Here....WK7: Blood Gases and pH Disorders

• When we inhale what do we breathe in?

• when we exhale, what comes out?

• we inhale oxygen (O2) and exhale carbon dioxide (CO2)

  • Our bodies uses the oxygen and releases carbon dioxide as a waste product

• What are blood gases?

• When people refer to blood gases, what is the main type of test they are referring to?

• What other blood gas test are there, and which is the gold standard?

• Blood gases are

  • a group of tests that measure the levels of gases (O2, CO2, HCO3-) and the pH level (acidity/Basic) in your blood

• When people refer to blood gases they mean artery blood gases, blood from artery.

• venous blood gas (VBG), capillary blood gas (CBG).

  • ABG test is the gold standard for assessing lung function and overall acid/base status.

• Bicarbonate formula

• Carbonic acid formula

• ABG stands for?

• HCO3- = Bicarbonate

• H2CO3 = Carbonic Acid

• ABG= Arterial Blood gas

• Artery

• Vein

• Artery

  • Carries blood away from the heart

  • Arteries walls are thick

  • Have no valves and have high blood pressure

  • Oxygenated

    • except for pulmonary artery

• Vein

  • Carries blood towards the heart

  • Veins walls are thin

  • Have valves and low blood pressure

  • Deoxygenated

    • except for pulmonary vein

• The pH of the blood from an artery should be?

• The pH of the blood from a vein should be?

• Low Ph is what

• High Ph is what

• The pH of the blood from an artery should be:

  • 7.35-7.45

• The pH of the blood from a vein should be

  • 7.31-7.41

• Ph

  • acidic when it is low

  • Alkaline aka basic when it is high

• What dos blood gas test tells us?

• Where should we collect a blood gas sample from?

• Should Blood gas test be STAT?

• Blood gas test tell us how well your lungs are moving oxygen and carbon dioxide, and the acid/basic status of your entire body

• We need a whole blood sample, preferable an arterial blood sample

  • Sites to acquire arterial blood are radial. femoral, or brachial

• Blood Gas assessment should be performed STAT

• What do blood gases test measure?

Arterial blood gas (ABG) test measures:

• pH:

  • Measures the acidity or alkalinity of the blood.

• pO2:

  • The partial pressure of oxygen, how much oxygen is present in the blood

• % O2 Sat:

  • The percentage of oxygen saturation, measures the percentage of oxygen that your red blood cells are carrying

• pCO2:

  • The partial pressure of carbon dioxide is how much carbon dioxide is in your blood.

• HCO3 (Bicarbonate):

  • How much bicarbonate is in your blood, which is usually to test how well your kidney is doing and your acid-base balance.

• Total CO2: The total amount of carbon dioxide in your blood.

  CO2 + H2O → H2CO3 → HCO3 + H

  • Carbon dioxide + water= Carbonic acid= bicarbonate +hydrogen Ion

• Base Excess:

  • Measures the amount of base (alkaline) in the blood

  • If negative, low on base

• Sometimes measures

  • Lactic acid, Hgb, & other tests.

• What 2 main form does oxygen exist in our blood?

Oxygen in your blood exists in two main forms:

1. Attached to Red Blood Cells (RBCs):

   • This is measured by oxygen saturation (% O2 Sat). Red blood cells have a protein called hemoglobin that binds to oxygen and carries it to your tissues and organs.

2. Dissolved in Blood Plasma:

   • This is measured by partial pressure of oxygen (pO2). Oxygen can be dissolved directly in the plasma, the liquid part of your blood, and is available for immediate use by your body.

• what are blood thinners?

• How to collect blood specimen for ABG?

• What are some rules regarding ABG specimens?

• What temperature do we test ABG and why?

• Blood thinners are just anti-coagulant medications

• ABG collection use heparin which is an anti-coagulant

• We collect ABG specimen without exposing it to air (anaerobically) and put it on ice to keep the blood cells from changing the gas levels.

