Fluids and Electrolytes

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nette90
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Fluids and Electrolytes
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2012-03-10 18:58:28
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Fluids Electrolytes Acid Base Homeostasis
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Pathophysiology Chapter 6
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  1. Fluid Compartments
    Intracellular fluid –inside the cells

    • Extracellular fluid –fluid outside the cells
    • •Interstitial fluid – between the cells
    • •Intravascular fluid – inside the blood vessels
    • •Transcellular fluid – third space
  2. Fluid Movement
    Tonicity – osmotic pressure of two solutions separated by a semipermeable membrane

    Isotonic– equal solute concentrations, causes no fluid shifts

    •Hypotonic– lower solute concentrations, causing fluids to shift out

    Hypertonic– higher solute concentrations, causing fluids to shift in
  3. Fluid Sources
    -Oral intake

    • Intravenous solutions
    • •Isotonic– 0.9% saline, lactated ringers

    •Hypotonic– 0.45% saline

    •Hypertonic – 5% dextrose in 0.9% saline, 3% saline
  4. Fluid Loses
    Urine

    Feces

    Insensible losses
  5. Fluid Balance Control
    •Thirst mechanism–Triggered by decreased blood volume and increased osmolarity

    •Antidiuretic hormone –Promotes reabsorption of water in the kidneys

    • •Aldosterone –Increases reabsorption of sodium and water
    • in the kidneys

    •Atrial natriuretic peptide –stimulates renal vasodilatation and suppresses aldosterone, increasing urinary output
  6. Fluid Excess
    • Edema
    • -Excess fluid in the interstitial space

    • Hypervolemia or fluid volume excess
    • -Excess fluid in the intravascular space

    Water intoxication -Excess fluid in the intracellular space
  7. Causes of Fluid Excess
    • •Excessivesodium or water intake
    • –High-sodium diet
    • –Psychogenic polydipsia
    • –Hypertonic fluid administration
    • –Free water
    • –Enteral feedings

    • •Inadequate sodium or water elimination
    • –Hyperaldosteronism
    • –Cushing’s syndrome
    • –Syndrome of inappropriate antidiuretic hormone
    • –Renal failure
    • –Liver failure
    • -Heart failure
  8. Fluid Excess
    •Manifestations: peripheral edema, periorbital edema, anasarca, cerebral edema, dyspnea, bounding pulse, tachycardia, jugular vein distension, hypertension, polyuria, rapid weight gain, crackles, and bulging fontanelles
  9. Fluid Excess (Diagnosis Treatment)
    • •Diagnosis: history, physical examination, daily weights, measurement of intake and output,
    • blood chemistry, urine analysis, and complete blood count

    •Treatment: wearing compression stockings, administering diuretics, restricting sodium and fluids, maintaining high Fowler’s position, and hypertonic solutions
  10. Fluid Deficit
    Dehydration

    • Hypovolemia or fluid volume deficit
    • •Decreased fluid in the intravascular space
  11. Causes of Fluid Deficit
    • Inadequate fluid intake:
    • -Poor oral intake
    • -Inadequate IV fluid replacement

    • •Excessive fluid or sodium losses
    • –Gastrointestinal losses
    • –Excessive diaphoresis
    • –Prolonged hyperventilation
    • –Hemorrhage
    • –Nephrosis
    • –Diabetes mellitus
    • –Diabetes insipidus
    • –Burns
    • –Open wounds
    • –Ascites
    • –Effusions
    • –Excessive use of diuretics
    • –Osmotic diuresis
  12. Fluid Deficit (Manifestations)
    •Manifestations: thirst, altered level of consciousness, hypotension, tachycardia, weak and thready pulse, flat jugular veins, dry mucous membranes, decreased skin turgor, oliguria, weight loss, and sunken fontanelles
  13. Fluid Deficit (Diagnosis/Treatment)
    •Diagnosis: history, physical examination, measurements of intake and output, daily weights, blood chemistry, urine analysis, and complete blood count

    •Treatment: indentify and manage underlying cause along with fluid replacement
  14. Electrolyte Balance
    • Cations
    • •Positively charged electrolytes

