Lewis acid-base theory. Very different from Brønsted-Lowrey acid-base.
Acid base balane
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Transcript of Acid base balane
Physiology of Acid-Base Balance
Physiology of Acid-Base Balance
Under the guidance of :
Dr. Sandeep Tandon
Professor and Head of Dept. of Pedodontics
Dr.
Ambika S. Rathore Dr. Rinku
Mathur Dr .Shantanu
Jain Dr. Tripti
Sharma Rai
Under the guidance of :
Dr. Sandeep Tandon
Professor and Head of Dept. of Pedodontics
Dr.
Ambika S. Rathore Dr. Rinku
Mathur Dr .Shantanu
Jain Dr. Tripti
Sharma Rai
2
CONTENT:CONTENT:♣ Introduction♣ Acid-Base Balance♣ ph Scale♣ Acidosis and Alkalosis♣ Compensatory Mechanisms♣ Disturbance in acid-base balance♣ Anion Gap♣ Factors affecting acid-base balance in
children♣ Infantile metabolic acidosis
♣ Introduction♣ Acid-Base Balance♣ ph Scale♣ Acidosis and Alkalosis♣ Compensatory Mechanisms♣ Disturbance in acid-base balance♣ Anion Gap♣ Factors affecting acid-base balance in
children♣ Infantile metabolic acidosis
3
IntroductionIntroduction♠Acid-base homeostasis is the
part of human homeostasis concerning the proper balance between acids and bases, in other words, the pH.
♠Chemical and physiologic processes responsible for the maintenance of the acidity of body fluids.
♠Acid-base homeostasis is the part of human homeostasis concerning the proper balance between acids and bases, in other words, the pH.
♠Chemical and physiologic processes responsible for the maintenance of the acidity of body fluids.
4
Acid Base HomeostasisAcid Base Homeostasis Chemical processes: extracellular intracellular buffers
The physiologic processes: the excretion of volatile acids by the lungs and fixed acids by the kidneys
Chemical processes: extracellular intracellular buffers
The physiologic processes: the excretion of volatile acids by the lungs and fixed acids by the kidneys
5
ACID-BASE BALANCEACID-BASE BALANCE
6
ACIDSACIDSAcids can be defined as a proton (H+) donor
Hydrogen containing substances which dissociate in solution to release H+
Acids can be defined as a proton (H+) donor
Hydrogen containing substances which dissociate in solution to release H+
H+OH-
H+
OH-
H+
OH-
H+
OH-
7
ACIDSACIDS• Physiologically important acids include:
–Carbonic acid (H2CO3)–Phosphoric acid (H3PO4)–Pyruvic acid (C3H4O3)–Lactic acid (C3H6O3)
• Physiologically important acids include:
–Carbonic acid (H2CO3)–Phosphoric acid (H3PO4)–Pyruvic acid (C3H4O3)–Lactic acid (C3H6O3)
Lactic acid
Pyruvic acid
Phosphoric acid
8
BASESBASES
9
BASESBASES Bases can be defined as:
♥ A proton (H+) acceptor♥ Molecules capable of accepting a
hydrogen ion (OH-)
Bases can be defined as:♥ A proton (H+) acceptor♥ Molecules capable of accepting a
hydrogen ion (OH-)
H+OH-
H+
OH-
H+
OH-
H+
OH-
10
BASESBASES• Physiologically important bases
include:
–Bicarbonate (HCO3- )
–Biphosphate (HPO4-2 )
• Physiologically important bases include:
–Bicarbonate (HCO3- )
–Biphosphate (HPO4-2 )
Biphosphate
11
pH SCALEpH SCALE
12
• pH refers to Potential Hydrogen• Expresses hydrogen ion concentration in
water solutions.• Water ionizes to a limited extent to form
equal amounts of H+ ions and OH- ions
H2O H+ + OH-
•H+ ion is an acid
•OH- ion is a base
• pH refers to Potential Hydrogen• Expresses hydrogen ion concentration in
water solutions.• Water ionizes to a limited extent to form
equal amounts of H+ ions and OH- ions
H2O H+ + OH-
•H+ ion is an acid
•OH- ion is a base
pH SCALEpH SCALE
13
• Pure water is Neutral♥ ( H+ = OH- )
• pH = 7• Acid
♥ ( H+ > OH- ) • pH < 7
• Base ♥ ( H+ < OH- )
• pH > 7• Normal blood pH is 7.35 - 7.45• pH range compatible with life is 6.8 - 8.0
• Pure water is Neutral♥ ( H+ = OH- )
• pH = 7• Acid
♥ ( H+ > OH- ) • pH < 7
• Base ♥ ( H+ < OH- )
• pH > 7• Normal blood pH is 7.35 - 7.45• pH range compatible with life is 6.8 - 8.0
pH SCALEpH SCALE
OH-
OH-
OH-
OH-
OH-
OH-
H+
H+
H+
H+
OH-
OH-
OH-
OH-OH-
H+
H+
H+
H+OH-
OH-
OH-
H+
H+
H+
H+H+
H+
H+
ACIDS, BASES OR NEUTRAL???
