Are you studying metabolic acidosis and need to know a mnemonic on how to remember the causes? This article will give you a clever mnemonic and simplify the signs and symptoms and nursing interventions on how to remember metabolic acidosis for nursing lecture exams and NCLEX.
This article will cover:
- Metabolic acidosis simplified
- Lab values expected with metabolic acidosis
- Causes of metabolic acidosis
- Signs and symptoms of metabolic acidosis
- Nursing interventions for metabolic acidosis
Lecture on Metabolic Acidosis
Metabolic Acidosis in Simple Terms: a metabolic problem due to the buildup of acid in the body fluids which affects the bicarbonate (HCO3 levels) either from:
- increased acid production (ex: DKA where ketones (acids) increase in the body which decreases bicarbonate)
- decreased acid excretion (ex: renal failure where there is high amount of waste left in the body which causes the acids to increase and bicarb can’t control imbalance)
- loss of too much bicarb (diarrhea)
When this acidic phenomena is taking place in the body other systems will try to compensate to increase the bicarb back to normal. One system that tries to compensate is the respiratory system.
In order to compensate, the respiratory system will cause the body to hyperventilate by increasing breathing through Kussmaul’s respirations. Kussmaul respirations are deep, rapid breathes. The body hopes this will help expel CO2 (an acid) which will “hopefully” increase the pH back to normal.
Lab values expected in Metabolic Acidosis:
- HCO3: decreased <22
- Blood pH: decreased <7.35
- CO2: <35 or normal (may be normal but if it is decreased this is the body’s way of trying to compensate). **Remember the respiratory system is causing hyperventilation. The respiratory system tries to increase the pH from its acidotic states through tachypnea with Kussmaul’s breathing. The goal is to “blow off” the CO2 which is acidic to help alleviate the already acidotic conditions in the body.
Memorize these normal values for ABGs:
- pH 7.35-7.45
- PaCO2 35-45
- HCO3 22-26
Causes of Metabolic Acidosis
High anion gap & Normal anion gap problems:
What is an anion gap? Simplified this is where the doctor look at various lab results from a patient’s lab work (such as electrolytes (chloride, bicarbonate, sodium) and calculates them to see the difference between the anions and cations.
If there is a gap (>14 mEq/L from normal (normal is: 10-14 mEq/L) there is high anion gap metabolic acidosis going on. In other words the anion gap tells us what type of acidosis we have going on which is important so it can be treated appropriately.
High Anion Acidosis is conditions that cause the body to produce too much acid or NOT enough bicarb (DKA, Aspirin toxicity, renal failure, high-fat diet, low carb diet, malnutrition)
Normal Anion acidosis is loss of the bicarbonate from the body. Examples: diarrhea via GI fluids, ostomies or fistula drainage (ileostomies or pancreatic fistula)…which are rich in alkalotic fluids, however when lost it causes acidosis, or drugs ingestion: Diamox (diuretic)…. carbonic anhydrase inhibitor which reduces reabsorption of bicarb.
Combine all of this to form the Mnemonic “Acidotic”
Aspirin toxicity: (high anion gap) which increases the acid in the body and this also causes respiratory alkalosis (hyperventilation)
Carbohydrates not metabolized (high anion gap): when there isn’t enough oxygen to break down carbs the pyruvic acids (that supplies the cells with energy) starts to turn into lactic acid and when you get acid building up you get acidosis
Insufficiency of kidneys (high anion gap): kidneys are failing to filter out metabolic waste products, acids increase, and bicarb cannot keep up so it depletes
Diarrhea (normal anion gap): profuse diarrhea leads to loss bicarbonate, DKA (diabetic ketoacidosis) body is breaking down ketones and is not metabolizing glucose correctly which leads to high blood glucose levels and breakdown of acids in the blood
Ostomy drainage (excessive) ileostomies, Ureteroenterostomies (normal anion gap)…ostomies are an opening of an organ to allow drainage…depending on where the ostomy is these fluids are rich in bicarb and if loss directly at this spot (instead of travelling through the body to form into stool (which doesn’t lose much bicarb)…it can deplete the bicarb fast.
fisTula (pancreatic fistula) (normal anion gap) fistula : a fistula is a passage between an hollow organ and body surface or between two organs….same concept with the ostomy…losing fluids where you shouldn’t be and they are not being absorbed by the body…you are wasting the bicarb
Intake of high-fat diet: eating too much fat leads to the building-up of waste product which in turn leads to buildup of ketones and acids
Carbonic anhydrase inhibitors (Diamox): diuretic which reduces the reabsorption of bicarb
Signs & Symptoms of Metabolic Acidosis
- ****Kussmaul’s respiration (body’s way of trying to compensate by exhaling the excessive CO2…in hopes of increasing bicarb and blood pH)
- Confused, weak, low blood pressure, cardiac changes (if hyperkalemic …can happen EXCEPT with diarrhea or with Diamox usage which causes hypokalemia), n & v
Nursing Interventions for Metabolic Acidosis
Vary depending on the causes of acidosis:
- Watch respiratory system and ABGs closely…if too bad may need intubation
- Assess other electrolyte levels (esp. potassium because during active acidosis it will be high…however when it resolves there is an extracellular to intracellular shift of K+ back into the cell which will causes hypokalemia)
- Watch neuro status, safety, and place in seizure precaution
- Dialysis may be needed if they patient is experiencing acidosis (high anion gap issue ex: renal failure)
- Diabetic ketoacidosis: administer prescribed insulin to help glucose go back into cell which will help the body start regulating how it metabolizes glucose…hence not more ketones (acids)