JDMA CREATIVES

TABLE OF
CONTENTS
1 Overview of ABG's

2 How do the Organs Compensate

3 Respiratory Acidosis vs. Respiratory Alkalosis

4 Metabolic Acidosis vs. Metabolic Alkalosis

5 Clinical Significance

4 ABG values to know

5 ABG practice question example

JDMA CREATIVES
 Overview of ABG's & how to interpret them
ABG stands for arterial blood gas, which is a medical test that measures the
levels of oxygen (O2), carbon dioxide (CO2), pH, and other parameters in
the arterial blood. ABG tests are commonly used to evaluate the function of
the lungs and the body's acid-base balance.
ABG results are typically reported as a set of values, including:
1. pH: The acidity or alkalinity of the blood. A normal pH is between
7.35 and 7.45.
2. PaO2: The partial pressure of oxygen dissolved in the arterial
blood. A normal value is between 75 and 100 mm Hg.
3. PaCO2: The partial pressure of carbon dioxide dissolved in the
arterial blood. A normal value is between 35 and 45 mm Hg.
4. HCO3-: The concentration of bicarbonate ions in the blood. A
normal value is between 22 and 26 mmol/L.
5. Base excess/deficit: A measure of the excess or deficit of base in the
blood. A normal value is between -2 and +2 mmol/L.

EXAMPLES OF INTERPRETATIONS

Interpreting ABG results can provide important information about a

patient's respiratory and metabolic status. A few examples of
interpretations include:
Respiratory acidosis
This occurs when the PaCO2 is high (> 45 mm Hg) and the pH is low (< 7.35),
indicating that there is too much carbon dioxide in the blood due to a
respiratory problem, such as COPD or asthma.
Respiratory alkalosis
This occurs when the PaCO2 is low (< 35 mm Hg) and the pH is high (> 7.45),
indicating that there is too little carbon dioxide in the blood due to
hyperventilation, anxiety or aspirin overdose.
Metabolic acidosis
This occurs when the HCO3- is low (< 22 mmol/L) and the pH is low (< 7.35),
indicating that there is an excess of acid in the blood due to metabolic
causes such as renal failure, diabetic ketoacidosis or lactic acidosis.
Metabolic alkalosis
This occurs when the HCO3- is high (> 26 mmol/L) and the pH is high (>
7.45), indicating that there is an excess of base in the blood due to metabolic
causes such as vomiting, antacid overuse or diuretic use.

It is important to note that ABG results should be interpreted in the

context of the patient's overall clinical condition and other laboratory
results. Consultation with a healthcare provider is recommended for
proper interpretation and management of abnormal ABG results.
JDMA CREATIVES
 How do the Organs Compensate
When there is an imbalance in the acid-base status of the body, the organs
work together to compensate and maintain a normal pH level. The kidneys
and lungs are the main organs involved in acid-base balance regulation.

Lungs
The lungs compensate for changes in acid-base balance by adjusting the
rate and depth of breathing. When there is too much carbon dioxide in the
blood (respiratory acidosis), the lungs increase the rate and depth of
breathing to expel more carbon dioxide and increase the amount of oxygen.
Conversely, when there is too little carbon dioxide in the blood (respiratory
alkalosis), the lungs decrease the rate and depth of breathing to retain more
carbon dioxide and decrease the amount of oxygen.

Kidneys
The kidneys compensate for changes in acid-base balance by regulating
the excretion or reabsorption of bicarbonate ions (HCO3-) and hydrogen
ions (H+). When there is too much acid in the blood (metabolic acidosis),
the kidneys increase the production and excretion of HCO3- and decrease
the reabsorption of H+. Conversely, when there is too much base in the
blood (metabolic alkalosis), the kidneys decrease the production and
excretion of HCO3- and increase the reabsorption of H+.

These compensatory mechanisms may take several hours to days to fully

restore the acid-base balance, depending on the severity and duration of
the imbalance. It is important to note that these compensatory
mechanisms have limits and cannot fully compensate for all types and
severities of acid-base imbalances. Therefore, prompt medical
intervention and treatment may be necessary to correct severe or
persistent acid-base imbalances.
JDMA CREATIVES
 Respiratory Acidosis vs. Respiratory Alkalosis

Respiratory acidosis and respiratory alkalosis are both medical conditions

that occur due to imbalances in the body's acid-base balance, which is
regulated by the lungs and kidneys. Here are some details on their
differences:

RESPIRATORY ACIDOSIS RESPIRATORY ALKALOSIS

Respiratory acidosis is a Respiratory alkalosis, on the
medical condition characterized other hand, is a condition
by an increase in carbon dioxide characterized by a decrease in
(CO2) in the blood, which leads carbon dioxide in the blood,
to a decrease in blood pH. leading to an increase in blood
pH.