  • if the ABG is exposed to air, the oxygen and carbon dioxide levels in the sample will change, giving us wrong results.

• We test the blood at body temperature (37 degrees Celsius) because that's how it is in your body.

  • The machine heats the blood to that temperature.

• Some pre-analytical errors can be due to:

  • hint there are 5

• What does ABG have to be on and what time can we test it?

1) Air bubbles:

• Air bubbles: If air gets into the blood sample, it increases the oxygen (pO2), pH,

  • Also decreases the carbon dioxide (pCO2) levels, making the test results wrong

2) Clot

• Can not run clotted whole blood on instrumentation since the machine cannot read it

3) Glycolysis:

• "The blood cells keep using oxygen and making carbon dioxide even after the sample is taken.

• This decreases the pH and oxygen levels

  • Increases the carbon dioxide levels

4) Temperature:

• pH is temperature dependent so the temperature can change the Ph levels

5) Mixing:

• We have to gently turn the sample upside down and back a few times to mix it, don't shake it.

Ice and Time

• ABG usually comes on ice, and must be run w/in 30 min

• Ranges for

  • pH

  • pO2

  • O2 saturation

  • pCO2

  • HCO3-

• pH

  • 7.35-7.45

• pO2

  • 80-100 mmHg

• O2 Saturation

  • greater or equal to 95%

• pCO2

  • 35-45 mmHg

• HCO3-

  • 22-26 mEq/L

Do not need to know the rest, just these

• What is one electrochemistry test and how do we use it?

• What is one machine that allows us to measure the hemoglobin concentration?

Electrochemistry test includes (there are many more as well)

• Ion selective electrodes

  • which is a machine that uses special sensors that measure the amounts of different ions (like hydrogen ions) in the blood.

Hemoglobin Concentration

• Co-oximeters are spectrophotometers that shines light through the blood to measure the different types of hemoglobin (the stuff that carries oxygen)

• What 3 gases do the machines directly measure?

• what does the machine then calculate?

• Machines usually directly measure

  • pH

  • Oxygen

  • carbon dioxide \

• The machine then calculates other values like bicarbonate, base excess, and Oxygen Saturation aka % O2 Saturation, which is how much oxygen your red blood cells are carrying."

• Acidic solution means what

• Basic solution means what

• What is the bicarbonate-carbonic acid system?

  • what does it help do?

• More H+ ions: The solution is acidic (pH is low).

• Fewer H+ ions: The solution is basic (pH is high).

CO2 + H2O → H2CO3 → HCO3- + H+

The bicarbonate-carbonic acid system acts as a buffer to keep your body's pH level within a healthy range.

• It helps neutralize excess acids or bases to maintain that balance

• what is the bicarbonate-carbonic acid system formula?

  • is it reversible?

• What happens to the formula when there is too much acid?

• What happens when there is too much base?

• At a normal pH of 7.45 the ratio of bicarbonate to carbonic acid is

is reversible:

CO2 + H2O → H2CO3 → HCO3- + H+

When there's too much acid (too many H+ ions) in your blood, bicarbonate (HCO3-) acts like a sponge to soak up those extra H+ ions, forming carbonic acid (H2CO3)

• HCO3− + H+→ H2CO3

When there's too much base (too few H+ ions) in your blood, carbonic acid (H2CO3) can release H+ ions to balance things out. This helps neutralize the excess base

• H2CO3 → H+ + HCO3−

20:1

is 20 bicarbonates to 1 carbonic acid

• Define hypoventilation

• Define hyperventilation

• What does base excess show?

• What does oxygen saturation tell us?

• High carbon dioxide means you're not breathing enough (hypoventilation)

  • low carbon dioxide means you're breathing too much (hyperventilation) since you are exhaling all of the CO2

• Base excess shows if there's too much or too little base in the blood:

  • Too little base (deficit) means too much acid (acidosis),

  • Too much base (excess) means too little acid (alkalosis)

• O2 Saturation

  • Oxygen Saturation aka how much oxygen your blood is carrying, can be calculated using pH and oxygen levels.

