An athletic 19-year-old private first class in the US Army is running his 1.5 mile PT test. He is trying to get under 9 minutes. What factors will facilitate the unloading of oxygen to his heart and legs during this test?

Answer: CO2, Acidosis, Exercise, and Increased temperature

An 8-year-old boy is noticed by his mother to be heading to the bathroom every 30 minutes. He also has tried to make toast for breakfast using the microwave. He said, “that was dumb” when he realized his mistake. What would you expect this boy’s serum
potassium level to be less than?

Answer: 3.5 mg/dL - the reference range for serum potassium is 3.5-5.0 mg/dL

note: This means that much of the intracellular potassium will be excreted in the urine

While assessing the ions in a solution, the laboratory technician notices that the HCO3 concentration is 20 times higher than the concentration of H2CO3 The pKa of H2CO3 is 6.35.
What is the pH of the solution?

A. 7.25
B. 7.45
C. 7.65
D. 7.85

The correct answer is C. The Henderson-Hasselbalch equation is used to figure this out.
pH = pKa + log (Base/Acid)
pH = 6.35 + log (20/1)
pH = 6.35 + 1.30
pH = 7.65

This pH is close to the homeostatic physiologic state. While the carbonic acid buffer is one of the most prevalent in our bodies, it is by no means the only buffer system in our body. The rest of the acidity comes from the proteins and other factors to bring the pH closer to 7.4.

. A 37-year-old male smoker is having difficulty breathing. It is known that 2,3-DPG is significantly decreased in smokers versus nonsmokers. What effect does this low concentration have on the patient’s hemoglobin to carry oxygen?
A. Favors oxygen unloading into the tissues
B. Favors oxygen retention in the tissues
C. Favors the oxidation of hemoglobin
D. Favors the reduction of hemoglobin

The correct answer is B. Increased 2,3-DPG concentration leads to a “right-shift”, therefore if it’s lacking, then we have a “left shift” of the curve. This leads to oxygen retention on hemoglobin and allows for more hemoglobin to be saturated at a specific partial pressure of Oxygen.
Remember the mnemonic “CADET face right!

A 67-year-old male was arrested in Georgia for bootlegging liquor. Upon questioning, he said that, “he never tried the stuff anymore, because it made him feel too loopy and lightheaded.” It was later found that his liquor contained enough methanol to cause substantial harm to anyone who drank a substantial amount of it. Many of those who imbibed on his moonshine, ended up in metabolic acidosis. In what form would the excess H+ be removed from the body?
A. CO2
B. H+
C. HCO3-
D. H2CO3

The correct answer is A. Remember the enzyme carbonic anhydrase and how it can interconvert CO2 , H2O, H2CO3, H+, and HCO3. Each one of those molecules can transform into another quite rapidly. Metabolic acidosis is an excess of H+ in the body. The HCO3- will bind to the H+ to form H2CO3 , which will then be turned into carbon dioxide and water to be excreted.

. A 16-year-old girl is having an anxiety attack. She is tachycardic (fast heart rate), diaphoretic (sweating), and hyperventilating (breathing quickly). Because the hyperventilation gets rid of a lot of CO2
, what would you expect her Cl- level to be?
A. High
B. Low
C. Normal
D. There is no relationship between acid-base balance and chloride

The correct answer is A. We would expect her chloride level to be elevated. This young girl is breathing rapidly which efficiently removes CO2 from the lungs. With such rapid breathing, you
can blow off so much CO2 that you become alkalemic. This is called respiratory alkalosis and occurs with hyperventilation. The treatment for hyperventilation is to breathe into a bag. You breathe back in the same CO2 that you breathed out, so it helps you not become so alkalotic. Because this girl is already alkalotic, the bicarbonate (HCO3-) in her blood will be exchanged for Cl -in the RBCs. This will cause an increase in the extracellular Chloride concentration
(hyperchloremia)

A 37-year-old professional football player overdosed on opiates prescribed by his physician for a broken femur. He presents to the emergency room in an ambulance and he is found to be apneic (not breathing). He has a tachycardia with a faint pulse and the patient is on a bag-valve mask with 100% O2. His physician wants to check blood gases to ensure adequate oxygenation. What electrode will the laboratory technicians use to assess pO2?

