Fluid, electrolytes & acid base imblances.

1. Fluid, Electrolyte and
Acid- base balance and
disorders
Medical Surgical nursing I
2024 cohort
17th
FEBRUARY 2025
By D. Kamalizeni
1

2. 2
Learning Objectives
(Refer to content of similar nature covered
in Biochemistry, Biophysiscs and HAP)
•Describe an overview of the fluid,
electrolyte and acid base balance in the
body.
•Describe the common alterations in fluid
and electrolyte balance

3. Learning Objectives/Outcomes
CTs…..,
• Describe the assessment parameters for the
client with potential or actual fluid,
electrolyte and acid-base imbalance.
• Plan appropriate care for patients to
promote fluid, electrolyte and acid-base
balance
3

4. Overview of fluid and electrolytes
balance in the body (revision)
Fluids constitute about 50 to +60% of the body
Fluids occupy 2 main compartments in the
body: Intracellular fluid (ICF);(2/3) and
Extracellular (ECF);(1/3)
Body fluids serve as universal solvents for
varied solutes broadly classified as electrolytes
and non-electrolytes and balance of these is a
must for health living
4

5. Overview of electrolytes and non-
electrolytes
Electrolytes:
•Substances that dissociate/split into charged
particles(ions) when put in a solution; eg,
Sodium Chloride, Calcium Carbonate,
Potassium Chloride
•Ions are electrically charged particles:
•Can therefore conduct electrical current hence
are called electrolytes
5

6. Electrolytes CTs….,
• In their ionized forms, some of these elements
play NB roles in the body:
Sodium maintains water balance,
Potassium and Calcium are necessary for nerve
impulse conduction, muscle contraction
• Composition of the electrolytes and
concentration of specific ions varies btn ICF &
ECF
6

7. Overview of electrolytes and non-
electrolytes CTs
Non-electrolytes:
•Substances which do not dissociate into ions
when put in a solution
•Have bonds that prevent them from
dissociating when put in a solution
•No electrically charged species are created
when they dissolve in water; Eg glucose , urea
7

8. Overview of Acids and Bases
Are also electrolytes; they ionize and dissociate
in water
Acids
Substances that release hydrogen ions;
Also called proton donors
When dissolved in water, they release hydrogen
ions (protons) and anions, eg include;
Hydrochloric acid (HCL)
8

9. Acids/bases CTs
The concentration of the protons (hydrogen
ions) determines the acidity of a solution
Bases
• Substances that take up hydrogen ions, ie,
Proton acceptors, eg, Sodium Hydroxide
(NaOH)
• If this dissolves in water, it dissociates and
liberates hydroxyl ions and Sodium ions
9

10. Acids/bases CTs
The hydroxyl ion then binds to (accepts) a
proton (hydrogen ion) present in the
solution
The rxn above produces water and
simultaneously reduces the acidity
(hydrogen ion concentration) in the solution
10

11. pH and acid base concentration)
The more hydrogen ions in a solution, the more
acidic the solution is.
Conversely, the greater the concentration of
hydroxyl ions, the lower the concentration of
hydrogen ions; the more basic or alkaline the
solution becomes
The relative concentration of hydrogen ions in
various body fluids is measured in a concentration
units called `pH units`
11

12. The pH scale
Devised by a Danish biochemist in the 1909
The scale runs from 1 to 14
At pH 7, the solution is neutral; neither acidic nor
basic; (hydrogen ions = hydroxyl ions) eg, pure water
Solution below pH 7 is acidic; (hydrogen ions
outnumber hydroxyl ions)
That above pH 7 are alkaline ( hydrogen ions are
decreasing)
12

13. Balance
Balance is the state of equilibrium (Stability),
where waste and excess products are efficiently
removed and necessary nutrients are always
available.
Intake of fluids = fluids excreted from body in
human homoeostatic state. Thereby maintaining
optimal hydration
In order to maintain homeostasis, fluid, electrolyte,
and acid/base levels must remain nearly constant
within their normal limits.
13

14. Balance CTs…..,
In nursing, fluid balance refers to procedure
of measuring fluid input and output to
determine fluid need
14

