Arterial Blood Gas Review

Question 1

What should be the first choice for ABG draws?

Other arteries? 2

Answer 1

1. The radial artery is superficial, has collaterals and is easily compressed
   It should be the first choice
2. Other arteries:
   - femoral,
   - brachial

Question 2

What test should you do to make sure the pt has collateral cicrulation before doing ABGs?

Answer 2

Allen test

Question 3

ABGs: Performing the Procedure

12

Answer 3

1. Put on gloves
2. Prepare the site (Drape the bed and cleanse the radial area with alcohol)
3. Position the wrist (hyper-extended, using a rolled up towel if necessary)
4. Palpate the arterial pulse and visualize the course of the artery
5. Open the ABG kit
6. Line the needle up with the artery, bevel side up
7. Enter the artery and allow the syringe to fill spontaneously
8. Withdraw the needle and hold pressure on the site
9. Protect needle
10. Remove any air bubbles
11. Gently mix the specimen by rolling it between your palms
12. Place the specimen on ice and transport to lab immediately

Question 4

What an ABG measures and the normal range? 5

Answer 4

1. pH (7.35-7.45)
2. CO2 (35-45 mmHg)
3. O2 (83-102 mmHg)
4. HCO3 (22-28 mmol/L)
5. Anion gap (10-16 mmol/L)

Question 5

Acidosis can cause what?

Answer 5

1. Decreased force of cardiac contraction
2. Decreased vascular response to catecholamines
3. Decreased response to the effects and action of certain medications

Question 6

Alkalosis can interfere with

what body functions? 3

Answer 6

1. Tissue oxygenation
2. Neurological and
3. muscle function

Question 7

Oxygen-Hgb Dissociation

1. Hemoglobin transports what?
2. Alterations in homeostasis will affect the rate of what?

Answer 7

1. oxygen

2. unloading of the oxygen from the hemoglobin

Question 8

1. PO2 of the aterial end of the capillary?

2. PO2 of the venous end of the capillary?

Answer 8

1. 95 mm/Hg

2. 40 mm/Hg

Question 9

What controls pH?

5

Answer 9

1. Diet
2. Metabolic production of CO2
3. Regulation through the GI tract
4. Influence of other electrolytes
5. BUFFERS

Question 10

Acid/Base Balance
1. pH describes what?

2. pH is inversely proportional to the what?
3. Normal range?

Answer 10

1. = how acidic or alkaline the blood is
2. H+ concentration
3. 7.35-7.45

Question 11

3 systems maintain body pH

Answer 11

1. Chemical buffering
2. The respiratory center
3. The kidneys

Question 12

What substances are involved in chemical buffering? 3

Answer 12

1. Carbonic acid
2. Phosphate
3. Plasma proteins

Question 13

The carbonic acid buffering system is the main buffer

1. Whats the equation?
2. CO2 is a byproduct of what?
3. CO2 is best trabsported as?
4. As the CO2 increased so does the what?
5. The higher the H+ (or CO2) the ______ the pH?

Answer 13

1. H2O + CO2 ↔ H2CO3 ↔ HCO3- + H+
2. CO2 is a by product of cellular metabolism
3. CO2 is best transported as HCO3-
4. As the CO2 increases so does the H+ concentration
5. lower

Question 14

The respiratory buffer
1. Concentrations of what will trigger the respiratory center?

2. What will be altered to either increase or decrease ventilation? 2
3. This response occurs in what amount of time?

Answer 14

1. • CO2,
   • carbonic acid
   • HCO3
2. • Respiratory rate
   • tidal volume
3. 1-3 minutes

Question 15

THE RENAL BUFFER
1. The kidneys can excrete either acid or alkaline urine, thereby adjusting what?

2. How do they do this?
3. This response takes place over what timeline, but represents a more powerful regulatory system?

Answer 15

1. the pH of the blood
2. Excrete or retain HCO3- and H+
3. hours or even days

Question 16

Physiological Buffer Systems

1. Chemical buffer systems occur how quickly?
2. Respiratory and renal systems: Describe the rate and capacity of these compared to the chemical buffer system?

Answer 16

1. almost immediately
2. • Act more slowly than chemical buffer systems
   • Have more capacity than chemical buffer systems

Question 17

Chemical Buffer Systems

Chemical buffer: system of one or more compounds that act to resist pH changes when strong acid or base is added: There are 3?

Answer 17

1. Bicarbonate buffer system
2. Phosphate buffer system
   3 Protein buffer system

Question 18

What are the normals for the following:

1. pH?
2. PCO2?
3. HCO3-?

Answer 18

1. 7.4
2. 40 mmHg
3. 24 mEq/L

Question 19

Causes of respiratory acidosis

5

Answer 19

1. Central nervous system depression…medications such as narcotics, sedatives, or anesthesia
2. Impaired muscle function…spinal cord injury, neuromuscular diseases, or neuromuscular blocking drugs
3. Pulmonary disorders…atelectasis, pneumonia, pneumothorax, pulmonary edema or bronchial obstruction
4. Massive pulmonary embolus
5. Hypoventilation due to pain, chest wall injury, or abdominal pain

Question 20

Signs & symptoms of Respiratory Acidosis

1. Respiratory? 3
2. Nervous? 3
3. CVS? 2

Answer 20

1. Respiratory :
   - dyspnea,
   - respiratory distress and/or
   - shallow respiration
2. Nervous:
   - Headache,
   - restlessness and
   - confusion
3. CVS:
   - Tachycardia
   - dysrhythmias

