disorders of acid-base balance · 2020. 10. 2. · alkalaemia alkalosis ph of arterial blood < 7,35...
TRANSCRIPT
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DISORDERS OF
ACID-BASE
BALANCE
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ACID-BASE BALANCE
ISOHYDRIA – stability of H+ concentration
[H+] = 40 nmol/L = 0,00000004 mol/L
pH = - log [H+]
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ACID-BASE BALANCE
ISOHYDRIA – stability of H+ concentration
[H+] = 40 nmol/L = 0,00000004 mol/L
pH = - log [H+]
pH → main determinant of physiological & biochemical processesactivity of enzymes varies due to charge and conformation of proteins
effecting activity of transport proteinseffecting molecule distributions across cell membranesalterations in drug dissociation
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pH
Physiological value of pH?
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pH
pH 7,4 ± 0,05
pH 7,4 pH 7,35
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sources of H + :
1. the metabolism of proteins and phospholipids + incomplete metabolism of fatty acids and carbohydrates
→ non-volatile acids (40 mmol/d)
sulfuric acid phosphoric acid
lactic acid ketone bodiesuric acid
• no further dissociation• elimination by kidneys
2. complete metabolism of fatty acids & carbohydrates
→ CO2 (20 000 mmol/d)
ACID-BASE BALANCE
H+ source
fixed acids CO2
CO2 + H2O H 2CO3 H+ + HCO3
–
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MECHANISMS FOR MAINTAINING AB BALANCE
1. bicarbonate – carbonic buffer
2. hemoglobin buffer
3. protein buffer
4. phosphate buffer
BUFFERING SYSTEMS:
buffer systems
ECF
bicarbonate
protein
ICF
hemoglobin
phosphate
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BICARBONATE –CARBONIC BUFFER
efficient:• biggest in extracellular fluid • open system
BUFFERING SYSTEM:
CO2 + H2O H 2CO3 H+ + HCO3
–
weak acid strong base
MECHANISMS FOR MAINTAINING AB BALANCE
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CO2 + H2O H 2CO3 H+ + HCO3
–
pH = [HCO3
–][H2CO3]pCO2
Henderson-Hesselbach‘sequation
pH = pK + log [HCO3
–][H2CO3]
pH = pK + log [HCO3
–][H2CO3]
24 mmol/L
1,2 mmol/L6,37,4
MECHANISMS FOR MAINTAINING AB BALANCE
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CO2 transport
• CO2 diffuse into plasma- 90% in RBC• carbon anhydrase – H2C03 production
(H+, HCO3-)• H+ ion binds to HGB (HGB buffering)
• HCO3- diffuse into plasma• in lung capillaries - ox. HGB
H+ release• H2CO3 synthesis (H2O + CO2)
MECHANISMS FOR MAINTAINING AB BALANCE
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elimination of H + elimination of non-volatilereabsorption of HCO3
– acidsHPO42- + H + → H2PO4NH3 + H + → NH4+
MECHANISMS FOR MAINTAINING AB BALANCE
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BICARBONATE –CARBONIC BUFFER: open system
pCO2 HCO3–
↓↑ reabsorption of HCO3–
prox. & distal. tubule– dissociation of H2CO3
H+ elimination into tubular fluidHCO3
– reabsorbed
elimination of CO2
ventilation regulated by respiratory center (med. oblongata)responding via alteration in
frequency & depth
respiratory component onset – minutes
metabolic componentonset – days
H+ + HCO3– H2CO3 CO2 + H2O
MECHANISMS FOR MAINTAINING AB BALANCE
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MECHANISMS FOR MAINTAINING AB BALANCE
ACIDAEMIA ACIDOSIS
ALKALAEMIA ALKALOSIS
pH of arterial blood < 7,35
pH of arterial blood > 7,45
processes resulting in pH decrease
• ↓ serum HCO3–
• ↑ pCO2
processes resulting in pH increase
• ↑ serum HCO3–
• ↓ pCO2
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pH = [HCO3
–]
pCO2
pH HCO3– pCO2 compensation
physiological values 7,4 ± 0,05 24± 2 mmol/L5,3 ± 0,5 kPa(40 mmHg)
Metabolic acidosis
Metabolic alkalosis
Respiratory acidosis
Respiratory alkalosis
primary change
compensatory change
hyperventilation
ACID-BASE BALANCE
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respiratory compensation of metabolic acidosis:KUSSMAUL BREATHING pattern
ACID-BASE BALANCE
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pH = [HCO3
–]
pCO2
pH HCO3– pCO2 compensation
physiological values 7,4 ± 0,05 24± 2 mmol/L5,3 ± 0,5 kPa(40 mmHg)
Metabolic acidosis
Metabolic alkalosis
Respiratory acidosis
Respiratory alkalosis
primary change
compensatory change
hyperventilation
hypoventilation ?
