ACID – BASE DISORDERS [Case-based Discussion]
PREAMBLE <ul><li>pH </li></ul><ul><li>Buffers of Body </li></ul><ul><li>Significance of [H + ] ion conc. </li></ul><ul><li...
<ul><li>NaHCO 3  = HCO 3  =  Salt  = 20 </li></ul><ul><li>  H 2 CO 3   PCO 2   Weak Acid  1 </li></ul><ul><li>= Metabolic ...
30 7.5 35 45 C [  ?   ] 38 7.4 25 40 B [Normal] 40 7.4 15 25 A [  ?   ] H + nmol/L pH [HCO 3 ] mmol/L PCO 2 [mmHg] Cases
40 25 PCO 2 [mmHg 25 15 [HCO 3 ] mmol/L 7.4 7.4 pH 38 40 H + nmol/L B A Parameters
 
METABOLIC ACIDOSIS <ul><li>Renal Failure </li></ul><ul><li>Diabetic Acidosis </li></ul><ul><li>NH 4 Cl Ingestion </li></ul...
METABOLIC ALKALOSIS <ul><li>NaHCO 3  Ingestion </li></ul><ul><li>Prolonged Vomiting </li></ul><ul><li>Too much intake of A...
RESPIRATORY ACIDOSIS <ul><li>Asphyxia: </li></ul><ul><ul><li>Drowning </li></ul></ul><ul><ul><li>Strangulation </li></ul><...
RESPIRATORY ALKALOSIS <ul><li>Voluntary Hyperventilation </li></ul><ul><li>Ascent to High Altitude Unacclimatised </li></ul>
 
<ul><li>Patient A  is a 57-year-old man who has been depressed for some time. In a suicide attempt early that morning he h...
Answer Patient A <ul><li>There is a metabolic acidosis (reduced pH and low standard [HCO 3 -  ]) </li></ul><ul><li>There h...
<ul><li>Patient B  is a 76-year-old woman who is suffering from an acute exacerbation of chronic obstructive airways disea...
Answer Patient B <ul><li>There is a respiratory acidosis [reduced pH and raised P CO2  ].  </li></ul><ul><li>There is meta...
<ul><li>Patient C  is a 40-year-old man who is known to be an insulin-dependent diabetic. He was unconscious at admission ...
Answer Patient C <ul><li>There is a metabolic acidosis [reduced pH and reduced standard [HCO 3 -  ]. </li></ul><ul><li>The...
<ul><li>Patient D  is a 16-year-old girl who is complaining of breathlessness of sudden onset. She appears agitated and is...
Answer Patient D <ul><li>There is a respiratory alkalosis [elevated pH and reduced P CO2  ]. </li></ul><ul><li>There is no...
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Acid base disorders by Dr. Aslam

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Acid base disorders by Dr. Aslam

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Acid base disorders by Dr. Aslam

