1. A CID B ASE B ALANCE Spring 2010

2. W HAT YOU WILL LEARN  Definition of Acid-Base Balance  Deference between regulation of buffers, respirations and renal system  What acidosis is and the Difference between Metabolic and Respiratory  What alkalosis is and the Difference between Metabolic and Respiratory  Complications and diseases associated with both processes

3. KEY TERMS

4. W HAT IS A CID B ASE B ALANCE  Acid-Base Balance refers to homeostasis of hydrogen ion concentration in body fluids  Expressed as pH  Acids  Bases  Health problems that may lead to an imbalance

5. P H AND H YDROGEN I ON C ONCENTRATION  Lower the pH Higher the ?  Heath Issues that can cause decrease in pH  Higher the pH Lower the ?  Heath issues that can cause increase in pH  Normal pH of blood 7.35 to 7.45 (arterial)  Normal pH of blood 7.32 to 7.42 (venous)  Critical Values of pH

6. A CID -B ASE R EGULATION  Buffer Systems  Respiratory System  Renal System

7. B UFFER S YSTEM  What is a Buffer?  Fastest acting and primary regulator of Acid- base balance  3 types of chemical buffers  Buffers can not work with out proper function of what systems

8. B ICARBONATE B UFFER  Bicarbonate is found in Extra-cellular and intra- cellular fluid  Controls small fluctuation in pH  Responds immediately  Mainly buffers what 2 fluids  Assisted by what organs

9. P HOSPHATE B UFFER  Found in intra-cellular fluid as bicarbonates.  Control small fluctuation in pH  Responds Quickly  Effective in Renal tubules, due to high levels of phosphates

10. P ROTEIN B UFFER  Most abundant buffer in the body  Found in ICF as hemoglobin and ECF as albumin and globulins  Works rapid  Works along same lines of bicarbonate system

11. R ESPIRATORY R EGULATION  Helps maintain pH  Second line of defense  Responds with in minutes  Temporary  Relies on Kidneys for long term regulation

12. R ESPIRATORY  CO2 levels in blood regulated by Lungs  Receptors in brain Medulla sense Ph changes  Rate and Depth of Breathing changed to compensate  Low pH = faster or deeper breaths to eliminate more CO2 from lungs; CO2 blood levels in blood drop and pH increases

13. R ESPIRATORY  High pH levels  Respirations slow and shallow  Reduces CO2 elimination  Lower pH

14. R ESPIRATORY  PaCO 2 (partial pressure of Arterial CO 2 in arterial blood)  Used to assess effectiveness of ventilation  PaCO 2 levels reflect CO 2 in the blood.  Normal levels 35-45 mm Hg

15. R ENAL S YSTEM FOR R EGULATION  Slowest of all regulating systems  Can permanently adjust Blood pH  Considered most powerful  Kidneys can reabsorb acids and bases and excrete them in urine  Kidneys produce bicarbonate to replenish  Kidneys regulate bicarbonate  Normal levels of bicarbonate 22-26 mEq/L in ABG  Three mechanism of acid eliminations

16. R ENAL 1. Secretion of small amounts of free hydrogen in renal tubule 2. Combination of hydrogen with ammonia to form ammonium 3. Excretion of weak acids

17. R ENAL To much Acid or not enough Base  ph drops – kidneys reabsorb sodium bicarb  Hydrogen phosphate and ammonia excreted by kidneys  Urine more Acidic (Normal Acidic level is 6pH)  Bicarb levels rise to normal levels and ph Increases

18. R ENAL More base and less acid  pH rises Kidneys excrete bicarb retain hydrogen  Urine becomes alkaline, Bicarb levels drop and pH decreases

19. I MBALANCES  Occur with compensatory mechanism fail  Acidosis is excess of hydrogen ions and arterial pH of less that 7.35  Alkalosis is excess of base mainly bicarb in ECF caused by increase of pH greater than 7.45  ROME Respiratory Opposite Metabolic Equal