15. Importance of body fluids
Fluid essential to life and vital for:
– Controlling body temp
– Delivery of nutrients and gases to cells
– Removal of waste
– Acid – base balance
– Maintenance of cellular shape
15

16. Fluid compartments
– Intracellular fluid Compartment
and
– Extracellular fluid Compartment
• Interstitial Fluid/space – surrounds cells
• Intravascular - within blood vessels (Plasma)
16

17. Electrolyte composition in fluid
compartments
Each fluid compartment has a distinctive
pattern of concentration of the
electrolytes/nonelectrolytes
ICF contain small amounts of sodium and
chloride ions in contrast to ECF, plasma has
high protein content
17

18. Electrolyte Balance
Refers to keeping the concentration of each
electrolyte within normal limits
The most important electrolytes for body
function are Na+
,K+
,Ca2+
and Mg2+
,Cl-
,
Phosphate, sulphate and bicarbonate are
important as well.
Concentrations are different in the ICF and
ECF.
18

19. MAJOR CATIONS AND ANIONS
19

20. TRANSPORT AND MOVEMENT
OF WATER AND SOLUTES
Read on:
OSMOSIS
passage of a solvent through a membrane from
a dilute solution to a more concentrated one)
DIFFUSION
Movement of molecules from regions of high
concentration to regions of low
concentration
20

21. Reading assignment CTs
FACILITATED DIFFUSION
moving a substance using a carrier from
outside the cell to the inside
ACTIVE TRANSPORT
Use of energy to move particles against their
gradient
21

22. Osmosis: Where will be the
direction of water flow?
22

23. Diffusion (Trace direction of flow
of the molecules)
23

24. Facilitated diffusion
24

25. Regulation of fluid homeostasis:
(reading assignment: review
work)
4 mechanisms that regulate fluid homeostasis
• ADH (Antidiuretic hormone) Hormone
that stimulates the kidneys to reabsorb
more water; reducing urine volume
(revisit how changes in blood volume or B/P
influence ADH secretion)
• Thirst Mechanism
This is to do with the driving force for
water intake: what happens when you have
a dry mouth? A lowered B/P?
25

26. Regulation of fluid homeostasis
CTs…,
• Aldosterone (hormone that regulates
sodium reabsorption)
(Read in the context of `renin-
angiotensin-aldosterone mechanism)
Low Blood Volume triggers renin
release which catalyzes production of
Angiotensin II which trigger the adrenal
cortex to release aldosterone .
Aldesterone increases reabsorption of
sodium hence fluid retention.
26

27. Regulation of fluid homeostasis
CTs
• Sympathetic Nervous System
What is the role of the nervous system
in all of the above mechanisms????
There is a deviation from normal, such
deviations must be detected,
information sent to appropriate centers,
appropriate organs/systems triggered to
respond accordingly to normalize the
deviations
27

28. Terms to Remember
Isotonic: Fluid with same concentration of
solutes to normal human plasma (implications
if infused into the human body?)
Hypertonic: Fluid with a greater conc. of
solutes to normal human plasma.
(implications if infused into the human body?)
Hypotonic: Fluid with a lesser conc. of
solutes to normal human plasma.
(implications if infused into the human body?)
28

29. Acid/Base Balance
Revision material
29

30. ACID-BASE BALANCE
Maintenance of hydrogen ion concentration in
the body fluid.
Any substance that can donate free H+ ions to
a solution is called an ACID.
Any substance that can decrease H+ ions in a
solution is a BASE.
Number of H+ ions in any solution is
indicated by means of the pH scale.
30

31. pH
Is a measurement of the acidity and
alkalinity of blood
Conversely proportion to the number of
hydrogen ions in the blood
The more hydrogen present, the lower the
pH will be (acidic)
The fewer the hydrogen present; the higher
the pH will be (alkalinity)
31

32. The Blood pH
Normal pH in human arterial blood is 7.35-
7.45
For normal metabolism to take place; the
body must maintain this narrow range all
the time
Significant changes in this blood pH range
interferes with cellular functioning and if
not corrected, can lead to death
32

33. ???????????????????????????
???????????????????????????
How is the body able to self-
regulate acid-base balance in
order to maintain pH within
the normal range for normal
cell function????
33