ACID-BASE BALANCE
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ACID-BASE BALANCE
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anion deficiency, AG
AG = [Na+] – ([Cl –] + [ HCO3–])
AG = 140 – (104 + 24) = 12 mmol/L (norm 8-12 mmol/L)
albumin, phospate, sulphate, lactate
ANION GAP
accumulation of anions
reaction with HCO3–
AG
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METABOLIC ACIDOSIS
pH < 7,35 primary decrease of HCO3–
pH = [HCO3
–]
pCO2
pH HCO3– pCO2 compensation
physiological value 7,4 ± 0,05 24± 2 mmol/L 5,3 ± 0,5 kPa(40 mmHg)
Metabolic acidosis
concentration of plasma HCO3
– < 22 mmol/L
DISORDERS OF ACID-BASE BALANCE
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pH < 7,35 primary decrease of HCO3–
1. reaction with H + (non-volatile acids) • ↑ intake of substances producing H +
• metabolic production of non-volatile acids
• ↓ excretion of H +
2. ↑ losses of HCO3–
concentration of plasma HCO3
–< 22 mmol/L
METABOLIC ACIDOSIS
DISORDERS OF ACID-BASE BALANCE
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intoxication by salicylates – metabolic block
intoxication by inorganic acids
ketoacidosis: insufficient glucose utilization
1. reaction with H + (acids)
METABOLIC ACIDOSIS
DISORDERS OF ACID-BASE BALANCE
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intoxication by salicylates – metabolic block
intoxication by inorganic acids
ketoacidosis: insufficient glucose utilization
diabetic: fatty acids oxidation – source H +
hyperkalemiastarvation: (fever with anorexia - mild ketoacidosis)
reduced carbohydrates intake →↓ insulin secretion ↑ glucagon secretion
alcoholic
H+
K+
H+ H+
H+
1. reaction with H + (acids)
METABOLIC ACIDOSIS
DISORDERS OF ACID-BASE BALANCE
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lactic acidosis: lactate overproduction
type A: circulatory shock, heart failure, anemia, CO poisoningtype B: organ failure (kidney, liver), malignant tumors
intoxication by methanol, etylene glycol, paraldehyd
METABOLIC ACIDOSIS
DISORDERS OF ACID-BASE BALANCE
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2. ↑ losses of HCO3–
hyperchloremic acidosis
severe diarrhea – loss of HCO3–, Na+, K+, H2O
chronic vomiting –loss of duodenal content (pH 7-8,5),loss of HCO3– > gastric acidsaccumulation of Cl-
renal tubular acidosis –↓ H+ excretion & HCO3
– loss
chronic renal insufficiency: ↓ H + excretionloss of functional parts of kidney parenchyma↓ nb of nephrons - SO4
2- , PO43- , organic aids accumulation
normal Anion GAP
METABOLIC ACIDOSIS
DISORDERS OF ACID-BASE BALANCE
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METABOLIC ACIDOSIS
DISORDERS OF ACID-BASE BALANCE
K+
H+ H+
H+
-
compensatory hyperventilation KUSSMAUL BREATHING
↓ pH – stimulation of peripheralreceptors
H+ crossing blood-brain barrier↓ pH - in respiratory center in
medulla oblongata
METABOLIC ACIDOSIS
DISORDERS OF ACID-BASE BALANCE
-
pH = [HCO3
–]
pCO2
pH HCO3– pCO2 compensation
Physiological values 7,4 ± 0,05 24± 2 mmol/L 5,3 ± 0,5 kPa(40 mmHg)
metabolic alkalosis
pH > 7,45 primary increase of HCO3–
concertation of plasma HCO3
– > 26 mmol/L
DISORDERS OF ACID-BASE BALANCE
METABOLIC ALKALOSIS
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pH > 7,45 primary increase of HCO3–
concentration ofplasma HCO3
– > 26 mmol/L
1. ↑ concentration of HCO3–
• ↑ intake (IV infusion, oral intake)
• ↓ excretion
2. ↑ loss of acids (hydrochloric acid)
DISORDERS OF ACID-BASE BALANCE
METABOLIC ALKALOSIS
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↑ intake:
intravenous infusion
oral intake – huge capacity for elimination in healthy kidneys
blood transfusion – sodium citrate (anticoagulant)
↓ excretion:primary hyperaldosteronismadministration of mineralocorticoids↑ aldosterone –Na + reabsorption, HCO3
– reabsorptionK + & H+ elimination
1. ↑ concentrations of HCO3–
DISORDERS OF ACID-BASE BALANCE
METABOLIC ALKALOSIS
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hypochloremic alkalosis:
vomitingremoval of gastric content
loss of gastric acid = loss of HCl
dehydration↓ ECF - RAAS activation –↑ release of aldosterone
→ retention of Na+ a H2O→ loss of H +
2. ↑ losses of acids
normal Anion Gap
DISORDERS OF ACID-BASE BALANCE
METABOLIC ALKALOSIS
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DISORDERS OF ACID-BASE BALANCE