1
2
3
14
pH SCALEpH SCALE• Normal hydrogen ion concentration in
ECF= 38-42 nM/L.• Ph scale- simplify the mathematical
handling of large numbers.
Unit changes in pH represent a tenfold change in H+ concentrations
• Normal hydrogen ion concentration in ECF= 38-42 nM/L.
• Ph scale- simplify the mathematical handling of large numbers.
Unit changes in pH represent a tenfold change in H+ concentrations
pH = log 1 / H+ concentration
15
pH SCALEpH SCALE
Ph of the ECF: 7.40 Ph of the ECF: 7.40
ACIDOSIS ALKALOSISNORMAL
DEATH DEATH
Venous Blood
Arterial Blood
7.3 7.57.46.8 8.0
16
Determination of Acid Base Status
Determination of Acid Base Status
Henderson-Hasselbalch equation Normal acid-base ratio= 1:20
ph of arterial blood= indirect method
Henderson-Hasselbalch equation Normal acid-base ratio= 1:20
ph of arterial blood= indirect method
• pH = pK + log HCO3
CO2
• pH = pK + log HCO3
CO2
17
ACIDOSIS / ALKALOSISACIDOSIS / ALKALOSIS
18
ACIDOSIS / ALKALOSISACIDOSIS / ALKALOSIS
• Acidosis♠ A condition in which the blood has too much
acid (or too little base), frequently resulting in a decrease in blood pH
• Alkalosis♠ A condition in which the blood has too much
base (or too little acid), occasionally resulting in an increase in blood pH
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♥ Alkalosis♥ Alkalosis
Acidosis / AlkalosisAcidosis / Alkalosis
H+ OH-
©Acidosis
H+ OH-
20
ACIDOSIS / ALKALOSISACIDOSIS / ALKALOSIS• pH changes have dramatic effects on
normal cell function1) Changes in excitability of nerve and
muscle cells2) Influences enzyme activity3) Influences K+ levels
• pH changes have dramatic effects on normal cell function1) Changes in excitability of nerve and
muscle cells2) Influences enzyme activity3) Influences K+ levels
21
Changes in Cell Excitability
Changes in Cell Excitability
pH decrease (more acidic) depresses the central nervous systemCan lead to loss of consciousness
pH increase (more basic) can cause over-excitabilityTingling sensations, nervousness, muscle
twitches
pH decrease (more acidic) depresses the central nervous systemCan lead to loss of consciousness
pH increase (more basic) can cause over-excitabilityTingling sensations, nervousness, muscle
twitches
22
Influences on Enzyme Activity
Influences on Enzyme Activity
pH increases or decreases can alter the shape of the enzyme rendering it non-functional.
Changes in enzyme structure can result in accelerated or depressed metabolic actions within the cell.
pH increases or decreases can alter the shape of the enzyme rendering it non-functional.
Changes in enzyme structure can result in accelerated or depressed metabolic actions within the cell.
23
Influences On K+ LevelsInfluences On K+ Levels
When reabsorbing Na+ from the filtrate of the renal tubules K+ or H+ is secreted (exchanged).
Normally K+ issecreted in muchgreater amountsthan H+
When reabsorbing Na+ from the filtrate of the renal tubules K+ or H+ is secreted (exchanged).
