Acid Base Balances - Abg

Front 1

Purpose of Acid-Base

Back 1

Maintain a steady balance between acids and bases to achieve homeostasis

Front 2

Health problems leading to imbalance:____________

Back 2

DM
COPD
kidney disease
vomiting, diarrhea

Front 3

Overview of Acid-Base Physiology

Back 3

Nature of acids & bases
Acid
releases a H+ ion when dissolved in water
Base
bind to a H+ ion when dissolved in water

Front 4

Normal Arterial Blood Gas Values
Adult

Back 4

pH (arterial) 7.35-7.45
pCO2 (mmHg) 35-45
HCO3 (mEq/L) 22-26
pO2 (mmHg) 80-100
SaO2 (%) 95-100

Front 5

Normal Arterial Blood Gas Values
Child(c)

Back 5

pH (arterial) 7.37-7.43
pCO2 (mmHg) 35-41
HCO3 (mEq/L) 18-25
pO2 (mmHg) 80-100
SaO2 (%) 95-100

Front 6

Normal Arterial Blood Gas Values
Adolescents (a)

Back 6

pH (arterial) 7.35-7.41
pCO2 (mmHg) 38-44
HCO3 (mEq/L) 23-25
pO2 (mmHg) 80-100
SaO2 (%) 95-100

Front 7

Normal Arterial Blood Gas Values
Infants

Back 7

pH (arterial) 7.36-7.42
pCO2 (mmHg) 30-34
HCO3 (mEq/L) 17.2-23.6
pO2 (mmHg) 80-100
SaO2 (%) 95-100

Front 8

pH values
base bicarbonate:carbonic acid

Back 8

< 6.8 death
6.8-7.35 acidosis
7.35-7.45 normal
7.45-7.8 alkalosis
> 7.8 death
1 carbonic acid : 20 bicarbonate

Front 9

Alterations in Acid-Base Balance

Back 9

Respiratory or Metabolic

Front 10

Respiratory imbalances

Back 10

affect carbonic acid concentrations

Front 11

Metabolic imbalances

Back 11

affect base bicarbonate

Front 12

Three mechanisms to regulate acid-base balance

Back 12

Buffer systems
Respiratory system
Renal system

Front 13

Regulators of Acid/Base:Buffers

Back 13

Neutralize acids or change strong acids to weak acids
Primary regulators
React immediately
Cannot maintain pH without adequate respiratory and renal function

Front 14

Regulators of Acid/BaseRespiratory System

Back 14

Respiratory system: eliminates CO2
Respiratory center in medulla
controls breathing
Responds within minutes/hours
Inc. respirations → more CO2 expelled & less remains in blood
• Dec. respirations → more CO2 remains in blood

Front 15

Regulators of Acid/Base: Renal System

Back 15

Kidneys: essential buffer system for acids
Renal system: eliminate H+ and reabsorb HCO3-
Responds within hours to days
Elderly clients
acid-base imbalances more difficult to correct

Front 16

Compensation

Back 16

Body uses regulatory mechanism to return pH to it’s normal level
Complete compensation
Partial compensation
Uncompensated
Decompensation

Front 17

Acid-Base Imbalances (cont'd)

Back 17

Imbalances occur when compensatory mechanisms fail
Alterations in acid-base balance
Respiratory acidosis
Respiratory alkalosis
Metabolic acidosis
Metabolic alkalosis
Mixed acid-base disorders

Front 18

Blood Gas Values

Back 18

Arterial blood gas (ABG) values provide information about
Acid-base status
Underlying cause of imbalance
Body’s ability to regulate pH
Overall oxygen status

Front 19

Interpretation of ABGs

Back 19

Diagnosis in six steps
Evaluate pH
Analyze PaCO2
Analyze HCO3-
Determine if CO2 or HCO3- matches the alteration
Decide if body attempting to compensate

Front 20

Acid-Base Mnemonic—ROME

Back 20

Respiratory
Opposite
pH PaCO2 ↑ Alkalosis ↓
pH PaCO2 ↓ Acidosis ↑
Metabolic
Equal
pH PaCO2 ↓ Alkalosis ↓
pH PaCO2 ↑ Acidosis ↑

Front 21

Respiratory Acidosis

Back 21

Carbonic acid excess caused by
Hypoventilation
Respiratory failure

Front 22

Respiratory Acidosis
Clinical presentation
Cardiovascular

Back 22

Hypotension
Delayed cardiac conduction → heart block, ECG changes
Peripheral vasodilation w/thready, weak pulse
Tachycardia
Warm, flushed skin

