ACID BASE BALANCE Flashcards
DIARRHEA
- washed out a lot of HCO3 (decrease in HCO3)
- thus generating H+ ion fix acid metabolic acidosis
- is due to INCREASE in H+ ion fixed acids
- second by DECREASE in HCO3
RESPIRATORY ACIDOSIS (acute)
- respiratory depression (anesthetics, morphine)
- pulmonary edema, cardiac arrest
- airway obstruction
- muscle relaxant
- sleep apnea
- chronic obstructive lung disease
- restrictive lung disease
- neuromuscular defects (MS, muscular dystrophy)
- obesity hypoventilation syndrome
RESPIRATORY ALKALOSIS (acute)
- anxiety
- fever
- hypoxemia
- pneumothorax ( in some cases) atelectasis pulmonary shunt increase ventilation leading to LOW arterial CO2
- ventilation- perfusion inequality
- hypotension
- high altitude
RESPIRATORY ACIDOSIS
- Hypoventilation
- INCREASE PaCO2
- will make the curve shift to the R
- INCREASE H+ is the cause of acidosis
- slight INCREASE HCO3 it is not part of the compensation, rather part of the disturbance (22-26)
- an increase of 10 mm Hg of CO2 will increase HCO3 by 1 mmol
RESPIRATORY ALKALOSIS
- HYPERVENTILATION
- that causes a DECREASE in PaCO2 (main cause)
- shift to the L
- decrease in H+ ion caused the alkalosis
- slight DECREASE in HCO3
- a decrease of PaCO2 by 10 mm Hg, the HCO3 decreases by 2 mmol
METABOLIC ACIDOSIS
- LACTIC ACIDOSIS (increase acid production)
- KETOACIDOSIS (increase acid production faster than the kidney produced)
- RTA type II (loss of HCO3)
- DIARRHEA (loss of HCO3)
METABOLIC ACIDOSIS
- decrease ability of the nephron to excrete fixed acid and thus, failure to add new HCO3 to body stores
- acute and chronic renal disease or failure
- inability to synthesize ammonia
- RTA type I
METABOLIC ALKALOSIS
- VOMITING
- GASTRIC SUCTIONING
- PRIMARY HYPERALDOSTERONISM, results from too much lost in H+ ions in the urine
- LOSS OF BICARBONATE-FREE FLUID (contraction alkalosis)
- maintenance:
- volume depletion
- increase aldosterone
METABOLIC
- main causes are HCO3 or H+
METABOLIC ACIDOSIS
- excess of H+ ions
- shift to the L
- BIG DECREASE in HCO3
- assuming CO2 is 40
METABOLIC ALKALOSIS
- caused by DECREASE IN H+ ions
- vomiting stomach contents
- BIG INCREASE IN HCO3
RESPIRATORY ACIDOSIS
- increase CO2
- decrease pH
- normal to increase HCO3
to compensate increase above normal HCO3
RESPIRATORY ALKALOSIS
- decrease CO2
- increase pH
- normal to decrease HCO3 to compensate decrease HCO3 to below normal
METABOLIC ACIDOSIS
- no change CO2 40 mm Hg
- decrease pH
- big decrease HCO3 to compensate increase it
- hyperventilating
METABOLIC ALKALOSIS
- no change in CO2 40 mm Hg
- increase pH
- big increase in HCO3 to compensate decrease it
- hypo-ventilating
normal values:
pH first
- 7.4
- low- acidosis
- high- alkalosis
normal values: PCO2 second (RESPIRATORY COMPONENT)
- 40 mmHg
- high- acidosis
- low- alkalosis
normal values: (METABOLIC COMPONENT)
HCO3 last
- 24 mmol/L
- low- acidosis
- high- alkalosis
CONCEPT:
pH low plus PCO2 high = respiratory acidosis but if you add HCO3 low= metabolic acidosis or mixed acidotic problem VIA
case: arterial components: pH = 7.3 low acidosis PCO2 = 30 mm Hg low rule out respiratory component, metabolic (40) PO2 = 95 mm Hg distractors serum: HCO3 = 14 mEq/L low acidosis
- METABOLIC due to low PCO2 and big decrease in HCO3 ACIDOSIS due to low pH
case:
arterial component: pH = 7.6 high alkalosis PCO2 = 20 mm Hg low rule in respiratory PO2 = 95 mm Hg serum: HCO3 = 18 mEq/L low acidosis
RESPIRATORY due to low PCO2 ALKALOSIS due to high pH
concept;
HCO3 low
concept:
HCO3 high > PCO2 low meaning it is more of a METABOLIC PROBLEM
