Week 1: Lab Values and Interpretation: Acid Base Balance

normal body function depends on

regulation of hydrogen ion concentration (h+)

normal serum pH

7.35-7.45

ph is ____ proportionate to hydrogen ion concentration

inversely

3 main mechanisms to control pH

buffer pairs, respiratory system, kidneys

buffer pairs

circulate in blood and have immediate action on ph

-sodium bicarbonate carbonic acid system

respiratory system

alters co2 levels by changing RR, occurs within mins to hours

kidney function

modify excretion rate of acids and production/absoroption of bicarbonate ions (within 24-48 hours)

acidosis def

relative excess of acid in body (ph <7.35)

what causes acidosis

accumulation of acid/depletion of alkaline reserve in blood/body, H+ ions increase and ph decreases

alkalosis

excess base in body (ph>7.45)

alkalosis is caused by

h+ ions decrease, ph increases

arterial blood gasses check

amount of dissolved o2 and carbon dioxide in arterial blood and measures arterial blood ph

as co2 increases

ph decreases (respiratory acidosis)

as co2 decreases

ph increases (respiratory alkalosis)

as H+ concentration increases, ph

decreases

as H+ concentration decreases, ph

increases

metabolic acidosis

decrease in bicarb ions (base) because of metabolic or renal problems

metabolic alkalosis

loss of H+ ions through kidneys or GI tract due to metabolic or renal problems

3 main causes of metabolic acidosis

excess loss of bicarb ions, increased utilization of serum bicarb/buffer increases acids, renal disease/failure

what causes excessive loss of bicarb ions

diarrhea

what causes utilization of serum bicarb or buffer increases acids

people with DM who produce a lot of ketoacids and use up bicarb ions

in metabolic acidosis, what is ration of carbonic acid to bicarb

1:20

what happens with those in renal disease/failure that causes metabolic acidosis

decreased acid excretion and decreased production of bicarb ion

metabolic acidosis effects

-ph less than or equal to 7.35

-HCO3 less than 24

-PaCO2 normal or slightly low (35-45)

Signs of metabolic acidosis

headahce, blow bp, hyperkalemia, muscle twitches, warm skin, nausea, vomiting, changes in LOC, Kussmaul respirations

treating metabolic acidosis underlying causes includes

correcting electrolyte imbalance and giving NaCO3 for severe acidosis (ph less than 7.2)

signs of metabolic alkalosis

confusion, tachycardia, hypoventilation, dizzy, irritable, nausea, anxiety, seizures

metabolic alklalosis causes

increase in serum bicarbonate ions, hypokalemia, excessive ingestion of antacids

increase of serum bicarbonate ion is due to

loss of hydrochloric acid from stomach due to vomiting and drainage of stomach

clinical manifestations of metabolic alkalosis

ph more than 7.45, paCO2 increased or normal (35-45), HCO3 more than 30

treating metabolic alkalosis

treat underlying cause and administer potassium chloride

who is at risk for acid base disturbances

pulmonary disease, cvd, renal disease, hypermetabolic stage, type I DM, mechanical ventilation pts, on TPN or tube feeds high in carbs, vomiting and diarrhea