M1 Acid Base Flashcards
Three mechanisms of regulating acid base balance
Buffering system
Respiratory compensation
Metabolic/renal compensation
Resp reguation of acid base 101
Lungs regulate CO2 that combines with H2O which forms H2CO3 - carbonic acid
H2 CO3
Carbonic acid
regulated by resp A/B system
What part of brain regulates Resp A/B balance
Medulla chemo receptors
Breathing faster/deeper - hyperventilation =
Breathing slower/shallower - hypoventilation =
CO2 elimination, increases pH
CO2 accumulation, decrease pH
Renal regulation of A/B balance
KIDNEYS key player
reabsorb or excrete acids or bases
can produce HCO3 bicarbonate
Carbonic acid
Bicarbonate
H2CO3 - acidic
HCO3 - basic
1 part carbonic acid =
20 parts bicarbonate
Kidney pH adjustments take ___ …
TIME
days to weeks
Normal Acid Base values
pH
PaCO2
HCO3
Pao2
Sao2
pH 7.35-7.45
PaCO2 45-35
HCO3 22-28
Pao2 80-100
Sao2 greater than %95
SpO2 -
Sao2 -
Pao2 -
SpO2 = oxygen saturation as measured by pulse oximeter
Sao2 = oxygen saturation as measured by blood analysis (e.g. a blood gas)
Pao2 = partial pressure of oxygen in the blood
ABG interpretation steps
classify pH
assess PaCO2
assess HCO3
determine compensation
total, partial, uncompensated
Respiratory acidosis
Decrease in rate of alveolar ventilation
pH less than 7.35
PaCO2 greater than 45mmHg
compensation = increase in HCO3
Respiratory acidosis causes
respiratory center depression
drug sedation/anesthesia
resp arrest
impaired ventilation/airway obstruction
Acidosis S/S CNS
Decrease in excitability
Drowsiness
Disorientation
Coma
restlessness
headache
Acidosis S/S cardiovascuar
Dysrhythmia
Decreased contractility
Hypotension
Resp alkalosis causes
Hypoxemia
Anemia
Fever
Dyspnea
Anger
S/S of alkalosis CNS/lytes/cardio
Increased excitability
numbness
tingling
confusion
blurred vision
Hypokalemia
Hypocalcemia
hypertension
Respiratory alkalosis renal compensation
HCO3 reabsorption drops
Metabolic acidosis 101
lab values
primary decrease in plasma bicarbonate
pH less than 7.35
HCO3 less than 22
Compensation = decrease in PaCO2
Metabolic acidosis causes
Loss of HCO3 - diarrhea
Decreased acid elimination - renal failure
Excess acid production -
Starvation
Diabetic/alcoholic ketoacidosis
Cardiac arrest
Sepsis
Shock
Metabolic alkalosis 101
lab values
Increase in bicarbonate in ECF (extracellular fluid)
pH greater than 7.45
HCO3 greater than 28
Compensatory increase in PaCO2
Metabolic alkalosis causes
Excess of base/loss of acid
Vomiting
GI suction
Alkali intake increase
med or diet
Furosemide diuretic
Methazolamide/acetazolamide and A/B balance
Carbonic anhydrase inhibitor
causes increase in metabolic acidity
Calcium carbonate antacids and A/B balance
Used to treat GERD
will lower pH
may result in metabolic alkalosis
Myasthenia gravis (MG)
Chronic autoimmune disorder
Antibodies destroy communication between nerves and muscle
Potassium and Acid Base Balance
Acidosis causes decreased K(+) secretion and increased reabsorption. SO, MORE K+
Alkalosis has the opposite effects, often leading to hypokalemia. SO, LESS K+
Increased anion gap indicates
Decreased anion gap indicates
Metabolic acidosis
Metabolic alkalosis
Normal anion gap range
8-12
Only thing the lungs control
CO2
Simple nursing intervention for hyperventilation
paperbag
CO2 is high
CO2 is low
Breathing slow and low, retaining
Breathing fast, blowing off
What is the anion gap
What does it represent
Values
Difference between all positively charged and negatively charged electrolytes
represents unmeasured phosphate sulfate and proteins that act as Acid Base buffers
8 to 12mEq/L
Reverse metabolic acidosis by giving
Sodium bicarbonate
When giving sodium bicarb to correct metabolic acidosis pt will become at risk of
why
cardiac arrest
potassium will shift back into cells resulting in hypokalemia
Diuretics like thiazide and furosemide can cause
This is due to
Metabolic alkalosis
Urination of lytes (potassium) and acids
Hypocalcemia symptoms
tingling in fingers/toes
dizziness
tetany
Why does metabolic alkalosis cause hypocalcemia
loss of H+ creates excess (-) ions, Ca++ binds to those and gets used up, creating hypocalcemia
Hypokalemia symptoms
heart palpitations
muscle weakness
prominent U waves
Why does metabolic alkalosis cause hypokalemia
Body holds on to H+ to correct issue.
Excess H+ replaces K+ and K+ gets excreted
This results in hypokalemia
Best way to narrow down cause of metabolic alkalosis
Urine chloride level
Carbonic anhydrase inhibitor med
MOA
Acetazolamide
enhance bicarbonate exertion
used for metabolic alkalosis
atelectasis
lung collapse
COPD causes
resp acidosis
When CO2 combines with water it becomes
Acidic
Acidic pt behavior =
alkalotic pt behavior =
lethargic
excitable
PT with Pulmonary embolism will first have resp alkalosis then acidosis why
first they hyperventilate due to panic, then the clot blocks off CO2 exchange sites
Only way to rid of CO2
exhalation
Can lungs fix them selves
NO, need kidneys to adjust
Kidneys control both
Hydrogen and bicarb
High anion gap =
accumulation of fixed acid