Answer:
Clarke Electrode, which is amperometric and measures the current produced after being exposed to a standardized potential between two electrodes.

What are the blood gas ranges you need to know?

pH: 7.35-7.45

pCO₂: 34-45 mm/Hg

pO₂: 90-100 mm/Hg

HCO₃: 22-28 mEq/L

What is the only value on the ABG that is calculated and NOT directly
measured?

HCO3 - is calculated from the Henderson-Hasselbalch equation using pCO2 as the acid species, a pKa of 6.4 for H2CO3, and the pH. I don’t think that you’ll be required to calculate it, but you will NEED to know that HCO3 - is CALCULATED and NOT directly measured.

What is the variable which is altered in respiratory acid-base disorders?

pCO2 is decreased in hyperventilation. With more breaths per minute, more CO2 is removed from the blood. pCO2 is increased in many other pulmonary disorders which impair gas exchange in the pulmonary capillaries (e.g. emphysema, atelectasis [collapsed alveoli], pneumonia, Acute Respiratory Distress Syndrome
[ARDS], pulmonary edema, etc.).

How is the primary cause of alkalosis determined?

With an alkalotic pH, either pCO2 is decreased or HCO3 is increased. Usually, whichever one deviates in the direction that would cause the pH change is the primary cause

What is hyperventilation cause?
.

respiratory alkalosis because the person is breathing so quickly and has adequate gas exchange, so they are breathing off all of their CO2

What are examples of Respiratory Alkalosis?

1. High pH
2. Low pCO2
3. Variable HCO3- (due to compensation and chronicity)
4. Is the pH in the 7.35-7.45 window?

What do the following diseases have in common: Emphysema, Pneumonia, Bronchiectasis, Atelectasis, ARDS, Pulmonary Edema, etc

respiratory acidosis because of the inefficient gas exchange inside the lungs. These patients may be short of breath and breathing quickly, but they can’t get rid of their CO2.

What are examples of Respiratory Acidosis?

1. Low pH
2. High pCO2
3. Variable HCO3- (due to compensation and chronicity)
4. Is the pH in the 7.35-7.45 window?

What do the following diseases have in common: Hypercortisolism, Adrenal Hyperplasia, Diuretics, etc

= metabolic alkalosis because they all create a basic environment for the body. In hyperaldosteronism, the kidney is forced to retain
Na+ at the expense of K+ , but still tries desperately to regulate the K+ concentration in the body. It is able to reabsorb a fraction of the K+ , but it costs one H +, causing alkalosis.

What are examples of Metabolic Alkalosis?

1. High pH
2. High HCO3 -
3. Usually High pCO2
4. Is the pH in the 7.35-7.45 window?

What do the following diseases have in common: Acute Kidney Injury, Diabetes, Salicylate Toxicity, Lactic Acidosis, etc

= metabolic acidosis because each pathology creates an acid that cannot be removed as quickly by the kidneys … so it hangs around for a while.

What are examples of Metabolic Acidosis Example:

1. Low pH
2. Low HCO3-
3. Usually Low pCO2
4. Is the pH in the 7.35-7.45 window?

What primary and compensatory patterns would you expect in someone with hyperaldosteronism?

Answer:
We would expect to see a primary metabolic alkalosis with a secondary respiratory acidosis. The mechanism revolves around the function of aldosterone which retains Na + in exchange for K+ causing hypokalemia. The peritubular capillaries have a H+/K+ exchange pump which goes at full force to retain as much K+ as possible, but does so at the cost of a H +. The body is now starving for both H + and K+ !

What are the common pre-analytical errors and how to minimize them?

1. Blood gases must ALWAYS be collected on ice in a fluoride tube and be assessed within 30 minutes, leukocytes continue to metabolize oxygen after the sample is taken, so rapid assessment is ALWAYS best

2. Electrodes don’t allow for diffusion very easily when there is protein build-up on the membranes, nor do they function outside of the standard temperature or barometric pressure that they are supposed to operate under. However, improper calibration is one of the most
common sources of error.

