Calculations IV Flashcards
Acid-Base and arterial blood gases:
pH decreases as a solution becomes more ___________
acidic
Acid-Base and arterial blood gases:
pH increases as a solution becomes more ___________
basic (alkaline)
Human blood has a pH of __________________
7.4, slightly alkaline
As a solution becomes more acidic (the concentration of protons increases), and the pH ____________
decreases
As a solution becomes more basic (the concentration of protons decreases), and the pH _______________
increases
Pure water is neutral having a pH of
7
Stomach acid has a pH of ________
2, and is therefore acidic.
The acid-base status of a patient can be determined with an arterial blood gas (ABG).
The primary buffering system of the body is the ____________ system.
bicarbonate/carbonic acid
The kidneys help to maintain a neutral pH by controlling bicarbonate (HCO3) reabsorption and elimination.
The lungs help maintain a neutral pH by controlling carbonic acid (which is directly proportional to the partial pressure of carbon dioxide or pCO2) retained or released from the body. Carbon dioxide acts as a buffer and an acid.
(ABG) Arterial Blood Gases: what does each letter represent?
A/B/C/D/E
pH/pCO2/pO2/HCO3/O2 Sat
(ABG) Arterial Blood Gases:
What is the reference range for pH?
7.35-7.45
(ABG) Arterial Blood Gases:
What is the reference range for CO2?
35-45 mmHg
(ABG) Arterial Blood Gases:
What is the reference range for O2?
80-100 mmHg
(ABG) Arterial Blood Gases:
What is the reference range for HCO3?
22-26 mEq/L
(ABG) Arterial Blood Gases:
What is the reference range for
> 95%
Our lungs and our kidneys help regulate ___________
acid-base balance in the body
The lungs can help us retain or blow off ________
CO2
- which is an acid in the pulmonary system
Our kidneys help us retain or excrete _______
bicarbonate (HCO3)
- a basic component in the metabolic system
When interpreting ABGs:
1) First step is too look at the pH and see if it is within range or if,
too low
too high
If the pH is low, then we know we have an acidosis
If the pH is high, then we know we have an alkalosis
When interpreting ABGs:
2) Second step is too determine what other ABGs are abnormal:
If the CO2 is too high then we have a ____1______.
If the CO2 is too low then we have a _____2______.
remember CO2 is eliminated through the _____3______
1) acidosis (respiratory)
2) alkalosis (respiratory)
3) lungs
When interpreting ABGs:
2) Second step is too determine what other ABGs are abnormal:
If the HCO3 is too high then we have a ______1______.
If the HCO3 is too low then we have a ______2_______.
remember HCO3 is eliminated through the _____3_____
1) alkalosis (metabolic)
2) acidosis (metabolic)
3) kidneys
When interpreting ABGs:
3) Third step: Which of the abnormal values in step 2 matches with the pH in step 1?
ex. pH is decreased, CO2 is increased, and HCO3 is normal
pH indicated acidosis.
CO2 elevated also indicates acidosis.
so, patient has a respiratory acidosis.
When interpreting ABGs:
4) Step 4: What if both CO2 and HCO3 are abnormal?
Usually only one of the values will match the pH, the other will go in the opposite direction from the pH. This is called compensation.
ex. pH is decreased, CO2 is decreased, and HCO3 is decreased
pH indicates acidosis.
CO2 indicates alkalosis.
HCO3 indicates acidosis.
This would be considered metabolic acidosis. with some degree of respiratory compensation.
pH/pCO2/pO2/HCO3/O2 Sat
what are the reference ranges for each component in an arterial blood gas (ABGs):
pH = 7.35-7.45
pCO2 = 35-45 mmHg
pO2 = 80-100 mmHg
HCO3 = 22-26 mEq/L —————- for an arterial blood draw, if a venous blood draw values will differ.
O2 sat = > 95%
** remember we don’t use the pO2 or O2 saturation, when interpreting ABGs**
when a patient is experiencing metabolic acidosis, it is common to calculate an ________________.
anion gap
The anion gap is the difference in the measured cations and measured anions in the blood.
exs. of metabolic acidosis
a mnemonic to remember the causes of a gap acidosis is
CUTE DIMPLES =
DKA, toxicity,
cyanide, uremia, toluene, ethanol (alcoholic ketoacidosis), diabetic ketoacidosis, isoniazid, methanol, propylene glycol, lactic acidosis, ethylene glycol, salicylates
The anion gap is considered high if it is, __________________
> 12 mEq/L (meaning the patient has a gap acidosis)
Buffer Systems and Ionization:
When the pKa = pH, this is the point which ____________
half the compound is protonated, and half is NOT protonated.
Buffer Systems and Ionization:
Any time you are given a pKa, it refers to the ____________
acid form losing protons to the base form.
Buffer Systems and Ionization:
If the pH > pKa, then ____
more of the acid is ionized, and more of the conjugate base is un-ionized.
Buffer Systems and Ionization:
If the pH < pKa, then ______
more of the acid is un-ionized, and more of the conjugate base is ionized.
Buffer Systems and Ionization:
If the pH = pKa, then ________
the ionized and un-ionized forms are equal.
Percent ionization:
Is the percentage of the drug in the solution that has deprotonated.
The lower a patient’s neutrophil count, the more ______ that patient is to infection.
susceptible