Normally K+ issecreted in muchgreater amountsthan H+
K+
K+K+K+K+K+K+
Na+Na+Na+Na+Na+Na+
H+
24
Influences On K+ LevelsInfluences On K+ Levels
If H+ concentrations are high (acidosis) than H+ is secreted in greater amounts.
This leaves less K+ than usual excreted.
The resultant K+ retention can affect cardiac function and other systems.
If H+ concentrations are high (acidosis) than H+ is secreted in greater amounts.
This leaves less K+ than usual excreted.
The resultant K+ retention can affect cardiac function and other systems.
K+K+K+
Na+Na+Na+Na+Na+Na+
H+H+H+H+H+H+H+
K+K+K+K+K+
25
SOURCE OF HYDROGEN ION
SOURCE OF HYDROGEN ION
H2CO3
H+
HCO3-
CO2 + H2O H2CO3 H+ + HCO3
-
26
Regulation of Acid Base Balance
Regulation of Acid Base Balance
• Two types of acids are produced in the body:
Volatile acids : CO2 produced during the metabolism of carbohydrates and lipids
Non-volatile acids: metabolism of
protein e.g. sulphuric acids
• Two types of acids are produced in the body:
Volatile acids : CO2 produced during the metabolism of carbohydrates and lipids
Non-volatile acids: metabolism of
protein e.g. sulphuric acids
27
Compensatory mechanisms
Compensatory mechanisms
1) Chemical Buffers♥ React very rapidly
(less than a second)
2) Respiratory Regulation♥ Reacts rapidly (seconds to minutes)
3) Renal Regulation♥ Reacts slowly (minutes to hours)
4) Intracellular Shifts of Ions
1) Chemical Buffers♥ React very rapidly
(less than a second)
2) Respiratory Regulation♥ Reacts rapidly (seconds to minutes)
3) Renal Regulation♥ Reacts slowly (minutes to hours)
4) Intracellular Shifts of Ions
28
Acid-base buffer systemAcid-base buffer system♣ Maintains the pH by binding with
free hydrogen ions.♣ Combination of weak acid and a
base (unprotonated compound).♣ Three major chemical buffer
systems Bicarbonate system Phosphate system Protein system
♣ Maintains the pH by binding with free hydrogen ions.
♣ Combination of weak acid and a base (unprotonated compound).
♣ Three major chemical buffer systems
Bicarbonate system Phosphate system Protein system
29
BICARBONATE BUFFER SYSTEMBICARBONATE BUFFER SYSTEM• This system is most important because
the concentration of both components can be regulated:♥ Carbonic acid by the respiratory
system♥ Bicarbonate by the renal system
• This system is most important because the concentration of both components can be regulated:♥ Carbonic acid by the respiratory
system♥ Bicarbonate by the renal system
30
H2CO3 H+ + HCO3-
♠Hydrogen ions generated by metabolism or by ingestion react with bicarbonate base to form more carbonic acid
H2CO3 H+ + HCO3-
♠Hydrogen ions generated by metabolism or by ingestion react with bicarbonate base to form more carbonic acid
HCO3-H2CO3
31
BICARBONATE BUFFER SYSTEMBICARBONATE BUFFER SYSTEMEquilibrium shifts toward the formation of
acid♥ Hydrogen ions that are lost (vomiting)
causes carbonic acid to dissociate yielding replacement H+ and bicarbonate
Equilibrium shifts toward the formation of acid♥ Hydrogen ions that are lost (vomiting)
causes carbonic acid to dissociate yielding replacement H+ and bicarbonate
H+ HCO3-
H2CO3
32
Loss of HCl
Addition of lactic acid
BICARBONATE BUFFER SYSTEMBICARBONATE BUFFER SYSTEM
H+ HCO3-H2CO3H2OCO2 + +
Exercise
Vomiting
33
Na2HPO4 + H+ NaH2PO4 + Na+
Most important in the intracellular system
Na2HPO4 + H+ NaH2PO4 + Na+
Most important in the intracellular system
PHOSPHATE BUFFER SYSTEMPHOSPHATE BUFFER SYSTEM
H+ Na2HPO4+
NaH2PO4Na++
34
♠Regulates pH within the cells and the urinePhosphate concentrations are higher
intracellular and within the kidney tubules.