3. Probably one of the most common sources of error for the Clarke electrode is improper collection. If the sample can be exposed to room air during collection, transportation, or measurement; be deliberate and cautious with how you handle blood gas samples.

What is the appropriate collection tube, transportation requirement, and time limit to analyze the sample? the lab technician should check for when receiving an ABG sample

Blood gases need to be collected in a fluoride tube (gray top), transported on ice, and assessed within 30 minutes.

A 43-year-old male with a 64 pack-year smoking history presents to his family physician complaining of being short of breath and for a cough that “just won’t go away.” He is breathing quickly and a pulse oximeter shows that his oxygen saturation is 83%. He has been suffering from emphysema for the last 9 years. What type of acid-base imbalance would you expect to see in this patient?
A. Respiratory Alkalosis
B. Respiratory Acidosis
C. Metabolic Alkalosis
D. Metabolic Acidosis

The correct answer is B. Respiratory Acidosis occurs because even though the patient is likely breathing quickly, he is unable to efficiently transfer oxygen and carbon dioxide into/out of his blood because of his pulmonary disease (emphysema). So, if you were
thinking hyperventilation would cause respiratory alkalosis, that is a great thought, but each time he breathes, it doesn’t contain much expired CO2 because of the inefficient gas exchange in his lungs. Here are values that I would expect in a patient such as this:

2. A 38-year-old female presents to the endocrinologist after struggling to control her blood pressure for over 5 years. An abdominal CT scan is ordered and she is diagnosed with an unknown adrenal mass with primary hyperaldosteronism. On physical exam, the physician noted that she had bradypnea (slow breathing rate). If the urinary potassium excretion is high, what would you expect in this case?
A. Partially compensated metabolic acidosis
B. Partially compensated metabolic alkalosis
C. Fully compensated metabolic acidosis
D. Fully compensated metabolic alkalosis

The correct answer is D. Our patient should have a fully compensated process because she’s been living with it for 5 years. The tumor is likely hypersecreting aldosterone which will cause the kidneys to retain Na+ at the expense of K+. One of the main reasons why
this has an effect on Acid-Base homeostasis is because of a K+/H+ channel in the distal convoluted tubule of the nephron. Since our body is short on K + , it’s going to get as much as it can through this channel. We reclaim a K+, but give up a H+, leaving us in an
alkalotic state. Here is a panel that I would expect from such a patient:

A 33-year-old anxious female is feeling overwhelmed about life. She tells her physician that she can’t seem to accomplish what she wants to and just thinking about meeting with a doctor about it caused her to need to sit in her car in the parking lot and “breathe it out.” She was in obvious distress but after the physician calmed her down, she apologized for getting “out of control” and drove herself home. What results would you expect if an ABG were done on this patient?
A. Partially compensated respiratory acidosis
B. Partially compensated respiratory alkalosis
C. Uncompensated respiratory acidosis
D. Uncompensated respiratory alkalosis

The correct answer is D. This woman is hyperventilating which will cause her to breathe off her CO2. This will decrease her pCO2 and thereby, decrease the H + that is produced from carbonic anhydrase. The circulating HCO3- goes unchecked and causes an alkalotic state. Because HCO3 - cannot be excreted immediately by the kidney, the
expected compensatory pattern of metabolic acidosis would not be seen acutely and would likely take a day or two to develop. Here is a panel that I would expect from such a patient:

What is the definition of Acidosis?

is any concentration of Hydrogen atoms above the baseline and has a pH lower than 7.35, we see this in vivo as increased pCO2 or decreased HCO3

What is the definition of Alkalosis?

is any concentration of Hydrogen atoms below the baseline and has a pH higher than 7.45, we see this in vivo as decreased pCO2 or increased HCO3

What is the difference between Hypoxia vs Hypoxemia?

