Acid-base Imbalances Flashcards
What is an acid?
A substance that releases H+
What is a base?
A substance takes up H+
What two types of acids are continuously being made and how are they excreted?
- carbonic acid —> excreted through lungs
- metabolic acid —> excreted by the kidneys
What is buffering?
Process of body fluids resisting large changes in pH when acids or bases are added or removed
What are buffers?
Pairs of weak acids and its base
For the ECF, what is the most important buffering system?
Bicarbonate buffering system
What does the bicarbonate buffering system consist of and what is the ratio?
-20 bicarbonate: 1 carbonic acid
How quickly does the respiratory buffer work?
Minutes
What does free H+ form in the pulmonary capillaries? What does it turn into in the lungs? How is that blown off? What does this do to the blood pH?
- it forms carbonic acid
- it turns into H2O and CO2
- it is blown off by breathing
- blood becomes less acidic and increases pH
How quickly does the renal buffer system work?
24 hours initially then possible days for effective action
What do the kidney reabsorb/conserve in the renal buffer system? What do they eliminate? What does this do to blood pH?
- they conserve bicarbonate
- they eliminate H+ (excretion of acidic urine)
- blood less acidic, increase pH
How does acidosis occur?
- buffers overwhelmed and body fluids have too much acid
- acid excretion not able to keep up with acid production or intake
How does alkalosis occur?
- too little acid, buffers unable to keep pH in normal range
- occurs when there is too much bicarbonate added to the system and acid excretion > production
What are the general risk factors of acid-base imbalances?
- excessive production or intake of metabolic acid
- altered acid buffering due to a loss or gain of HCO3
- altered acid excretion
- abnormal shift of H+ into the cells
Examples of excessive production or intake of metabolic acid
DKA, poisoning
Examples of altered acid buffering due to a loss or gain of HCO3
Loss: Diarrhea
Gain: overuse of antacid or Na+ bicarbonate therapy
Examples of altered acid excretion
- renal failure
- ppl with respiratory issues (COPD, atelectasis, PNA)
- elderly-kidneys do not work as well
What causes an abnormal shift of H+ into cells?
Hypokalemia- K+ ions leave cells and H+ enters cell to maintain electrochemical charge
Normal ABG levels
-pH—> 7.35-7.45 PaCO2 —> 35-45 PaHCO3 —> 22-26 PaO2 —> 80-100 SaO2 —> 96-100%
What is respiratory acidosis?
Too much CO2 being retained in the body
What causes respiratory acidosis?
Hypoventilation
What can cause hypoventilation?
- CNS depressants (narcotics, a esthetics, barbiturates) —> decreased respiratory center-CO2 retained
- Pulmonary conditions (COPD —> decrease in SA in alveoli for gas exchange—pulmonary edema, PNA —> inhibits effective gas exchange)
- respiratory muscle weakness (chest injuries, polio, guillian barre syndrome) —> decreased respiration’s and CO2 is retained
Respiratory Acidosis values and treatment
- pH —> decreased
- PaCO2 —> increased
- compensation HCO3 —> increased
-treat cause of hypoventilation (give NARCAN, high Fowler’s,provide O2)
S/S Respiratory acidosis (8)
- rapid, shallow breaths
- low BP
- dyspnea
- HA
- hyperkalemia
- dysrhythmias
- drowsy, dizzy, disoriented
- muscle weakness, hyper reflexive.
What causes respiratory alkalosis?
Hyperventilation
Respiratory alkalosis values and treatment
- pH high
- PaCO2 low
- compensation occurs with low HCO3
-treat cause of hyperventilation
S/S respiratory alkalosis (8)
- seizures
- deep,rapid breathing
- hyperventilation
- tachycardia
- hypokalemia
- paresthesias
- lethargy/confusion
- N/V
Metabolic acidosis etiology (too much acid in the body (6) and bicarbonate deficit (1)
- too much acid
- starvation, severe malnutrition
- renal failure
- DKA
- hyperthyroidism
- trauma/shock
- excess exercise, severe infection, fever
Bicarbonate deficit —> diarrhea
Metabolic acidosis values
- low pH
- low HCO3
- compensation LOW PaCO2
Which respiration’s are known as a sign of metabolic acidosis?
Kussmaul respirations (fast and deep respiration’s)
S/S metabolic acidosis (8)
- HA
- low BP
- hyperkalemia
- muscle twitching
- warm, flushed skin
- N/V/D
- changes in LOC
- Kussmaul respiration’s
What is the anion gap? What does is diagnose?
- balance between cations and anions
- diagnoses metabolic acidosis
What is the anion gap equation? What is the Normal range?
Na+K-Cl-HCO3
The normal range is 12 + - 4 mEq/L
What does a normal anion gap mean?
Loss of bicarbonate (diarrhea, GI fistula, diuretics, early renal insufficiency, TPN w/o bicarbonate)
What does a high anion gap mean?
Acid accumulation (ketoacidosis, lactic acidosis, ingestion of toxins)
What does a low anion gap mean?
Hyponatremia
THIS IS EXTREMELY RARE
How can metabolic alkalosis happen?
Acid deficit —vomiting, GI suction
Bicarbonate excess—peptic ulcers -> pt takes excessive amount of acid neutralizers
Lab values for metabolic alkalosis
What patients to monitor
- pH high
- HCO3 high
- compensation PaCO2 high
Clients on NG suction, severe vomiting, or on meds that decrease acid secretion (cimetidine, omeprazole)
S/s Metabolic alkalosis
- restless; followed by lethargy
- dysrhythmias
- hypoventilation
- confusion
- N/V/D
- hypokalemia
- muscle twitching, cramps
- paresthesias
What do ABGs determine? Which values do they look at?
- which acid-base imbalance is happening
- looks at pH, PaCO2, HCO3
What is base excess? What is the normal range?
Indicates how well buffers are managing acid
Normal range= -2 or +2 mmoL/L
What does uncompensated mean?
PH and either PaCO2 or HCO3 are abnormal
What does partially compensated mean?
All values are abnormal
What does fully compensated mean?
PaCO2 and HCO3 are abnormal and pH is normal
It is respiratory if pH and PaCO2 move in ____directions
Opposite
It is metabolic if pH and HCO3 move in the ____ direction.
Same