  • To get a more accurate reading you can figure out the hemoglobin levels

• What 3 main system does our body uses to have our blood gases balances?

Your body keeps your blood gases balanced using three main systems:

• Chemical Buffers which are chemicals in the blood (buffers) that soak up extra acids or bases, those chemicals include

  • bicarbonate aka HCO3-

  • Phosphate aka HPO4^2-

  • Protein-like hemoglobin

• Respiratory system

  • hypoventilation (breathing slowly)

  • Hyperventilation (fast breathing)

• Renal aka kidney system by removing or keeping acid/base

H₂O + CO₂ « H₂CO₃ « H⁺ + HCO₃^-

• why is this equation so important?

  • 3 main reasons

1. H₂CO₃ disassociates into CO₂ and H₂O , this allows your lungs to get rid of carbon dioxide and acquire water

2. Changes in carbon dioxide changes your breathing (ventilation aka respiratory) rate,

3. your kidneys can change the amount of bicarbonate (HCO3-)

• Why are phosphate buffers important?

• where does phosphate buffer help out at?

• Why are protein buffers important?

• Name one protein buffer and how does it help.

Phosphate Buffers:

• Phosphate Buffers help maintain pH balance by reacting with excess acids or bases. This forms compounds that only slightly change the pH, thus minimizing major pH shifts.

• Phosphate buffers are effective in the renal tubules (the tiny tubes in the kidneys)

Protein Buffers:

• Protein buffers, which includes hemoglobin and other proteins, help maintain pH both inside and outside of cells.

• Protein buffers are the most abundant buffers in your body.

• Hemoglobin is a protein buffer and thus, hemoglobin in red blood cells maintains blood pH by binding to hydrogen ions (H+).

• Hemoglobin Buffering System is what

• What happens when your cells use oxygen?

• What does most of the carbon dioxide turn into inside the RBCs?

• What causes bicarbonate (HCO3-) to diffuse out into the plasma?

• What is the Chloride Shift and why does it happen?

• Why do H+ ions remain inside the RBCs?

Hemoglobin Buffering System

H₂O + CO₂ « H₂CO₃ « H⁺ + HCO₃^-

• When your cells use oxygen, they make carbon dioxide and then RBC comes by and picks it up.

  • Most of this carbon dioxide turns into carbonic acid, which splits into hydrogen ions and bicarbonate.

  • The increase in bicarbonate (HCO3-) inside RBCs causes it to diffuse out into the plasma.

  • Chloride Shift: To maintain electrical neutrality, chloride ions (Cl-) move into the RBCs to replace the bicarbonate ions that left.

  • The H+ ions remain inside the RBCs. They don't come out because their role is to be neutralized by binding to hemoglobin and other intracellular buffers.

    • This helps prevent changes in pH inside the RBC

• Hemoglobin Buffering system for your Lungs; what are the steps

• What happens when CO2 is not removed from the blood and is piled up instead?

H₂O + CO₂ « H₂CO₃ « H⁺ + HCO₃^-

Hemoglobin Buffering system for your Lungs

1. Oxygen (O2) from the lungs diffuses into the blood and binds to hemoglobin (forming oxyhemoglobin, O2Hb).

2. As oxygen binds to hemoglobin, hydrogen ions (H+) that were previously attached to hemoglobin are released

3. These H+ ions then combine with bicarbonate ions (HCO3-) in the blood to form carbonic acid (H2CO3)

4. Carbonic acid (H2CO3) quickly breaks down into water (H2O) and carbon dioxide (CO2)

5. The carbon dioxide (CO2) diffuses into the alveoli (tiny air sacs in the lungs) and is then exhaled out of the body

If CO2 is not removed from the blood, it piles up. The piled-up CO2 can then react with water to form more carbonic acid (H2CO3), which dissociates into more H+ ions and bicarbonate (HCO3-).

