Arterial Blood Gases Flashcards
pH
measurement of blood acidity or alkalinity; inversely proportional to the number of H+ ions; scale 1 (very acidic)- 14 (very alkaline), 7 (water) is neutral
normal blood pH
7.35-7.45
Respiratory Buffer Response
Normal by-product of cellular metabolism is CO2. CO2 is carried in the blood to the lungs, excess CO2 combines with H2O to form carbonic acid (H2CO3). Carbonic acid level will change blood pH, lungs will increase or decrease the rate and depth of ventilation until appropriate CO2 level has been re-established. Compensation begins within 1-3 minutes of imbalance.
Renal Buffer Response
Kidneys excrete or retain bicarbonate (HCO3) in effort to maintain blood pH level. As pH decreases, kidneys will compensate by retaining HCO3 and as pH rises, kidneys excrete HCO3 in urine. Compensation may take hours to days to correct imbalance.
Respiratory Acidosis
pH < 7.35 with PaCO2 >45 mmHg. Caused by accumulation of carbonic acid.
- Caused by any condition resulting in hypoventilation
- CNS depression due to head injury, CNS depression from medications, impaired respiratory muscle function, spinal cord injury, pulmonary disorders, massive pulmonary embolus, hypoventilation due to pain, chest wall injury, or abdominal distention.
Signs of Respiratory Acidosis
dyspnea respiratory distress shallow respirations h/a restlessness confusion drowsiness unresponsiveness tachycardia dysrhythmias
Treatment of Respiratory Acidosis
increasing ventilation
treating the cause of hypoventilation
Respiratory Alkalosis
pH > 7.45 with PaCO2 < 35 mmHg.
- Caused by any condition resulting in hyperventilation
- anxiety, fear, pain, increased metabolic demands, certain medications, CNS lesions
Signs and symptoms of Respiratory Alkalosis
light-headedness numbness tingling confusion inability to concentrate blurred vision dysrhythmias palpitations dry mouth diaphoresis tetanic spasms in extremities
Treatment of Respiratory Alkalosis
resolving underlying problem
monitor for respiratory muscle fatigue
Metabolic Acidosis
pH < 7.35 and HCO3 (bicarbonate) of < 22 mEq/L
- Caused by either a deficit of base in the blood or excess of acids, other than CO2
- Diarrhea, intestinal fistulas, renal failure, diabetic ketoacidosis, starvation, salicylate intoxication
Signs and Symptoms of Metabolic Acidosis
h/a confusion restlessness>lethargy>stupor>coma cardiac dysrhythmias Kussmaul respirations warm, flushed skin N&V
Treatment of Metabolic Acidosis
restore tissue restoration of hypoxic tissue
Find source of acid overload
Metabolic Alkalosis
pH > 7.45 with HCO3 > 26 mEq/L
-Caused by excess base consumption with antacids, bicarbonate or lactate during dialysis; loss of acids from vomiting, gastric suction, hypochloremia, excess administration of diuretics, or high levels of aldosterone.
Signs and Symptoms of Metabolic Alkalosis
dizziness lethargy disorientation seizures coma muscle weakness muscle twitching, cramping and tetany N&V respiratory depression
