Acid base determination


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  • Positive test means color does not return
  • ABGs are based on normals for healthy adults at sea level. Newborns have a lower PaO2, as do older adults. From ages 60-90, an older adult’s PaO2 decreases 10 mmHg per decade. Pts w/ chronic lung dxs may have a PaO2 of 60 mmHg and a PaCO2 of 50 mmHg as baseline. Attempts to return to ‘normal’ would be catastrophic for these clients. For an individual receiving oxygen therapy, the PaO2 should rise approximately 50 mmHg for each 10 percent rise in oxygen concentration.
  • Less than 35, alkalosis. Causes: Alveolar hyperventilation, hypoxia, anxiety, PE, pregnancy, hyperventilation with mechanical ventilator, compensatory mechanism to metabolic acidosis, head injury, fever, fear, pain Acidosis acute causes: alveolar hypoventilation, respiratory depression, oversedation, drug overdose, head injury, decreased ventilation, respiratory muscle fatigue, neuromuscular disease, mechanical ventilation w/ underventilation, altered diffusion / ventilation – perfusion mismatch from pulmonary edema, severe atelectasis, pneumonia, severe bronchospasm. Chronic acidosis causes usually COPD
  • Carbon dioxide is considered an acid because it combines w/ water to form carbonic acid
  • pH is key to determining extent of compensation.
  • UGI tract losses include vomitting and NG suctioning
  • If pt is severely anemic, O2 levels will drop
  • Bases bind free hydrogen ions in solution. Bases are hydrogen acceptors that reduce the amount of free hydrogen ions in solution. HCO3 is a weak base and HCO3 ions in the body prevent major changes in pH.
  • Acid base determination

    1. 1. Acid-Base Determination Spring Semester, 2006 Nursing 2904 Carol Isaac MacKusick, MSN, RN, CNN
    2. 2. Arterial Blood Gases <ul><li>Technique for ABG Sampling </li></ul><ul><ul><li>Allen’s Test </li></ul></ul><ul><ul><ul><li>Once arterial site is selected, must test for collateral circulation </li></ul></ul></ul><ul><ul><ul><li>Allen test used for radial and ulnar arteries </li></ul></ul></ul><ul><ul><ul><li>Simultaneously compress the radial and ulnar arteries, ask client to make fist until hand blanches, ask client to open fist, release pressure from ulnar artery, check for return of pinkness to hand </li></ul></ul></ul>
    3. 3. ABG Technique <ul><li>Indwelling arterial catheter or arterial puncture </li></ul><ul><li>If arterial puncture </li></ul><ul><ul><li>Painful to client </li></ul></ul><ul><ul><li>Same procedure as catheter except for flushing line </li></ul></ul><ul><ul><li>HOLD pressure </li></ul></ul><ul><ul><li>Complications: Arterial vessel tears, air embolism, hemorrhage, arterial obstruction, loss of an extremity, and infection </li></ul></ul>
    4. 4. ABG Technique <ul><li>Arterial line (a-line) </li></ul><ul><ul><li>Used to obtain direct and continuous BP measurements in critically ill clients and to obtain frequent ABG measurements </li></ul></ul><ul><ul><li>Nursing responsibilities for a-line </li></ul></ul><ul><ul><ul><li>Setting up the equipment </li></ul></ul></ul><ul><ul><ul><li>Calibrating equipment to ensure accurate readings </li></ul></ul></ul><ul><ul><ul><li>Assist physician with procedure of inserting a-line </li></ul></ul></ul>
    5. 5. ABG Technique <ul><li>A-line Nursing Responsibilities </li></ul><ul><ul><li>Secure pressure tubing to prevent dislodgement and possible exsanguination </li></ul></ul><ul><ul><li>Put a pressure bag around the flush solution bag and inflate to about 300 mmHg to prevent blood from backing up into pressure tubing </li></ul></ul><ul><ul><li>Flush solution may or may not have heparin added </li></ul></ul>
