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arterial blood gases
___ is the measurment of partial pressure of O2, CO2, pH, and HCO3 in arterial blood
O2, CO2, pH, and HCO3
ABG is the measurement of partial pressure of what 4 thing in arterial blood?
Acidosis
___ is a pathologic state characterized by an increased in H+ ions in the arterial blood
increase
Acidosis is a pathologic state characterized by an ___ in H+ ions in the arterial blood
unbound
only ___ H+ ions are harmful in acidosis
< 7.35
when is a persons blood considered to be acidosis?
H+, CO2, and H2CO3
what are 3 acids
lungs; kidneys
some acids exit the body via ___; other acids are buffered and excreted via ___
metabolic
acids are produced during a ___ process
alkalosis
___ is a pathologic state characterized by a decrease in H+ ions in the arterial blood
decrease
Alkalosis is a pathologic state characterized by a ___ in H+ ions in the arterial blood
> 7.45
when is a persons pH in the blood considered alkalosis?
Anion Gap
___ is the difference between the extracellular anions (potassium is not always factored in) and cations; assists in identifying the cause of metabolic acidosis
Base excess
___ is the amount of excess or insufficient level of bicarbonate in the system (a negative base excess indicates deficient amount of base in the blood)
HCO3
what is an example of a base?
buffer
___ is a chemical substance that reduce changes in systemic pH by releasing or binding H+ ions
H+
buffer is a chemical substance that reduce changes in systemic pH by releasing or binding ___ ions
normal
buffers try to keep the pH in ___ range
compensatory mechanisms
___ is mechanisms that try to prevent large changes in pH and/or attempt to correct alterations in acid-base balance
always
compensatory mechanisms ___ alter the pH toward a normal level
lungs and kidneys
what are the two most important organs for compensatory mechanisms
pressure exerted by a single gas
what is partial pressure?
number of H+ ions
what is pH?
pH decreases
if H+ increases, what happens to the pH?
pH increases
if the H+ decreases, what happens to the pH
CO2
___ is a normal byproduct of cellular metabolism; this is transported in the lungs via circulatory system and is exhaled
carbonic acid (CO2 + H2O = H2CO3)
excess CO2 will be combine with H2O and form ___
-acidotic
-alkalotic
excess CO2 will be combine with H2O and form carbonic acid (CO2 + H2O = H2CO3). the blood pH will then change to a more ___ state due to an increase in acid (carbonic acid) or to an ___ state due to a decrease in acid
increase (acidosis) or decrease (alkalosis)
excess CO2 will be combine with H2O and form carbonic acid (CO2 + H2O = H2CO3). the blood pH will then change to a more acidotic state due to an increase in acid (carbonic acid) or to an alkalotic state due to a decrease in acid. the lungs will then be stimulated to either ___ or ___ the rate and depth of respiration to compensate for this change and to get the pH back to the normal level
keep the pH within normal limits. (acid-base ratio 1:20)
what is the goal of buffers, lungs, and kidneys
no
are buffers able to excrete?
bind or release
buffers ___ or ___ H+ ions to minimize changes in pH - unable to excrete
moment-by-moment
buffers are a ___ regulation
proteins, carbonic acid-bicarbonate, phosphate
what are 3 examples of buffers that bind to or release H+?
expiration
the lungs eliminate CO2 by ___
1-3 minutes
12-24 hrs
the activation of the lungs occurs within ___ and last up to ___
cannot eliminate H+
what can the lungs NOT eliminate?
excrete:
-HCO3 (alkalosis)
-H+
Increase production and retain:
-HCO3 (acidosis)
what do the kidneys excrete when regulating the pH and also increase production and retain?
24hrs
pH is within normal limits
the kidneys begin to work within approximately ___ and last until ___
H2O + CO2 <--> H2CO3 <--> H + HCO3
what is the formula the body uses to keep the pH WNL?
CO2
___ is NOT an acid singly, but can lead to carbonic acid with water
7.35 - 7.45
what is the normal range of pH?
80-100 mmHg
what is the normal range of PO2?
35-45 mmHg
what is the normal range of PCO2?
22-26 mEq/L
What is the normal range for HCO3?
95-100%
What is the normal range of SaO2?
-2 -+ 2 mEq/L
what is the normal range of base excess
Step 1: Check the pH
-is it WNL? (7.35-7.45)
-Acidotic? (< 7.35)
-Alkalotic? (>7.45)
Step 2: check the CO2
-is it WLN? (35-45)
-low? (<35)
-high? (>45)
Step 3: Check HCO3
-is it WNL? (22-26)
-low? (<22)
-high (>26)
what are the first 3 steps when interpreting ABG's
the pH and CO2 arrows will be going in OPPOSITE directions
how do we determine an ABG is a respiratory problem?
pH and HCO3 arrows will be going in the SAME direction
how do we determine an ABG is a metabolic problem?
-pH: decrease
-PCO2: increase
-HCO3: normal
what will the pH, PCO2, and HCO3 of respiratory acidosis look like?
-pH: increase
-PCO2: decrease
-HCO3: normal
what will the pH, PCO2, and HCO3 of respiratory alkalosis look like?
-pH: decrease
-PCO2: normal
-HCO3: decrease
what will the pH, PCO2, and HCO3 of metabolic acidosis look like?
