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NUR 101 Assessment #4 > Acid-Base Balance > Flashcards

Acid-Base Balance Flashcards

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1
Q

Electrolytes

* Bicarbonate (HCO3-)

* Major buffer in the body

* In ECF & ICF

* Normal serum level is ___ - ___ mEq/L

A

22-26

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2
Q

Function

* Maintains acid-base balance by functioning as the primary buffer in the body; levels rise and fall to maintain pH

Regulation

* Lost through diarrhea, diuretics, renal insufficiency

* Excess possible if person ingests quantities of acid neutralizers

A

Source

* Present in acid neutralizers (e.g. sodium bicarbonate)

* Not consumed in the diet; produced by the body to meet current needs

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3
Q

Normal Blood pH Scale

pH : 7.35 - 7.45

PaCO2 (respiratory) : ___ - ___

HCO3 (metabolic) : ___ - ___

A

35-45

22-26

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4
Q

Acid-Base Regulation

Acids & bases are formed in the body as part of normal metabolic processes

A ___ or ___ is a compound that combines with (accepts) H+ ions in solution

A(n) ___ is any compound that contains H+ ions that can be released

* e.g. common strong = HCI - gastric secretions

A

base; alkali

acid

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5
Q

pH Measurement

* The amount of acid or base present in a solution is measured as pH

* The pH is reported on a scale of 1 to 14

> 1 to 6.9 is acidic

> 7 is neutral

> 7.1 to 14 is basic, or alkaline

A

Strong acid = lower pH

Strong base = high pH

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6
Q

Normal serum pH - arterial blood and tissue fluid normally have a pH of 7.35 to 7.45; therefore, they are slightly alkaline

* A serum pH below 7.30 or above 7.52 alters enzymatic activity and creates myocardial irritability

* A serum pH below 6.9 or above 7.8 is usually fatal

A

3 complex mechanisms maintain acid-base balance;

  1. Buffers
  2. Respiratory control of carbon dioxide
  3. Renal regulation of bicarbonate (HCO3-)
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7
Q

Regulation - Buffers

* Buffer systems prevent wide swings in pH

* Consist of a weak acid and a weak base

* Buffer molecules keep strong acids or bases from altering the pH either by absorbing or releasing free H+

A

Blood and tissue fluids depend on this buffer system to maintain constant pH

Buffers

  • Proteins (plasma : (-) & (+) ions)
  • Hemoglobin (found on RBC)
  • Phosphate (weak base & weak acid)
  • Bicarbonate: carbonic acid (weak base & weak acid)
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8
Q

Regulation - Respiratory Mechanisms

* The lungs are the 2nd line of defense to restore normal pH

* They control the body’s carbonic acid supply via CO2 retention or removal to maintain the 20:1 ratio of base to acid

* When the serum pH is too acidic (pH is low), the lungs remove CO2 through rapid, deep breathing. This reduces the amount of CO2 available to make carbonic acid

* When the serum pH is too alkaline (pH is high), the lungs try to conserve CO2 through shallow respirations

A
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9
Q

Respiratory regulation of blood pH

H2CO3 - carbonic acid

A
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10
Q

Regulation - Renal Mechanisms

* The last line of defense is the kidneys, which regulate the concentration of plasma bicarbonate (HCO3)

* If the serum pH is too acidic, the kidneys conserve additional bicarbonate to neutralize the acid

* If the serum pH is too alkaline, the kidneys excrete additional bicarbonate to lower the amount of base and thereby decrease the pH

* The kidneys also buffer pH by forming acids and ammonium (a base)

A
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11
Q

Regulation

Acidosis = serum pH falls below ___

Alkalosis = serum pH increases above ___

A
  1. 35
  2. 45
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12
Q

ABGs measure;

pH

partial pressure of oxygen (PO2)

partial pressure of carbon dioxide (PCO2)

saturation of oxygen (SaO2)

bicarbonate (HCO3)

A

Respiratory disturbance alters carbonic acid = RESPIRATORY ACIDOSIS OR ALKALOSIS

Metabolic disturbance alters bicarbonate = METABOLIC ACIDOSIS OR ALKALOSIS

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13
Q

Key Point: Acid-base balance is reflected by the pH, PCO2, and HCO3- values

A respiratory disturbance alters the ___ portion of the buffering system, and the resulting imbalance is labeled respiratory acidosis or respiratory alkalosis

A metabolic disturbance alters the ___ portion of the buffering system, so the resulting imbalance would be labeled metabolic acidosis or metabolic alkalosis

A

carbonic acid

bicarbonate

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14
Q
A
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15
Q

Acidosis or Alkalosis? Interpreting ABGs

Step 1: Examine the pH Is it acidotic, alkalotic, or normal?