34. Regulation of Acid-Base Balance
in the body
High concentrations of acids & bases
are extremely damaging to the human
cells
Acid-base balance in the body is
regulated by chemical buffer systems
and the physiological buffer systems
( kidneys and lungs)
34

35. Overview of the buffer systems
• Delicate mechanisms that help the body to
self regulate acid-base balance in order to
maintain pH within the normal range:
1.The chemical buffer systems (Bicarbonate,
Phosphate and protein buffer systems)
2.The physiological buffer systems
(Respiratory and Renal systems)
35

36. The Chemical Buffer systems
(self study)
Consists of one or more compounds
that resist changes in pH when strong
acid or a strong base is added
Achieved by binding to hydrogen
ions when pH drops and releasing
them when pH rises
36

37. The Chemical Buffer systems CTs
The Bicarbonate Buffer system
•Mixture of carbonic acid and Sodium bicarbonate
in the same solution
•Buffers mostly ECF
The Phosphate buffer system
Works nearly identical to the bicarbonate buffer
system
Mixture of HCL and Sodium phosphate
37

38. The Chemical Buffer systems
CT..,
Protein Buffer system
Involves the proteins in the plasma and in
the cells
PLEASE EXPLORE MORE ON THESE 3
CHEMICAL BUFFER SYSTEMS
38

39. The physiological buffer systems
The respiratory buffer system
•CO2 is normal by-product of cellular
metabolism
•This CO2 is carried in the blood to the
lungs
•Excess CO2 in the blood combines with
water to form carbonic acid
39

40. The respiratory buffer system
cts..,
• The carbonic acid later dissociates to release
the hydrogen ions and Bicarbonate
• The blood pH will therefore change
according to the levels of carbonic acid
• This triggers the respiratory system to either
increase or decrease the rate/depth of
ventilation until the appropriate amount of
CO2 is re-established
40

41. SUMMARY OF RESPIRATORY
REGULATION OF HYDROGEN
IONS
Self study
41

42. The respiratory buffer system
CT..,
Activation of the resp system to
compensate for the imbalance starts
to occur within 1 to 3 minutes
The resp syst compensates for
changes in pH by responding to
changes in CO2 in the blood
42

43. The renal buffer system
To maintain the pH of blood within normal
ranges the kidneys excrete or retain
bicarbonate(HCO3)
A decrease in blood pH will cause the
kidneys to retain bicarbonate,(weak base
which will accept the hydrogen ions) and an
increase in pH will cause excretion of
bicarbonate through urine
43

44. NOTE
Respiratory and renal systems
together:
•Form the physiological buffer systems
that control pH by regulating amount of
acid or base in the body
•Both act more slowly than chemical
buffer systems
44

45. Issues of nursing concern
Fluid, electrolytes & acid-base disorders
45

46. ALTERED FLUID, ELECTROLYTE
AND ACID-BASE BALANCE
Fluid imbalances
Reflect an increase or decrease in total body
fluid or an altered distribution of body fluids.
2 major alterations:
– Fluid Volume Deficit (Hypovolemia) too little -
Dehydration
– Fluid Volume Excess (Hypervolemia) too much
-Overhydration
46

47. 47
Fluid Deficit
Causes
• Abnormal losses through skin ( sweating),
GIT (Vomiting or Diarrhea) or kidneys
through polyuria
• Decreased intake of fluid
• Bleeding

48. Fluid Deficit cont..
Signs and symptoms
Signs of dehydration
– Decreased skin
turgor
– Sunken eyes
– Lethargy
– Dry mucous
membranes
– Decreased tearing
and salivation
weight loss
Weak and rapid
pulse
Decreased blood
pressure
Reduced urine
output and
concentrated
48

49. Classification of FVD
Mild – 2% of body
weight loss
Moderate – 5% of
body weight loss
Severe – 8% or
more of body
weight loss
49

50. Images of clinical manifestations
of FVD
50

51. Clinical manifestation of FVD cts
…..(concentrated urine and
flattened neck veins
51

52. 52
Fluid Excess
Causes
• Too rapid administration of intravenous
fluid
• Disturbed regulation of fluid balance i.e in
heart failure, renal failure

53. Fluid Excess cont…
Signs and symptoms
• Weight gain
• Increased respiratory
rate
• Full, Bounding
increased pulse rate
• Increased blood
pressure
• Moist breath sounds
(rales), dyspnoea;
SOB
Increased urine
output
Hypertension
Edema
53

54. Distended neck veins, crackles,
weight gain in FVE
54

55. Electrolytes imbalances
Sodium, Potassium, calcium
Magnesium
55

56. Sodium
Normal range in plasma 136-145mEq/L
Has most significant osmotic effect in the
extracellular fluid.
Sodium’s major roles act on nerve impulse
conduction, muscle contraction, and
regulation of water movement.