Question 21

If CO2 level extremely high what may be noted? 2

Answer 21

1. drowsiness

2. unresponsiveness

Question 22

Management of respiratory acidosis

3

Answer 22

1. Increase the ventilation
2. Causes that can be treated rapidly include pneumothorax, pain and CNS depression due to medication
3. If the cause can not be readily resolved then will require mechanical ventilation

Question 23

Causes of respiratory alkalosis

5

Answer 23

1. Psychological responses, anxiety or fear
2. Pain
3. Increased metabolic demands such as fever, sepsis, pregnancy or thyrotoxicosis
4. Medications such as respiratory stimulants
5. Central nervous system lesions

Question 24

Signs & symptoms of respiratory alkalosis

1. CNS? 6
2. CV? 2
3. Other? 3

Answer 24

1. CNS:
   - Light headedness,
   - numbness,
   - tingling,
   - confusion,
   - inability to concentrate and
   - blurred vision
2. • Dysrhythmias
   • palpitations
3. • Dry mouth,
   • diaphoresis
   • tetanic spasms of the arms and legs

Question 25

Management of respiratory alkalosis 3

Answer 25

1. Resolve the underlying problem 2. Monitor for respiratory muscle fatigue 3. When the respiratory muscles become exhausted, acute respiratory failure may ensue

Question 26

Causes of metabolic acidosis | 6

Answer 26

1. Renal failure 2. Diabetic ketoacidosis 3. Anaerobic metabolism (tissue death, lactic acidosis) 4. Starvation 5. Salicylate intoxication (common board question) 6. Sepsis (such bad tissue hypoxemia)

Question 27

Sign & symptoms of metabolic acidosis 1. CNS? 4 2. CVS? 1 3. Resp? 1 4. Other? 2

Answer 27

1. CNS: - Headache, - confusion and - restlessness progressing to lethargy, - then stupor or coma 2. CVS: Dysrhythmias 3. Kussmaul’s respirations 4. - Warm, flushed skin as well as - nausea and vomiting

Question 28

Management of metabolic acidosis | 5

Answer 28

1. Treat the cause 2. Hypoxia of any tissue bed will produce metabolic acids as a result of anaerobic metabolism even if the pao2 is normal 3. Restore tissue perfusion to the hypoxic tissues 4. The use of bicarbonate is indicated 5. Hydration

Question 29

Causes of metabolic alkalosis 1. Ingestion of? 3 2. Other? 5

Answer 29

1. Ingestion of excess antacids, 2. excess use of bicarbonate, 3. or use of lactate in dialysis 1. Protracted vomiting, 2. gastric suction, 3. hypochloremia, 4. excess use of diuretics or 5. high levels of aldosterone

Question 30

Signs and symptoms of metabolic alkalosis 1. CNS? 4 2. M/S? 3 3. Other? 2

Answer 30

1. CNS: - Dizziness, - lethargy disorientation, - seizures - coma 2. M/S: - weakness, - muscle twitching, - muscle cramps - tetany 3. -Nausea, vomiting and -respiratory depression Difficult to treat

Question 31

The Base Excess 1. Amount of what? 2. What are these values? 3. A negative base excess indicates what?

Answer 31

1. Amount of excess or insufficient level of bicarbonate 2. -2 to +2mEq/L 3. A negative base excess indicates a base deficit in blood

Question 32

Base Excess: 1. Calculated value estimates what? 2. It is an estimate of the what?

Answer 32

1. the metabolic component of an acid based abnormality 2. amount of strong acid or base needed to correct the metabolic component of an acid base disorder (restore plasma pH to 7.40 at a Paco2 40 mmHg)

Question 33

Regulation of Anions 1. What is the major anion in the ECF? 2. What does it help do?

Answer 33

1. Cl– | 2. Helps maintain the osmotic pressure of the blood

Question 34

Regulation of Anions 1. __% of Cl– is reabsorbed under normal pH conditions 2. When acidosis occurs, _______ chloride ions are reabsorbed 3. Other anions have transport maximums and excesses are excreted how?

Answer 34

1. 99 2. fewer 3. in urine

Question 35

What is the anion gap? Calculation? Normal range?

Answer 35

unmeasured anions = protein, phosphate, citrate, sulfate AG= Na - (Cl- + Bicarbonate) 7-13 mmol/L

Question 36

ABG step one?

Answer 36

What is the pH? Acidemia pH less than 7.35 Alkalemia pH > 7.45

Question 37

1. ABG analysis Step 2 2. IN primary respiratory disorders? 3. In primary metabolic disorders?

Answer 37

1. What is the PaCO2? 2. In primary respiratory disorders pH and CO2 change in opposite directions 3. In primary metabolic disorders pH and CO2 change in the same direction

Question 38

1. ABG analysis Step 3 2. If it is a respiratory problem what is happening with the bicarb? 3. If it is a metabolic problem what is happening with the CO2?

Answer 38

1. Is there compensation? 2. Going up 3. Going up

Question 39

ABG analysis Step 4?

Answer 39

Assess the PaO2 | Hypoxemia if

Question 40

ABG analysis Step 5? 3

Answer 40

1. Anion Gap = (Na+) – [Cl- + HCO3-] 2. The number of anions (-) and cations (+) should be equal but a standard blood gas doesn’t measure them all so there is a difference of 10-16 3. This may be helpful in sorting out causes of metabolic acidosis as some causes have an increased anion gap and some have a normal gap

Question 41

Do problems in Slide show starting on slide 51

Answer 41

51