Acid-base disorders Flashcards
normal pH
7.35 - 7.45
normal PaCO2
35 - 45 mmHg
normal HCO3
22 - 26 mEq/L
compensated
any pH b/t 7.35 - 7.45
uncompensated
any pH outside 7.35 - 7.45
partial compensation
moves pH toward normal but pH is still abnormal
Respiratory disorder
pH & PaCO2 move in opposite directions
Metabolic disorder
pH & PaCO2 move in same direction
ROME mnemonic
Respiratory Opposite
Metabolic Equal
Respiratory acidosis
- alveolar ventilation fails to keep up w/ CO2 production
PaCO2 = CO2 production/alveolar ventilation
Causes of increased CO2 production
- sepsis
- overfeeding
- MH
- intense shivering
- prolonged SZ activity
- thyroid storm
- burns
causes of decreased CO2 elimination
- airway obstruction
- increased dead space
- increased Vd/Vt
- ARDS
- COPD
- respiratory center depression
- OD
- inadequate NMB reversal
causes of rebreathing
- incompetent unidirectional valve
- exhausted soda lime
In acute respiratory acidosis, for every 10 mmHg increase in PaCO2, pH decreases by:
0.08
In chronic respiratory acidosis, for every 10 mmHg increase in PaCO2, pH decreases by:
0.03
How does the body compensate for respiratory acidosis?
kidneys excrete hydrogen & conserve HCO3
Consequences of respiratory acidosis
Respiratory alkalosis
alveolar ventilation exceeds CO2 production
Etiologies of respiratory alkalosis
- iatrogenic (mechanical ventilation)
- hypoxia
- pain
- anxiety
- pregnancy
- drugs (progesterone, salicylates)
- PE
Consequences of respiratory alkalosis
CV
- dysrhythmias
- decreased coronary blood flow
- decreased myocardial contractility
- decreased P50 (left shift)
CNS
- inhibition of respiratory drive
- cerebral vasoconstriction
- neuronal irritability
- confusion
Electrolytes
- decreased serum K+
- decreased serum Ca+
Anion gap
Anion gap = major cations - major anions
[Na] - [Cl] + [HCO3] = 8-12 mEq/L
- Accumulation of acid –> gap acidosis
- Loss of bicarb or ECF dilution –> non-gap acidosis
Anion gap vs. Non-gap acidosis
How does the body compensate for metabolic acidosis?
eliminates CO2 by increasing minute ventilation
PaCO2 decreases by ____ mmHg for every HCO3 decrease of ___ mEq/L
1-1.5 , 1
Metabolic acidosis Tx
Anion Gap Acidosis
- NaHCO3 controversial
- lactic acidosis = IVF, O2, CV support
- DKA = IVF, insulin
- Uremia or drug-induced = dialysis
Non- Gap Acidosis
- NaHCO3
Etiologies of Metabolic Alkalosis
Addition of HCO3
- NaHO3 administration
- mass transfusion
Loss of nonvolatile acid
- vomiting, NG suction
- loss of acid in urine
- diuretics
- ECF depletion
Increased mineralocorticoid activity
- cushing’s syndrome
- hyperaldosteronism
PaCO2 increases _____ mmHg for every HCO3 increased of ___ mEq/L
Metabolic Alkalosis Tx
- tx underlying cause
- acetazolamide (increases HCO3 excretion)
- Spironolactone (mineralocorticoid antagonist)
- dialysis