Front 23

Respiratory Acidosis
Clinical presentation
CNS

Back 23

HA
SZ
Altered LOC
Papilledema
Muscle twitching
Drowsiness → coma

Front 24

Respiratory Acidosis
Clinical presentation
Respiratory

Back 24

Dysnpnea
Hypoventilation with hypoxia

Front 25

Respiratory Acidosis
Compensation

Back 25

Kidneys conserve HCO3- and secrete H+ into urine

Front 26

Therapeutic Management: Respiratory Acidosis

Back 26

Correct underlying cause
Improve ventilation
Pulmonary hygiene measures
Adequate fluid intake
Supplemental oxygen
Mechanical ventilation

Front 27

Respiratory Alkalosis
Primary cause:
Other causes:

Back 27

Carbonic acid deficit caused by
Hyperventilation
Primary cause: hypoxemia from acute pulmonary disorders
Other causes: Anxiety, CNS disorders, & mechanical over-ventilation

Front 28

Respiratory Alkalosis
Clinical Presentation:

Back 28

Hyperventilation
Lethargy
Light-headedness
confusion
Tachycardia
Dysrhythmias
Nausea, Vomiting, Epigastric pain
Tetany, Numbness, tingling of extremeties, seizures

Front 29

Respiratory Alkalosis
Compensation

Back 29

Rarely occurs due to aggressive treatment of causes of hypoxemia

Front 30

Therapeutic Management: Respiratory Alkalosis

Back 30

Treat underlying cause
Have pt breathe CO2 by using rebreather mask or paper bag
Give O2 therapy if pt is hypoxic
Med as needed with antianxiety drugs

Front 31

Metabolic Acidosis

Back 31

An imbalance in which pH decreases & HCO3 decreases
Causes: Ketoacidosis, lactic acid accumulation w/ shock, severe diarrhea, renal disease.

Front 32

Metabolic Acidosis
Clinical Presentation

Back 32

Drowsiness
confusion
headache
coma

Front 33

Metabolic Acidosis
Compensatory mechanisms

Back 33

Increased CO2 excretion by lungs
Kussmaul respiration
Kidneys excrete acid

Front 34

Therapeutic Management: Metabolic Acidosis

Back 34

Correct underlying problem
Provide hydration
Admin alkalotic IV solution
Na Bicarb or Na Lactate
Mechanical ventilation

Front 35

Metabolic Alkalosis
Base bicarbonate excess caused by

Back 35

Prolonged vomiting
Gain of HCO3-

Front 36

Metabolic Alkalosis
Clinical Presentation:

Back 36

Dizziness
irritability
nervousness
confusion

Front 37

Metabolic Alkalosis
Compensatory mechanisms

Back 37

Decreased respiratory rate to increase plasma CO2
Renal excretion of HCO3-

Front 38

Metabolic Alkalosis
Priority nursing diagnoses

Back 38

Fluid volume imbalance

Front 39

Metabolic Alkalosis
Therapeutic Management

Back 39

Electrolyte replacement

Front 40

Interpretation of ABGs
Respiratory

Back 40

↑ pH, ↓ PaCO2
↓ pH, ↑ PaCO2

Front 41

Interpretation of ABGs
Metabolic

Back 41

↑ pH, ↑ HCO3
↓ pH, ↓ HCO3

Front 42

pH 7.36
PaCO2 67 mm Hg
PaO2 47 mm Hg
HCO3 37 mEq/L
What is this?

Back 42

Respiratory Acidosis with
Metabolic compensation

Front 43

pH 7.18
PaCO2 38 mm Hg
PaO2 70 mm Hg
HCO3- 15 mEq/L
What is this?

Back 43

Metabolic Acidosis with
Respiratory compensation

Front 44

pH 7.60
PaCO2 30 mm Hg
PaO2 60 mm Hg
HCO3- 22 mEq/L
What is this?

Back 44

Respiratory Alkalosis with
Metabolic compensation

Front 45

pH 7.58
PaCO2 35 mm Hg
PaO2 75 mm Hg
HCO3- 50 mEq/L
What is this?

Back 45

Metabolic Alkalosis with
Respiratory Alkalosis

Front 46

pH 7.28
PaCO2 28 mm Hg
PaO2 70 mm Hg
HCO3- 18 mEq/L
What is this ?

Back 46

Metabolic Acidosis with
Respiratory compensation

Front 47

Jeri’s been on a 3-day party binge
Friends are unable to awaken her
Assessment reveals level of consciousness difficult to arouse
Respiratory rate 8
Shallow breathing pattern
Diminished breath sounds
What ABGs do you expect?
What is your treatment?

Back 47

pH high
PaCO2 Low
PO2 Low
HCO3- High
Give O2