Acid/Base Balances

1. Acid/BaseBalances By: Diana Blum MSN MCC NURS 2140

2. Acid /Base Balance Acid base balance is the regulation of free hydrogen ions in extra-cellular fluid. Acids: dissociate in solution to release H+. Bases: combine with free H+ and remove it from solution.

4. Homeostasis • Hydrogen ion: smallest ionic particle and very reactive • Small changes can alter protein and enzyme functioning • Affects organ function: heart, kidneys, lungs • Affects clotting cascade • Affects drug metabolism • Plasma PH: indicator of hydrogen ion concentration • Ex: pH of 7.50 is equivalent to 50 nmol/L of hydrogen ion • As Hydrogen ion increases pH decreases and vice versa

6. Life • pH range compatible with life is 6.8-7.8

7. Acids • Form hydrogen ions and are proton donors • Ex: HCL gives up H+ ion when added to blood • Strong acids give up hydrogen easily • Lower PH • Weak acids keep a grip on their hydrogen ions • Higher PH

8. Bases • Combine with hydrogen ions • Proton acceptors • Ex: NaHCO3- (sodium bicarb) removes hydrogen when added to blood

9. Carbon Dioxide/Respiratory Acid • Potential acid • When dissolved it becomes carbonic acid • Body metabolism will constantly produce • 288L/day produced and excreted by ventilation

10. Metabolic Acid • Not many produced on daily basis • Main acids are: • Lactic • Pyruvic • Ketoacids • Beta hydroxybutyric • Eliminated by kidneys or Metabolized by liver

11. Defense Mechanisms • First: Buffering • 2nd : Changing CO2 level • 3rd : changing the level of HCO3 -

12. Buffers

13. Buffer Systems • Helps minimize change in pH • React quickly to prevent excess changes • Primary Buffers: carbonic acid and bicarb • Aerobic metabolism: • Anaerobic metabolism:

14. Buffer continued • Excess CO2 exhaled • Bicarb is retained by glomerular filtration and also excreted by renal tubule • So what really happens??? • Intracellular Buffer is phosphate • Protein buffers in blood are plasma protein and hemoglobin • Bone is a buffer

15. Balance in the body is maintained by three buffer mechanisms

16. R.O.M.E. • Respiratory Opposite • Example: pH low PCO2 high HCO3 ok= respiratory acidosis • Metabolic Equal • Example: pH is high HCO3 is high it is metabolic

18. Categories of Interest • Respiratory Acidosis: • Respiratory Alkalosis: • Metabolic Acidosis: • Metabolic Alkalosis:

20. Lungs

21. The Lungs • Regulate plasma pH on minute to minute basis by regulating carbon dioxide. • CO2 measured as partial pressure in arterial blood=PaCO2 • Depth and rate of ventilation will alter • Minute Ventilation= how much air moved in 1 minute • Increase= blowing off CO2 to compensate • Dead Space} wasted ventilation/no part in gas exchange

22. Lungs continued • Respiratory center= • Hypercarbic Drive= response to acute respiratory acidosis • Determinant of ventilation • Hypoxic Drive= Drive to breath…responds to low oxygen levels, high CO2, and acidosis • Hyperventilation: low PaCO2/hypocapnia • Hypoventilation: high PaCO2/ hypercapnia • Kussmals respirations: rapid deep breaths and attempt of lungs to correct pH by decreasing respiratory acid (compensation)

24. Kidneys • Secrete hydrogen ions • Reclaim bicarb during the filtering process in the glomerulas. • Ammonia

25. Norms • pH: 7.35-7.45 • pCO2: 35-45 • HCO3: 22-26 • RR=12-20

26. Interpretation • 1} Assess the pH • 2} Is it Respiratory or Metabolic • Look at PaCO2 • Look at Bicarb level • 3} Compensation • Complete or partial

27. 1}

28. 2}

29. 2}

31. Imbalances • Result from disease, organ dysfunction, pathologic reasons

32. Respiratory Acidosis

33. Referred as primary hypercapnia • Excess CO2 decreases pH • Regulated by RR • Management: • Treat underlying cause • Sodium Bicarb not always given • BiPAP • CPAP • Vent