    6. 6. ABG Technique <ul><li>A-line Nursing Responsibilities </li></ul><ul><ul><li>Monitor circulation distal to insertion site </li></ul></ul><ul><ul><li>Notify physician of any alteration in circulation </li></ul></ul><ul><ul><li>Observe for signs of infection </li></ul></ul><ul><ul><li>ABGs and blood samples can be drawn without pain or discomfort to client </li></ul></ul><ul><ul><li>Manual baseline blood pressures should be taken at least once per shift to correlate with arterial readings </li></ul></ul>
    7. 7. A-Line <ul><li>Works with stopcocks </li></ul><ul><li>Discard 3-5 cc’s to clear catheter of any flush system fluid </li></ul><ul><li>Obtain 1 cc sample in a heparinized syringe </li></ul><ul><li>Remove air and place on airtight cap </li></ul><ul><li>Put on ice to ensure accuracy </li></ul><ul><li>Flush the line </li></ul>
    8. 8. ABG Interpretation <ul><li>Look at PaO 2 </li></ul><ul><ul><li>Reflects 3% of total oxygen in blood </li></ul></ul><ul><ul><li>Normal range 80-100 mmHg at sea level; lower at higher elevations </li></ul></ul><ul><ul><li>Normal level for infants breathing room air is 40-70 </li></ul></ul><ul><ul><li>Older adults, 80 mmHg – 1 mmHg for every year over the age of 60 </li></ul></ul>
    9. 9. ABG Interpretation <ul><li>PaO 2 </li></ul><ul><ul><li>If PaO 2 more than lowest level for age, it is normal </li></ul></ul><ul><ul><li>Abnormally low PaO 2 = hypoxemia </li></ul></ul><ul><ul><li>At any age, PaO 2 lower than 40 mmHg represents a life-threatening situation </li></ul></ul>
    10. 10. ABG Interpretation <ul><li>Look at pH </li></ul><ul><ul><li>Normal 7.35-7.45 </li></ul></ul><ul><ul><li>Below 7.35 = Acidosis </li></ul></ul><ul><ul><li>Higher than 7.45 = Alkalosis </li></ul></ul>
    11. 11. ABG Interpretation <ul><li>Look at PaCO 2 </li></ul><ul><ul><li>Indicates whether the client can ventilate well enough to rid the body of waste products from metabolism </li></ul></ul><ul><ul><li>Normal 35-45 mmHg </li></ul></ul><ul><ul><li>Less than 35, alkalosis </li></ul></ul><ul><ul><li>Greater than 45, acidosis </li></ul></ul>
    12. 12. Less than 35, alkalosis. <ul><li>Causes: </li></ul><ul><ul><li>Alveolar hyperventilation, </li></ul></ul><ul><ul><li>hypoxia, </li></ul></ul><ul><ul><li>anxiety, </li></ul></ul><ul><ul><li>PE, </li></ul></ul><ul><ul><li>pregnancy, </li></ul></ul><ul><ul><li>hyperventilation with mechanical ventilator, </li></ul></ul><ul><ul><li>compensatory mechanism to metabolic acidosis, </li></ul></ul><ul><ul><li>head injury, </li></ul></ul><ul><ul><li>fever, </li></ul></ul><ul><ul><li>fear, </li></ul></ul><ul><ul><li>pain </li></ul></ul>
    13. 13. Greater than 45, acidosis: <ul><ul><ul><ul><li>alveolar hypoventilation, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>respiratory depression, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>oversedation, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>drug overdose, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>head injury, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>decreased ventilation, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>respiratory muscle fatigue, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>neuromuscular disease, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>mechanical ventilation w/ underventilation, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>altered diffusion / ventilation – perfusion mismatch from pulmonary edema, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>severe atelectasis, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>pneumonia, severe bronchospasm. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Chronic acidosis causes usually COPD </li></ul></ul></ul></ul>acute causes:
    14. 14. Respiratory Alkalosis <ul><li>Clinical Presentation </li></ul><ul><ul><li>Cardiovascular </li></ul></ul><ul><ul><ul><li>Increased myocardial irritability, palpitations </li></ul></ul></ul><ul><ul><ul><li>Increased HR </li></ul></ul></ul><ul><ul><ul><li>Increased sensitivity to digitalis </li></ul></ul></ul><ul><ul><li>Respiratory </li></ul></ul><ul><ul><ul><li>Rapid, shallow breathing </li></ul></ul></ul><ul><ul><ul><li>Chest tightness and palpitations </li></ul></ul></ul>
    15. 15. Respiratory Alkalosis <ul><li>Clinical presentation </li></ul><ul><ul><li>CNS </li></ul></ul><ul><ul><ul><li>Dizziness, lightheadedness, anxiety, panic, tetany, convulsions, difficulty concentrating, blurred vision, numbness and tingling in extremities, hyperactive reflexes </li></ul></ul></ul><ul><ul><li>Diagnostic findings </li></ul></ul><ul><ul><ul><li>High pH, low PaCO 2 </li></ul></ul></ul><ul><ul><ul><li>Hypokalemia, hypocalcemia </li></ul></ul></ul>
    16. 16. Respiratory Alkalosis <ul><li>Compensation </li></ul><ul><ul><li>Kidneys conserve H and excrete HCO 3 </li></ul></ul><ul><ul><li>Low HCO 3 indicates body’s attempt to compensate </li></ul></ul><ul><ul><li>With partial compensation, pH is elevated </li></ul></ul><ul><ul><li>With full compensation, pH returns to normal </li></ul></ul>
    17. 17. Respiratory Alkalosis <ul><li>Priority nursing diagnoses </li></ul><ul><ul><li>Sensory perceptual alterations R/T neurological deficits </li></ul></ul><ul><ul><li>Altered thought processes R/T altered cerebral functioning </li></ul></ul><ul><ul><li>Ineffective breathing pattern R/T hyperventilation </li></ul></ul><ul><ul><li>Risk for injury R/T weakness, seizures </li></ul></ul>
    18. 18. Respiratory Alkalosis <ul><li>Management </li></ul><ul><ul><li>Treat underlying cause </li></ul></ul><ul><ul><li>Rebreathe CO 2 using a rebreather mask or paper bag </li></ul></ul><ul><ul><li>Give oxygen if hypoxic </li></ul></ul><ul><ul><li>Medicate as needed with antianxiety drugs </li></ul></ul>
    19. 19. Respiratory Alkalosis <ul><li>Planning and Implementation </li></ul><ul><ul><li>Provide support and reassurance </li></ul></ul><ul><ul><li>Monitor VS and ABGs </li></ul></ul><ul><ul><li>Assist client to breathe slowly </li></ul></ul><ul><ul><li>Provide paper bag or rebreather mask </li></ul></ul><ul><ul><li>Protect from injury </li></ul></ul><ul><ul><li>Administer antianxiety medications and monitor response </li></ul></ul>
    20. 20. ABG Interpretation <ul><li>Look at PaCO 2 </li></ul><ul><ul><li>> 45 is acidosis </li></ul></ul><ul><ul><li>Acute ventilatory failure results when PaCO 2 exceeds 50 mmHg & pH < 7.30 </li></ul></ul><ul><ul><li>Chronic ventilatory failure when PaCO 2 >50 and pH > 7.30 </li></ul></ul>
    21. 21. Respiratory Acidosis <ul><li>Clinical presentation </li></ul><ul><ul><li>Cardiovascular </li></ul></ul><ul><ul><ul><li>Hypotension </li></ul></ul></ul><ul><ul><ul><li>Delayed cardiac conduction that can lead to heart block, peaked T waves, prolonged PR intervals, and widened QRS complexes </li></ul></ul></ul><ul><ul><ul><li>Peripheral vasodilation with thready, weak pulse </li></ul></ul></ul><ul><ul><ul><li>Tachycardia </li></ul></ul></ul><ul><ul><ul><li>Warm, flushed skin </li></ul></ul></ul>
    22. 22. Respiratory Acidosis <ul><li>Clinical Presentation </li></ul><ul><ul><li>Respiratory </li></ul></ul><ul><ul><ul><li>Dyspnea, may have hypoventilation with hypoxia </li></ul></ul></ul><ul><ul><li>CNS </li></ul></ul><ul><ul><ul><li>Headache, seizures, altered mental status, papilledema, muscle twitching, decreased LOC, drowsiness -> coma </li></ul></ul></ul><ul><ul><li>Diagnostics </li></ul></ul><ul><ul><ul><li>Decreased pH, elevated PaCO 2 </li></ul></ul></ul><ul><ul><ul><li>Hyperkalemia </li></ul></ul></ul>
