Acid and Bases Flashcards
What organ is essential for acid and bases imbalance and what does it do?
- Kidneys
Essential to help buffer acids
Which population is most susceptible for acid and bases imbalances?
older adults because of a decrease in thirst sensation
What does acidity or alkalinity depend on?
Hydrogen ions concentration
- Increase hydrogen = acidity
- Decrease in hydrogen = alkalinity
What is the relationship between hydrogen concentration and pH?
- Inverse relationship
1) Lower the pH = higher hydrogen concentration
2) Higher the pH = lower hydrogen concentration
What is the pH range for acidosis, alkalosis and neutral?
pH < 7.35 = acidosis
pH > 7.45 = 7.45 alkalosis
7.35 < pH < 7.45 = 7.45 neutral
What are the 3 ways to regulate acid-base and their time frame?
1) Buffer system (react immediately)
2) Respiratory system (responds in minutes and reaches max effectiveness in hours)
3) Renal system (response 2-3 days but can maintain balance indefinitely)
Explain the buffer system for acid-base regulation
Primary regulator and the fastest. It acts chemically to change strong acids into weaker acids or bind acids to neutralize their effect
What is the major buffer for the buffer system?
Carbonic-acid bicarbonate
How do cells act as a buffer?
By shifting H+ in and out. With accumulation of H+ in the ECF, the intracellular compartment can accept hydrogen in exchange for another cation
How does H+ levels in the ECF when the cells act as a buffer result in hyper/hypo kalemia?
1) ECF levels of H+ are increased, H+ enters cells in exchange for K+ which = hyperkalemia
2) ECF levels of H+ are decreased, H+ enters the plasma in exchange for K+ which = hypokalemia
What does a buffer consist of?
Weakly ionized acid or a base and its salt
Combining strong acids with a base prevents acids from causing large decrease in pH
Explain the respiratory system for acid-base regulation
Lungs help maintain normal pH by excreting CO2 and water which are by-products of cellular metabolism
- When carbonic acids from the buffer system gets broken down, the by-products are water and co2 which gets excreted by the lungs.
What happens when the respiratory system is the cause of acid-base imbalance?
It loses the ability to correct a pH altercation
Define hyperventilation from the respiratory system
decreases CO2 which increases pH
Define hypoventilation from the respiratory system
Increase CO2 which will decrease pH
Explain the renal system for acid-base regulation
Under normal conditions, kidneys reabsorb and conserve the bicarbonate they filter. With the generation of additional bicarbonate, it will eliminate excess H+
1) Secretion of small amounts of free hydrogen into the renal tubule
2) Combination of H+ with ammonia (NH3) to form ammonium (NH4)
3) Excretion of weak acids
What is the acidic excretion of urine by the kidneys?
Urine w/ a pH of 6
What happens when the renal system is the cause of acid-base imbalance?
It loses its ability to correct a pH alteration
Define alterations in acid-base balance
Produced when the ration of 1:20 between acid and base content is altered. Usually happens with disease. Compensatory process is an attempt to maintain the other side of the ratio. When the compensatory process fails, an acid-base imbalance results
What are the 2 classifications of alterations?
1) Respiratory: affects H2CO3 (carbonic acid)
2) Metabolic: affects HCO3 (carbonate)
Define respiratory acidosis w/ relation to hypoventilation and the compensatory effect
Occurs with hypoventilation which is the result in a build up of CO2. If this CO2 is not eliminated from the blood, acidosis results. To compensate, the kidneys conserve bicarbonate and secrete H+ into the urine
- Carbonic acid accumulates in the blood as well too which can cause academia
What are common causes of respiratory acidosis?
- COPD
- Overdose
What are clinical manifestations of respiratory acidosis?
Breathing is short and slow
What are some nursing management for respiratory acidosis?
Use semi fowlers position to facilitate ventilation
Define respiratory alkalosis w/ relation to hyperventilation
Occurs with hyperventilation which is the result of hypoxemia from acute pulmonary disorders (ex: pneumonia).
- Decrease in arterial CO2 levels lead to a decrease in carbonic acid concentration in the blood and an increase in pH
- Compensated respiratory mechanism for alkalosis is UNCOMMON unless patient is on a ventilator or has CNS condition
What are clinical manifestations of respiratory alkalosis?
panic attack, anxiety
Define metabolic acidosis
Occurs when an acid other than carbonic acids accumulates in the body OR when bicarbonate is lost from body fluids. Regardless, both causes bicarbonate deficit
What is the compensatory response for metabolic acidosis?
Increase CO2 excretion by the lungs
- Develop Kussmaul’s respiration which is deep rapid breathing
Define metabolic alkalosis with causes and compensatory effect
Occurs when acid is lost OR when bicarbonate increases
- Compensatory mechanism is a decreased respiratory rate to increase plasma CO2
- Once hypoxemia occur or plasma CO2 reaches a certain level, stimulation of chemoreceptors increases respirations
Renal excretion of bicarbonate also occurs
What are some causes of metabolic alkalosis?
- severe vomiting
- Excess aldosterone
- Potassium deficit
What is a key thing to monitor when managing a patient with metabolic alkalosis?
- Monitor potassium values (hypokalemia usually occurs but the levels will increase with treatment of alkalosis)
- Monitor heart as well for abnormal heart sounds related to decrease in potassium
What are mixed acid-base disorders?
Occurs when two or more acid-base disturbances are present at the same time
What is the pH range for respiratory acidosis combined with metabolic alkalosis?
May result in near normal pH
What is the pH range for respiratory acidosis combined with metabolic acidosis?
Causes greater decrease in pH than either disorder alone
What happens with mixed acidosis and mixed alkalosis?
1) Mixed acidosis = cardiopulmonary arrest = hypoventilation elevates CO2 and anerobic metabolism produces lactic acid
2) Mixed alkalosis = hyperventilating because of post-op pain and is also on NG suction
What does arterial blood gas values provide information on?
1) Acid base balance
2) Origin of the imbalance
3) Body ability to regulate pH
4) Reflection of patients overall oxygenation status
Where is blood obtained for blood gas values?
Any area of the body where there is a strong pulse. Usually from the radial pulse
What test must be positive before using the radial artery?
Allen test (YouTube Allen test)
What is step 1 of the arterial blood gas interpretation?
Determine whether the pH is acidic or alkalotic. pH is always first:
1) 7.35 < Value <7.45 - neutral 2) Value < 7.35 - acidosis
3) Value > 7.45 alkalotic
What is step 2 of the arterial blood gas interpretation?
Analyze the arterial partial pressure of carbon dioxide (PaC02). CO2 = 2nd after pH:
1) If PaCO2 < 35; the value is alkalotic
2) If PaCO2 > 45 the value is acidotic
What is step 3 of the arterial blood gas interpretation?
Analyze the bicarbonate (HCO3) level. HC03 = 3rd after CO2:
1) If HCO3 > 26; the value is alkalotic
2) If HCO3 < 22; the value is acidotic
What is step 4 of the arterial blood gas interpretation?
Determine whether the CO2 or the HCO3 level matches the acid or base alteration of the pH by using the tic tac toe table.
After determining the pH whether its acidosis or alkalosis determine which one it is.
what is a base?
hydrogen acceptor
what is an acid?
hydrogen donor
