intro to acid base physiology Flashcards
what is the normal pH of the body
7.4
(7.35 - 7.45)
acidemia pH and alkalemia pH?
- acidemia: pH < 7.35
- alkalemia: pH > 7.45
the acid-base balance is tightly regulated by two main systems:
- respiratory
- metabolic
respiratory acid-base
- CO2 is acidic
- is pCO2 increases, pH drops
what controls the partial pressure of CO2 in the blood
lung ventilation
metabolic acid-base
- HCO3- is alkaline
- if HCO3- increase, pH increase
what controls the amount of bicarbonate in the blood
kidney
what is the normal PCO2 in the arterial blood and venous blood
40 mmHg; 46 mmHg
what is pCO2
partial pressure of CO2 gas dissolved in the plasma
how is pCO2 measured
- blood gas analysis
- can be venous (PvCO2) or arterial (PaCO2)
what is ventilation
how much air is being moved by the lungs
hypoventilation
- too much CO2 is retained (not breathed off)
- pCO2 increases
- pH drops
hyperventilation
- too much CO2 is expelled
- pCO2 decreases
- pH rises
pCO2 can change quickly or slowly?
quick (within seconds or minutes)
what is the only cause of increase pCO2
hypoventilation
hypoventilation problems
- brain problem (anesthesia, brain disease)
- diaphragm problem
- blocked airways
hyperventilation problems
- fear or pain
- hypoexmia
- acidemia
respiratory acidosis
pCO2 is HIGH
“hypercapnic from hypoventilation”
respiratory alkalosis
pCO2 is LOW
“hypocapnic from hyperventilation”
name the acid base abnormality for a patient with a:
- PaCO2 - 71 mmHg
- PaCO2 - 28 mmHg
- PvCO2 - 40 mmHg
- respiratory acidosis (hypoventilation)
- respiratory alkalosis (hyperventilation)
- normal
what does HCO3- indicate and how can it be measured
- the amount of bicarbonate anion in the plasma
- measured on blood gas or serum chem analysis (called TCO2)
HCO3- changes slowly or quickly?
slowly (days)
HCO3- changes slowly or quickly?
slowly (days)
what are the two mechanisms for metabolic alkalosis
- kidney retains too much bicarb
- chloride loss from upper GI (vomiting, pyloric obstuction)
what are the 3 mechanisms for metabolic acidosis
- the kidney loses too much bicarb
- the colon can lose bicarb from lower GI via diarrhea
- you accumulate “poison anions” in your blood
metabolic acidosis
HCO3- is LOW
metabolic alkalosis
HCO3- is HIGH
what is the normal HCO3-
~24 mg/dL
name the acid base abnormality for a patient with a:
- HCO3 - 26 mg/dL
- TCO2 - 45 mg/dL
- HCO3 - 24 mg/dL
- TCO2 - 11 mg/dL
- metabolic alkalosis
- metabolic alkalosis
- normal
- metabolic acidosis
what is the HCO3- equation
H2O + CO2 <-> H2CO3 <-> H+ + HCO3-
what is base excess
the amount of HCl or HCO3- required to return 1L of blood (at 38 deg. C with a standardized PCO2 and Hb) to a pH of 7.40
what are the 4 main derangements of pH in the blood
- respiratory acidosis and alkalosis
- metabolic acidosis and alkalosis
what is the anion gap
measure many plasma anions (chloride) but in some diseases or intoxications, unmeasured anions can build up
what is the anion gap equation
([Na+] + [K+]) - ([Cl-] + [HCO3-])
an excess of unmeasured anions causes a high ____ ____, this makes the bicarbonate decrease, leading to a:
anion gap; metabolic acidosis
what might be causing a high anion gap
“find the poison anion”
K.L.U.E
(ketone, lactate, uremic toxin, ethylene glycol)
what are the two flavors or metabolic acidosis
- Normal anion gap metabolic acidosis (NAGMA) (kidney problem)
- High anion gap metabolic acidosis (HAGMA) (poison anion problem)
- pH - 7.134
- pH - 7.51
- pH - 6.91
- pH - 7.4
- pH - 7.93
- pH - 7.39
- acidmia
- alkalemia
- acidemia
- normal
- alkalemia
- normal
compensatory acidois/alkalosis
if a patient has an acid-base abormality it will compensate normalaize pH
