Acid Base Disorders Flashcards
acids produced by the body (+source) (4)
- sulfuric, phosphoric and uric acids - metabolism
- ketone bodies - fat oxidation
- lactic acid - anaerobic glucose metabolism
- carbonic acid - dissolved CO2
normal pH of body
7.38-7.42
mechanisms body uses to maintain alkaline pH
- buffer system of blood
- lungs regulate carbonic acid concentration
- kidneys regulate bicarb concentration
normal ratio bicarb/carbonic acid
20 parts bicarb to 1 part carbonic acid
carbonic acid
H2CO3
CO2 + H2O conversion by carbonic anhydrase in kidney
dissociates into H+ and bicarbonate ions
renal control of pH (H+)
H+ ions enter renal tubule in exchange for sodium ions
sodium enters plasma with HCO3
maintains concentration of sodium w/in body and removes acid
metabolic acidosis lab valvues
low pH
low bicarbonate
metabolic alkalosis
high pH
high bicarbonate
respiratory acidosis
low pH
high pCO2
respiratory alkalosis
high pH
low CO2
acidosis symptoms (CNS)
DEPRESSION of CNS
cardiac arrhythmia (hyperK)
alkalosis symptoms (CNS)
EXCITED CNS
altered mental status, spasm, contraction, seizures
acidosis symptoms (cardiac, vascular, pulmonary)
decreased CO, arrhythmias, increased risk of VFib
vasodilation/HoTN
vasoconstriction in lungs, hyperventilation (move blood thru faster and unload CO2)
alkalosis symptoms (cardiac, vascular, pulmonary)
increased contractility (then decrease) refractory ventricular arrhythmia
coronary vasospasm/constriction
vasodilation of pulmonary vasculature, hypoventilation (move blood thru slower)
acidosis symptoms (Neuro, endocrine)
confusion, coma
insulin resistance, inhibitor of ATP synthesis
hyperkalemia
alkalosis symptoms (Neuro, endocrine)
cerebral vasoconstriction – HA, lethargy, tetany, seizures
hypokalemia (all low electrolytes)
stimulation of anaerobic glycolysis/lactic acid production
acid base disturbance with normal ABG
compensatory acid base disorders often develop to counteract
however, the body NEVER overcorrects
2 things req. for diagnosing acid base problems
arterial blood gas
basic metabolic panel
clinical presentation often clues you in
management is focused on correcting UNDERLYING cause
pH values
normal, panic
normal: 7.35-7.45
panic: <7.3, >7.6
pCO2 values
normal, panic
norm: 35-45 mmHg
Panic: <20 or >70
HCO3 values
normal, panic
normal: 22-26
panic: <10, >40
venous blood gas
convert venous sample measurements to arterial if this is what is given
steps in approaching an acid base problem
- academia or alkemia?
- respiratory or metabolic?
- acute or chronic (if respiratory)?
- anion gap? (metabolic acidosis)
respiratory acidosis patho
increased pCO2
lungs fail to excrete carbon dioxide –> retention leads to rise in pCO2 in plasma
increased formation of carbonic acid and lowered pH