If the pH is low (<7.35), the blood is acidic

If the pH is high (>7.45), the blood is alkalotic

If the pH is between 7.35 and 7.45, the blood is normal

Neutral pH is 7.4

A

The partial pressure of oxygen (PO2) and saturation of oxygen (SaO2) are also part of the ABG result, but they affect tissue oxygenation

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16
Q

Acidosis or Alkalosis? Interpreting ABGs

Step 2: Check the amount of carbon dioxide in the blood (PCO2) Is there too much or too little?

If PCO2 is <35 mm Hg, there is too little acid in the blood (respiratory ___)

If PCO2 is >45 mm Hg, there is too much acid in the blood (respiratory ___)

If PCO2 is 35 to 45 mm Hg, the cause for the abnormal pH is not respiratory

A

alkalosis

acidosis

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17
Q

Acidosis or Alkalosis? Interpreting ABGs

Step 3: Think about bicarbonate level (HCO3-) Is there too little or too much?

If HCO3- is <22 mEq/L, there is too little base in the blood (metabolic ___)

If HCO3- is >26 mEq/L, there is too much base in the blood (metabolic ___)

If HCO3- is 22 to 26 mEq/L, the cause for the abnormal pH is not metabolic

A

acidosis

alkalosis

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18
Q

Respiratory ___

Caused by conditions or medications that IMPAIR GAS EXCHANGE at the alveolar-capillary membrane, depressed respiratory rate and depth, or injury to the respiratory center in the brain

A

Acidosis

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19
Q

Clinical Manifestations

Acute:

Increased pulse and respiratory rate

Headache, dizziness

Confusion, decreased level of consciousness (LOC)

Muscle twitching

Chronic: Weakness, headache

A

Interventions

  • Provide pulmonary hygiene (methods used to clear mucous & secretions from airways)
  • Institute measures to improve gas exchange, such as chest physiotherapy, bronchodilators, antibiotics possible
  • Provide supplemental oxygen
  • Maintain hydration
20
Q

Respiratory Acidosis is an acid-base imbalance characterized by increased partial pressure of arterial CO2 and decreased blood pH

A

Contributing Factors

  • Chronic obstructive respiratory disorders
  • Chest wall trauma, pulmonary edema, atelectasis, pneumothorax, drug overdose, pneumonia, Guillain-Barre syndrome
  • Any condition that results in hypoventilation
21
Q

Signs & Symptoms/Clinical Manifestations

  • Increased pulse, RR, & BP
  • Mental cloudiness & feeling of fullness in head
  • Weakness, dull headache

Labs indicated: ABG studies reveal abnormal values: pH below 7.35 & pCO2 above 45 mmHg

A

Nursing Diagnoses

  • Impaired gas exchange
  • Ineffective breathing pattern
  • Ineffective tissue perfusion
  • Acute confusion
  • Risk for injury
22
Q

Medical Management/Nursing Interventions

  • Institute safety measures
  • Assist w/positioning
  • Monitor I&O and administer fluids as ordered
  • Administer oxygen and medications for order; monitor hourly VS and respiratory status (may require mechanical ventilation)
  • Monitor ABGs - pH, PaCO2, HCO3
A
23
Q

Respiratory ___

Retention of CO2 by lungs

A

Acidosis

24
Q

Respiratory ___

Caused by hyperventilation resulting from anxiety, fever, sepsis, thyrotoxicosis, lesion in the respiratory center in the brain, or excessive ventilation w/a mechanical ventilator

A

Alkalosis

25
Q

Clinical Manifestations

  • Confusion, difficulty focusing
  • Headache
  • Tingling
  • Palpitations
  • Tremors
A

Interventions

  • If caused by anxiety, encourage the patient to relax and breathe slowly
  • For other causes: identify and treat the underlying disorder
26
Q

Respiratory Alkalosis is an acid-base imbalance characterized by ___ partial pressure of arterial CO2 and increased blood pH

A

decreased

27
Q

Contributing Factors

  • Hyperventilation due to anxiety
  • Hypoxia
  • Improper mechanical ventilation
  • Fever
  • Salicylate poisoning
A

Signs & Symptoms/Clinical Manifestations

  • Lightheadedness
  • Inability to concentrate
  • Convulsions
  • Positive Chvostek’s sign
  • Nausea & vomiting
  • Muscle twitching
28
Q

Labs indicated: ABGs reveal abnormal values: pH above ___ and partial pressure of CO2 below ___

A

7.45

35

29
Q

Nursing Diagnoses

  • Impaired gas exchange
  • Ineffective breathing pattern
  • Ineffective tissue perfusion
  • Acute confusion
  • Risk for injury
A