20. R ESPIRATORY O PPOSITE  Respiratory Acidosis level  pH < that 7.35  PaCO 2 is > 45 mm Hg  Respiratory Alkalosis  pH > than 7.45  PaCO 2 is < 35 mm Hg

21. M ETABOLIC E QUAL  Metabolic Acidosis Levels  pH is < 7.35  HCO 3 < 24 mEq/L  Metabolic Alkalosis  pH is >7.35  HCO 3 > 28 mEq/L

22. R ESPIRATORY A CIDOSIS  Occurs whenever there is hypoventilation  Common Causes include  COPD  Over sedation  Chest Wall abnormality (obesity)  Severe Pneumonia  Atelectasis  Respiratory Muscle Weakness (Gilliain-Barre syndrome)  Mechanical hypoventilation

23. C LINICAL MANIFESTATIONS  Neurologic  Cardiovascular  Gastrointestinal  Neuromuscular  Respiratory

24. D IAGNOSTIC F INDINGS  pH < 7.35  PaCo2 > 45mm Hg  HCO3 is normal if uncompensated  HCO3 is elevated if compensated  Hyperkalemia

25. T HERAPEUTIC M ANAGEMENT N URSING D IAGNOSIS  Treatment of underlying cause  Improved Ventilation  Nursing Diagnosis  Ineffective breathing Patterns  Impaired Gas Exchange  Medications  Bronchodilators  Antibiotics  Agents used to decrease viscosity of secretions  Anticoagulants and thrombolytic to prevent emboli

26. R ESPIRATORY A LKALOSIS  Caused by Hyperventilation as result of pulmonary disorders  Mechanical over ventilation  Hypoxia  Pulmonary Emboli  Anxiety  Fear  Pain  Exercise  Fever

27. C LINICAL MANIFESTATIONS  Cardiovascular  Respiratory  Neurologic  Gastrointestinal  Neuromuscular  Respiratory

28. C LINICAL F INDINGS  pH > 7.45  PaCO2 < 35mm Hg  HCO3 normal if uncompensated  HCO3 decreased if compensated  Urine pH > 6  Hypokalemia  Hypocalcemia

29. T HERAPEUTIC M ANAGEMENT N URSING D IAGNOSIS  Therapeutic Management  Treatment of underlying cause  Re-breathe CO2 Re-breather Mask or paper bag  O2 if patient is Hypoxic  Nursing Diagnosis  Medication  Sedatives to control Hyperventilation  Antianxiety Me

30. M ETABOLIC A CIDOSIS  Base bicarbonate loss from body fluids or occurs when other acid other than Carbonic Acid accumulates Either way Bicarbonate is deficient  Very rarely occurs spontaneously  Usually occurs accompanied by other problems

31. C LINICAL M ANIFESTATIONS  Neurologic  Cardiovascular  Gastrointestinal  Neuromuscular  Respiratory

32. C LINICAL F INDINGS  pH < than 7.35  Remember in Metabolic you look at HCO3  HCO3 < 22 mEq/L  PaCO2 is normal if uncompensated  PaCO2 is decreased in compensated  Hyperkalemia  EKG Changes

33. T HERAPEUTIC M ANAGEMENT N URSING D IAGNOSIS  Correct Underlying Problem  Hydration  Nutrients  Electrolytes  Administration of Sodium Bicarb or Sodium lactate  Administration of N/S Reg. Insulin and potassium for DKA  Nursing Diagnosis

34. M ETABOLIC A LKALOSIS  Loss of acid or gain on bicarbonate – Which in turn causes Increase pH and Increase in HCO3  Conditions that cause Alkalosis  Gastric suction, Prolonged vomiting  Ingestion of bicarbonate bases (baking soda antacids)  Diuretic Therapy  Potassium Deficit

35. C LINICAL M ANIFESTATIONS  Respiratory  Cardiovascular  Gastrointestinal  Neuromuscular  Respiratory

36. C LINICAL F INDINGS  pH > 7.45  Remember HCO3 is the focus  HCO3 > 26 mEq/L  PaCO2 is normal uncompensated  PaCO2 is elevated if compensated  Urine pH is >6 if compensated  Hypokalemia  Hypocalcemia  Hyponatremia and Hypochloremia

37. T HERAPEUTIC M ANAGEMENT N URSING DIAGNOSIS  Correct Underlying Problem  Provide sufficient chloride to enhance renal absorption of sodium and excretion of HCO3 and restore normal fluid balance  Nursing Diagnosis

39. ABG I NTERPRETATION  Step One  Assess the pH to determine if the blood is within normal range, alkalotic or acidotic. If it is above 7.45, the blood is alkalotic. If it is below 7.35, the blood is acidotic.