• This increase in hydrogen ions (H+) leads to a condition called acidosis, where the blood becomes too acidic.

• What is the second line of defense?

• what does this second line of defense control?

• What changes our breathing state?

• When do you breathe faster?

• When do u breathe slower?

H₂O + CO₂ « H₂CO₃ « H⁺ + HCO₃^-

Gasses in your blood: Respiratory system

• Your lungs control carbon dioxide levels and are the second line of defense.

Chemoreceptors aka sensors in your brain changes your breathing rate

• If carbon dioxide is high (and pH is low), you breathe faster (hyperventilate).

  • breathing faster we exhale more CO2

  • By exhaling more CO₂, we reduce the amount of carbonic acid (H₂CO₃) in your blood.

  • This helps lower the concentration of hydrogen ions (H⁺) and increase the pH.

• If carbon dioxide is low (and pH is high), you breathe slower (hypoventilate)

  • breathing slowly conserves CO2 and allows us to form more carbonic acid (H₂CO₃)

  • This increases the concentration of hydrogen ions (H⁺) and decreases the pH

• What is your third line of defense?

• How long does this third line of defense take?

• How does this third line of defense work?

  • if it is to acid what do they do?

  • If it is to basic, what do they do?

H₂O + CO₂ « H₂CO₃ « H⁺ + HCO₃^-

Third line of defense is your kidneys:

• Kidneys take hours to days to work and control bicarbonate levels.

• If your blood is too acidic, they keep bicarbonate.

• If it's too basic, they get rid of it.

• Kidney’s tubule cells can also make new bicarbonate to increase pH

• The kidney can also produce acids and ammonia (NH3).

• Kidney controls what

  • lungs controls what

• What does the pH of your blood depend on?

• Label Picture

H₂O + CO₂ « H₂CO₃ « H⁺ + HCO₃^-

• Your kidneys control bicarbonate,

  • your lungs control carbon dioxide.

• The pH of your blood depends on the balance between these two.

• The Henderson- Hasselbalch equation shows how they're related (shown in the pic)

  • Basically, Kidney function divided by lung function."

1. What is the normal blood pH

2. Define Complete compensation

3. Define partial Compensation

1) Normal blood pH is 7.35 to 7.45.

• Below 7.35 is acidosis/acidemia (too much acid)

• Above 7.45 is alkalosis/alkalemia (too much base)

2) Complete Compensation

• When the body's mechanisms (respiratory and renal systems) fully correct the pH imbalance and restores the pH to the normal range (7.35-7.45)

• The ratio of bicarbonate (HCO3-) to carbonic acid (H2CO3) is brought back to the ideal 20:1

3) Partial Compensation

• When the body's mechanisms have started to correct the pH imbalance but haven't fully restored the pH to the normal range yet

• The pH is still outside the normal limits but is approaching normal as the body continues to adjust.

• Respiratory Compensation

• Metabolic Compensation

H₂O + CO₂ « H₂CO₃ « H⁺ + HCO₃^-

Respiratory Compensation

If the problem is in your body's metabolism (metabolic acidosis or alkalosis), your lungs (respiratory) help out by changing your breathing in order to fix the pH balance.

• Breathing faster (hyperventilation):

  • If there's too much acid (low pH), you breathe faster to get rid of more CO2.

  • Helps in metabolic acidosis

• Breathing slower (Hypoventilation):

  • If there's too much base (high pH), you breathe slower to keep more CO2.

  • Helps in metabolic alkalosis

Metabolic Compensation

If the problem is your respiratory aka lungs (lungs acidosis or alkalosis), then your kidney (metabolic) tries to fix it by changing the bicarbonate levels

• If there's too much acid (low pH), your kidneys will reabsorb more bicarbonate (HCO3-) to raise the pH.