    23. 23. Respiratory Acidosis <ul><li>Compensation </li></ul><ul><ul><li>Increased rate and depth of respirations to blow off CO 2 </li></ul></ul><ul><ul><li>Kidneys eliminate H ions and retain HCO 3 </li></ul></ul><ul><ul><li>HCO 3 levels rise when body attempts to compensate </li></ul></ul><ul><ul><li>With partial compensation, pH remains decreased </li></ul></ul><ul><ul><li>With full compensation, pH returns to normal </li></ul></ul>
    24. 24. Respiratory Acidosis <ul><li>Priority Nursing Diagnoses </li></ul><ul><ul><li>Ineffective breathing pattern R/T hypoventilation </li></ul></ul><ul><ul><li>Impaired gas exchange R/T alveolar hypoventilation </li></ul></ul><ul><ul><li>Sensory-perceptual alterations R/T acid-base alterations </li></ul></ul><ul><ul><li>Anxiety R/T breathlessness </li></ul></ul><ul><ul><li>Risk for injury R/T decreased LOC </li></ul></ul><ul><ul><li>Risk for decreased CO R/T dysrhythmias </li></ul></ul>
    25. 25. Respiratory Acidosis <ul><li>Management </li></ul><ul><ul><li>Treatment directed at underlying cause and improving ventilation </li></ul></ul><ul><ul><li>Implement pulmonary hygiene measures </li></ul></ul><ul><ul><li>Provide adequate fluid intake </li></ul></ul><ul><ul><li>Administer supplemental oxygen cautiously in client with chronic respiratory acidosis </li></ul></ul><ul><ul><li>Mechanical ventilation if necessary </li></ul></ul>
    26. 26. Respiratory Acidosis <ul><li>Planning and Implementation </li></ul><ul><ul><li>Assess respiratory rate and depth </li></ul></ul><ul><ul><li>Monitor for complications and response to tx </li></ul></ul><ul><ul><li>Assess for tachycardia and irregularities </li></ul></ul><ul><ul><li>Assess LOC </li></ul></ul><ul><ul><li>Monitor ECG for dysrhythmias </li></ul></ul><ul><ul><li>Monitor serum electrolytes and ABGs </li></ul></ul><ul><ul><li>Administer oxygen as indicated and ordered </li></ul></ul>
    27. 27. Respiratory Acidosis <ul><li>Planning and Implementation </li></ul><ul><ul><li>Administer medications as ordered and indicated </li></ul></ul><ul><ul><ul><li>Bronchodilators to decrease bronchospasm </li></ul></ul></ul><ul><ul><ul><li>Antibiotics to treat infections </li></ul></ul></ul><ul><ul><ul><li>Respiratory agents to decrease viscosity of secretions </li></ul></ul></ul><ul><ul><ul><li>Anticoagulants and thrombolytics to prevent or treat PE </li></ul></ul></ul><ul><ul><li>Provide good oral hygiene frequently </li></ul></ul><ul><ul><li>Maintain safe positioning </li></ul></ul>
    28. 28. Respiratory Acidosis <ul><li>Planning and Implementation </li></ul><ul><ul><li>Keep a calm, quiet environment </li></ul></ul><ul><ul><li>Assess for cyanosis </li></ul></ul><ul><ul><li>Orient confused client frequently </li></ul></ul><ul><ul><li>Position to facilitate maximum lung expansion </li></ul></ul><ul><ul><li>Provide adequate fluid intake </li></ul></ul>
    29. 29. ABG Interpretation <ul><li>Look at HCO 3 level </li></ul><ul><ul><li>Reflects kidney function </li></ul></ul><ul><ul><li>Normal 22-26 mEq/L </li></ul></ul><ul><ul><li>< 22, Metabolic Acidosis </li></ul></ul><ul><ul><li>> 26, Metabolic Alkalosis </li></ul></ul><ul><ul><li>Causes: Ketoacidosis, lactic acidosis, CKD, diarrhea, severe infection, fever, trauma, starvation, laxative abuse </li></ul></ul>
    30. 30. Metabolic Acidosis <ul><li>Clinical presentation </li></ul><ul><ul><li>Cardiovascular </li></ul></ul><ul><ul><ul><li>Hypotension, dysrhythmias, peripheral vasodilation, cold, clammy skin </li></ul></ul></ul><ul><ul><li>Respiratory </li></ul></ul><ul><ul><ul><li>Deep, rapid, Kussmaul’s respirations </li></ul></ul></ul><ul><ul><li>CNS </li></ul></ul><ul><ul><ul><li>Drowsiness, coma, HA, confusion, lethargy, weakness </li></ul></ul></ul>