METABOLIC ALKALOSIS
K+K+
K+
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pH = [HCO3
–]
pCO2
pH HCO3– pCO2 compensation
physiological values 7,4 ± 0,05 24± 2 mmol/L 5,3 ± 0,5 kPa(40 mmHg)
Respiratory acidosis
pH < 7,36 primary increase in pCO2
pCO2 > 5,8 kPa
DISORDERS OF ACID-BASE BALANCE
RESPIRATORY ACIDOSIS
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pH < 7,36 primary increase in pCO2pCO2 > 5,8 kPa
exhaled CO2 < metabolic production
HYPERCAPNIA
DISORDERS OF ACID-BASE BALANCE
RESPIRATORY ACIDOSIS
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ACUTE: failure of ventilation & depression of resp. center
cardiopulmonal failure – sudden failure in ventilation & perfusionpulmonary embolization, heart failure
drugs intoxication (hypnotics, sedatives, morphium) depression of respiratory center
trauma, infection, ischemia of CNS – local damage
CHRONIC: ↓ alveolar ventilation
chronic obstructive pulmonary disease (emphysema, bronchitis)
↓ effective alveolar ventilationsufficient renal compensation: ↑ HCO3
– reabsorptionadaptation to hypoxemia →↑ nb of RBC (erythrocythemia)
DISORDERS OF ACID-BASE BALANCE
RESPIRATORY ACIDOSIS
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DISORDERS OF ACID-BASE BALANCE
RESPIRATORY ACIDOSIS
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pH > 7,44 primary decrease in pCO2
pCO2 < 4,8 kPa
pH = [HCO3
–]
pCO2
pH HCO3– pCO2 compensation
physiological values 7,4 ± 0,05 24± 2 mmol/L 5,3 ± 0,5 kPa(40 mmHg)
respiratory alkalosis
DISORDERS OF ACID-BASE BALANCE
RESPIRATORY ALKALOSIS
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pH > 7,44 primary decrease in pCO2pCO2 < 4,8 kPa
HYPOCAPNIA
exhaled CO2 > metabolicproduction
DISORDERS OF ACID-BASE BALANCE
RESPIRATORY ALKALOSIS
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CNS DISORDERS
cerebrovascular incidents – hypoxia in area of resp. center
trauma, inflammation, tumors – stimulation of CNS
drugs (salicylates, progesterone) – stimulation of resp. center
fear, anxiety, hysterical fit – hyperventilation due to subjective feeling of air shortage
LUNG DISEASE
gas exchange disorders – ventilation/perfusion imbalance
pulmonary fibrosis, edema, pneumonia, asthma
mountain sickness↓ pO2 stimulation of hyperventilation
DISORDERS OF ACID-BASE BALANCE
RESPIRATORY ALKALOSIS
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DISORDERS OF ACID-BASE BALANCE
RESPIRATORY ALKALOSIS
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MIXED ACID-BASE DISORDERS
acute disorder
chronic disorderCOMPENSATION
metabolic acidosis + metabolic alkalosis
metabolic acidosis + respiratory acidosis
diarrhea + vomiting
circulatory failure: lactic acidosis + respiratory failure
↓HCO3– /↑ HCO3
–
↓HCO3– /↑ pCO2
DISORDERS OF ACID-BASE BALANCE
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COMPENSATION OF AB DISORDERS
Uncompensated disorder:• pH – abnormal• HCO3 – conc. or pCO2 - abnormal
Partially compensated disorder:• pH – abnormal• HCO3 – conc. - abnormal• pCO2 – abnormal
Compensated disorder:• pH – normal• HCO3 – conc. – abnormal but neutralized• pCO2 – abnormal but neutralized
Corrected disorder:• pH – normal• HCO3 – conc. – normal (returned to physiological value)• pCO2 – normal (returned to physiological value)
DISORDERS OF ACID-BASE BALANCE
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DISORDERS OF ACID-BASE BALANCE
VIDEOs explaining AB disorders
Introduction to Acid-Base Disorders:https://www.youtube.com/watch?v=jWpKJVop6G8
Metabolic acidosis - The Acid-Base Serieshttps://www.youtube.com/watch?v=IF6oF5H43Ac
Metabolic alkalosis - The Acid-Base Serieshttps://www.youtube.com/watch?v=Wf0ruPTmP1o&list=PLN4mLNb7L4VeCRfA7kB2Sj0sYvaxW4KB5&index=4
Respiratory acidosis - The Acid-Base Serieshttps://www.youtube.com/watch?v=wZICSJZOTH4&list=PLN4mLNb7L4VeCRfA7kB2Sj0sYvaxW4KB5&index=3
Respiratory alkalosis - The Acid-Base Serieshttps://www.youtube.com/watch?v=7aPzaVkCjss&list=PLN4mLNb7L4VeCRfA7kB2Sj0sYvaxW4KB5&index=2
https://www.youtube.com/watch?v=jWpKJVop6G8https://www.youtube.com/watch?v=IF6oF5H43Achttps://www.youtube.com/watch?v=Wf0ruPTmP1o&list=PLN4mLNb7L4VeCRfA7kB2Sj0sYvaxW4KB5&index=4https://www.youtube.com/watch?v=wZICSJZOTH4&list=PLN4mLNb7L4VeCRfA7kB2Sj0sYvaxW4KB5&index=3https://www.youtube.com/watch?v=7aPzaVkCjss&list=PLN4mLNb7L4VeCRfA7kB2Sj0sYvaxW4KB5&index=2