CAUSES CAUSES
Respiratory acidosis can be Respiratory alkalosis can be
caused by a variety of factors, caused by hyperventilation due
including lung diseases, such as to anxiety, high altitude, or
chronic obstructive pulmonary aspirin overdose.
disease (COPD), obesity
hypoventilation syndrome, and
asthma.

SYMPTOMS SYMPTOMS
Symptoms of respiratory acidosis Symptoms of respiratory alkalosis
include shortness of breath, fatigue, include lightheadedness, confusion,
confusion, headache, and lethargy. numbness, and tingling in the hands
and feet.
 DIAGNOSIS DIAGNOSIS
Both conditions can be diagnosed Both conditions can be diagnosed
through blood tests that measure through blood tests that measure
the levels of CO2 and pH in the the levels of CO2 and pH in the
blood. blood.

TREATMENT TREATMENT
Treatment for respiratory acidosis Treatment for respiratory alkalosis
involves addressing the involves addressing the underlying
underlying cause of the condition, cause of hyperventilation, such as
such as administering breathing into a paper bag or
supplemental oxygen or providing emotional support to
bronchodilators for lung diseases. reduce anxiety.

PROGNOSIS PROGNOSIS
The prognosis for respiratory The prognosis for respiratory
acidosis depends on the severity alkalosis is also good, as the
and underlying cause of the condition can usually be treated
condition. With proper treatment, by addressing the underlying
most people with respiratory cause.
acidosis can recover.
JDMA CREATIVES
Metabolic Acidosis vs. Metabolic Alkalosis

Metabolic acidosis and metabolic alkalosis are two medical conditions

that occur due to imbalances in the body's acid-base balance, which is
regulated by the kidneys. Here are some details on their differences:

METABOLIC ACIDOSIS METABOLIC ALKALOSIS

Metabolic acidosis is a medical Metabolic alkalosis, on the
condition characterized by an other hand, is a condition
excess of acid in the blood, characterized by a deficiency of
which leads to a decrease in acid in the blood, leading to an
blood pH. increase in blood pH.

CAUSES CAUSES
Metabolic acidosis can be Metabolic alkalosis can be
caused by a variety of factors, caused by excessive
including uncontrolled diabetes, vomiting or use of certain
kidney failure, lactic acidosis, medications, such as
and excessive alcohol diuretics.
consumption.

SYMPTOMS SYMPTOMS
Symptoms of metabolic acidosis Symptoms of metabolic alkalosis
include rapid breathing, confusion, include muscle cramps, nausea,
fatigue, headache, and decreased vomiting, and weakness.
appetite.
 DIAGNOSIS DIAGNOSIS
Both conditions can be diagnosed Both conditions can be diagnosed
through blood tests that measure through blood tests that measure
the levels of bicarbonate and pH the levels of bicarbonate and pH
in the blood. in the blood.

TREATMENT TREATMENT
Treatment for metabolic acidosis Treatment for metabolic alkalosis
involves addressing the involves addressing the underlying
underlying cause of the condition, cause of the condition, such as
such as administering insulin for administering antiemetics to
uncontrolled diabetes or reduce vomiting or stopping the use
providing dialysis for kidney of diuretics.
failure.

PROGNOSIS PROGNOSIS
The prognosis for both metabolic The prognosis for both metabolic
acidosis and metabolic alkalosis acidosis and metabolic alkalosis
depends on the severity and depends on the severity and
underlying cause of the condition. underlying cause of the condition.
With proper treatment, most With proper treatment, most
people with these conditions can people with these conditions can
recover. recover.
JDMA CREATIVES
 Clinical Significance
As a nursing student, you should have a basic understanding of ABGs
and their clinical significance. Here are some additional things you
should know about ABGs:

Indications
ABG testing is typically done in patients with respiratory or metabolic
disorders, such as COPD, asthma, pneumonia, heart failure, sepsis, kidney
failure, and diabetic ketoacidosis

Procedure
ABG testing involves taking a blood sample from an artery, usually the
radial artery in the wrist. The procedure is invasive and may cause
discomfort, bleeding, and bruising. Proper technique and infection control
measures should be followed to minimize the risk of complications.

Interpretation
ABG results are interpreted based on the values of pH, PaCO2, HCO3-, and
PaO2. Normal ranges may vary depending on age, sex, altitude, and other
factors. Abnormal ABG results can indicate respiratory or metabolic
acidosis or alkalosis, which can have serious consequences if left untreated.
ABGs can also provide information about the effectiveness of oxygen
therapy, mechanical ventilation, and other interventions.

