Acid-Base Balance Flashcards
Normal pH of bloodsss
7.35-7.45
____________ respiration is what happens when you breathe oxygen into your lungs and breathe out CO2 and H2O (as vapour).
external
____________ respiration is what happens at the tissue level when the arterial capillary beds allow the diffusion of O2 into the cell and the venule capillary beds release CO2 into the plasma for return back to the lungs.
Internal
Normal cellular metabolism produces biproducts that make the body more
Acidic
3 systems that maintain acid base
Buffer (quickest)
Resp system (minutes)
Renal system (slowest) - days
buffer system
Occuring immediately
Takes CO2 and H2O making carbonic acid
If there are too many hydrogen ions (to acidic) they can be exchanged for potassium ions and if there are too few hydrogen ions, K+ are absorbed out of blood and H+ are added in (Vis versa)
Resp systems responds
In minutes, max effect is in hours
What does the buffer system often result in electrolyte wise
Alkalosis = hypokalemia
Acidosis = hyperkalemia
During acidosis, if kidneys cannot fix imbalance, the single charge Hydrogen must be put into the cells to get it out of the blood stream, and is exchanged
How do lungs contribute to acid base balance
Rapid respirations
exhalation of CO2
decreased acidity
Slow respirations
retention of CO2
increased acidity
How do kidneys contribute to AB regulation
Excretion or retention of acids and bicarbonate (HCO3)
Primary regulatory mechanism (Formula)
H2O + CO2- H2CO3 HCO3- + H+
What is the balance of CO2 to bicarb to keep the body in a homeostatic state
1 part H2CO3 (Carbon dioxide + H2O)
20 parts HCO3 (Bicarbonate)
Hendersin-hasselcanlch relationship
What determines what type of acidosis/alkalsosis
Respiratory (lungs)
metabolic (kidneys)
What causes respiratory acidosis
Anything that causes hypoventilation, for example:
COPD
barbituate or sedative overdose
severe pneumonia
Atelectasis
Respiratory muscle weakness
mechanical hypoventilation
MS, ALS
Manifestations of resp acidosis
Drowsiness, headache, coma, disorientation
Decrease BP VFib, seizures, Dyspnea, hypoventilation with hypoxia
How is resp acidosis treated
Underlying cause must be treated
Nalaxone for drug overdose
Oxygen therapy (low flow)
Respiratory therapy
Causes of resp alkalsosi
Anything causing hyperventilation
2o to hypoxia, fear/anxiety, fever
Stimulated respiratory center
CNS disorders, sepsis, brain injury, salicylate poisoning
Mechanical overventilation
S/s of resp alkalosis
Lethargy, lightedheadedness, Increased HR, dysrythmias, tetany, n/v
Seizing forearms, hands
Resp alkalosis interventions
Treat underlying cause
Rebreather mask
Decrease anxiety
O2 if hypoxia is cause
Causes of metabolic acidosis
Accumulation of acid
diabetic ketoacidosis, septic shock (lactic acid accumulation), starvation
Loss of bicarbonate
-diarrhea, renal failure
Decrease in Bicarbonate, decrease in pH
Manifestations of metabolic acidosis
Deep rapid breathing, N/V, abdom pain, diarrhea, decrease in BP, dysrythmias periph vasodialation, drowsiness, confusion, headache
Interventions for metabolic acidosis
Treat underlying cause
Respiratory support
Administer sodium bicarbonate (If serious)
Metabolic alkalosis
Loss of acid
NG suctioning, prolonged vomiting, loss of K+ due to diuretic therapy
Gain in bicarbonate
Ingestion of baking soda
Manifestations of metabolic alkalosis
Dizziness, irritability, nervousness, confusion, tachycardia, dysrythmias, anorexia, nausea, vomiting, hypoventilation
Intevention for metabolic alkalosis
Treat underlysing cause
Replace lost fluids and elctroltes
support renal fucniotn
admin acetazolamide - promotes loss of bicarb in urine
10 marks on ABG interpretation of MT
pH is basically measureing amount of
Hydrogen
98.5% of O2 in blood is carried attatched to
Hem
What is the change in chemical bonds from cells in blood to lungs
H+ + HCO3 (Hydrogen and bicarb)
H2CO3 (Carbonic acid)
H2o + CO2
Renal system time to response
2-3 days, some level of response within 24 hours
Can maintain balance for long period of time
High CO2 in the blood causes *
Acidity
ABG range for survival
6.8-7.8
Bicarbonate ions are
A weak base
H2CO3 is
Carbonic acid is A strong acid
COPD cause of acidosis?
Scarring in lungs, therefore NOT proper diffusion of gas across aveolar membrane
CO2 is retained bc it is not easily exchanged across aveolar
How to reverse resp alkalosis
Breathing into paper bag
Why are NGs set to low intermittant suction
Too avoid causing metabolic alkalosis
ABG
Arterial Blood gas test
PaO2 and normal level
Partial pressure of free floating oxygen in blood
Normal is 80-100 mmHg
Hypoxemia
Low oxygen IN the blood
Low PaO2
Step by step approach to ABG
pH - too high or low
PaCO2 level (representing acid)
- Is there respiratory compenent
Assess HCO3 (Kidney system)
- Is there a metabolic component
Does the PaCO2 or HCO3 match with the pH alteration
Identify PRIMARY disorder
As pH goes up CO2 goes
DOWN
As pH goes up HCO3
Goes Up
Uncompensated means
Opposite system (Lungs for kidneys or vis versa) has not kicked in yet
If pH is low with a high paCO2 but Bicarb levels are normal, this would be uncompensated resp acidosis
Normal ABG values
pH 7.35 – 7.45
PaO2 80 – 100 mmHg
PCO2 35 – 45 mmHg
HCO3- 22 – 26 mEq/L
Partially compensated
Both systems, metabolic and resp are working to restore pH, but pH is STILL currently outside of homeostatic range
Fully compensated
pH is normal, but resp and metabolic compensatory buffer systems are working in opposite directions