More phosphate ions are found in tubular fluids
More powerful thanbicarbonate buffer system
♠Regulates pH within the cells and the urinePhosphate concentrations are higher
intracellular and within the kidney tubules.
More phosphate ions are found in tubular fluids
More powerful thanbicarbonate buffer system
PHOSPHATE BUFFER SYSTEMPHOSPHATE BUFFER SYSTEM
HPO4-2
35
PROTEIN BUFFER SYSTEMPROTEIN BUFFER SYSTEM• Proteins are excellent buffers because they
contain both acid and base groups that can give up or take up H+
• Proteins are extremely abundant in the cell• The more limited number of proteins in the
plasma reinforce the bicarbonate system in the ECF
• Proteins are excellent buffers because they contain both acid and base groups that can give up or take up H+
• Proteins are extremely abundant in the cell• The more limited number of proteins in the
plasma reinforce the bicarbonate system in the ECF
36
Hemoglobin buffers H+ from metabolically produced CO2 in the plasma only
As hemoglobin releases O2 it gains a great affinity for H+
Hemoglobin buffers H+ from metabolically produced CO2 in the plasma only
As hemoglobin releases O2 it gains a great affinity for H+
HbO2
O2 O2
O2
37
• H+ generated at the tissue level from the dissociation of H2CO3 produced by the addition of CO2
• Bound H+ to Hb (Hemoglobin) does not contribute to the acidity of blood
• H+ generated at the tissue level from the dissociation of H2CO3 produced by the addition of CO2
• Bound H+ to Hb (Hemoglobin) does not contribute to the acidity of blood
HbO2
O2 O2
O2
38
• As H+Hb picks up O2 from the lungs the Hb which has a higher affinity for O2 releases H+ and picks up O2
• Liberated H+ from H2O combines with HCO3
-
HCO3- H2CO3 CO2 (exhaled)
• As H+Hb picks up O2 from the lungs the Hb which has a higher affinity for O2 releases H+ and picks up O2
• Liberated H+ from H2O combines with HCO3
-
HCO3- H2CO3 CO2 (exhaled)
HbO2
O2 O2
H+
39
RESPIRATORY CENTRE
RESPIRATORY CENTRE
Respiratory centers
Medulla oblongata
Pons
40
CHEMOSENSITIVE AREASCHEMOSENSITIVE AREAS Chemo sensitive areas of the respiratory
center are able to detect blood concentration levels of CO2 and H+
Increases in CO2 and H+ stimulate the respiratory center♣ The effect is to raise
respiration rates ♣ But the effect
diminishes in1 - 2 minutes
Chemo sensitive areas of the respiratory center are able to detect blood concentration levels of CO2 and H+
Increases in CO2 and H+ stimulate the respiratory center♣ The effect is to raise
respiration rates ♣ But the effect
diminishes in1 - 2 minutes
CO2CO2
CO2CO2CO2
CO2CO2
CO2
CO2
41
RESPIRATORY CONTROL OF pHRESPIRATORY CONTROL OF pH
pH rises toward normal
rate and depth of breathing increase
CO2 eliminated in lungs
H+ stimulates respiratory center in medulla oblongata
H2CO3 H+ + HCO3-
H+ acidosis; pH drops
CO2 + H2O H2CO3
cell production of CO2 increases
42
RENAL RESPONSERENAL RESPONSE• The kidney compensates for Acid - Base
imbalance within 24 hours and is responsible for long term control
• The kidney in response:– To Acidosis
• Retains bicarbonate ions and eliminates hydrogen ions
– To Alkalosis• Eliminates bicarbonate ions and retains
hydrogen ions
• The kidney compensates for Acid - Base imbalance within 24 hours and is responsible for long term control
• The kidney in response:– To Acidosis
• Retains bicarbonate ions and eliminates hydrogen ions
– To Alkalosis• Eliminates bicarbonate ions and retains
