Acid Base Balance

Question 1

Acid + example

Answer 1

substance that releases H+ when dissolved in water/body fluids

H+ = proton

Question 2

Base + example

Answer 2

substance that accepts or binds to hydrogen ions

HCO3-

Question 3

Acidosis

Answer 3

the process by which protons are produced in a large amount

increase in proton production

Question 4

Alkalosis

Answer 4

the process by which there is a decrease in proton production/concentration (H+)

Question 5

Buffer

Answer 5

can react as either acid or base, depending on pH of the solution

Question 6

What are arterial blood gases

Answer 6

Provide valuable information on patient’s acid-base and oxygenation status

Reflect respiratory and metabolic functions

Constant byproduct of cellular metabolism: CO2 and water

Question 7

What is pH and normal value?

Answer 7

7.35-7.45
* Concentration of hydrogen ions
* Hydrogen ions = acidic

Question 8

What does PCO2 tell you and normal value?

Answer 8

35-45mmHg

Partial pressure of carbon dioxide

Question 9

The amount of CO2 is directly proportional to:

Answer 9

the number of hydrogen ions; corresponds with acid

Question 10

The more carbon dioxide in your blood the more _____ your blood is

Answer 10

Acidic

Question 11

Carbon dioxide levels will be altered in ______

Answer 11

respiratory acidosis/alkalosis

Controlled by lungs

Question 12

Bicarb normal value

Answer 12

22-28mmol/l

Question 13

The more bicarbonate you have in your blood, the more ____ it is

Answer 13

basic

Question 14

Bicarbonate levels will be altered in:

Answer 14

Metabolic acidosis/alkalosis

Question 15

Normal PaO2 levels and when are decreases seen?

Answer 15

80-100mmHg

decreases above sea level and with increasing age

Question 16

What does PaO2 give information on?

Answer 16

does not give information on whether patient is in respiratory/metabolic acidosis only hypoxemia

Question 17

Normal base excess level

Answer 17

0 + 2.0mEq/L

Question 18

4 Steps of ABG analysis

Answer 18

1. Identify acidosis/alkalosis
   - look at pH
2. Identify respiratory/metabolic
   - look at CO2 (altered in resp)
   - look at HCO3 (altered in metabolic)
3. Identify compensation
   - other value normal = none
   - other value outside = compensated
   > normal pH = full
   > abnormal pH = partial

Question 19

Respiratory Alkalosis Values

Answer 19

high pH, low CO2, normal HCO3 (unless compensated)

Question 20

Respiratory Acidosis Values

Answer 20

low pH, high CO2, normal HCO3 (unless compensated)

Question 21

Metabolic Alkalosis Values

Answer 21

high pH, high HCO3, normal CO2 (unless compensated)

Question 22

Metabolic Acidosis Values

Answer 22

low pH, low HCO3, normal CO2 (unless compensated)

Question 23

What causes respiratory acidosis + 3 conditions

Answer 23

Retention of CO2
* CNS Depression
* Neuromuscular Disorder
* Obstructive Lung Disease

Question 24

What causes respiratory alkalosis + 3 conditions

Answer 24

Excretion of CO2
* CNS Hyperactivity (anxiety, fever, pain)
* Hypoxemia - can stimulate hyperventilation
* Increased ICP

Question 25

What 3 things cause metabolic acidosis?

Answer 25

Gain of Acid (DKA, lactic acidosis) Loss of Base Inability to excrete acid

Question 26

What 3 things cause metabolic alkalosis?