case:
arterial components:
pH = 7.2 low acidosis
PCO2 = 80 mm Hg high rule in respiratory component
PO2 = 70 mm Hg
serum:
HCO3 = 30 mEq/L high saying no metabolic acidosis
RESPIRATORY ACIDOSIS
case:
arterial component: pH = 7.6 high alkalosis PCO2 = 52 mm Hg high rule out respiratory component hypoventilation compensation to the problem PO2 = 70 mm Hg serum: HCO3 = 44 mEq/L high rule in metabolic
METABOLIC ALKALOSIS
arterial PCO2 = 55 mm Hg
serum HCO3 = 20 mEq/L
no pH
mixed respiratory and metabolic alkalosis
due to PCO2 is inverse to HCO3
CO2
- respiratory compensation
HCO3 (distal tubule collecting duct)
- renal compensation
if the kidney is working otherwise it would be respiratory
H+ ions
- increase acidosis
- to become normal shift to the L going to CO2 respiratory variable thus decrease it by hyperventilating and increase in plasma HCO3
- WINTERS FORMULA
H+ ions
- decrease in alkalosis
- to become normal shift to the R by hypo-ventilating and increase CO2 and decreasing HCO3 by dumping it in urine
“Winters’ Formula”,[1] named for Dr. R.W. Winters,[
is a formula used to evaluate respiratory compensation when analyzing acid-base disorders and a metabolic acidosis is present. It can be given as
P_{CO_2} = (1.5 \times HCO_3^-) + 8 \pm 2,
where HCO3− is given in units of mEq/L and pCO2 will be in units of mmHg.
Winters’ formula gives an expected value for the patient’s PCO2; the patient’s actual (measured) PCO2is then compared to this.
If the two values correspond, respiratory compensation is considered to be adequate.
If the measured PCO2 is higher than the calculated value, there is also a primary respiratory acidosis.
If the measured PCO2 is lower than the calculated value, there is also a primary respiratory alkalosis.
Alkalosis
Note that Winter’s formula pertains to settings of metabolic acidosis.
To calculate the expected pCO2 in the setting of metabolic alkalosis, the following equations are used:
pCO2 = 0.7 [HCO3] + 20 mmHg +/- 5 pCO2 = 0.7 [HCO3] + 21 mmHg
acute metabolic/respiratory
acute hypoventilation/hyperventilation
acute lactic acidosis
- no compensation
ACIDOSIS
- INCREASE HCO3 forming acid urine
ALKALOSIS
- DUMP/DECREASE HCO3 in the urine causing an alkaline urine
The urine anion gap
is calculated using measured ions found in the urine. It is used to aid in the differential diagnosis of metabolic acidosis.
The term “anion gap” without qualification usually implies serum anion gap. The “urine anion gap” is a different measure, principally used to determine whether the kidneys are capable of appropriately acidifying urine.
Determining the cause of a metabolic acidosis that lacks a serum anion gap often depends on determining whether the kidney is appropriately excreting acid.
Urine anion Gap (NH4)
Urine anion gap is calculated by subtracting the urine concentration of chloride (anions) from the concentrations of sodium plus potassium (cations):
= Na+ + K+ − Cl−
A positive urine anion gap suggests a low urinary NH4+ (e.g. renal tubular acidosis).
A negative urine anion gap suggests a high urinary NH4+ (e.g. diarrhea).
positive ions in plasma anion gap
- measure only SODIUM (140)
negative ions in plasma anion gap
- measure CHLORIDE (108) and HCO3 (24) = 132 meaning less than the SODIUM CONCENTRATION
- difference between SODIUM and the total negative ion is the ANION GAP (140- 132) = 8 mmol
DIARRHEA
- washed out HCO3
- and Na
LACTIC ACIDOSIS
- H+ neutralized by using HCO3
- HCO3 IS CONVERTED TO LACTATE
just got off the airplane
- acute respiratory alkalosis no compensation
