Your SlideShare is downloading. ×
  • Like
Blood Gas Analysis
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×

Now you can save presentations on your phone or tablet

Available for both IPhone and Android

Text the download link to your phone

Standard text messaging rates apply

Blood Gas Analysis

  • 5,889 views
Published

 

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
No Downloads

Views

Total Views
5,889
On SlideShare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
400
Comments
3
Likes
4

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. Blood Gas analysis
    DR. MANSOOR AQILASSOCIATE PROFESSOR,KING SAUD UNIVERSITY HOSPITALSRIYADH.
  • 2. Clinical case
  • 3. Maintained within narrow limits
    pH 7.36 to 7.44
    pH = Alkalemia (Alkalosis)
    pH = Acidemia (Acidosis)
    BLOOD pH
  • 4. NORMAL
    7.4
    ACIDOSIS
    ALKALOSIS
    7.8
    7.0
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 6. BLOOD pH
  • 7. The challenge
    7.4
    ACIDOSIS
    7.8
    7.0
    Volatile ACID (CO2) &
    Fixed acids
    Defense of normal alkalinity
  • 8. Types of Acids
    Volatile acids
    Easily move from liquid to gas state within the body
    Lung can remove
    H2CO3 + renal enzyme  H2O + CO2 (both of which are exhaled)
    Carbon dioxide is therefore considered an acid
  • 9. Types of Acids
    • Nonvolatile acids(Fixed acids)
    Cannot be changed to gas state within the body
    Examples
    Keto acids
    Lactic acids
  • 10. The challenge
    Sources of acids:
    Volatile acid
    CO2 + H2O  H2CO3  H+ + HCO3
    Fixed acids
    Organic and inorganic source
    Lactic acid, ketones, Sulfuric and phosphoric acid
    Kidney plays an important role handling fixed acids.
  • 11. HYDROGEN ION SOURCES
    • CO2 15000 mmol/day
    CO2 + H2O H2CO3 H+ + HCO3-
    • Noncarbonic acids 70 mmol/day
  • DEFENCE AGAINST pH CHANGE
    Acute (minutes to hours)
    Ventilation
    Buffering
  • 12. DEFENCE AGAINST pH CHANGE
    Acute (minutes to hours)
    Long term
    Renal excretion
    Hepatic metabolism
  • 13. Chemical Buffers
    The body uses pH buffers in the blood to guard against sudden changes in acidity
    A pH buffer works chemically to minimize changes in the pH of a solution
    H+
    OH-
    H+
    Buffer
    OH-
    OH-
    H+
  • 14.
  • 15. BUFFERS
    Intracellular Buffers
    Proteins
    Haemoglobin
    Phosphate
    Extracellular Buffers
    Proteins
    Bicarbonate
  • 16.
  • 17. Biological systems and Buffering:
    The power of a buffer depends on:
    Concentration of the buffer.
    Whether the pK is close to the pH of the system.
  • 18. Bicarbonate buffer systems:
    CO2 + H2O  H2CO3  H+ + HCO3-
    Maintains a ratio of 20 parts bicarbonate to 1 part carbonic acid
  • 19. Bicarbonate Buffer System
    If strong acid is added:
    HCl + NaHCO3 = H2CO3 + NaCl
    Hydrogen ions released combine with the bicarbonate ions and form carbonic acid (a weak acid)
    The pH of the solution decreases only slightly
  • 20. BICARBONATE BUFFER SYSTEM
    H+
    H2CO3H+ + HCO3-
    Hydrogen ions generated by metabolism or by ingestion react with bicarbonate base to form more carbonic acid
    H2CO3
    HCO3-
    20
  • 21. BICARBONATE BUFFER SYSTEM
    H+
    Equilibrium shifts toward the formation of acid
    Hydrogen ions that are lost (vomiting) causes carbonic acid to dissociate yielding replacement H+ and bicarbonate
    H2CO3
    HCO3-
  • 22. Bicarbonate Buffer System
    If strong base is added:
    NaOH + H2CO3 = NaHCO3 + H2O
    It reacts with the carbonic acid to form sodium bicarbonate (a weak base)
    The pH of the solution rises only slightly
    This system is the only important ECF buffer
  • 23. Bicarbonate buffer systems:
    CO2 + H2O  H2CO3  H+ + HCO3-
    pK = 6.1 [HCO3-] = 24 mmol/L