    • Anions
    • •Negatively charged electrolytes

    • Play a role in
    • •muscle and neural activity
    • •acid-baseand fluid balance
  15. Sodium
    • •Normal range 135-145 mEq/L
    • •Most significant cation and prevalent electrolyte of extracellular fluid

    • -Controls serum osmolality and water balance
    • -Plays a role in acid-base balance
    • -Facilitates muscles and nerve impulses
    • -Dietary intake main source
    • -Excreted through the kidneys and gastrointestinal tract
  16. Hypernatremia
    Sodium > 145 mEq/L

    • Serum osmolarity increases
    • Results in fluid shifts
  17. Causes of Hypernatremia
    • •Excessive sodium:
    • –Excessive sodium ingestion
    • –Hypertonic IV saline (3% saline) administration
    • –Cushing’s syndrome
    • –Corticosteroid use

    • •Deficient water:
    • –Decreased water ingestion
    • –Loss of thirst sensation
    • –Inability to drink water
    • –Third spacing
    • –Vomiting
    • –Diarrhea
    • –Excessive sweating
    • –Prolong episode of hyperventilation
    • –Diuretic use
    • –Diabetes insipidus
  18. Hypernatremia
    •Manifestations: increased temperature, warm and flushed skin, dry and sticky mucous membranes, dysphagia, increased thirst, irritability, agitation, weakness, headache, seizures, lethargy, coma, blood pressure changes, tachycardia, weak and thready pulse, edema, and decreased urine output
  19. Hypernatremia (Diagnosis/Treatment)
    •Diagnosis: history, physical examination, blood chemistry, and urine analysis

    •Treatment: fluid replacement (oral or hypotonic saline solution) and diuretics
  20. Hyponatremia
    • Sodium < 135 mEq/L
    • Serum osmolarity decreases
  21. Causes of Hyponatremia
    • Deficient sodium:
    • -Diuretic use
    • -Gastrointestinal losses
    • -Excessive sweating
    • -Insufficient aldosterone levels
    • -Adrenal insufficiency
    • -Dietary sodium restrictions

    • Excessive water :
    • •Hypotonic intravenous saline (0.45% saline)
    • •Hyperglycemia
    • •Excessive water ingestion
    • •Renal failure
    • •Syndrome of inappropriate antidiuretic hormone
    • •Heart failure
  22. Hyponatremia (Manifestations)
    Manifestations: anorexia, gastrointestinal upset, poor skin turgor, dry mucous membranes, blood pressure changes, pulse changes, edema, headache, lethargy, confusion, diminished deep tendon reflexes, muscle weakness, seizures, and coma
  23. Hyponatremia (Diagnosis/Treatment)
    •Diagnosis: history, physical examination, blood chemistry, and urine analysis

    •Treatment: limit fluids and increase dietary sodium
  24. Chloride
    Normal range 98-108 mEq/L

    • -Mineral electrolyte
    • -Major extracellular anion
    • -Found in gastric secretions, pancreatic juices, bile, and cerebrospinal fluid
    • -Plays a role in acid-base balance
    • -Dietary intake main source
    • -Excreted through the kidneys
  25. Hyperchloremia
    Chloride > 108 mEq/L

    • Causes
    • •Increased chloride intake or exchange: hypernatremia, hypertonic intravenous solution, metabolic acidosis, and hyperkalemia

    •Decreased chloride excretion: hyperparathyroidism, hyperaldosteronism, and renal failure
  26. Hyperchloremia (Manifestations/Diagnosis/Treatment)
    Manifestations: reflect the underlying cause

    Diagnosis: history, physical examination, blood chemistry, urine analysis, and arterial blood gases

    Treatment: identify and manage underlying cause, diuretics, and bicarbonate
  27. Hypochloremia
    Chloride < 98 mEq/L

    • Causes
    • •Decreased chloride intake or exchange: hyponatremia, 5% dextrose in water intravenous solution, water intoxication, and hypokalemia

    •Increased chloride excretion: diuretics, vomiting, metabolic alkalosis, and other gastrointestinal losses
  28. Hypochloremia
    Manifestations: reflect the underlying cause

    Diagnosis: same as for hyperchloremia

    • Treatment: identify and manage underlying cause, sodium replacement (oral or intravenous), ammonium
    • chloride, and saline irrigation of gastric tubes
  29. Potassium
    • Normal range 3.5-5 mEq/L
    • The primary intracellular cation