hydrogen ions
43
ELECTROLYTE SHIFTSELECTROLYTE SHIFTS
cell
H+
K+
AcidosisCompensatory Response Result
- H+ buffered intracellularly
- Hyperkalemia
H+
K+
cell
AlkalosisCompensatory Response Result
- Tendency to correct alkalosis
- Hypo kalemia
-Diabetic ketoacidosis
44
DISTURBANCE OF ACID BASE BALANCE
DISTURBANCE OF ACID BASE BALANCE
♠Four general categories, depending on the source and direction of the abnormal change in H+ concentrations:
♥ Respiratory Acidosis♥ Respiratory Alkalosis♥ Metabolic Acidosis♥ Metabolic Alkalosis
♠Four general categories, depending on the source and direction of the abnormal change in H+ concentrations:
♥ Respiratory Acidosis♥ Respiratory Alkalosis♥ Metabolic Acidosis♥ Metabolic Alkalosis
45
RESPIRATORY ACIDOSISRESPIRATORY ACIDOSIS
46
RESPIRATORY ACIDOSISRESPIRATORY ACIDOSIS• Caused by hyperkapnia due to
hypoventilation– Characterized by a pH decrease and
an increase in CO2
• Caused by hyperkapnia due to hypoventilation– Characterized by a pH decrease and
an increase in CO2
CO2 CO2
CO2
CO2
CO2
CO2CO2
CO2CO2
CO2
CO2 CO2
CO2
pH
pH
47
RESPIRATORY ACIDOSISRESPIRATORY ACIDOSIS
♥ Respiratory acidosis develops when the lungs don't expel CO2 adequately
♥ Emphysema, chronic bronchitis, severe pneumonia, pulmonary edema, and asthma
♥ Respiratory acidosis develops when the lungs don't expel CO2 adequately
♥ Emphysema, chronic bronchitis, severe pneumonia, pulmonary edema, and asthma
48
RESPIRATORY ACIDOSISRESPIRATORY ACIDOSIS♠ Decreased CO2 removal can
be the result of:1) Obstruction of air
passages2) Decreased respiration
(depression of respiratory centers)
3) Decreased gas exchange between pulmonary capillaries and air sacs of lungs
4) Collapse of lung
♠ Decreased CO2 removal can be the result of:1) Obstruction of air
passages2) Decreased respiration
(depression of respiratory centers)
3) Decreased gas exchange between pulmonary capillaries and air sacs of lungs
4) Collapse of lung
49
4) Collapse of lungCompression injury, open thoracic
wound
4) Collapse of lungCompression injury, open thoracic
wound
Left lung collapsed
50
RESPIRATORY ACIDOSISRESPIRATORY ACIDOSIS
◊ breathing is suppressed holding CO2 in body◊ pH = 7.1
H2CO3
HCO3-
2 20:
CO
2CO
2
CO
2CO
2
51
BODY’S COMPENSATION♠ kidneys conserve HCO3
- ions to restore the normal 40:2 ratio (20:1)♠ kidneys eliminate H+ ion in acidic urine
H2CO3
HCO3-
2 30:
HCO3-
H2CO3
HCO3-
H+
+
acidic urine
52
♠ therapy required to restore metabolic balance♠ lactate solution used in therapy is converted to bicarbonate ions in the liver
H2CO3 HCO3-
2 40:
Lactate
Lactate
LIVER
HCO3-
53
RESPIRATORY ALKALOSISRESPIRATORY ALKALOSIS♣ Normal 20:1 ratio is increased
♣ pH of blood is above 7.4
♣ Normal 20:1 ratio is increased♣ pH of blood is above 7.4
H2CO3 HCO3-
20:= 7.4
H2CO
3 HCO3
-
0.5 20:= 7.4
54
RESPIRATORY ALKALOSISRESPIRATORY ALKALOSIS◊ Cause is Hyperventilation
♥ Leads to eliminating excessive amounts of CO2
♥ Increased loss of CO2 from the lungs at a rate faster than it is produced
♥ Decrease in H+
◊ Cause is Hyperventilation♥ Leads to eliminating excessive amounts of
CO2
♥ Increased loss of CO2 from the lungs at a rate faster than it is produced
♥ Decrease in H+
CO
2
CO
2
CO
2
CO
2
CO
2 CO
2
CO
2CO
2
CO
2
CO
2CO
2
CO
2
55
RESPIRATORY ALKALOSISRESPIRATORY ALKALOSIS• Can be the result of:
1) Anxiety, emotional disturbances
2) Respiratory center lesions3) Fever
4) Salicylate poisoning (overdose)
5) Assisted respiration