• If there's too much base (high pH), kidneys get rid of bicarbonate (HCO3-) to lower the pH.

• 4 types of Acid-base problems, what are they?

H₂O + CO₂ « H₂CO₃ « H⁺ + HCO₃^-

4 types of Acid-Base Problems:

1. Metabolic Acidosis

   • Too much acid in stomach due to increase in acids or decrease of metabolic buffers like bicarbonate (HCO3-)

   • Lung will hyperventilate to decrease CO2 and kidney will retain buffers mainly bicarbonate and increasing excretion of acids

   • Anion gap is important for metabolic acidosis and a normal one is called hyperchloremia metabolic acidosis which is where chloride is a lot and bicarbonate not so much

2. Metabolic Alkalosis

   • too much base in stomach

   • Decrease of H+ and increase of bicarbonate (HCO3-) concentration, leading to increase in pH

   • The lungs will respond by hypoventilation, so CO2 increases in body in order to decrease the pH

   • Renal might happen by retaining acid and increasing the excretion of buffers mainly bicarbonate (HCO3-)

3. Respiratory Acidosis

   • Too much acid in your lungs by hypoventilation which leads to CO2 being piled up in your body which means more H+ and thus. lowers your pH

   • The kidney will respond by excreting acid, mainly H+ and retaining bicarbonate to increase pH

4. Respiratory Alkalosis

   • too much base in your lungs

   • May occur due to hyperventilation which leads to a decrease of pCO2 in the blood and thus decrease of H+ which leads to increase in pH

   • If this continues for a long time then the renal will start by retaining acid and excretion of buffer, mainly bicarbonate (HCO3-). This will lower the pH

• pH drops, is called what and what happens?

• pH rises, is called what and what happens?

• pH drops so is called acidosis which increases the number of H+ ions

  • which means the loss of bases and acids are piling up

• pH increases so is called alkalosis which decrease in the number of H+ ions

  • which means the increase of bases

• pCO2 is a

• HCO3- is a

• is a respiratory component

• is a metabolic component

• pH normal range is what

  • what happens if it is low or high

• pCO2 normal range is what

  • what happens if it high or low

• HCO3- normal range is what

  • what happens if the range is high or low

• pH normal range is 7.35-7.45

  • low pH is acidic

  • high pH is basic

• pCO2 normal range is 4.7-6.0 kPa aka 35-45 mmHg

  • increase in pCO2 means is acidic

  • Decrease in pCO2 means basic

• HCO3- normal range is 22-26 mmol/L aka 22-26 meq/L

  • decrease in HCO3- is acid

  • increase in HCO3- is basic

Problem: Plz use tik tac toe method

Patients has the following:

• pH = 7.12

• pCO2= 13.9 (104) KPa (mmHg)

• cHCO3-= 33 (33) mmol/L (meq/L)

• Since we got 3 in a row and pCO2 is respiratory, we can conclude this is respiratory acidosis

• Then look for if the body tries to compensate for this:

  • if body did not do anything then the bicarbonate will be in the normal range

  • Since bicarbonate is not in reference range, the body is handling this situation

1. Define septic/sepsis

2. Define lactate

3. Define hematocrit

1. infected with microorganisms, especially harmful bacteria.

2. Lactate, also known as lactic acid, is a substance produced in the body during intense physical activity or when oxygen levels are low

3. Hematocrit (HCT) refers to the percentage of red blood cells (RBCs) in the total volume of blood.

   • basically, tells u how much RBC there are in the entire blood

• Metabolic aka what?

  • what does metabolic manage?

• Respiratory aka what?

  • what does respiratory manage?

• Metabolic aka Kidneys manages bicarbonate (HCO3-)

  • which controls the body's base aka alkaline levels

• Respiratory aka Lungs manages carbonic acid (H2CO3) which is made from CO2

  • which controls the body’s acid levels

kidneys balance the base; lungs balance the acid.