    • Plays a role in electrical conduction, acid-base balance, and metabolism
    • -Dietary intake main source
    • -Excreted through the kidneys and gastrointestinal tract
  30. Hyperkalemia
    • Potassium > 5 mEq/L
    • Causes:
    • •Deficient excretion: renal failure, Addison’s disease, certain medications, and Gordon’s syndrome

    Excessive intake: oral potassium supplements, salt substitutes, and rapid intravenous administration of diluted potassium

    Increased release from cells: acidosis, blood transfusions, and burns or any other cellular injuries
  31. Hyperkalemia
    • Manifestions: paresthesia, flaccid paralysis, bradycardia, dysrhythmias, electrocardiogram changes, cardiac arrest, respiratory depression, abdominal cramping, nausea,
    • and diarrhea

    Diagnosis: history, physical examination, blood chemistry, 12-lead electrocardiogram, and arterial blood gas
  32. Hyperkalemia (Treatment)
    • Treatment:
    • •Correct acidosis, usually with sodium bicarbonate
    • •Calcium gluconate
    • •Decrease dietary potassium intake
    • •Dialysis
    • •Kayexalate
    • •Intravenous fluids
    • •Potassium-losing diuretics
    • •Insulin
  33. Hypokalemia



    Potassium < 3.5 mEq/L

    • Causes
    • Excessive loss: vomiting, diarrhea, nasogastric suctioning,
    • fistulas, laxatives, potassium-losing diuretics, Cushing’s syndrome, and corticosteroids

    •Deficient intake: malnutrition, extreme dieting, and alcoholism

    •Increased shift into the cell: alkalosis and insulin excess
  34. Hypokalemia
    Potassium < 3.5 mEq/L

    • Causes
    • Excessive loss: vomiting, diarrhea, nasogastric suctioning,
    • fistulas, laxatives, potassium-losing diuretics, Cushing’s syndrome, and corticosteroids

    •Deficient intake: malnutrition, extreme dieting, and alcoholism

    •Increased shift into the cell: alkalosis and insulin excess
  35. Hypokalemia (Maniofestations/Diagnosis)
    • Manifestations: muscle weakness, paresthesias, hyporeflexia, leg cramps, weak and irregular pulse, hypotension, dysrhythmias, electrocardiogram changes, decreased bowel sounds, abdominal distension, constipation, ileus,
    • and cardiac arrest

    Diagnosis: history, physical examination, blood chemistry, 12-lead electrocardiogram, and arterial blood gas
  36. Hypokalemia
    Treatment: identify and manage underlying cause along with potassium replacement (oral or intravenous)
  37. Calcium
    Normal range 4-5 mEq/L

    Mostly found in the bone and teeth

    • Plays a role in blood clotting, hormone secretion, receptor functions, nerve transmission, and muscular contraction
    • -Has inverse relationship with phosphorus
    • -Has synergistic relationship with magnesium
  38. Calcium(Regulators)
    Dietary intake main source

    • •Vitamin D aids absorption
    • -Excreted through the gastrointestinal trace

    • Regulated by:
    • -Vitamin K
    • -Parathyroid hormone
    • -Calcitonin
  39. Hypercalcemia


    Calcium > 5 mEq/L

    • Causes:
    • •Increased intake or release: calcium antacids, calcium supplements, cancer, immobilization, corticosteroids, vitamin D deficiency, and hypophosphatemia

    • •Deficit excretion: renal failure, thiazide diuretics, and
    • hyperparathyroidism
  40. Hypercalcemia
    • Manifestations: dysrhythmias,
    • electrocardiogram changes, personality changes, confusion, decreased memory, headache, lethargy, stupor, coma, muscle weakness, decreased deep tendon reflexes, anorexia, nausea, vomiting, constipation, abdominal pain,
    • pancreatitis, renal calculi, polyuria, and dehydration
  41. Diagnosis: history, physical examination, blood chemistry, and 12-lead electrocardiogram
  42. Hypercalcemia (Treatment)
    Treatment:

    • -Identify and manage underlying cause
    • -Manage symptoms
    • -Phosphate
    • -Increase mobility
    • -Calcitonin
    • -Intravenous fluids
    • -Diuretics
  43. Hypocalcemia
    • Calcium < 4 mEq/L
    • Causes
    • •Excessive losses: hypoparathyroidism, renal failure, hyperphosphatemia, alkalosis, pancreatitis, laxatives, diarrhea, and other medications

    Deficient intake: decreased dietary intake, alcoholism, absorption disorders, and hypoalbuminemia
  44. Hypocalcemia (Manifestations)
    • Manifestations: dysrhythmias, electrocardiogram
    • changes, increased bleeding tendencies, anxiety, confusion, depression, irritability, fatigue, lethargy, paresthesia, increased deep tendon reflexes, tremors, muscle
    • spasms, seizures, laryngeal spasms, increased bowel sounds, abdominal cramping, and positive Trousseau’s and Chvostek’s signs
  45. Hypocalcemia (Diagnosis/Treatment)
    Diagnosis: same as hypercalcemia

    • Treatment
    • •Identify and manage underlying cause
    • •Calcium replacement (oral or intravenous)
    • •Vitamin D
    • Phosphorus
  46. Phosphorus
    Normal range 2.5-4.5 mg/dL

    • Mostly found in the bones and small amoutns are in the
    • bloodstream

    • Plays a role in bone and tooth mineralization, cellular metabolism, acid-base balance, and cell
    • membrane formation

    • -Dietary intake mainsource
    • -Excreted through the kidneys
  47. Hyperphosphatemia
    Phosphorus > 4.5 mg/dL

    • Causes
    • •Deficient excretion: renal failure, hypoparathyroidism, adrenal insufficiency, hypothyroidism, and laxatives

    •Excessive intake or cellular exchange: cellular damage, hypocalcemia, and acidosis
  48. Hyperphosphatemia (Manifestations/Diagnosis/Treatment)
    Manifestations: rarely seen alone

    Diagnosis: history, physical examination, and blood chemistry

    • Treatment:
    • -Identifyand manage underlying cause
    • -Aluminum hydroxide or aluminum carbonate
    • -Treat hypocalcemia
  49. Hypophosphatemia
    Phosphorus < 2.5 mg/dL

    • Causes
    • •Excessive excretion or cellular exchange: renal failure, hyperparathyroidism, and alkalosis

    • Deficient intake: malabsorption, vitamin D
    • deficiency, magnesium and aluminum antacids, alcoholism, and decreased dietary intake
  50. Hypophosphatemia (Manifestations/Diagnosis/Treatmnet)
    Manifestations: similar to hypercalcemia

    Diagnosis: history, physical examination, and blood chemistry

    • Treatment:
    • -Identify and manage the underlying cause
    • -Phosphorus replacement (oral or intravenous)
  51. Magnesium
    Normal range 1.8-2.5 mEq/L

    • An intracellular cation
    • -Mostly stored in the bone and muscle

    Plays a role in muscle and nerve function, cardiac rhythm, immune function, bone strength, blood glucose managment, blood pressure, energy metabolism, and protein synthesis

    • -Dietary intake main source
    • -Excreted through the kidneys
  52. Hypermagnesemia
    Magnesium > 2.5 mEq/L

    Causes: renal failure, excessive laxative, and antacid use

    Manifestations: similar to hypercalcemia

    Diagnosis: history, physical examination, and blood chemistry

    Treatment: diuretics,dialysis, and intravenous calcium
  53. Hypomagnesemia
    Magnesium < 1.8 mEq/L

    Causes: inadequate intake, chronic alcoholism, malnutrition, pregnancy, diarrhea, diuretics, and stress

    Manifestations: similar to hypocalcemia

    Diagnosis: similar to hypermagnesemia

    Treatment: magnesium replacement (oral or intravenous)
  54. Acid-Base Balance
    • Measured by pH
    • -Normal serum pH 7.35-7.45

    • Body fluids, kidneys, and lungs maintain balance
    • Subtle changes can cause serious effects
  55. pH Regulation


    pH reflects hydrogen concentrations

    • •Hydrogen is an acid
    • -The more hydrogen, the lower the pH

    • Acids are byproducts of metabolism
    • -Volatile acids
    • -Volatile gases
    • -Nonvolatile gases

