1. Changes in pH of body 1
Presented byPresented by
Pratiksha BhandariPratiksha Bhandari
B.Sc. Nursing 2013 BatchB.Sc. Nursing 2013 Batch
College of Nursing, BPKIHSCollege of Nursing, BPKIHS

2. General objectives
• At the end of the session, students will be able to know
about changes in pH of body.
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3. Specific objectives
• At the end of the session, students will be able to:
1.Define pH.
2.List normal pH values.
3.Differentiate between acid and base.
4.List the effects of pH change.
5.Enlist deviations from normal acid base status.
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4. pH
• It is the negative logarithm of concentration of
solution.
• Optimal pH: The pH value at which maximum range
of enzyme reaction occurs.
• pH = -log [H++
]]
• Normal pH = 7.35-7.45Normal pH = 7.35-7.45
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5. pH values
• Arterial blood: 7.41
• Venous blood: 7.35
(due to H2CO3)
• Interstitial fluid: 7.35
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6. pH scale 6

7. Acids
• Acids are hydrogen containing substances which
dissociate in solution to release HH++
• Acids can be defined as a proton (HH++
) donor.
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8. Acids
• Physiologically important acids include:
• Carbonic acid (HCarbonic acid (H22COCO33))
• Phosphoric acid (HPhosphoric acid (H33POPO44))
• Pyruvic acid (CPyruvic acid (C33HH44OO33))
• Lactic acid (CLactic acid (C33HH66OO33))
• These acids are dissolved in body fluids.
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9. Acids
• Sources of Hydrogen Ions.
oCell metabolism (CO2)
oFood products: Yoghurt, Citric acid in fruits
oMetabolic Intermediate by-products: Lactic acid, Pyruvic
acid, Acetoacetic acid and fatty acids.
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10. Acids
• Some disease processes: diabetes causes improper
metabolism of fats which results in the generation of
a waste product called a Keto Acid.
• Proteins (red meat products): Breakdown leads to
productions of sulfuric acid and phosphoric acid.
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11. Base
• A proton (HH++
) acceptor.
• Molecules capable of accepting a hydrogen ion.
• Physiologically important bases include:
o Bicarbonate (HCOBicarbonate (HCO33
--
))
o Biphosphate (HPOBiphosphate (HPO44
-2-2
))
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12. Acidity Vs Alkalinity
• The normal blood pH range is 7.35 to 7.45.
• When the pH is below 7.35, the blood is said to be acidic.
• When the pH is above 7.45, the blood is said to be alkalotic.
• Significant changes in the blood pH above 7.8 or below 6.8 will
interfere with cellular functioning, and if uncorrected, will lead
to death.
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13. Acidity Vs Alkalinity 13

14. Effects of PH changes
• pH changes have dramatic effects on normal
cell function
1)Changes in excitability of nerve and muscle
cells
2)Influences enzyme activity
3)Influences KK++
levels
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15. 1. CHANGES IN CELL EXCITABILITY
a. pH decrease (more acidic) depresses the
central nervous system
• Can lead to loss of consciousness
b. pH increase (more basic) can cause over-
excitability
a. Tingling sensations, nervousness
muscle twitches
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16. CHANGES IN CELL EXCITABILITY 16
p
H
p
Excitabilit
y
Excitabili

17. 2. INFLUENCES ON ENZYME ACTIVITY
• pH increase or decrease can alter the shape of the enzyme .
• Enzyme then become inactive or it can cause the enzyme to
completely break apart. (Substrate is specific substance on
which a given enzyme acts).
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18. 3. Influences of PH on K+
level
• Acidosis may lead to hyperkalemia by two
mechanism:
1.Hydrogen ions are exchanged with potassium in the
cells.
2.Hydrogen ions leaves less potassium from renal
tubules.
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19. Acidosis leads to Hyperkalemia
• Acidosis leads to hyperkalemia .ThisAcidosis leads to hyperkalemia .This
causes a shift of potassium ions out of thecauses a shift of potassium ions out of the
cells.cells.
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H+
H+
H+
H+
H+
H+
H+
H+
H+
K+
K+K+
K+
K+
K+
ACIDOSIS