40. ABG’S Step Two  If the blood is alkalotic or acidotic, we now need to determine if it is caused primarily by a respiratory or metabolic problem. To do this, assess the PaCO2 level. Remember that with a respiratory problem, as the pH decreases below 7.35, the PaCO2 should rise. If the pH rises above 7.45, the PaCO2 should fall. Compare the pH and the PaCO2 values. If pH and PaCO2 are indeed moving in opposite directions, then the problem is primarily respiratory in nature.

41. ABG’ S  Step Three  Finally, assess the HCO3 value. Recall that with a metabolic problem, normally as the pH increases, the HCO3 should also increase. Likewise, as the pH decreases, so should the HCO3. Compare the two values. If they are moving in the same direction, then the problem is primarily metabolic in nature.

42. ABG’S pHPaCO2HCO3 Respiratory Acidosis Normal Respiratory Alkalosis Normal Metabolic Acidosis Normal Metabolic Alkalosis Normal

43. T EST O URSELVES  Jane Doe is a 45-year-old female admitted to the nursing unit with a severe asthma attack. She has been experiencing increasing shortness of breath since admission three hours ago. Her arterial blood gas result is as follows:  Clinical Laboratory PATIENT: DOE, JANE DATE: 6/4/03 18:43 pH 7.22 PaCO2 55 HCO3- 25

44. Follow the steps: 1. Assess the pH. It is low (normal 7.35-7.45); therefore, we have acidosis. 2. Assess the PaCO2. It is high (normal 35-45) and in the opposite direction of the pH. 3. Assess the HCO3. It has remained within the normal range (22-26).

45. A NSWER  Acidosis is present (decreased pH) with the PaCO3 being increased, reflecting a primary respiratory problem. For this patient, we need to improve the ventilation status by providing oxygen therapy, mechanical ventilation, pulmonary toilet or by administering bronchodilators.

46. A NOTHER CHANCE  John Doe is a 55-year-old male admitted to your nursing unit with a recurring bowel obstruction. He has been experiencing intractable vomiting for the last several hours despite the use of antiemetic. Here is his arterial blood gas result: Clinical Laboratory PATIENT: DOE, JOHN DATE: 3/6/03 08:30 pH 7.50 PaCO2 42 HCO3 - 33

47.  Follow the three steps again:  1. Assess the pH. It is high (normal 7.35-7.45), therefore, indicating alkalosis.  2. Assess the PaCO2. It is within the normal range (normal 35-45).  3. Assess the HCO3. It is high (normal 22-26) and moving in the same direction as the pH.

48. A NSWER Alkalosis is present (increased pH) with the HCO3 increased, reflecting a primary metabolic problem. Treatment of this patient might include the administration of I.V. fluids and measures to reduce the excess base.

49. C OMPENSATION  The bodies attempt to return to normal state using the opposite system  pH is out of balance because of a respiratory disorder, it will be the renal system that makes the corrections to balance the body pH  renal system is to blame for the pH disorder, the respiratory system will have to compensate  Complete compensation returns the pH balance to normal.  There are times when the imbalance is too large for compensation to return the pH to normal. This is called incomplete compensation.

50. NURSING SCHOOL SURVIVAL RULES  When in doubt, wash your hands.  The correct answer is either "hand washing" or "patent airway."  If it moves, ambulate it. If it doesn't move, turn and reposition it Q2H.  Remember the 11th Commandment: Thou shalt not cross thy sterile field.  The instructor is ALWAYS right.  See Rule #5.