-pH: increase
-PCO2: normal
-HCO3: increase
what will the pH, PCO2, and HCO3 of metabolic alkalosis look like?
-pH and CO2 are out of range ONLY
or
-pH and HCO3 are out of range ONLY
for step 5 of interpretation of the ABG's, how do we asses for if something is uncompensated?
pH, CO2, and HCO3 are ALL out of range
for step 5 of interpretation of the ABG's, how do we asses for if something is partially compensated?
-pH is WNL
-CO2 and HCO3 are out of range
is the pH closer to acidosis or alkalosis?
-if pH is < 7.40 = acidosis
-if pH is > 7.40 = alkalosis
for step 5 of interpretation of the ABG's, how do we asses for if something is fully compenated?
-hypoxemia
-hyperventilation
with step 6 of ABG Interpretation, a low PO2 indicates ___ and can cause ___
PO2
with step 6 of ABG Interpretation, a low ___ indicates hypoxemia and can cause hyperventilation
respiratory acidosis
___ is the most common respiratory arterial blood gas
inadequate ventilation (Hypoventilation)
what is respiratory acidosis caused by?
-H2O
-H2CO3
the lungs do not ride the body for CO2 during respiratory acidosis; excess CO2 binds with ___ forming ___
-decreased pH (< 7.35)
-increased CO2 (>45)
what are 2 characteristics of respiratory acidosis
-hypoventilation
-CNS depression
-narcotics, sedatives, anesthesia
-impaired respiratory function d/t trauma
-pneumonia, atelectasis, pulmonary edema
-pulmonary embolism
what are 6 causes of Respiratory acidosis?
-causes dilation of cerebral vessels- cerebral and behavioral changes
-weakness
-tremors
-paralysis
-stupor: coma
-warm/flushed skin
what are the 6 manifestations of Respiratory Acidosis
renal compensation: kidneys produce more HCO3
what is the compensation for Respiratory acidosis
-increased pH (> 7.45)
-decreased CO2 (<35)
what are 2 characteristics of Respiratory Alkalosis
HYPERVENTILATION (rapid respiratory rate) secondary to pain, anxiety, fear, fever, sepsis, CNS lesion
what is the cause of Respiratory Alkalosis
-constriction of cerebral vessels
-dizziness/ panic
-light headedness
-tetany
-numbness/ tingling of fingers/toes
-seizures
-cardiac dysrythmias
what are the 7 manifestations of Respiratory Alkalosis
renal compensation: kidney decrease production of HCO3
what is the compensation for Respiratory Alkalosis
metabolic acidosis
___ is the most common metabolic arterial blood gas
-decreased pH (< 7.35)
-decreased HCO3 (<22)
what are 2 characteristics of metabolic acidosis
DKA and CKD
Metabolic Acidosis is usually secondary to significant health problems such as ___ and ___
-decreased production of HCO3 (renal failure)
-increased loss of HCO3 (diarrhea)
-decreased acid secretion of kidneys (renal failure)
-increased production of acids (lactic acidosis)
-ASA toxicity
-starvation
-anaerobic metabolism
-hypoxia
what are the 8 causes of Metabolic Acidosis?
-hyperkalemia (acidosis)
-anorexia (N/V)
-abdominal pain
-weakness
-confusion
-stupor/coma
-peripheral vasodilation
-dysrhythmias
-warm/flushed skin
-bone disease
what are 10 manifestations of metabolic acidosis?
respiratory compensation: increased respiratory rate and depth (Kussmauls respiration)
what is the compensation for Metabolic Acidosis
-increased pH (> 7.45)
-increased HCO3 (>26)
what are 2 characteristics of Metabolic Alkalosis?
-increased renal production of HCO3
-excess ingestion of alkali (antacids or baking soda)
-GI suctioning, vomiting, bulimia, diuretic therapy
-excess adrenocorticosteroid hormones
what are 4 causes of Metabolic Alkalosis?
-hypokalemia
-hyperactive reflexes
-tetany
-confusion/ seizures
-hypotension
-dysrhythmias
what are 6 manifestations of Metabolic Alkalosis
respiratory compensation: decreased respiratory rate
what is the compensation for Metabolic Alkalosis
partially compensated respiratory acidosis
what is ABG Interpretation:
-pH = 7.33
-PCO2 = 60
-HCO3 = 34
uncompensated metabolic alkalosis
what is ABG Interpretation:
-pH = 7.48
-PCO2 = 42
-HCO3 = 30
normal ABG
what is ABG Interpretation:
-pH = 7.38
-PCO2 = 38
-HCO3 = 24
uncompenstated respiratory acidosis
what is ABG Interpretation:
-pH = 7.21
-PCO2 = 60
-HCO3 = 24
Fully compensated respiratory alkalosis
what is ABG Interpretation:
-pH = 7.45
-PCO2 = 26
-HCO3 = 16
uncompensated metabolic alkalosis
what is ABG Interpretation:
-pH = 7.50
-PCO2 = 42
-HCO3 = 33
fully compensated respiratory acidosis
what is ABG Interpretation:
-pH = 7.35
-PCO2 = 48
-HCO3 = 28
-R: respiratory
-O: opposite
-M: metabolic
-E: equal
what is a way to remember the ABG interpretation?