Nursing considerations
Nurses play an important role in monitoring ABG results and assisting with
ABG testing and interpretation. They should ensure that the patient is
properly positioned, relaxed, and informed about the procedure.
They should also assess the site for bleeding, hematoma, and infection, and
monitor vital signs, oxygen saturation, and respiratory status before and
after the test. Nurses should communicate ABG results to the healthcare
team and collaborate on the development of a care plan based on the
patient's individual needs and goals.

Troubleshooting
In some cases, ABG results may be inaccurate or misleading due to
technical errors, sample contamination, or physiological variations.
Nurses should be aware of potential sources of error, such as air
bubbles in the syringe, inadequate flushing of the line, and improper
calibration of the equipment. They should also recognize common
causes of discrepancy between ABG results and clinical findings, such
as chronic respiratory compensation, mixed acid-base disorders, and
drug-induced changes in acid-base balance.
JDMA CREATIVES
 ABG values to know
As a nursing student, you should be familiar with the normal ranges for
the following ABG values:

pH: 7.35-7.45
PaCO2: 35-45 mmHg
HCO3-: 22-28 mEq/L
PaO2: 75-100 mmHg
SaO2: > 95%

It is important to note that normal ranges may vary depending on age,

sex, altitude, and other factors, and that ABG values should be
interpreted in the context of the patient's clinical condition and medical
history. Abnormal ABG values can indicate respiratory or metabolic
acidosis or alkalosis, which can have serious consequences if left
untreated. It is important to identify and address the underlying cause
of the acid-base imbalance, and to monitor the patient's response to
treatment using ABG results and other clinical indicators.

Here are some additional ABG values and terms that nursing students
should know:

Base excess/deficit (BE)

This is a measure of the amount of excess or deficit of bicarbonate ions
in the blood, relative to the normal range. A negative BE indicates
metabolic acidosis, while a positive BE indicates metabolic alkalosis.
Anion gap (AG)
This is a measure of the difference between the concentration of
positively charged ions (such as sodium and potassium) and negatively
charged ions (such as chloride and bicarbonate) in the blood. A high AG
indicates the presence of unmeasured anions, which may be due to
conditions such as lactic acidosis, ketoacidosis, and renal failure.
 Respiratory compensation
This is the body's natural mechanism to compensate for acid-base
imbalances by adjusting the respiratory rate and depth to increase or
decrease the elimination of carbon dioxide. Respiratory compensation
is indicated by changes in PaCO2 that are opposite in direction to the
changes in HCO3-.
Mixed acid-base disorders
These are complex acid-base imbalances that involve multiple
primary and compensatory disturbances. Mixed acid-base disorders
may be caused by conditions such as sepsis, liver failure, and drug
toxicity.
Fick's principle
This is a physiological principle that describes the relationship
between oxygen consumption, cardiac output, and arterial oxygen
content. Fick's principle can be used to calculate the patient's oxygen
delivery (DO2) and oxygen consumption (VO2) based on ABG results
and other clinical data.
Acid-base nomogram
This is a graphical tool used to interpret ABG results and diagnose
acid-base disorders. The nomogram plots the pH, PaCO2, and HCO3-
values on a triangular grid, and provides reference lines for normal
values and acid-base disorders. The nomogram can help identify the
primary disorder, assess compensation, and predict the expected
changes in ABG values with treatment.
JDMA CREATIVES
 ABG practice question example
Here is an example of an ABG practice question:
A 55-year-old woman presents to the emergency department with
shortness of breath, fatigue, and confusion. She has a history of chronic
obstructive pulmonary disease (COPD) and is a heavy smoker. Her ABG
results are as follows:
pH: 7.28
PaCO2: 70 mmHg
HCO3-: 30 mEq/L
PaO2: 60 mmHg

What is the most likely diagnosis?

a) Respiratory acidosis
b) Respiratory alkalosis
c) Metabolic acidosis
d) Metabolic alkalosis

Answer: a) Respiratory acidosis

Explanation
The low pH and high PaCO2 indicate respiratory acidosis, which is a
condition in which the lungs are unable to remove enough carbon
dioxide from the body, leading to an excess of acid in the blood. The high
HCO3- suggests that the kidneys are attempting to compensate for the
acidosis by retaining bicarbonate. The low PaO2 indicates hypoxemia,
which is common in patients with COPD. The patient's history of COPD
and heavy smoking are also consistent with respiratory acidosis.