    3 systems work to maintain acid-base balance―the buffers, respiratory system, and renal system.
  56. Buffers
    Chemicals that combine with an acid or base to change pH

    -Immediate reaction to counteract pH variations until compensation is initiated

    4 major buffer mechanisms—the bicarbonate-carbonic acid system, the phosphate system, the hemoglobin system, and the protein system
  57. Bicarbonate-Carbonic Acid System
    Most significant in the extracellular fluid

    Carbonic acid and bicarbonate are the key players

    Carbonic acid forms from carbon dioxide reacting with water

    Carbonic anhydrase causes carbonic acid to separate into hydrogen and bicarbonate

    Carbonic anhydrase in the lungs allows for carbon dioxide excretion and in the kidneys allows for hydrogen excretion
  58. Phosphate System
    Similar to the bicarbonate-carbonic acid system

    Phosphates are in high concentrations in the intracellular fluid

    Some phosphates act as weak acids, and some act as weak bases

    This system primarily occurs in the kidneys by accepting or donating hydrogen
  59. Hemoglobin System
    Primarily occurs in the capillaries

    Acidity and hypoxia causes hemoglobin to release the oxygen

    Hemoglobin then becomes a weaker acid, taking up extra hydrogen

    Binding with oxygen makes hemoglobin more prone to release hydrogen

    • Hydrogen reacts with bicarbonate to form carbonic acid, which is converted to carbon dioxide and
    • released into the alveoli
  60. Protein System
    Most abundant buffering system

    Proteins can act as an acid or base by binding to or releasing hydrogen

    Occurs in the intracellular and extracellular spaces

    Hydrogen and carbon dioxide diffuse across the cell membrane to bind with protein inside the cell

    Albumin and plasma are the primary buffers in the intravascular space
  61. Potassium
    Potassium and hydrogen move interchangeably in and out of the cell to balance pH

    With extracellular excess, hydrogen moves inside the cell for buffering, and, in exchange, potassium moves out

    Potassium imbalances can lead to pH imbalances
  62. Respiratory Regulation
    Alters carbon dioxide excretion

    Speeding up respirations will excrete more carbon dioxide, decreasing acidity

    Slowing down respirations will excrete less carbon dioxide, increasing acidity

    Uses chemoreceptors

    Responds quickly, but is short-lived
  63. Renal Regulation
    Alters the excretion or retention of hydrogen or bicarbonate

    More effective by permanently removing hydrogen

    Responds slowly, but longer lasting
  64. Compensation
    The body never overcompensates

    • The cause of the imbalance often determines the compensatory change
    • -If the problem causing the pH imbalance originates in the lungs, the kidneys initiates efforts to correct it
    • -If the problem causing the pH imbalance originates outside the lungs, the lungs initiate efforts to correct it
  65. Metabolic Acidosis
    Results from a deficiency of bicarbonate or an excess of hydrogen

    • Causes
    • Bicarbonate deficit: intestinal and renal losses

    •Acid excess: tissue hypoxia resulting in lactic acid accumulation, ketoacidosis, drugs, toxins, and renal retention
  66. Metabolic Acidosis (Manifestations)
    • Manifestations
    • •Appear as regulatory systems fail to maintain pH within normal range

    •Occur in combination with manifestations of underlying condition

    •Include: headache, malaise, weakness, fatigue, lethargy, coma, warm and flushed skin, nausea, vomiting, anorexia, hypotension, dysrhythmias, shock, Kussmaul’s respirations, and hyperkalemia
  67. Metabolic Acidosis ( Diagnosis/Treatment)
    Diagnosis: history, physical examination, arterial blood gases, blood chemistry, and complete blood count

    • Treatment
    • -Identifying and treating the causative condition

    •Strategies to correct the acidosis include: Intravenous bicarbonate, correction of electrolyte disturbances, improving oxygenation, and insulin
  68. Anion Gap
    Helpful in determining the cause of metabolic acidosis

    Identifies the anions that are not measured

    Conditions that cause excess acid will increase the anion gap; otherwise, the anion gap is normal
  69. Anion Gap (How does it work?)
    The sum of cations should be approximately equal to the sum of anions in the extracellular fluid