57. Hypernatremia
Can occur due to loss of too much water or
addition or retention of too much salt.
Can cause confusion, lethargy, and
eventually seizures and death.
Retention of sodium can occur due to
excessive aldosterone secretion and renal
failure.

58. Hyponatremia
Can be due to decreased sodium intake, loss
through vomiting or diarrhea, aldosterone
deficiency, diuretics.
Symptoms include: muscular weakness,
dizziness, headache, tachycardia and shock.

59. Potassium
Normal range 3.5-5.0 mEq/L
Most abundant cation in intracellular space.
Works most on neuromuscular and cardiac
function.
Also helps maintain fluid balance and pH
balance.

60. K+ imbalances
Hypokalemia- poss. causes: loss due to
vomiting or diarrhea, decreased intake,
aldosterone excess, diuretics, or kidney
disease.
– 1st
symptoms: muscle fatigue and cramps,
arrhythmias, increased urine output
Hyperkalemia- poss. causes: excessive
intake, renal failure, aldosterone deficiency
– Irritability, diarrhoea, nausea/vomiting,
muscle weakness, confusion, numbness

61. Calcium
Normal range of unattached Ca2+
in plasma 4.5-5.5
mEq/L. ~Same amount attached to plasma
proteins.
Most calcium in the body is bound with phosphate
in the bones and teeth. In fluids, mostly an
extracellular cation.
Plays important role in blood clotting,
neurotransmitter release, muscle tone, and
excitability of nervous and muscle tissue.

62. Ca2+
imbalances
Hypocalcemia- poss causes: decreased Ca2+
intake, increased loss, elevated levels of
phospates.
– Numbness and tingling of fingers, hyper reflexes,
increased risk of fractures, muscle cramps, tetany, and
convulsions
Hypercalcemia- poss causes:
hyperparathyroidism, excessive intake of vitamin
D, or some diseases of bone.
– Lethargy, weakness, anorexia, n/v, bone pain, polyuria,
depression, confusion, stupor, and coma

63. Magnesium
Normal range in plasma 1.3-2.1 mEq/L
54% magnesium deposited in bone matrix.
Mg2+
is the 2nd
most common intracellular
cation.
important in neuromuscular activity, nerve
impulse transmission, myocardial function,
and parathyroid hormone secretion.
63

64. Mg2+
imbalances
Hypomagnesemia- poss. causes: inadequate
intake or excessive loss in urine and feces.
– Weakness, tetany, delerium, anorexia, nausea,
vomiting, cardiac arrhythmias
Hypermagnesemia- poss. causes: renal failure, or
increased intake such as magnesium containing
antacids or other medications.
– Hypotension, muscular weakness or paralysis, nausea,
vomiting, and altered mental functioning.

65. pH imbalances
Acidosis- arterial blood pH < 7.35. Poss. causes:
hypoventilation, ketoacidosis, esp diabetic or
alcoholic, renal failure, toxins, very severe
diarrhea.
– if arterial blood pH <7, pt becomes disoriented,
comatose, may die.
Alkalosis- arterial blood pH > 7.45. Poss. causes:
hyperventilation, metabolic alkalosis rare.
– CNS and peripheral nerve overexcitability,
nervousness, muscle spasms, convulsions, and death.