  • 24. Bicarbonate buffer systems:
  • 25. Phosphate buffer systems
    Phosphate buffer H2PO4- / HPO4
    pK = 6.8 and has a low concentration.
    Role as intracellular and urinary buffer.
  • 26. Phosphate buffer systems
    H2PO4- / HPO4-2
  • 27. Protein buffers:
    A. Amino acid residues of proteins take up H+
    (pK=7.0) are most important
    NH2 NH3-
    B. Hemoglobin is important due to high concentrationand its increased buffering capacity when deoxygenated.
  • 28. Relative Buffering power:
  • 29. Relative Buffering power:
  • 30. Compensation
  • 31. Renal buffering mechanisms
    Renal - kidney excretes H+ and replenishes [HCO3-] .
    But, this is a slow process taking hours to days.
  • 32. Renal buffering mechanisms
  • 33. Renal buffering mechanisms
  • 34. METABOLIC DISORDERS
  • 35. RESPIRATORY ACIDOSIS
    7.4
    7.8
    7.0
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 37. RESPIRATORY ACIDOSIS
    H2O + CO2  H2CO3  H+ + HCO3-
    Cause - hypoventilation
    Retention of CO2
    Drives equation rightward
    Increases both [H+] and [HCO3-]
  • 38. RESPIRATORY ALKALOSIS
    7.4
    7.8
    7.0
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 40. RESPIRATORY ALKALOSIS
    H2O + CO2  H2CO3  H+ + HCO3-
    2. Respiratory Alkalosis
    cause - hyperventilation
    Blows off CO2
    Drives equation leftward decreasing both [H+] and [HCO3-]
  • 41. METABOLIC ACIDOSIS
    7.4
    7.8
    7.0
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 43. Metabolic Acidosis
    Deficit in HCO3- and decreased pH
    Causes:
    Increased production of nonvolatile acids.
    Decreased H+ secretion in the kidney
    Increased HCO3- loss in kidney
    Increased Cl- reabsorption by the kidney.
  • 44. Metabolic Acidosis
    Body response is increased ventilation to blow off excess CO2
  • 45. METABOLIC ALKALOSIS
    7.4
    7.8
    7.0
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 47. Metabolic Alkalosis
    Primarily due to Increased HCO3- , increased pH
    Causes
    • Administration of excess HCO3-
    • 48. Increased secretion of H+ by kidney and gut
    • 49. Sudden volume contraction which leads to increased Na+retention.This leads to water and HCO3- to follow the Na+
  • PARTIALLY COMPENSATED RESPIRATORY ACIDOSIS
    7.4
    7.0
    7.8
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 51. PARTIALLY COMPENSATED RESPIRATORY ALKALOSIS
    7.4
    7.8
    7.0
    ACID
    (CO2)
    METABOLIC COMPONENT
    RESPIRATORY COMPONENT
  • 53. 7.4
    7.0
    7.8
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
    PARTIALLY COMPENSATED METABOLIC ACIDOSIS
  • 55. PARTIALLY COMPENSATED METABOLIC ALKALOSIS
    7.4
    7.8
    7.0
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 57. MIXED ACIDOSIS
    7.4
    7.8
    7.0
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 59. COMPENSATED STATE
    7.4
    ACIDOSIS
    ALKALOSIS
    7.8
    7.0
    ACID
    (CO2)
    RESPIRATORY COMPONENT
    METABOLIC COMPONENT
  • 61. Acute ventilatory failure (acute respiratory acidosis)
    N
  • 62. Chronic ventilatory failure
    (compensated respiratory acidosis)
    Normal
  • 63. Acute alveolar hyperventilation(acute respiratory alkalosis)
    Normal
  • 64. Chronic alveolar hyperventilation(compensated respiratory alkalosis)
    Normal
  • 65. Acute metabolic acidosis
    Normal
  • 66. Chronic metabolic acidosis
    Normal
  • 67. Acute Metabolic Alkalosis
    Normal
  • 68. Chronic metabolic alkalosis
    Normal
    Normal
  • 69. Anion Gap
    AG = [Na + ] - [Cl ‾ + HCO3‾ ]
    • AG represents unaccounted for anions (R ‾ )
    • Normal anion gap = 10
  • 70. Anion Gap
    Cations are Na + & K +
    Major Anions are Cl ‾ & HCO3 ‾
  • 71. Anion gap
    Unmeasured Anions
    vs
    Unmeasured Cations
    Proteins, mostly albumin 15 mEq/L