    • Sodium is the most plentiful cation in the extracellular
    • fluid while bicarbonate and chloride are the most abundant anions

    To determine the anion gap, the bicarbonate and chloride results are added together and subtracted from the sodium

    Normal anion gap is 6–9 mEq/L
  70. Metabolic Alkalosis
    Results from excess bicarbonate or deficient acid or both

    • Causes
    • •Excess bicarbonate: excessive antacid use, use of bicarbonate-containing fluids, and hypochloremia

    Deficient acid: gastrointestinal loss, hypokalemia, renal loss, hypovolemia , and hyperaldosteronism
  71. Metabolic Alkalosis (Manifestations)
    • Manifestations
    • •Appear as regulatory systems fail to maintain pH within normal range

    •Occur in combination with manifestations of underlying condition

    •Include: mental confusion, hyperactive reflexes, paresthesia, tetany, seizures, respiratory depression, dysrhythmias, and coma
  72. Metabolic Alkalosis (Diagnosis/Treatment)
    Diagnosis: history, physical examination, arterial blood gases, blood chemistry, and complete blood count

    • Treatment
    • -•Identifying and treating the causative condition

    •Strategies to correct the alkalosis include: adequate hydration, correcting electrolyte disturbances, Diamox, arginine hydrochloride, and administering a weak hydrochloric acid solution
  73. Respiratory Acidosis
    Results from carbon dioxide retention, which increases carbonic acid

    Caused by conditions that result in hypoventilation or decreased gas exchange

    • •Includes: acute asthma exacerbations, chronic obstructive pulmonary disease, airway obstructions, pulmonary edema, pneumonia, drug overdose, respiratory failure,
    • and central nervous system depression
  74. Respiratory Acidosis
    Manifestations

    •Appear as regulatory systems fail to maintain pH within normal range

    •Occur in combination with manifestations of underlying condition

    • •Include: headache, blurred vision, tremors, muscle twitching, vertigo, irritability, disorientation, lethargy, coma, tachycardia leading to bradycardia, blood pressure
    • fluctuations, and diaphoresis
  75. Respiratory Acidosis (Diagnosis/Treatment)
    Diagnosis: history, physical examination, arterial blood gases, blood chemistry, complete blood count , and chest X-ray

    • Treatment: oxygen therapy, mechanical ventilation, positioning the patient for optimum ventilation, bronchial hygiene measures, bronchodilators, and manage causative
    • conditions
  76. Mixed Disorders
    • Respiratory and metabolic disorders resulting in an acidotic
    • or alkalotic state

    Both the respiratory and renal systems demonstrate an imbalance of acid or base

    • Causes: pulmonary edema, aspirin overdose, fever, and vomiting
    • -Critical and complex condition
  77. Arterial Blood Gas Interpretation
    • pH – serum hydrogen concentration
    • -Indicates acid-base status

    • PaCO2 - partial pressure of carbon dioxide
    • -Indicates the adequacy of pulmonary ventilation

    • HCO3– bicarbonate
    • -Indicates the activity in the kidneys to retain or excrete bicarbonate
  78. Arterial Blood Gas Interpretation
    • PaO2 - partial pressure of oxygen
    • -Indicates serum oxygen concentration

    • Base excess/deficit
    • -Indicates serum buffer concentration, particularly bicarbonate

    •Positive values indicate an excess of base or a deficit of acid

    •Negative values indicate a deficit of base or an excess of acid
  79. Steps in Arterial Blood Gas Interpretation
    • .Look for patterns
    • •Two As = acidosis
    • -One of the As is CO2 = respiratory disorder
    • -One of the As is HCO3 = metabolic disorder

    • •Two Bs = alkalosis
    • -One of the Bs is CO2 = respiratory disorder
    • -One of the Bs is HCO3= metabolic disorder

    •Three As or Bs = a mixed disorder

    •All As = mixed respiratory and metabolic acidosis

    •All Bs = mixed respiratory and metabolic alkalosis
  80. Steps in Arterial Blood Gas Interpretation
    5.Determine compensation:

    •The unpaired result is within normal range =uncompensated

    •The unpaired result is the opposite letter of the pairs but the pH is still abnormal = partially compensated

    •The unpaired result is the opposite letter and the pH has returned to normal range = fully compensated

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