    31. 31. Metabolic Acidosis <ul><li>Clinical presentation </li></ul><ul><ul><li>GI </li></ul></ul><ul><ul><ul><li>N, V, diarrhea, abdominal pain </li></ul></ul></ul><ul><li>Diagnostics </li></ul><ul><ul><li>pH low, HCO 3 low, hyperkalemia </li></ul></ul><ul><ul><li>ECG changes related to high potassium levels </li></ul></ul><ul><ul><ul><li>Tall, tented T waves </li></ul></ul></ul><ul><ul><li>Increased anion gap calculations </li></ul></ul><ul><ul><li>Base excess decreases </li></ul></ul>
    32. 32. Metabolic Acidosis <ul><li>Compensation </li></ul><ul><ul><li>Lungs eliminate CO 2 </li></ul></ul><ul><ul><li>Kidneys conserve HCO 3 </li></ul></ul><ul><ul><li>Urine pH less than 6 </li></ul></ul><ul><ul><li>PaCO 2 decreases with compensation </li></ul></ul><ul><ul><li>pH returns to normal with full compensation </li></ul></ul>
    33. 33. Metabolic Acidosis <ul><li>Priority Nursing Diagnoses </li></ul><ul><ul><li>Decreased CO R/T dysrhythmias or FVD </li></ul></ul><ul><ul><li>Risk for sensory/perceptual alterations </li></ul></ul><ul><ul><li>Risk for injury </li></ul></ul><ul><ul><li>Risk for FVD </li></ul></ul>
    34. 34. Metabolic Acidosis <ul><li>Management </li></ul><ul><ul><li>Treat underlying problem </li></ul></ul><ul><ul><li>Provide hydration to restore water, nutrients, electrolytes </li></ul></ul><ul><ul><li>Administer IV alkalotic solution (NaHCO 3 or sodium lactate) may be indicated </li></ul></ul><ul><ul><li>Mechanical ventilation if necessary </li></ul></ul>
    35. 35. Metabolic Acidosis <ul><li>Planning and Implementation </li></ul><ul><ul><li>Monitor ABGs </li></ul></ul><ul><ul><li>Monitor I&O </li></ul></ul><ul><ul><li>Measure daily weights </li></ul></ul><ul><ul><li>Assess VS, especially respirations </li></ul></ul><ul><ul><li>Assess LOC </li></ul></ul><ul><ul><li>Assess GI function </li></ul></ul>
    36. 36. Metabolic Acidosis <ul><li>Planning and Implementation </li></ul><ul><ul><li>Monitor ECG for conduction problems </li></ul></ul><ul><ul><li>Monitor serum electrolytes </li></ul></ul><ul><ul><li>Protect from injury </li></ul></ul><ul><ul><li>Administer medications and fluids as needed </li></ul></ul>
    37. 37. ABG Interpretation <ul><li>Look at HCO 3 level </li></ul><ul><ul><li>If > 26, metabolic alkalosis </li></ul></ul><ul><ul><li>Causes: Fluid loss from UGI tract, diuretic therapy, severe hypokalemia, alkali administration or steroid therapy, excessive ingestion of bicarbonate-based antacids, binge – purge syndrome </li></ul></ul>
    38. 38. Metabolic Alkalosis <ul><li>Clinical Presentation </li></ul><ul><ul><li>Cardiovascular </li></ul></ul><ul><ul><ul><li>Tachycardia, dysrhythmias, hypertension, atrial tachycardia, PVCs </li></ul></ul></ul><ul><ul><li>Respiratory </li></ul></ul><ul><ul><ul><li>Hypoventilation, respiratory failure </li></ul></ul></ul><ul><ul><li>CNS </li></ul></ul><ul><ul><ul><li>Dizziness, irritability, nervousness, confusion, tremors, muscle cramps, hyperreflexia, tetany, paresthesias, seizures </li></ul></ul></ul>
    39. 39. Metabolic Alkalosis <ul><li>Clinical presentation </li></ul><ul><ul><li>GI </li></ul></ul><ul><ul><ul><li>Anorexia, N, V, paralytic ileus </li></ul></ul></ul><ul><li>Diagnostics </li></ul><ul><ul><li>High pH and HCO 3 , hypokalemia, hypocalcemia, hyponatremia, hypochloremia </li></ul></ul><ul><ul><li>Base excess increases </li></ul></ul>
    40. 40. Metabolic Alkalosis <ul><li>Compensation </li></ul><ul><ul><li>Lungs retain CO 2 ; and kidneys conserve H and excrete HCO 3 </li></ul></ul><ul><ul><li>PaCO 2 increases with compensation </li></ul></ul><ul><ul><li>Urine pH greater than 6 </li></ul></ul><ul><ul><li>pH returns to normal with full compensation </li></ul></ul>
