Acid-Base Balance Flashcards
The terms acidosis and alklaosis refer to acid-base derangments that produce either excess ___ or excess ____, respectively that may be present regardless of pH.
H+ (hydrogen); OH- (hydroxide)
The relationship of CO/HCO3 buffer system to pH is expressed by teh _____ equtaion.
Henderson-Hasselbalch
What is the Henderson-Hasselbalch equation?
pH = 6.1 + log (serum bicarb concentration/0.03 x PaCO2)
____ - chemical species that can act as a proton (H+) donor
acid
_____ - chemical speciies that can act as a proton (H+) acceptor
Base
What does pH stand for?
potential of hydrogen
With increased pH, the hydrogen ion increases or decresaes?
decreases
With decreased pH, the hydrogen ion increases or decreases?
increases
What does the Henderson-Hasselbach equation describe?
The relationship between plasma pH and the ration of plasma PCO2 and HCO3
What is the immediate buffer system?
carbonic acid-bicarbonate system
What is the primary ECF buffer system?
Carbonic acid bicarbonate buffer system
The carbonic acid-bicarbonate buffer system maintains a ratio of ____ bicarbonate to ____ carbonic acid.
20 parts; 1 part
What uses the process of hydration of CO2 to break it down so it can be neutralized?
Carbonic acid-bicarbonate buffer system
The respiatroy buffer system acts within ____ to ____.
minutes to 12-24 hours
How does the respiratory buffer system work?
H2CO3 is converted to CO2 and excreted by lungs
Alveolar ventilation increases as pH _____.
decreases
How does renal buffer system work?
Regulates amount of bicarbonate absorbed or excreted; regulates ammonia and electrolytes
Renal regulation of buffer system: Within the renal tubule CO2 combines with _____ in the presence of carbonic anhydrase to form H2CO3 which readily disassociates into ___ and ___. The proximal tubules normal reabsorb 80-90% of this filtered ______.
H2O; H+ and HCO3; HCO3
What GI issues cause metabolic alkalosis?
vomiting, NG drainage, chloride wasting diarrhea
What urinary issues cause metabolic alkalosis?
diuretic administration, hyperaldosteronism
What are some examples of excessive HCO3 loads that can cuase metabolic alkalosis?
- NaHCO3 admin
- Lactate, acetate, citrate admin
- Alkali admin to patients w/ renal failure
- abrupt correction of chronic hypercapnia
Metabolic alkaloses can be characterized as ___ responsive or resistant.
chloride
How is volume-depletion metabolic alkalosis treated?
Chloride replacement along wtih fluid resuscitation using saline
Salien is a weak acid or base?
acide
If metabolic alkalosis has been caused by gastric losses of hydrohloric acid, _____ can be given to stop perpetuation of the alklaosis.
PPI
Metabolic alkalosis associated with loop diuretics can be improved by adding or substituting ______ diuretics.
postassium-sparing
What fluid is preferable in metabolic alkalosis treatment?
NS
What happens to serum potassium with metabolic alkalosis?
decreases
What happens to iCa with metabolic alklosis?
decreases
A ___ shift in the oxyhemoglobin dissociation curve occurs with metabolic alkalosis.
leftward
HCO3 decreases by ___ for each ___ mmHg decrease in PaCO2 below 40.
2-5; 10
What are causes of respiratory alklaosis? (6)
- iatrogenic (hyperventilation)
- high altitude
- CNS injury
- hepatic disease
- pregnancy
- ASA OD
____ OD is associated with respiratory alklosis?
Salicylate (ASA)
The ____ and ___ that may co-exist with respiratory alklosis may also require treatment.
hypokalemia and hypochloremia
T/F: Seizures, bradycardia, hyperkalemia, and lethargy and confusion are associated with respiratory alkalosis.
false - seizures, tachycardia, hypokalemia, & lethargy and confusion
What are 8 causes of respiratory acidosis?
- drug-induced ventilatory depression
- permissive hypercapnia
- UA obstruction
- status asthmaticus
- restriction of ventilation
- disorders of NM function
- MH
- hyperalimentation
What acid base condition occurs with status asthmatiuc?
respiratory acidosis
What patient population do you want to be careful when correcting respiratory acidosis?
COPD/those used to chronic incrased PaCO2 … rapid lowering of PaCO2 in these patients decreases body stores of CO2 more rapidly than the kidneys can produce corresponding decrease in HCO3 (this metabolic alklaosis –> seizures, etc.)
Hyperkalemia or hypokalemia occurs with respiratory acidosis?
hyperkalemia
Metabolic acidosis with signficant reduction of pH can cause what 4 physiologic effects?
- increased PVR
- reduced myocardial contractiliy
- decreased SVR
- impaired response of CV system to catecholamines
Metabolic acidosis is divided into what 2 groups?
normal anion gap and high anion gap
When does a high anion gap occur?
When a fixed acid is added to the extracellular space, the acid dissociates, the H+ ion combines with bicarbonate form in carbonic acid, and the decreased bicarbonate concentration produced an increased anion gap
What are some examples of high anion gap metabolic acidosis?
Lactic acidosis, DKA, renal failure, poisonings
Non-anion gap metabolic acidosis is the result of __________.
a net increase in Cl concentration
A normal anion gap acidosis is also known as?
hyperchloremic metabolic acidosis
What are the most common causes of a normal-anion gap acidosis?
IV infusion of NS and GI and renal losses of bicarb (diarrhea, renal tubular acidosis, early renal faiure)
What type of respiration occurs with metabolic acidosis?
Kussmaul
What poisonings and intoxications are assoicated with metabolic acidosis?
intoxicaiton - methanol, ethylene glycol, ASA
poisoning - cyanide, carbon monoxide
What acid-base disorder is associated with rhabdo?
metabolic acidosis
What can cause lactic acidosis?
severe tissue hypoxia d/t hypoxemia, hypoperfusion, ischemia, or inability to use O2 (cyanide)
Define base excess.
Amount of acid or base that must be added to return blood pH to 7.4 and PaCO2 to 40 at full O2 sat and 37C.
A ____ value base excess indicates metabolic alkalosis.
positive
A ____ value base excess indicates metabolic acidosis.
negative
How is metabolic acidosis commonly treated?
sodium bicarbonate
How does sodium bicarbonate work?
Bicarbonate combines with hydrogen ions and in the presence of the enzyme carbonic anhydrase becomes CO2 and H2O.
Sodium bicarbonate is best reserved for patients with adequate ventilation and pH ____
<7.2
What is the first treatment for lactic acidosis?
Fluids/volume resuscitation and oxygenation
