessive carbon dioxide loss
Conditions (which causes ____):
Anxiety, severe pain, aspirin overdose, hepatic cirrhosis, during blood extraction
Compensation: _____
>Induce metabolic acidosis: to induce,
decrease bicarbonate by excreting more
thru kidney function
(+) ____ – potassium is excreted together with bicarbonate, leading to reabsorption of Na and Cl molecule
Bicarbonate falls ___ for each ___ fall in pCO2
Respiratory Alkalosis
hyperventilation
decreased reabsorption
Hypokalemia
2 meq/L
10 mmHg
In Alkalosis, ____ ensues due to. _____, which can lead to death because of respiratory muscle spasm.
tetany
hypocalcemia
In Alkalosis, ____ ensues due to. _____, which can lead to death because of respiratory muscle spasm.
tetany
hypocalcemia
In Acidosis, there is an inhibition of the neural mechanisms which will then lead to ____. A blood pH of ____ has been proven fatal
coma
6.9
Arterial Blood Gas ref range
pH
pCO2 (mm Hg)
HCO3 mmol/L
Total CO2 content
pO2 mmol/L
SO2 (%)
O2Hb (%)
7.35-7.45
35-45
22-26
23-27
80-110
>95
>95
PARAMETERS OF INTEREST
-Evaluate (normal pH - 7.35-7.45)
-Evaluate the ventilation (Lungs)
-Evaluate the metabolic Process (kidneys)
-Determine which is the Primary (1°) and
compensating disorder
- Determine the degree of compensation
- pO2 = 81 - 100 mmHg (adequate oxygenation)
PARAMETERS OF INTEREST
-Evaluate (normal pH - 7.35-7.45)
-Evaluate the ventilation (Lungs)
-Evaluate the metabolic Process (kidneys)
-Determine which is the Primary (1°) and
compensating disorder
- Determine the degree of compensation
- pO2 = 81 - 100 mmHg (adequate oxygenation)
Evaluate (normal pH - 7.35-7.45)
<7.35 - acidosis
>7.45 – alkalosis
Evaluate the ventilation (Lungs)
pC02 - 35 - 45 mm Hg
< 35 respiratory alkalosis
> 45 respiratory acidosis
Evaluate the ventilation (Lungs)
pC02 - 35 - 45 mm Hg
< 35 respiratory alkalosis
> 45 respiratory acidosis
Evaluate the metabolic Process (kidneys)
HC03 = 22-26 meq/L
< 22 - metabolic acidosis
>26 – metabolic alkalosis
Determine which is the Primary (1°) and
compensating disorder
pH
Determine the degree of compensation
non- compensatory
partial compensatory
complete compensation
pO2 = 81 - 100 mmHg (adequate oxygenation)
p02 Hypoxemia:
mild = 61 - 80
moderate = 41 - 60
severe = 40 or less
pO2 = 81 - 100 mmHg (adequate oxygenation)
p02 Hypoxemia:
mild = 61 - 80
moderate = 41 - 60
severe = 40 or less
pH is based on HCO3 and H2CO3
H2CO3 = _____
HENDERSON-HASSELBACH EQUATION
pCO2 x 0.03 (solubility coefficient;
other references: 0.029)
HENDERSON-HASSELBACH EQUATION
formula to be used
pH = 6.1 + log HCO3 /
pCO2 x 0.03
HENDERSON-HASSELBACH EQUATION Alternative Formula: if incase the given is only tCO2 and pCO2
pH = 6.1 + log tCO2 − (pCO2 x 0.03)
pCO2 x 0.03
Representative conjugate base
Maintains pH at normal level
Measured directly
___: renal regulatory mechanism
Bicarbonate (HCO3-)
kidney
Weak acid
Not directly measured; it is measured thru the breakdown products specifically pCO2 (representative of H2CO3)
tCO2 = HCO3- + H2CO3
___: respiratory regulatory
mechanism
Carbonic acid (H2CO3)
Lungs
body’s mechanism which allows it to revert back the pH level into normal
range
One buffer system adjusts for the other buffer system which has primary disturbance
Degree of Compensation
Primary Disturbance
HCO3 (22-29mmol/L)
Metabolic acidosis <22 mmol/L
Metabolic alkalosis >29 mmol/L
pCO2 represent H2CO3 (35-45mmHg)
Respiratory alkalosis <35 mmHg
Respiratory acidosis >45 mmHg
Degree of Compensation
pH pCO2 H2CO3
Non-compensatory A A or N A or N
Partial compensatory A A A
Complete compensatory N A A
No compensation
Either pCO2/ H2CO3 is normal; pH is
abnormal
Ex: _______ - pCO2 is
abnormal, while H2CO3 did not adjust and is normal. Since this is acidosis, pH in effect will be acidic or in abnormal range.
Non-compensatory
Respiratory acidosis
With compensation but insufficient to
compensate pH → abnormal
pCO2 and H2CO3 are abnormal; pH is
abnormal
Partial compensatory
With sufficient compensation; thus
normalizing pH
Complete compensatory
Evaluate according to the given result based on normal range
↓ pO2 (<85 mmHg) = ____ – using blood sample; or ___ if O2 source is from oxymeters
Degree of Oxygenation (pO2= 85-105 mmHg)
hypoxemia
hypoxia
Mild >61; <85
Moderate >41; <60
Severe <40
Evaluate according to the given result based on normal range
↓ pO2 (<85 mmHg) = ____ – using blood sample; or ___ if O2 source is from oxymeters
Degree of Oxygenation (pO2= 85-105 mmHg)
hypoxemia
hypoxia
Mild >61; <85
Moderate >41; <60
Severe <40
