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38 Cards in this Set
- Front
- Back
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sources of acid production in body
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catabolism of carbs, fats, proteins
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aerobic metabolism yields
eliminated how? |
CO2
lungs expiration |
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anaerobic metabolism (of what?) yields
eliminated how? |
glucose and fat and some proteins
lactic acid, sulfuric acid, phosphoric acid kidney excretion |
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dietary sources vs metabolic sources and their production
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dietary: fixed: cysteine and methionine -> sulfuric acid & phsophate diesters -> phosphoric acid
metabolic (incomplete oxidation): glucose -> H+ and lactate & triglyceride -> H+ beta-OH butryate metabolic (complete oxidation): carb, fat, protein -> H+ and HCO3 |
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intracellular pH
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7.10
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extracellular pH
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7.40
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arterial blood pH
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direct extracellular
surrogate intracellular measure |
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pH reflects ______
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equilibrium
-major buffering system HCO3 and CO2 -renal and respiratory regulated |
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acidemia =
alkalemia = |
pH < 7.36
pH > 7.44 |
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acidosis/alkylosis
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primary process generating H+ or decreasing H+
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metabolic disorders reflect...
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primary changes in plama [HCO3] due to excessive intake, production, or loss of HCO3 or inappropriate handling of H+ and anions from dissociated non-volatile acids
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metabolic acidosis:
primary deviation? compensatory response? |
dec [HCO3]
dec [PaCO2] |
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metabolic alkalosis:
primary deviation? compensatory response? |
inc [HCO3]
inc [PaCO2] |
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respiratory acidosis:
primary deviation? compensatory response? |
inc [HCO3]
inc [PaCO2] |
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metabolic alkalosis:
primary deviation? compensatory response? |
dec [HCO3]
dec [PaCO2] |
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ABG contain
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heparin as an anticoagulant
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what happens if there is an air bubble in ABG sample
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air which is high in O2 and almost none CO2
allows both gases to diffuse down their partial pressure gradients to raise sample's PaO2 and decrease PaCO2 causing an increase in pH (alkalosis) |
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3 P's calculated in ABG
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arterial pH
arterial pCO2 arterial pO2 (acid-base balance components: pCO2 and pH) |
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henderson-hasselbach equation for bicarb-carbonic acid
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pH = pK + log [HCO3]/[H2CO3]
pK = 6.1 OR pH = pK + log [HCO3]/[(0.03)(PaCO2)] |
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when pH is 7.4 what is the ratio of HCO3 to H2CO3
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20:1
important to maintain!! |
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reference ranges:
pHa |
7.36-7.44
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reference ranges:
[H+] |
40 nM
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reference ranges:
PaCO2 |
35-45 mm Hg
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reference ranges:
PaO2 |
85-100 mm Hg (when breathing room air)
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what is responsible for the majority of acid production
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CO2
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what is responsible for the bulk of buffering capacity
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bicarbonate/carbonic acid system
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cations/anions measured in blood
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Na+ K+ Cl- HCO3-
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anion gap calculation
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Ag = (Na+K)-(Cl-+HCO3-)
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normal reference range for AG
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8-18 mM
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assessing acid-base balance:
Step 1 |
check arterial pH
pHa < 7.36 ACIDOSIS pHa > 7.44 ALKALOSIS |
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assessing acid-base balance:
Step 2 |
check PaCO2
acidotic pH: if PaCO2 < 40 mmHg: METABOLIC ACIDOSIS if PaCO2 > 40 mmHg: RESPIRATORY ACIDOSIS alkalotic pH: if PaCO2 < 40 mmHg: RESPIRATORY ALKALOSIS if PaCO2 > 40 mmHg: METABOLIC ALKALOSIS |
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assessing acid-base balance:
Step 3 |
calculate the AG
esp if step 2 is metabolic acidosis |
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assessing acid-base balance:
Step 4 |
assess results and prepare diff diagnosis
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causes of metabolic acidosis:
with AG |
Methanol
Uremia DKA Paraldehyde INH, Iron Lactic Acid Ethanol Salicylates |
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causes of metabolic acidosis:
non-AG |
Hypertonic saline
Acetazolamide Renal tubular acidosis Diarrhea Ureteral diversion Pancreatic fistula |
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causes of metabolic alkalosis
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Hypokalemia (K+ out, acid in)
Admin of excess HCO3- Vomiting or gastrointestinal suction (inc acid, inc bicarb) Corticosteroid excess Primary hyperaldosteronism (inc Na+/H+/K+ dumped out) |
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causes of respiratory acidosis
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-obstructive lung dz (COPD, emphysema)
-impaired function of respiratory center (head trauma, sedation, anesthesia) -hypoventilation by mechanical ventilator |
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causes of respiratory alkalosis
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-hypoxemia
-anxiety -hyperventilation by mechanical ventilator -metabolic acidosis -septicemia -trauma |