66. 66
Nursing Process – Assessment
Take nursing history
obtain clinical measurements; weight, VS and
I&O
Physical exam
– Assessing skin turgor
– Neuromuscular assessment
Reviewing results of laboratory tests
performed

67. 67
Nursing history
Obtain data from the client about:
Current and past medical history
– Reveals conditions that may affect fluid
balances
– Medications like steroids, diuretics and
treatment prescribed like infusions

68. Nursing history cont…
Fluid and food intake
– What amount and type of fluids, food do you drink each
day?
– Have there been any recent changes in food or fluid
intake?
– Have you experienced any nausea, pain or loss of appetite
that has altered your intake?
Fluid output
– Find out if noticed any recent changes in frequency or
amount of urine output
68

69. 69
Clinical measurements
Daily weight: measurements should be
under standard conditions, i.e. at the same
time each day, wearing the same or similar
clothing, using same scale.
– Each Kg lost or gained is equivalent to one litre
of fluid gained or lost.
VS every 4 hours

70. 70
Clinical measurements cont..
Intake and output
– Intake and output is recorded on a graphic sheet
which is individualized for each hospital.
– Fluid balance charting allows for careful
monitoring of fluid input and output
– Usu. Measured over a 24hr period

71. 71
Clinical measurements cont..
Guidelines for performing intake and output:
It should be performed when:
Fluid intake and urinary output is less than normal
e.g. urine output less than 30mls per hour
Abnormal fluid losses are occurring e.g vomiting,
bleeding
Intravenous therapy is being administered
Patient has medical problems that affect fluid and
electrolyte status
Patient is not physiologically stable e.g. after surgery

72. 72
Monitoring Intake and Output
– Assess intake and output accurately at scheduled
intervals and evaluate closely for reduced urine
output and for a positive or negative fluid balance on
24 hour calculations
– Urine output is measured every time the patient
voids. It should be transferred into a calibrated
container so that a measurement can be obtained and
recorded
– If patient has foley catheter, collection bag is
emptied and urine is measured at the end of each
shift

73. 73
Clinical measurements cont..
– Any other drainage is also emptied and measured at
the end of each shift
– Oral fluids ingested, feeding delivered via any tube
that enters the body should be measured and recorded
– If patient has intravenous or blood transfusion,
calculate flow rate. Observe for sluggishness or lack
of dripping or dripping too fast so as to ensure that
fluid infuses at the proper rate
– Intake and output should be roughly equal when
balanced after 24hours

74. 74
TIME NG ORAL IV ORAL IV
TOTAL
TOTAL
INTAKE
VOMITUS STOOL NG
DRAINAGE
DRAINS URINE OUTPUT
TOTAL
6.00-7.00
7.00-8.00
9.00-10.00
Sample: Intake and Output chart
NAME OF PATIENT:……………………………..
AGE :……………………………….
SEX :……………………………….
DIAGNOSIS :………………………………
DATE :………………………………
Total intake:
Total output:
Total balance:
OUTPUT
INTAKE

75. Clinical measurement Cts…,
Patients output that exceeds intake is at risk
for fluid volume deficit and if intake
exceeds output is at risk for fluid volume
excess
A +ve fluid balance indicates that the input
has exceeded the output
75

76. Clinical measurement cts..
A –ve fluid balance is the reverse
Note: Adult urinary output is approximately
1500mls – 2000mls per day
Adult intake of fluid is approximately
3,000mls per day
76

77. 77
Physical exam
Focuses on skin, oral cavity, the eyes,
jugular veins, veins of the hands and the
neurologic system
– Integumentary: changes in the skin and mucous
membranes can indicate fluid imbalance
• Skin turgor is best assessed by pinching the area
over the hand, sternum, forehead or inner aspects of
the thigh. In children over the abdominal area or
medial aspects of the thigh:

78. 78
Physical exam cont..
Edema ( collection of interstitial fluid in
various parts of the body, i.e. around the
eyes, extremities
– Assessed by pressing a finger firmly over the
sternum or other body surface or boney
prominence for a period of 15 – 30 sec. Upon
removal of finger positive sign is a visible
fingerprint. Use edema scale rates according to
severity

79. 79
PITTING EDEMA SCALE
TRACE SMALL MEDIUM LARGE

80. 80
Physical exam cont..
Eyes, mouth, lips and tongue key indicators of fluid
volume imbalances: absence of tearing and salivation
(FVD), mucous membrane dry and sticky-mouth dry
and cracked-lips , eyes sunken of puffy
Veins: distention of neck veins accompanies fluid
volume overload. Jugular veins are visible in the
neck.
– To assess place the client with the head elevated to
30º- 45º.