6) High altitude (low PO2)
• Can be the result of:1) Anxiety, emotional
disturbances
2) Respiratory center lesions3) Fever
4) Salicylate poisoning (overdose)
5) Assisted respiration
6) High altitude (low PO2)
56
Kidneys compensate by:♣ Retaining hydrogen ions♣ Increasing bicarbonate
excretion
Kidneys compensate by:♣ Retaining hydrogen ions♣ Increasing bicarbonate
excretion
H+
HCO3-
HCO3-
HCO3-
HCO3-
HCO3-
HCO3-
HCO3- HCO3
-
HCO3-
HCO3-
H+
H+
H+
H+H+
H+
H+
H+
H+
H+
57
RESPIRATORY ALKALOSISRESPIRATORY ALKALOSIS
therapy required to restore metabolic balance HCO3
- ions replaced by Cl- ions
H2CO3 HCO3-
0.5 10:
Cl-
Chloride containing solution
58
METABOLIC ACIDOSISMETABOLIC ACIDOSIS Occurs when there is a decrease in the
normal 20:1 ratio♠Decrease in blood pH and bicarbonate
level
Excessive H+ or decreased HCO3-
Occurs when there is a decrease in the normal 20:1 ratio♠Decrease in blood pH and bicarbonate
level
Excessive H+ or decreased HCO3-
H2CO3 HCO3-
1 20:= 7.4
H2CO3
HCO3-
1 10:= 7.4
59
METABOLIC ACIDOSISMETABOLIC ACIDOSIS♣ Acidosis results from excessive loss of HCO3
- rich fluids from the body or from an accumulation of acids.♣ Accumulation of non-carbonic plasma
acids uses HCO3- as a buffer for the
additional H+ thus reducing HCO3- levels
♣ Acidosis results from excessive loss of HCO3-
rich fluids from the body or from an accumulation of acids.♣ Accumulation of non-carbonic plasma
acids uses HCO3- as a buffer for the
additional H+ thus reducing HCO3- levels
Lactic Acid
Muscle Cell
60
METABOLIC ACIDOSISMETABOLIC ACIDOSIS Metabolic acidosis is always
characterized by a reduction in plasma HCO3
- while CO2 remains normal
Metabolic acidosis is always characterized by a reduction in plasma HCO3
- while CO2 remains normal
HCO3-
CO2
Plasma Levels
61
METABOLIC ACIDOSISMETABOLIC ACIDOSISThe causes of metabolic acidosis can be
grouped into five major categories;
1) Ingesting an acid or a substance that is metabolized to acid
2) Abnormal Metabolism3) Kidney Insufficiencies4) Strenuous Exercise5) Severe Diarrhea
The causes of metabolic acidosis can be grouped into five major categories;
1) Ingesting an acid or a substance that is metabolized to acid
2) Abnormal Metabolism3) Kidney Insufficiencies4) Strenuous Exercise5) Severe Diarrhea
62
METABOLIC ACIDOSISMETABOLIC ACIDOSIS Treating the underlying cause of
metabolic acidosis is the usual course of action♥ Control diabetes with insulin or treat
poisoning by removing the toxic substancefrom the blood
♥ Occasionallydialysis is neededto treat severeoverdoses andpoisonings
Treating the underlying cause of metabolic acidosis is the usual course of action♥ Control diabetes with insulin or treat
poisoning by removing the toxic substancefrom the blood
♥ Occasionallydialysis is neededto treat severeoverdoses andpoisonings
63
METABOLIC ACIDOSISMETABOLIC ACIDOSIS
Metabolic acidosis may also be treated directly♥ If the acidosis is mild,
intravenous fluids and treatment for the underlying disorder may be all that's needed
Metabolic acidosis may also be treated directly♥ If the acidosis is mild,
intravenous fluids and treatment for the underlying disorder may be all that's needed
64
METABOLIC ACIDOSISMETABOLIC ACIDOSIS
When acidosis is severe, bicarbonate may be given intravenously♥ Bicarbonate provides
only temporary relief.
When acidosis is severe, bicarbonate may be given intravenously♥ Bicarbonate provides
only temporary relief.
