The document discusses acid-base balance and acid-base disorders. It describes three main systems that help maintain pH balance - buffers, the respiratory system, and the renal system. It explains how to interpret arterial blood gases by evaluating the pH, pCO2, HCO3, and other values to determine if a patient has respiratory or metabolic acidosis or alkalosis. Compensation by other systems is discussed when one system is imbalanced. Interpreting values and identifying primary vs compensated disorders is key to proper nursing care.

1. Acid-Base BalanceC Washington RN, MSNEd

2. Acid-Base BalanceHomeostasis & optimal cellular functionHydrogen ion concentration of body fluids wnlHydrogen ion concentration fallspH risessolution become more alkaline or basic

3. 3 Systems that maintenance pHBuffersMoves or release hydrogen ionsRespiratory systemRegulate carbonic acid by eliminating or retaining CO2Renal systemLong term regulation of acid-base in bodyABG Interpretation: 1st StepDetermine if the pH represents acidosis or alkalosis or is perfectly normal

4. Acid-Base DisordersHydrogen ions (H+) determines acidity of body fluidsAcids release H+ ions in solutionBases accepts H+ ions in solution

5. Acid-Base DisordersH+ ions concentration of a solution is measured by its pHNormal pH7.35-7.45 (pH of 7 is neutral)

6. Relationship between H+ ions & pH H+ ion concentration increases

7. pH falls

8. Solution becomes more acid

9. H+ ions concentration falls

10. pH rises

11. Solution becomes more alkaline

12. Acidic or AlkaloticpH 7.0pH 7.9pH 7.4pH 7.5pH 7.3

13. Note:pH alone is not sufficient to tell us whether an imbalance is due to a respiratory or metabolic problem

14. Evaluate other values of ABGs to determine the primary problem

15. Or whether the body is attempting to compensate for the imbalanceRegulation of Acid-Base BalanceBuffer Systems

16. Protein molecules, phosphate

17. Helps to maintain a stable pH

18. Removes or release H+ ions

19. Excess acid (acidosis) pH

20. buffers bind with H+ ions

21. To alkaline (alkaline) pH >7.45

22. buffers release H+ ionsMost Important Buffer systemBicarbonate-carbonic acid buffer systemControlled by lungs & kidneysAeorobic metabolism = to forms of acid respiratory acid (carbonic acid) metabolic acidsIn order to maintain proper pH balance, thebody attempts to maintain a ratio of 20:1 (bicarb to carbonic acid)

23. Regulation of Acid-Base BalanceRespiratory System

24. Eliminates or retains carbon dioxide

25. ↑ carbon dioxide (acid) stimulate respiration

26. ↑rate & depth of resp↓ pH to normal range

27. Alkalosis depresses respiration

28. ↓ rate & depth of resp retains carbon dioxideNormal PaCO2 = 35- 45 mmHg

29. ABG Interpretation: 2nd StepEvaluate the pCO2

30. Determine if it falls within the acceptable range

31. If pCO2 falls below the lower limit (resp alkalosis)

32. Id pCO2 falls above the upper limit (respiratory acidosis)

33. High pCO2 represents acidosis (retention of CO2)

34. Note: High value in pH represents alkalosis.

35. High CO2 =CO2 retention or hypoventilation

36. CO2 is acidotic in the blood=respiratory acidosisInterpreting pCO2 valuespCO2 of 22pCO2 of 32pCO2 of 35pCO2 of 40pCO2 of 45pCO2 of 50pCO2 of 60

37. Regulation of Acid-Base BalanceRenal System

38. Normal bicarbonate 22-26 mEq/L

39. Acidosis

40. Excess H+ ions

41. pH falls

42. kidneys excrete H+ and retain bicarbonate

43. Alkalosis

44. Kidneys retains H+ ions

45. excrete bicarbonateMetabolic ComponentsWhen there is a loss of acid in the body or

46. An excess base

47. HCO3 will be greater than 26

48. Resulting in metabolic alkalosis

49. When there is an excess of metabolic acid

50. Or not enough base

51. HCO3 will be less than 22

52. Causing metabolic acidosisABG Interpretation: 3rd StepDetermine the direction of the the metabolic component HCO#

53. Whether it is within normal limits

54. High (metabolic alkalosis)

55. Low (metabolic acidosis)Think of HCO3 as a base *too much causes metabolic alkalosis *too little causes metabolic acidosis

56. Interpreting HCO3 ValuesHCO3 of 22HCO3 of 16HCO3 of 30HCO3 of 25HCO3 of 12HCO3 of 27

57. Base Excess (BE)Metabolic component

58. Calculation of circulating buffer/base

59. Normal range BE is -2 to +2 BE of -8 represents a deficit of base=metabolic acidosis BE of +10 representsan excess of base=metabolic alkalosis

60. Metabolic AcidosisDeficit HCO3Common in cases of kidney disease and diabetesRespiratory AcidosisExcess HCO3Caused by hypoventilationMetabolic AlkalosisExcess HCO3Caused by diarrhea, steroid or diuretic therapy.Respiratory AlkalosisDeficit HCO3Caused by hyperventilationAcid-Base Imbalances

62. Acid-Base ImbalancesMetabolic Acidosis

63. Ph

64. HCO3-

65. Respiratory Acidosis

66. pH

67. PaCO2 > 45 mmHg