20. INFLUENCES ON K+
LEVELS
• Normally : When NaNa++
is reabsorbed from the filtrate
of the renal tubules , KK++
or HH++
is secreted
(exchanged).
• KK++
is secreted in much greater amounts than HH++
in
normal condition.
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21. INFLUENCES ON K+
LEVELS
• IfIf HH++
concentrations are high ( as in acidosis), thisconcentrations are high ( as in acidosis), this
leaves lessleaves less KK++
than usual excreted result in retentionthan usual excreted result in retention
of Kof K++
..
• The resultantThe resultant KK++
retention can affect cardiac functionretention can affect cardiac function
and other systems.and other systems.
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22. ACIDOSIS / ALKALOSIS
• Acidosis and alkalosis are not diseases but rather are the results
of a wide variety of disorders.
• A relative increase in hydrogen ions results in acidosis.acidosis.
• A relative increase in bicarbonate results in alkalosis.alkalosis.
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23. Summary
AlkalosisAlkalosis
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H+
OH-
AcidosisAcidosis
H+ OH-

24. ACIDOSIS / ALKALOSIS
• Normal base to acid ratio = 20:1
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25. ACIDOSIS / ALKALOSIS
• Deviations from normal Acid-Base status are
divided into four general categories;
• Respiratory Acidosis
• Respiratory Alkalosis
• Metabolic Acidosis
• Metabolic Alkalosis
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26. 1. Respiratory acidosis
• Characterized by a pH decrease and an increase in
COCO22.
• Causes :
- Obstruction of air passages: Vomit
- Decreased respiration
- Disease of lungs
- Collapse of lung
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27. Nursing management
• Treatment of underlying causes
• Pulmonary and oral hygiene: Frequent clearing of
mucus and discharge from the respiratory tract.
• Positioning: Upright/ semi-flowers position
(facilitates maximum lung expansion).
• Teach breathing technique.
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28. Nursing management
• Mechanical ventilation use/ adjustment to gradually
decrease Carbondioxide
• Monitor GCS
• Monitor respiratory rate/ depth/ pulse rate/
regularity/ cyanosis.
• Frequent evaluation of ECG changes and CXR
changes.
• Brochodilators use.
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29. 2. Respiratory alkalosis
• A primary disorder where the first change is a
lowering of PaCO2, resulting in an elevated pH .
• Due to hyperventilation.
• Causes :
• Anxiety
• Fever
• High altitude
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30. Nursing management
• Relaxation technique and adequate rest.
• Assist client to breathe more slowly.
• In case of hypoxia: Oxygen inhalation
• Anti-anxiety drugs, sedatives.
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31. 3. Metabolic acidosis
• A primary disorder where the first change is a
lowering of HCO3¯ , resulting in decreased pH.
• Causes :
- Acute or chronic renal failure
- Diabetic ketoacidosis
- Poisonings: Aspirin, methanol, CO, Cyanide
- Diarrhoea
- Renal tubular acidosis
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32. Nursing management
• Adequate hydration and electrolyte balance
• Strict I/O charting and daily weighing.
• Frequent ABG monitoring
• Mechanical ventilation
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33. 4. Metabolic alkalosis
• A primary disorder where the first change is an
elevation of HCO3¯ , resulting in increased pH.
• Causes :
- Ingestion of alkaline substance (antacids: The extra
bicarbonate is absorbed in plasma, increasing pH of
plasma.)
- Vomiting (HCl loss, loss of hydrogen ion)
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34. Nursing management
• Maintain fluid balance.
• Potassium supplementation.
• Monitor vital signs and neurological status.
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35. Summary
• pH is the negative logarithm of concentration of
solution.
• A relative increase in hydrogen ions results in
acidosis.acidosis.
• A relative increase in bicarbonate results in
alkalosis.alkalosis.
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36. 36

37. MCQ
1. All are the causes of metabolic acidosis except
a.Diuresis
b.Diabetic ketoacidosis
c.Starvation
d.Methanol poisoning
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38. MCQ
2. All are the causes of respiratory alkalosis except
a.Anxiety
b.Fever
c.High altitude
d.Poliomyelitis
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39. MCQ
3. Normal pH value is
a.<7.35
b.>7.45
c.7.35-7.45
d.All
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40. SAQ
• Define pH. What are the effects of pH changes?
• Enlist the causes of respiratory acidosis.
• Describe management of patient with acid-base
imbalances.
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41. 41

42. 42

43. References
• J. Roshan, J. Rijuta, J and J Health Science, Body fluid, 4th
edition, 2016, page no 22-26
• Mandal G.N. A textbook of Adult Nursing, 2nd
Edition, Makalu
Publication House, August 2013, Page no. 123-127
• C. Carroll, Conn’s current therapy, Acid-Base, W.B Saunders
Company, 1st
edition, 1986, Page no 929.
• F. Sandra, Clinical, pH changes, 4th
edition, 1996, page no 815,
822, 823.
• Cited on https://en.wikipedia.org/wiki/pH , assessed on 23rd
May,
2017.
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