65
METABOLIC ALKALOSISMETABOLIC ALKALOSIS♣ Elevation of pH due to an increased 20:1
ratio May be caused by:
• An increase of bicarbonate • A decrease in hydrogen ions
Imbalance again cannot be due to CO2
Increase in pH which has a non-respiratory origin
♣ Elevation of pH due to an increased 20:1 ratio May be caused by:
• An increase of bicarbonate • A decrease in hydrogen ions
Imbalance again cannot be due to CO2
Increase in pH which has a non-respiratory origin 7.4
66
METABOLIC ALKALOSISMETABOLIC ALKALOSIS A reduction in H+ in the case of
metabolic alkalosis can be caused by a deficiency of non-carbonic acids
This is associated with an increase in HCO3
-
A reduction in H+ in the case of metabolic alkalosis can be caused by a deficiency of non-carbonic acids
This is associated with an increase in HCO3
-
67
METABOLIC ALKALOSISMETABOLIC ALKALOSIS
• Can be the result of:1. Ingestion of Alkaline Substances2. Vomiting ( loss of HCl )
• Can be the result of:1. Ingestion of Alkaline Substances2. Vomiting ( loss of HCl )
68
METABOLIC ALKALOSISMETABOLIC ALKALOSIS• Gastric juices contain large amounts of HCl
• During HCl secretion, bicarbonate is added to the plasma
K+ H+
Cl-
HCO3-
HCl
69
HCl
METABOLIC ALKALOSISMETABOLIC ALKALOSIS
K+H+ Cl-
HCO3-
• The bicarbonate is neutralized as HCl is reabsorbed by the plasma from the digestive tract
H2CO3
70
HCl K+
HCO3-
During vomiting H+ is lost as HCl and the bicarbonate is not neutralized in the plasma
♥ Loss of HCl increases the plasma bicarbonate and thus results in an increase in pH of the blood
Bicarbonate not neutralized
71
H2CO
3HCO3
-
BODY’S COMPENSATION♥ breathing suppressed to hold CO2
♥ kidneys conserve H+ ions and eliminate HCO3
- in alkaline urine
1.25 30
CO2 + H2O
HCO3- + H+
HCO3-
H+
+
Alkaline urine:
72
METABOLIC ALKALOSISMETABOLIC ALKALOSIS
♠ Therapy required to restore metabolic balance
♠ HCO3- ions replaced by Cl- ions
H2CO3 HCO3-
1.25 25:
Cl-
Chloride containing solution
73
ACID – BASE DISORDERSACID – BASE DISORDERS
Clinical State Acid-Base Disorder
Pulmonary Embolus Respiratory Alkalosis
Cirrhosis Respiratory Alkalosis
Pregnancy Respiratory Alkalosis
Diuretic Use Metabolic Alkalosis
Vomiting Metabolic Alkalosis
Chronic Obstructive Pulmonary Disease Respiratory Acidosis
Shock Metabolic Acidosis
Severe Diarrhea Metabolic Acidosis
Renal Failure Metabolic Acidosis
Sepsis (Bloodstream Infection) Respiratory Alkalosis,Metabolic Acidosis
74
CLINICAL EVALUATION OF DISTURBANCES IN ACID BASE
STATUS
CLINICAL EVALUATION OF DISTURBANCES IN ACID BASE
STATUS
75
ANION GAPANION GAP• The term anion gap (AG) represents the
concentration of all the unmeasured anions in the plasma.
• The negatively charged proteins account for about 10% of plasma anions.
Reference range is 8 to 16 mmol/l.
• The term anion gap (AG) represents the concentration of all the unmeasured anions in the plasma.
• The negatively charged proteins account for about 10% of plasma anions.
Reference range is 8 to 16 mmol/l.
Anion gap = [Na+] - [Cl-] - [HCO3
-]
AG = [Na+] + [K+] - [Cl-] - [HCO3
-]
76
Major Clinical Uses of the Anion Gap
Major Clinical Uses of the Anion Gap
♥ To signal the presence of a metabolic acidosis and confirm other findings.
♥ Help differentiate between causes of a metabolic acidosis.
ORGANIC INORGANIC
♥ To assist in assessing the biochemical severity of the acidosis and follow the response to treatment .
♥ To signal the presence of a metabolic acidosis and confirm other findings.
♥ Help differentiate between causes of a metabolic acidosis.
ORGANIC INORGANIC
♥ To assist in assessing the biochemical severity of the acidosis and follow the response to treatment .