81. 81
Physical exam cont..
Neurologic: Fluid volume changes along
with serum sodium changes affect CNS
cells, resulting in confusion, stupor, seizure
or coma. Assessment of neuromuscular
irritability is particularly important when
imbalances in calcium, magnesium and
sodium are suspected

82. 82
Laboratory Tests
Serum electrolytes
Full blood count
– Hematocrit (Hct) measures the % of whole blood that is
composed of RBCs. Normal values; males 40%-54%, females
37%- 47%. Increased in FVD and decreased in FVE
– Hgb
Osmolality
– is an indicator of the concentration or number of particles
dissolved in serum and urine. Reported as milliosmols of
solute per kilogram of fluid (mOsm/kg)

83. 83
Laboratory Tests cont..
– Serum osmolality
• Is the measure of the solute concentration of the
blood. The particles included are sodium ions,
glucose and urea (blood urea nitrogen, or BUN)
• Used primary to measure the extent of dehydration.
Normal values are 280 to 300 mOsm/kg. An
increase=FVD; a decrease=FVE
– Urine osmolality
• Is the measure of the solute concentration of urine.
The particles included are nitrogenous wastes
• Normal values are 500 to 800 mOsm/kg. An
increase=FVD; a decrease=FVE

84. 84
Interventions for Fluid Imbalance
Fluid Deficit - Interventions
– Assess and document amount, colour and
characteristics of vomitus, diarrhea and drainage
from wounds or tubes, vital signs, weight and
skin turgor – accurate assessment enables the
nurse to develop appropriate plans for fluid
replacement therapy
– Oral fluid replacement :
• Facilitating fluid intake
– Explain to the client the reason for the required intake and
the specific amount needed. This gives the client a
rationale for the requirement and promotes compliance

85. 85
Interventions for Fluid Imbalance
cont…
• Establish a 24 hour plan for ingesting the fluids. E.g. if
2500ml is to be ingested in 24 hours, the plan may
specify 7am-3pm (1500ml); 3pm-11pm (1000ml). Try
to avoid ingestion of large amounts of fluids
immediately before bedtime to prevent the need to
urinate during sleeping hours
• Identify fluids or fluid-like substances the client likes
and make available a variety of those items. Rationale:
intake may be greater when desired fluids are ingested
• Be alert for the cultural implications of food and fluids.

86. 86
Interventions for Fluid Imbalance
cont…
ORT – special formula
Monitor closely for fluid overload, Monitor vital
signs every 4 hours, weight
Monitor I&O
IV Therapy
Drug Therapy : depends on cause: antiemetic,
antidiarrhea, antibiotic
Oral care,

87. 87
Interventions for Fluid Imbalance
cont…
Fluid Overload - Interventions
– Assessment of cardiopulmonary, renal, mental,
skin : inspect areas of edema; document location
and degree of edema on a scale of +1 to +4
– Weights, I&O, serum electrolytes,
– VS every 4 hours and prn; I&O
– Drug therapy – osmotic diuretics first, then loop
diuretic such as Lasix
– Diet Therapy – restrict fluid and sodium as specified
by physician
• Explain the reason for the restricted intake and how much
and what type of fluids are permitted orally.

88. Conclusion
Fluids account for a great proportion of the human
body
About 2/3 of the body is within the cells (functional
units of the body)
Body fluid serves as a universal solvent for a variety
of solutes
Concentration of such varied solutes and the solvent
must be within normal values for healthy life
88

89. Conclusion
Normal cell function depends on physical
and chemical homeostasis of the
surrounding fluids
The fact that on occasion an individual may
not quench for thirst or feel to urinate is a
reflection of the body`s ability for
maintaining it`s fluid, electrolyte and acid
base balances
89

90. REFERENCES
Craven, R.F. and Hirnle, C.J. (2019).
Fundamentals of Nursing: Human Health and
Function. Philadelphia: J.B Lippincolt Co. 5TH
Edition
Kozier, B. et all (2019). Fundamentals of Nursing:
Concepts, Process and Practice. Pearson
Education. Essex.
Marieb, (2013). Human Anatomy and Physiology.
9th
edition Chap 26
90