Answer 26

Loss of Acid (vomiting, increased aldosterone, total volume loss, administration of NaHCO3) gain of base excessive renal loss

Question 27

Effects of acidosis on the heart

Answer 27

1. hypotension due to decreased contractility, decreasing CO and MAP 2. hypotension due to increased vasodilation 3. increased HR causing VT arrhythmias 4. resistance to vasopressors

Question 28

Effects of alkalosis on the heart

Answer 28

1. increases vasoconstriction 2. increases HR leading to VT arrhythmias, vfib, SVT arrhythmias

Question 29

Effects of acidosis on the lungs

Answer 29

increases RR - increased WOB - fatigue

Question 30

Effects of alkalosis on the lungs

Answer 30

decreases RR - hypoxemia

Question 31

Effects of acidosis on metabolism

Answer 31

1. high proton concentration causes extra to intracellular fluid shift, increasing potassium ARRHYTHMIA RISK 2. high proton concentration alters insulins effect, promoting resistance INCREASING BG

Question 32

Effects of alkalosis on metabolism

Answer 32

Decreases potassium and magnesium (to a lesser extent)

Question 33

Effects of acidosis on CNS

Answer 33

Altered mental status – coma

Question 34

Effects of alkalosis on CNS

Answer 34

Altered mental status – coma Seizures/tetany

Question 35

Volatile Acids

Answer 35

Can be converted to gas for excretion by lungs carbonic acid to carbon dioxide

Question 36

Example of volatile acid

Answer 36

Carbonic acid

Question 37

Nonvolatile acids

Answer 37

Metabolic acids Cannot be converted to gas; must be excreted by kidneys Can only do a small amount each day - slow process

Question 38

Nonvolatile acid examples and how they are formed

Answer 38

1. Sulfuric acid: formed by protein breakdown 2. Fatty acids & ketoacids: formed by fat breakdown 3. Lactic acid: when cells metabolize under anaerobic (no oxygen) conditions

Question 39

How does the body acutely respond to acid base imbalances?

Answer 39

The bicarb/carbonic acid buffer system

Question 40

What occurs in the buffer system when there is a low pH?

Answer 40

Bicarbonate can bind to free H+ when too many are present, or release them when not enough are present, forming carbonic acid Carbonic acid can then be excreted through lungs

Question 41

What occurs in the buffer system when there is a high pH?

Answer 41

If there are too few H+ ions, carbonic acid will disassociate into a hydrogen ion and bicarbonate

Question 42

What does the carbonic anhydrase equation show

Answer 42

This reaction (driven by carbonic anhydrase enzyme) shows how H+ and CO2 levels are directly related. An increase in one causes an equal increase in the other

Question 43

Describe the carbonic anhydrase equation?

Answer 43

carbon dioxide + water <> carbonic acid <> hydrogen + bicarbonate

Question 44

What are the 3 buffering systems in the body?

Answer 44

1. Bicarbonate - acute/not highly effective 2. respiratory - fast system based on chemoreceptors of CO2 concentration 3. renal - slower regulates HCO3

Question 45

How do the lungs compensate/act as an acid-base buffer system?

Answer 45

Control carbon dioxide and thus carbonic acid excretion Ventilation based on CO2 levels via chemoreceptors

Question 46

How do the lungs compensate in acidosis?

Answer 46

Increased Rate and depth of ventilation = attempt to rid body of CO2 * Low pH stimulates chemoreceptors in CNS  stimulates an increase in RR (in attempt to breathe off CO2)

Question 47

How do the lungs compensate in alkalosis?

Answer 47

Decreased Rate and depth of ventilation = retention of CO2 * High pH inhibits chemoreceptors in CNS  lower RR  retention of CO2

Question 48

How do the kidneys compensate/act as an acid-base buffer?

Answer 48

Takes hours to days/longer * Regulate HCO3- level (excretion and reabsorption) in the renal tubules

Question 49

How do the kidneys compensate in acidosis?

Answer 49

kidneys excrete H+ and conserve HCO3-

Question 50

How do the kidneys compensate in alkalosis?

Answer 50

kidneys retain H+ and excrete (/decrease resabsorption) HCO3-

Question 51

Uncompensated ABG values

Answer 51

* Abnormal pH * One abnormal and one normal value (other system has not been compensated)

Question 52

Partially compensated ABG values

Answer 52

* Abnormal pH * Two abnormal values (opposite system has attempted to compensate)

Question 53

Fully compensated ABG values

Answer 53

* Normal pH * Two abnormal values (opposite system has compensated enough to move pH into normal range)