  1. 2. ACID – BASE DISORDERS [Case-based Discussion]
  2. 3. PREAMBLE <ul><li>pH </li></ul><ul><li>Buffers of Body </li></ul><ul><li>Significance of [H + ] ion conc. </li></ul><ul><li>pH of Body Fluids [plasma, gastric juice, pancreatic juice] </li></ul>
  3. 4. <ul><li>NaHCO 3 = HCO 3 = Salt = 20 </li></ul><ul><li> H 2 CO 3 PCO 2 Weak Acid 1 </li></ul><ul><li>= Metabolic = Dealt by Kidney = X =  </li></ul><ul><li> Resp Dealt by Lungs  X </li></ul>Buffer =
  4. 5. 30 7.5 35 45 C [ ? ] 38 7.4 25 40 B [Normal] 40 7.4 15 25 A [ ? ] H + nmol/L pH [HCO 3 ] mmol/L PCO 2 [mmHg] Cases
  5. 6. 40 25 PCO 2 [mmHg 25 15 [HCO 3 ] mmol/L 7.4 7.4 pH 38 40 H + nmol/L B A Parameters
  6. 8. METABOLIC ACIDOSIS <ul><li>Renal Failure </li></ul><ul><li>Diabetic Acidosis </li></ul><ul><li>NH 4 Cl Ingestion </li></ul><ul><li>K + injections </li></ul>
  7. 9. METABOLIC ALKALOSIS <ul><li>NaHCO 3 Ingestion </li></ul><ul><li>Prolonged Vomiting </li></ul><ul><li>Too much intake of Antacids </li></ul><ul><li>K + Deficiency </li></ul>
  8. 10. RESPIRATORY ACIDOSIS <ul><li>Asphyxia: </li></ul><ul><ul><li>Drowning </li></ul></ul><ul><ul><li>Strangulation </li></ul></ul><ul><li>Emphysema </li></ul>
  9. 11. RESPIRATORY ALKALOSIS <ul><li>Voluntary Hyperventilation </li></ul><ul><li>Ascent to High Altitude Unacclimatised </li></ul>
  10. 13. <ul><li>Patient A is a 57-year-old man who has been depressed for some time. In a suicide attempt early that morning he had swallowed the entire contents of a bottle of aspirin [salicylate]. His respiration is appreciably increased and an arterial blood sample gives the following results: </li></ul><ul><li>pH = 7.30 </li></ul><ul><li>P CO2 = 4kPa [30mmHg] </li></ul><ul><li>standard [HCO 3 - ] </li></ul><ul><li>= 16mmolL -1 </li></ul>Q’s: 1. Which is the type of Acid base upset? 2. Is there any nature of any compensatory response? 3. Which is the likely cause underlying the acid base upset?
  11. 14. Answer Patient A <ul><li>There is a metabolic acidosis (reduced pH and low standard [HCO 3 - ]) </li></ul><ul><li>There has been respiratory compensation [increased respiration, reduced P CO2 ]. </li></ul><ul><li>The cause is gastrointestinal absorption of salicylic acid. </li></ul>
  12. 15. <ul><li>Patient B is a 76-year-old woman who is suffering from an acute exacerbation of chronic obstructive airways disease precipitated by a lower respiratory tract infection. She appears centrally cyanosed [Section 4.7]. Arterial blood analysis gives the following results: </li></ul><ul><li>pH = 7.30 </li></ul><ul><li>P CO2 = 11kPa [83mmHg] </li></ul><ul><li>standard [HCO 3 - ] </li></ul><ul><li>= 34mmolL -1 </li></ul>Q’s: 1. Which is the type of Acid base upset? 2. Is there any nature of any compensatory response? 3. Which is the likely cause underlying the acid base upset?
  13. 16. Answer Patient B <ul><li>There is a respiratory acidosis [reduced pH and raised P CO2 ]. </li></ul><ul><li>There is metabolic compensation (raised standard [HCO 3 - ]). </li></ul><ul><li>The cause is reduced ventilation caused by chronic obstructive airways disease. </li></ul>
  14. 17. <ul><li>Patient C is a 40-year-old man who is known to be an insulin-dependent diabetic. He was unconscious at admission and is found to be extremely dehydrated. Arterial blood analysis is as follows: </li></ul><ul><li>pH = 7.10 </li></ul><ul><li>P CO2 = 3.3kPa [25mmHg] </li></ul><ul><li>standard [HCO 3 - ] </li></ul><ul><li>= 10mmolL -1 </li></ul>Q’s: 1. Which is the type of Acid base upset? 2. Is there any nature of any compensatory response? 3. Which is the likely cause underlying the acid base upset?
  15. 18. Answer Patient C <ul><li>There is a metabolic acidosis [reduced pH and reduced standard [HCO 3 - ]. </li></ul><ul><li>There is respiratory compensation [reduced P CO2 ]. </li></ul><ul><li>The cause is likely to be diabetic ketoacidosis caused by insulin deficiency. </li></ul>
  16. 19. <ul><li>Patient D is a 16-year-old girl who is complaining of breathlessness of sudden onset. She appears agitated and is breathing very rapidly but there is no other obvious abnormality on examination. Arterial blood analysis gives the following results: </li></ul><ul><li>pH = 7.55 </li></ul><ul><li>P CO2 = 3.3kPa [25mmHg] </li></ul><ul><li>standard [HCO 3 - ] </li></ul><ul><li>= 24mmolL -1 </li></ul>Q’s: 1. Which is the type of Acid base upset? 2. Is there any nature of any compensatory response? 3. Which is the likely cause underlying the acid base upset?
  17. 20. Answer Patient D <ul><li>There is a respiratory alkalosis [elevated pH and reduced P CO2 ]. </li></ul><ul><li>There is no metabolic compensation (normal standard [HCO 3 - ]). </li></ul><ul><li>The cause is likely to be hysterical overbreathing. </li></ul>
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