    Calcium 5 mEq/L
    Organic acids 5 mEq/L
    Potassium 4.5 mEq/L
    Phosphates 2 mEq/L
    Magnesium 1.5 mEq/L
    Sulfates 1 mEq/L
    Totals: 23 mEq/L
    11 mEq/L
  • 72. Rules For Analyzing The ABG’s
    • Look at the anion gap.
  • 73. Differential diagnosis of metabolic acidosis
    Elevated anion gap
    Uremia
    Ketoacidosis
    Lactic acidosis
    Methanol toxicity
    Ethylene glycol toxicity
    Salicylate
    Paraldehyde
    Normal anion gap
    Renal tubular acidosis
    Dirrhoea
    Carbonic anhydrase inhibition
    Ureteral diversion
    Early renal failure
    Hydronephrosis
    HCL administration
    Saline administration
  • 74. Diagnosis of acid base disturbance
  • 75. Determining the predicted “Respiratory pH”
    Acute 10 mmHg increase in PCO2 results in pH decrease of approximately 0.05 units
    Acute 10 mmHg decrease in PCO2 results in pH increase of approximately 0.10 units
  • 76. Determining the predicted “Respiratory pH”
    First determine the difference between the measured PaCO2 and 40 mmHg and move the decimal point two places left.
    60 - 40 = 20 X 1/2 0.10
    40 – 30 = 10 0.10
  • 77. Determining the predicted “Respiratory pH”
    If the PaCO2 is greater than 40 subtract half of the difference from 7.40
    ? If this Pt has pH = 7.2
    ? If this Pt has pH = 7.33
    60 - 40 = 20 X ½ =10 = 0.10
    pH = 7.40 – 0.10 = 7.30
  • 78. Determining the predicted “Respiratory pH”
    If the PaCO2 is less than 40 add the difference to 7.40
    40 - 30 = 10 0.10
    pH = 7.40 + 0.10 = 7.50
  • 79. Determining the predicted “Respiratory pH”
    pH 7.04
    PCO2 76
    76 - 40 = 36 X ½ = 18 0.18
    7.40 - 0.18 = 7.22
  • 80. Determining the predicted “Respiratory pH”
    pH 7.21
    PCO2 90
    90 - 40 = 50 X ½ = 25 0.25
    7.40 – 0.25 = 7.15
  • 81. Determining the predicted “Respiratory pH”
    pH 7.47
    PCO2 18
    40 – 18 = 22 0.22
    7.40 + 0.22 = 7.62
  • 82. Determining the Metabolic component
    RULE
    10 mmol/L variance from the normal buffer base represents a pH change of approximately 0.15 units.
  • 83. pH 7.21
    PCO2 90
    90 - 40 = 50 X ½ = 0.25
    7.40 – 0.25 = 7.15
    Determining the Metabolic component
    7.21 -7.15 = 0.06 X 2/3 = 0.04 = 4 mmol/L base excess
  • 84. pH 7.04
    PCO2 76
    76 - 40 = 36 X ½ = 0.18
    7.40 - 0.18 =7.22
    Determining the Metabolic component
    7.22 -7.04 = 0.18 X 2/3 =12 mmol/L base deficit
  • 85. Determining the Metabolic component
    pH 7.47
    PCO2 18
    40 – 18 = 22 = 0.22
    7.40 + 0.22 = 7.62
    Determining the Metabolic component
    7.62-7.47 = 0.15 X 2/3 =10 mmol/L base deficit
  • 86. Diagnosis of acid base disturbance
    Examine arterial pH: Is acidemia or alkalemia present?
    Examine PaCO2: Is the change in PaCO2 consistent with a respiratory component?
    If the change in PaCO2 does not explain the change in arterial pH, does the change in [HCO3–] indicate a metabolic component?
    Make a tentative diagnosis (see Table).
  • 87. Diagnosis of acid base disturbance
    Compare the change in [HCO3–] with the change in PaCO2. Does a compensatory response exist (Table)?
    If the compensatory response is more or less than expected, by definition a mixed acid–base disorder exists.
    Calculate the plasma anion gap in the case of metabolic acidosis.
    Measure urinary chloride concentration in the case of metabolic alkalosis.
  • 88.
  • 89. Clinical case
  • 90. Clinical case
  • 91. Clinical case
  • 92. Clinical case
  • 93. Clinical case
  • 94. Thank U
  • 95. Base Excess/ Deficit
    The degree of deviation from normal total body buffer base can be calculated independent of compensatory PCO2 changes
    The amount of acid of base that must be added to return the blood pH to 7.4 and PCO2 to 40 at full O2 saturation and 370 C