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General Factors affecting Acid-Base Balance in Infants
General Factors affecting Acid-Base Balance in Infants♠ Low Bicarbonate depends on Gestational Age♥ lower renal threshold ♥ lower capacity to reabsorb HCO3
-
♣ Very low birth weight babies: bicarbonate levels of 12-16 mmoles/l
♣ Term babies : levels of 20-22 mmol/l.
♠ Low Bicarbonate depends on Gestational Age♥ lower renal threshold ♥ lower capacity to reabsorb HCO3
-
♣ Very low birth weight babies: bicarbonate levels of 12-16 mmoles/l
♣ Term babies : levels of 20-22 mmol/l.
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The rate of metabolism in infants is twice as great in relation to body mass as in adults
Twice as much acid is formed which leads to a tendency toward acidosis
Functional development of kidneys is not complete until the end of the first month
Renal regulation of acid base may not be optimal.
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Low Reserve to excrete an Acid Load
Low Reserve to excrete an Acid Load
♥ Term infants, acid excretion is working near maximum capacity and there is little reserve to deal with acidosis.
♥ Preterm babies less capacity than a term neonate to buffer an acid load.
♥ Term infants, acid excretion is working near maximum capacity and there is little reserve to deal with acidosis.
♥ Preterm babies less capacity than a term neonate to buffer an acid load.
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Other FactorsOther Factors• Growth results in deposition of base in
new bone as the calcium salts in bone are alkaline salts.
• On a weight basis, fixed acid production is higher than in adults.
Neonates and children < 12 months
fixed acid production is 2 to 3 mmol/kg/day).
• Growth results in deposition of base in new bone as the calcium salts in bone are alkaline salts.
• On a weight basis, fixed acid production is higher than in adults.
Neonates and children < 12 months
fixed acid production is 2 to 3 mmol/kg/day).
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Infantile Metabolic Acidosis
Infantile Metabolic Acidosis
Different inborn errors of metabolism cause a metabolic acidosis:
organic acidosis (enzyme defect resulting in accumulation of acidic metabolic intermediates)
lactic acidosis hyperchloraemic acidosis
Feeding difficulties often in association with tachypnoea
Different inborn errors of metabolism cause a metabolic acidosis:
organic acidosis (enzyme defect resulting in accumulation of acidic metabolic intermediates)
lactic acidosis hyperchloraemic acidosis
Feeding difficulties often in association with tachypnoea
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• Lactic acidosis : enzyme defects and present during childhood.
♥ pyruvate carboxylase deficiency♥ fructose-1,6-diphosphatase
deficiency ♥ pyruvate dehydrogenase deficiency.
not an isolated finding as these children have serious dysfunctions of organ systems esp. affecting brain, liver and muscle.
• Lactic acidosis : enzyme defects and present during childhood.
♥ pyruvate carboxylase deficiency♥ fructose-1,6-diphosphatase
deficiency ♥ pyruvate dehydrogenase deficiency.
not an isolated finding as these children have serious dysfunctions of organ systems esp. affecting brain, liver and muscle.
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Other Acid-Base Disorders in Children
Other Acid-Base Disorders in Children
• Insulin dependent diabetes mellitus usually presents during childhood or adolesence.
• Poisoning in children may cause an acid-base disorder
• Insulin dependent diabetes mellitus usually presents during childhood or adolesence.
• Poisoning in children may cause an acid-base disorder
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REFERENCESREFERENCES• Fundamentals of physiology: a human
perspective: Lauralee Sherwood; Fluid and acid base balance; page:453-61
• Essentials of medical physiology: K Sembulingam; Acid base balance:36-47
• Ganong’s Review of Medical Physiology: Renal physiology: 679-682
• Fundamentals of physiology: a human
perspective: Lauralee Sherwood; Fluid and acid base balance; page:453-61
• Essentials of medical physiology: K Sembulingam; Acid base balance:36-47
• Ganong’s Review of Medical Physiology: Renal physiology: 679-682
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THANK YOUTHANK YOU
Presented by:
Dr. Ruby Kharkwal
1st year postgraduate student
Department of Pedodontics
Presented by:
Dr. Ruby Kharkwal
1st year postgraduate student
Department of Pedodontics