Medical Management/Nursing Interventions

  • Institute safety measures for the patient w/vertigo or the unconscious patient
  • Encourage the anxious patient to verbalize fears
  • Administer sedation as ordered to relax the patient
  • Keep the patient warm and dry
  • Encourage the patient to take deep, slow breaths or breathe into a brown paper bag (inspire CO2)
  • Monitor VS
  • Monitor ABGs, primarily PaCO2; a value <35 mmHg indicates too little CO2 (carbonic acid)
30
Q

Metabolic ___

Caused by:

  • Retained acids in the blood (renal impairment, uncontrolled DM, or starvation)
  • Decreased bicarbonate result from excessive GI loss
  • Excessive fluid intake of acids (ASA poisoning or prolonged infusions of chloride containing IV fluids)
A

Acidosis

31
Q

Clinical Manifestations

  • Headache, confusion, drowsiness
  • Weakness, peripheral vasodilation
  • Nausea & vomiting
  • Kussmaul’s breathing (rapid and deep)
  • Frequently associated with ___
A

hyperkalemia

32
Q

Interventions

  • Treatment is directed at correcting the underlying problem
  • Bicarbonate may be prescribed
A
33
Q

Metabolic ___ is an acid-base balance resulting from excessive absorption or retention of acid or excessive excretion of bicarbonate

A

Acidosis

34
Q

Contributing Factors

  • Ketoacidosis
  • Lactic acidosis
  • Prolonged fasting
  • Salicylic poisoning
  • Oliguric renal disease
  • Abnormal bicarbonate losses, which can occur in loss of fluid from lower GI tract from surgery, drains, or severe diarrhea
A

Signs & Symptoms/Clinical Manifestations

  • Headache, drowsiness, confusion, weakness
  • Increased respiratory rate & depth
  • Nausea & vomiting
  • Diminished cardiac output w/pH below 7, which results in hypotension, cold clammy skin and cardiac arrhythmias
35
Q

Labs indicated:

ABG studies reveal abnormal values: pH below 7.35 and HCO3 below 22 mEq/L; serum potassium level reveals ___

A

hyperkalemia

36
Q

Metabolic Acidosis

When acid accumulates in the body or when bicarbonate is lost from body fluid, a bicarbonate deficit results and metabolic acidosis occurs

A
37
Q

Metabolic ___

Caused by excessive acid loss due to vomiting or gastric suction, use of potassium-wasting diuretics, hypokalemia, excess bicarbonate intake, or hyperaldosteronism

A

Alkalosis

38
Q

Clinical Manifestations

  • Dizziness
  • Tingling of extremities
  • Hypertonic muscles
  • Decreased respiratory rate and depth
A

Interventions

  • Treatment is directed at correcting the underlying problem
  • Treatment often includes administration of NaCl solutions or sodium-rich fluids
39
Q

Metabolic ___ is an acid-base imbalance characterized by excessive loss of acid or excessive gain of bicarbonate

A

Alkalosis

40
Q

Contributing Factors

  • Vomiting
  • Gastric suctioning
  • Excessive intake of alkali (antacids, baking soda)
A

Signs & Symptoms/Clinical Manifestations

  • Tingling of fingers
  • Dizziness, confusion
  • Tetany
  • Slow, shallow respirations, possibly apnea
41
Q

Labs indicated:

ABG studies reveal abnormal values: pH above ___ and HCO3 above ___ mEq/L; urine chloride concentrations help to differentiate between vomiting or diuretic ingestion or one of the causes of mineralocorticoid excess

A

7.45

26

42
Q

?

Increased or decreased breathing rate to help balance pH levels

A

Respiratory compensation

43
Q
A
44
Q

Assessment - Focused Nursing History

  • N/V
  • Diarrhea
  • Diuretics
  • Medications
  • DM
  • Anxiety
A

Assessment - Focused Physical Assessment

  • Respirations, heart rate, respiratory rate, LOC, muscle twitching, headache, confusion, positive Chvostek sign (resp. alkalosis), lab studies
  • ABGs
  • Electrolytes - hyperkalemia (acidosis), hypokalemia (alkalosis)
45
Q

Nursing Diagnosis

  • Nursing diagnoses directly related to electrolyte or acid-base imbalances

> Impaired Gas Exchange and Risk for Electrolyte Imbalance

A

Example

  • Impaired Gas Exchange is appropriate for a client with a disorder affecting gas exchange at the alveolar-capillary membrane in the lungs
  • This condition limits the effectiveness of the carbonic acid-bicarbonate buffer system and alters serum pH, predisposing the patient to acid-base imbalances
46
Q

Nursing Interventions

Acid-Base Management

  • Promotion of acid-base balance and prevention of complications resulting from acid-base imbalance

Ex

  • Acid-Base Management: Metabolic Acidosis
A

NUR 101 Assessment #4 (5 decks)

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