Hypoxia is the general term that means we are breathing in less oxygen than we need

Hypoxemia means that we have low levels of oxygen in our blood

For the Henderson-Hasselbalch Equation what ratio of bicarbonate will you get when there is a pH of 7.4?

the ratio of Bicarbonate to Carbonic Acid in the body is 20:1

What is the most important buffer system in the human body?

Bicarbonate Buffer System - H2CO3 and HCO3-

!How is the bicarbonate concentration controlled?!

by the kidneys through metabolic compensation, and usually a Ph change occurs after a few days

!How is the pCO2 concentration controlled?!

by the lungs through respiratory compensation, and can occur immediately

What are the steps for the kidneys to control Acid-base balance?

1.NH3 production and NH4+ secretion in the urine

2.Na-H exchange pumps

3.Conservation of Filtered H2CO3

The tubular lumen is more acidic than the blood

NH3 binds to H+ in the urine filtrate creating NH4+

NH3 can diffuse through plasma membranes, but NH4+ is trapped

What are the steps for gas exchange in the peripheral tissue

1. CO2 carried in RBC

2. HCO3- dissolved in plasma as carbonic acid

3. CO2 dissolved in plasma.

What is the respiratory compensation pattern for: Metabolic acidosis?

Breathe more to reduce the acid to Decrease levels of pCO2 and Increase the levels of HCO3

What is the respiratory compensation pattern for: Metabolic alkalosis ?

Breathe slower to compensate to Increase the levels of pCO2 and Decrease the levels of HCO3

What is partial compensation in breathing?

is when the pH is outside the 7.35-7.45 window, but the pCO2 is indicating one direction (e.g. acidosis) and the HCO3- is indicating another (e.g. alkalosis)

For example, pH of 7.49, pCO2 high, HCO3- very high

What values do you need to know for ABG's

MEMORY TRICK: 35 and 45 have 3, 4, and 5, if you want to extend the chain, just add 2 and 6

A 22-year-old hyper-endurance athlete presents to the physician after running the Leadville 100. He is extremely exhausted, and doesn’t see why it is the case during this race, because it hasn’t been this way in the past. What do you think his laboratory results will indicate?

1. Partially compensated metabolic acidosis
2. Partially compensated metabolic alkalosis
3. Fully compensated metabolic acidosis
4. Fully compensated metabolic alkalosis

The correct answer is A. Our patient should have a partially compensated process because it’s acutely affecting him. His body is likely unable to respond to the increased demands that he is placing on his muscles in the Leadville 100 race. Lactic acidosis is likely in this scenario. The lactic acid buildup causes a metabolic acidosis and is normally remedied by oxygen and ensuring that there is good blood flow to the affected areas.

A 74-year-old Female is having trouble breathing. She presents at the ER and a chest film is obtained which shows diffuse pulmonary edema and a consolidation in her right lower lobe suggestive of pneumonia. What will her blood gas results likely show?

1. Partially compensated respiratory acidosis
2. Partially compensated respiratory alkalosis
3. Fully compensated respiratory acidosis
4. Fully compensated respiratory alkalosis

The correct answer is A. Our patient should have a partially compensated respiratory acidosis because it’s acutely affecting her. Her body is trying to respond to decreased oxygen absorption and increased CO2 retention because of the pulmonary edema (fluid on the lungs). She will breathe quicker and her kidneys will retain more HCO3- to balance the respiratory acidosis.

What are the arterial blood gas (ABG) patterns for: Respiratory Alkalosis

pH: up

PaCO2: down

HCO3: Variable

What are the arterial blood gas (ABG) patterns for: Respiratory Acidosis

pH: down

PaCO2: up

HCO3: Variable

What are the arterial blood gas (ABG) patterns for: Metabolic Alkalosis

pH: up

PaCO2: Variable

HCO3: up

What are the arterial blood gas (ABG) patterns for: Metabolic Acidosis

pH: down

PaCO2: Variable

HCO3: down

Given the AGB panel what would it be classified as:

pH 7.31

pCO2 15

HCO3 17

Metabolic acidosis

Given the AGB panel what would it be classified as:

pH 7.22

pCO2 87

HCO3 35

Respiratory acidosis

Given the AGB panel what would it be classified as:

pH 7.03

pCO2 13

HCO3 76

Do not report results

Given the AGB panel what would it be classified as:

pH 7.44

pCO2 13

HCO3 25

Respiratory alkalosis

Given the AGB panel what would it be classified as:

pH 7.56

pCO2 114

HCO3 42

Metabolic alkalosis

Given the AGB panel what would it be classified as:

pH 7.26

pCO2 72

HCO3 17

Mixed acidosis

Where is the standard choice to draw blood from a patient:

• indwelling arterial catheter in the radial artery: Note: these are places of error.
• Test is performed on Heparinized Whole Blood
• Collection is in a glass syringe with lyophilized heparin
• Specimen is stable on ICE for 1 hour and at RT for 30 minutes

What are ranges of samples that are exposed to air?

pH > 7.45 and a pCO2 < 35

What are sources for preanalytical error?

• wrong patient drawn
• inappropriate draw technique
• failure to follow protocol for drawing specimen
• introducing air into the syringe
• exposing the specimen to air
• delays in transport
• not keeping sample cold during transport
• failure to check patient demographics
• failure to mix sample properly
• failure to remove all air bubbles
• failure to remove fibrin clots

What are sources for analytical error?

• Creating a short sample
• failure to perform quality control
• failure to perform maintenance
• failure to perform calibration

What are sources for postanalytical error?

• reporting wrong results to the clinician
• transcription mistakes
• failure to interpret instrument flags or warning something may be wrong

How often is calibration required for a Clark electrode?

! Two points of calibration are required every eight hours and one point calibration at least every four hours. Because of electrode drift slow up ward or down ward drift.

What is potassium shift?

An increase in extracellular H+ ions will drive K+ out. The cell is nice enough to offer to take some of the burden of harboring the extra H+, but it does so in exchange for K+ to keep electrical neutrality

What is Chloride shift?

The high H+ concentration in the tissues draws the HCO- out of the cells and sucks the Cl- intracellularly

The lower H+ concentration in the lungs pulls the HCO- back into the cells and pumps the Cl- out

What acid base abnormality does someone have who is hyperventilating?

Primary Respiratory Alkalosis - Cause: Blow off CO2

By product Response: Compensatory Metabolic Acidosis - Excrete more HCO3- in the urine

What acid-base abnormality occurs in someone with inefficient gas exchange?

Primary Respiratory Acidosis - Cause: Can’t get rid of enough CO2

Response: Compensatory Metabolic Alkalosis - Retain more HCO3- in the kidneys

What acid-base abnormality occurs in someone with Ethanol Poisoning?

Primary Metabolic Acidosis - Cause: Ethanol causes a lactic acidosis

Response: Compensatory Respiratory Alkalosis - Breathe quickly to release extra H+

What acid-base abnormality occurs in someone who is severely vomiting?

Primary Metabolic Alkalosis - Cause: Loss of Hydrochloric Acid in vomitus

Response: Compensatory Respiratory Acidosis - Breathe slowly to retain H+

Given the AGB panel what would it be classified as:

pH 7.51

pCO2 79

HCO3 53

Metabolic alkalosis

Given the AGB panel what would it be classified as:

pH 7.39

pCO2 53

HCO3 51

Respiratory acidosis

Given the AGB panel what would it be classified as:

pH 7.29

pCO2 91

HCO3 16

Mixed acidosis

Given the AGB panel what would it be classified as:

pH 7.49

pCO2 11

HCO3 22

Respiratory alkalosis

Given the AGB panel what would it be classified as:

pH 7.56

pCO2 21

HCO3 62

Mixed alkalosis

Given the AGB panel what would it be classified as:

pH 7.38

pCO2 72

HCO3 56

Respiratory acidosis

If the PH is above or bellow 7.4 what does it mean?

Bellow 7.4= acidosis

above 7.4= alkalosis

If the PCO2 level is bellow 35 and above 45 what can you conclude?

then the cause is some sort of respiratory process

If the HCO3 is below 22 or above 28 what can you conclude?

then you should think of metabolic causes.