ABG, Blood Gases, Alkalosis, Acidosis....

         

Question	Answer	Hint
normal pH	pH 7.35-7.45
most common buffer system	CO2 + H2O — H2CO3 — H+ + HCO3-
normal ratio of carbonic acid to bicarbonate	1:20
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 abnormal, 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 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, increase 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 increase
treatment of respiratory alkalosis	treat underlying condition, support renal function w/ fluids, breath into bag or rebreather, sedatives