Glossary of nursing acid-base pH balance

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normal pH
pH 7.35-7.45
most common buffer system
CO2 + H2O --- H2CO3 --- H+ + HCO3-
normal ratio of carbonic acid to bicarbonate
respiratory acidosis
Increased CO2 results in decrease in pH
respiratory alkalosis
Decreased CO2 results in increase in pH
respiratory component of acid-base balance
CO2 (carbon dioxide)
metabolic acidosis
Increased HCO3 results in increase in pH
metabolic alkalosis
Decreased HCO3 results in decrease in pH
metabolic component of acid-base balance
HCO3 (bicarbonate)
normal PaCO2
35-45 mmHg
normal PaO2
83-100 mmHg
normal HCO3
22-26 mEq/L
ABG analysis step 1
if pH is <7.35, acidosis
if pH is >7.45, alkalosis
ABG analysis step 2
if CO2 is abnormal, respiratory
if HCO3 is abornmal, metabolic
ABG analysis step 3
pH is normal: fully compensated
pH & opposite number out of range: partially compensated
pH out of normal range, opposite number in normal range: no compensation
oxyhemoglobin curve
changes in pH alter ease with with hemoglobin releases O2 to plasma
values of metabolic acidosis
pH is low, HCO3 is low
values of metabolic alkalosis
pH is high, HCO3 is high
values of respiratory acidosis
pH is low, PaCO2 is high
values of respiratory alkalosis
pH is high, PaCO2 is low
causes of metabolic acidosis
diabetic ketoacidosis, starvation, lactic acidosis, excess ETOH or ASA, renal failure, diarrhea
s/s of metabolic acidosis
lethargy, confusion, stupor, coma, hyporeflexia, muscle weakness, bradycardia, thready pulses, low BP, Kussmaul resp, warm/flushed/dry skin, hyperkalemia
treatment of metabolic acidosis
treat the cause: insulin, hydration/electrolytes, antidiarrheals, sodium bicarbonate, dialysis
causes of metabolic alkalosis
antacid overuse, IV LR overuse, NaHCO3 overuse, vomiting, NG suctioning, thiazide diuretics
s/s of metabolic alkalosis
anxiety, irritability, hyperreflexia, muscle cramps/weakness, tachycardia, normal or low BP, shallow resps, hypokalemia, hypocalcemia
treatment of metabolic alkalosis
treat the cause: fluid/electrolyte replacement, NS IV, Ca++, K-sparing diuretics, antiemetics
causes of respiratory acidosis
head injury, Rx overdose, chest injury, electrolyte imbalance, severe obesity, ascites, hemothorax, COPD, aspiration, pneumonia, pulm edema, TB, PE
s/s of respiratory acidosis
skin pale to cyanotic & dry, incr. PaCO2
treatment of respiratory acidosis
increase CO2 excretion: bronchodilators, steroids, Mucomyst, O2, pulmonary hygiene, PAP
causes of respiratory alkalosis
hyperventilation - anxiety, fear, mechanical ventilation; hypoxemia - asphyxiation, shock, high altitude
s/s of respiratory alkalosis
numbness & tingling around mouth, extremities, resp. effort normal or incr.
treatment of respiratory alkalosis
treat underlying condition, support renal function w/ fluids, breath into bag or rebreather, sedatives

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