34. Respiratory Alkalosis

35. Lower than normal PaCO2 • Elevated pH • Excessive /deep ventilation causes CO2 to be blown off thereby increasing pH • Alveolar over ventilation • Other Causes: hypoxemia, neuro issues, pregnancy • Changes serum electrolytes • Management: treat underlying cause • Breath into a paper bag • Reassure • Be calm • Explain procedures

36. Metabolic Acidosis

37. Increase in total acid level thereby decreasing pH • Induced in 2 ways: • adding H+ ion or excreting H+ from dietary metabolism • Decrease in plasma bicarb to <22 • Other Causes: ETOH, DM, Aspirin OD, Antifreeze ingestion, GI disturbances • Management: assess anion gap, monitor electrolytes and ABGs, treat underlying cause, sodium bicarb admin is controversial

38. Metabolic Alkalosis

39. Increase Bicarb and pH • Other Causes: depletion in K+, Cl-, volume depletion • Hypomagnesaemia may also occur • Management: correct volume or electrolyte depletion, may get steroids, dialysis,HCL IV in severe cases

40. Compensation • Body’s normal way to normalize pH by neutralizing the opposite mechanism • Important to know cause and effect If you only treat compensatory response only pH will become more abnormal

41. Compensated ? / Uncompensated? Uncompensated: Ph and one other value abnormal Partially Compensated: ( All values are abnormal) Completely Compensated: (pH is the only normal value)

42. When compensation is present, we will see two imbalances. The question then becomes, which is the primary problem, and which imbalance is due to compensation. • The clue is the pH. • If the pH is leaning toward acidosis or alkalosis, then the parameter with the matching imbalance is the primary problem, and the other is due to compensation.

43. EXAMPLE • if the pH is normal in the presence of abnormal pO2/pCO2 – compensated • (the body has compensatedfor the abnormality and is able to maintain a normal pH) • if the pH is abnormal in the presence of abnormal pO2/pCO2 – uncompensated • (the body's defense mechanisms are no longer adequate to compensate, allowing the pH to move to an acidotic or an alkalotic state)

44. *Remember that compensation corrects the ph.

45. Examples Respiratory acidosis = low ph and high C02 hypoventilation (eg: copd, narcs or sedatives, atelectasis)*Compensated by metabolic alkalosis (increased HC03)examples:ph 7.20 C02 60 HC03 24 (uncompensated respiratory acidosis)ph 7.33 C02 55 HC03 29 (partially compensated respiratory acidosis)ph 7.37 C02 60 HC03 37 (compensated respiratory acidosis) Respiratory alkalosis = high ph and low C02 hyperventilation (eg: anxiety, PE, pain, sepsis)*Compensated by metabolic acidosis (decreased HC03)examples:ph 7.51 C02 26 HC03 25 (uncompensated respiratory alkalosis)ph 7.47 C02 32 HC03 20 (partially compensated respiratory alkalosis)ph 7.43 C02 30 HC03 19 (compensated respiratory alkalosis)

46. Metabolic acidosis = low ph and low HC03 ex:diabeticketoacidosis, starvation, severe diarrhea*Compensated by respiratory alkalosis (decreased C02)examples:ph 7.23 C02 36 HC03 14 (uncompensated metabolic acidosis)ph 7.31 C02 30 HC03 17 (partially compensated metabolic acidosis)ph 7.38 C02 26 HC03 20 (compensated metabolic acidosis) Metabloic alkalosis = high ph and high HC03 ex. severe vomiting, k+ deficit, dieuretics*Compensated by respiratory acidosis (increased C02)example:ph 7.54 C02 44 HC03 29 (uncompensated metabolic alkalosis)ph 7.50 C02 49 HC03 32 (partially compensated metabolic alkalosis)ph 7.44 C02 52 HC02 35 (compensated metabolic alkalosis)

47. Nursing Management • Promote healthy behaviors • Limit conversations • 6 small meals a day • Positioning • Stress reduction techniques

49. Practice

50. pH 7.33 • PCO2 50 • HCO3 26