click below
click below
Normal Size Small Size show me how
Renal 05 Acid/Base
Ryan: Acid-Base Balance
Question | Answer |
---|---|
What is normal pH? | 7.36 to 7.44 (use 7.4 for calculations) |
What is the equation for the buffer system in the body? | [H]=24*Pco2/HCO3 |
What's going on in metabolic acidosis? | Addition of acid or loss of bicarb from the body. |
What's happening in metabolic alkalosis? | Addition of bicarb or loss of acid from the body. |
What's occurring in respiratory acidosis? | Retention of CO2 by the lungs. |
What's going on in respiratory alkalosis? | Loss of CO2 by the lungs. |
What are the criteria for acidosis/alkalosis and respiratory/metabolic? | Metabolic = pCO2 <40, Respiratory = pCO2 >40 : Acidotic = pH <7.4, Alkolotic = pH >7.4 |
What is Winter's Formula and when do you use it? | pCO2= 1.5*HCO3 + 8 +/- 2 : Used to determine the presence of a secondary acid-base disorder. |
What are the relative changes with metabolic acidosis/alkalosis? | pH, HCO3, and pCO2 all increase or decrease |
What are the relative changes with respiratory acidosis/alkalosis? | pH increases (decreases), HCO3 and pCO2 decrease (increase) |
What is the serum anion-gap? | The circulating serum cations must equal the anions; keeping the serum electrically neutral. : Anion gap is if there is a difference in the cations/anions |
How do you measure the anion gap? | AG= Na-Cl-HCO3 |
What is the predominate cause of an increases ion gap? | Metabolic acidosis |
What is the normal range for AG? | Between 6 and 16 |
An increase in AG indicates what? | Presence of unmeasured anions. Usually (but not always) associated with a fall in serum bicarb (metabolic acidosis) |
Normal Anion Gap Metabolic Acidosis is also referred to as what? | Hyperchloremic Metabolic Acidosis, since Cl increases to keep the AG normal. |
What happens when you have a retention of acid with chloride as the anion? | Increase in serum Cl and an unchanged AG |
What happens when you have retention of an acid with non-chloride anions? | Serum Cl will be unchanged and the AG will increase. |
What is the delta/delta? | ratio between the change in the anion gap and the change in the plasma HCO3 concentration. |
What if the delta/delta is 1-2? | Pure, high AG metabolic Acidosis |
What if the delta/delta is <1? | High AG acidosis + hyperchloremic metabolic acidosis |
What if the delta/delta is >2? | High AG acidosis + metabolic alkalosis |
What does MUDPILES stand for? | Methanol, Uremia, Diabetic KA, Paraldehyde, INH/Iron, Lactic Acidosis, Ethylene glycol, Salicylates |
List some causes of Normal AG Metabolic Acidosis. | GI loss of HCO3, Renal loss of HCO3, HCl/HCl precursor ingestion or infusion |
What kind of things fall under GI loss of HCO3? | Diarrhea and urterosigmoidoscopy (lose the duodenum, thus lose the ability to make HCO3) |
What falls under Renal loss of HCO3? | Distal renal tubular acidosis (type I), Proximal renal tubular acidosis (type II), Hyperkalemic renal acidosis (type IV) |
What are the two categories for the causes of metabolic alkalosis? | Low urinary chloride (<20 meq/L [Cl responsive]) and High urinary chloride (>20 meq/L [Cl unresponsive]) |
What things are considered low urinary chloride? | Diuretics (remote), vomiting, GI suction, status post chronic hypercarbia |
What falls under high urinary Cl? | Diuretics (recent), High BP (primary hyperaldosteronism, Cushing's syndrome, Ectopic ACTH production), Low BP (Bartter's syndrome, Gitelman's syndrome, Sever K depletion) |
What are the categorical causes of respiratory acidosis? | CNS depression (not breathing off CO2) Neuromuscular disorders (can't inhale/exhale well) Thoracic cage restriction (can't take in deep breaths) impaired lung motion (not ventilating), acute obstructive pulmonary disease, chronic obstructive lung disease |
What are the categorical causes of respiratory alkalosis? | Anxiety, CNS disorders (blow off more CO2) Hormones, Drugs, Sepsis and endotoxemia, hyperthermia, hypoxia (can't ventilate) Pregnancy, cirrhosis, pulmonary edema, lung dz, pneumonia, ventilator induced |
Deviations from the normal value of the serum AG reflects what? | Either errors in the measurements of its constituents or in the concentrations of UC/UA |
Increased anion gap... | Decreased unmeasured cations (hypokalemia, calcemia, magnesemia) |
Decreased anion gap... | Increased UC (paraproteinemia, hypercalcemia, kalemeia) or Decreased UA (hypoalbuminemia, phosphatemia) |
What is the effect of hypoalbuminemia? | For each gram drop in serum albumin, the AG decreases by a factor of about 2.5 |
How do you measure the True AG when serum albumin is decreased? | TrueAG=[(4.5-Serum Alb)*2.5]+AG |
How do you calculate the Urinary Anion Gap? | UAG= Na+K+Cl |
What is the normal range for the UAG? | -10 to 10 |
Cl in the urine is also a measure of what? | NH4 |
If there was a loss of 10 meq of bicarb, how does the body respond? | By excreting H as NH4 if it can. Seen as an increase in Cl; as Cl increases UAG becomes more negative. |
What would happen to the UAG if there was a loss of HCO3 through the kidney? | NH4 excretion is decreased, thus UAG becomes more + |
What would happen to UAG if there was a loss of HCO3 through the GI tract? | NH4 excretion is increase, and the UAG becomes more negative |
What is the osmolar gap? | The difference between the measured and calculated serum osmolality |
How do you calculate the osmolar gap? | OG= 2*[Pna]+[BUN]/2.8+[Glucose]/18 |
What does an OG >20 indicate? | The presence of other osmolarly active substances in the blood. |