    41. 41. Metabolic Alkalosis <ul><li>Priority Nursing Diagnoses </li></ul><ul><ul><li>FVD R/T excessive GI losses </li></ul></ul><ul><ul><li>Decreased Cardiac Output R/T FVD and conduction problems secondary to hypokalemia and alkalosis </li></ul></ul><ul><ul><li>Knowledge deficit R/T appropriate use of K-wasting diuretics and antacids </li></ul></ul><ul><ul><li>Risk for impaired gas exchange </li></ul></ul><ul><ul><li>Risk for injury R/T hypotension </li></ul></ul>
    42. 42. Metabolic Alkalosis <ul><li>Management </li></ul><ul><ul><li>Treat underlying cause </li></ul></ul><ul><ul><li>Provide sufficient chloride to enhance renal absorption of Na and excretion of HCO 3 </li></ul></ul><ul><ul><li>Restore fluid balance </li></ul></ul>
    43. 43. Metabolic Alkalosis <ul><li>Planning and Implementation </li></ul><ul><ul><li>Assess LOC </li></ul></ul><ul><ul><li>Assess VS, especially respirations </li></ul></ul><ul><ul><li>Administer medication and IV fluids as indicated </li></ul></ul><ul><ul><ul><li>NS based IV fluid replacement </li></ul></ul></ul><ul><ul><ul><li>Potassium supplementation if hypokalemic </li></ul></ul></ul><ul><ul><ul><li>Histamine-2 receptor antagonists (Tagamet, Zantac) to reduce production of H ions and loss of H ions from GI drainage </li></ul></ul></ul><ul><ul><ul><li>Correct other electrolyte imbalances </li></ul></ul></ul>
    44. 44. Metabolic Alkalosis <ul><li>Planning and Implementation </li></ul><ul><ul><li>Monitor I&O </li></ul></ul><ul><ul><li>Monitor response to therapy </li></ul></ul><ul><ul><li>Protect from injury </li></ul></ul><ul><ul><li>Monitor ECG for conduction abnormalities </li></ul></ul><ul><ul><li>Monitor ABGs </li></ul></ul><ul><ul><li>Monitor serum electrolytes </li></ul></ul>
    45. 45. ABG Interpretation <ul><li>Look back at pH </li></ul><ul><ul><li>If abnormal, the PaCO 2 or HCO 3 level will be abnormal = Uncompensated </li></ul></ul><ul><ul><li>Abnormal pH, PaCO 2 , and HCO 3 = Partially compensated </li></ul></ul><ul><ul><li>Normal pH, abnormal PaCO 2 and HCO 3 = Compensated </li></ul></ul><ul><ul><ul><li>Primary disorder is the abnormality that caused the pH to shift initially. Look to see on which side of 7.4 is pH </li></ul></ul></ul>
    46. 46. ABG Interpretation <ul><li>O 2 saturation </li></ul><ul><ul><li>Measurement of amount of oxygen bound to available hemoglobin </li></ul></ul><ul><ul><li>Assessed through ABGs (SaO 2 ) or noninvasively through pulse oximetry (SpO 2 ) </li></ul></ul><ul><ul><li>Normal 93-97% </li></ul></ul><ul><ul><li>Must evaluate the hemoglobin level </li></ul></ul>
    47. 47. ABG Interpretation <ul><li>O 2 Content </li></ul><ul><ul><li>Measures total amount of oxygen carried in the blood, including the amount dissolved in plasma and the amount bound to hemoglobin </li></ul></ul><ul><ul><li>Normal is 20 ml per 100 ml blood </li></ul></ul>
    48. 48. ABG Interpretation <ul><li>Base Excess or Base Deficit </li></ul><ul><ul><li>Non-respiratory contribution to acid-base balance </li></ul></ul><ul><ul><li>Normal -2 to +2 mEq/L </li></ul></ul><ul><ul><li>Below -2, base deficit, metabolic acidosis </li></ul></ul><ul><ul><li>Above +2, base excess, metabolic alkalosis </li></ul></ul>
    49. 49. Mixed Acid-Base Disturbances <ul><li>Occurs when two or more independent acid-base disorders occur at the same time </li></ul><ul><li>Example: Client with metabolic acidosis from acute renal failure may also have a very slow respiratory rate and retain CO 2 -> respiratory acidosis </li></ul>
    50. 50. Mixed <ul><li>Mixed acidosis </li></ul><ul><ul><li>pH 7.25, PaCO 2 56, PaO 2 80, HCO 3 15 </li></ul></ul><ul><ul><li>Acute pulmonary edema, cardiac arrest </li></ul></ul><ul><li>Mixed alkalosis </li></ul><ul><ul><li>pH 7.55, PaCO 2 26, PaO 2 80, HCO 3 28 </li></ul></ul><ul><ul><li>Postoperative clients with severe hemorrhage, massive transfusions, excessive NG drainage </li></ul></ul>