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Flashcards in Arterial Blood Gas Review Deck (41):

What should be the first choice for ABG draws?

Other arteries? 2

1. The radial artery is superficial, has collaterals and is easily compressed
It should be the first choice

2. Other arteries:


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

Allen test


ABGs: Performing the Procedure

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


What an ABG measures and the normal range? 5

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)


Acidosis can cause what?

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


Alkalosis can interfere with
what body functions? 3

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


Oxygen-Hgb Dissociation
1. Hemoglobin transports what?
2. Alterations in homeostasis will affect the rate of what?

1. oxygen

2. unloading of the oxygen from the hemoglobin


1. PO2 of the aterial end of the capillary?

2. PO2 of the venous end of the capillary?

1. 95 mm/Hg

2. 40 mm/Hg


What controls pH?

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


Acid/Base Balance
1. pH describes what?

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

1. = how acidic or alkaline the blood is

2. H+ concentration

3. 7.35-7.45


3 systems maintain body pH

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


What substances are involved in chemical buffering? 3

1. Carbonic acid
2. Phosphate
3. Plasma proteins


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?

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


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?

-carbonic acid

-Respiratory rate
-tidal volume

3. 1-3 minutes


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?

1. the pH of the blood

2. Excrete or retain HCO3- and H+

3. hours or even days


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?

1. almost immediately

-Act more slowly than chemical buffer systems
-Have more capacity than chemical buffer systems


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?

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


What are the normals for the following:
1. pH?
2. PCO2?
3. HCO3-?

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


Causes of respiratory acidosis

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


Signs & symptoms of Respiratory Acidosis
1. Respiratory? 3
2. Nervous? 3
3. CVS? 2

1. Respiratory :
-respiratory distress and/or
-shallow respiration

2. Nervous:
-restlessness and

3. CVS:


If CO2 level extremely high what may be noted? 2

1. drowsiness
2. unresponsiveness


Management of respiratory acidosis

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


Causes of respiratory alkalosis

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


Signs & symptoms of respiratory alkalosis
1. CNS? 6
2. CV? 2
3. Other? 3

1. CNS:
-Light headedness,
-inability to concentrate and
-blurred vision


-Dry mouth,
-tetanic spasms of the arms and legs


Management of respiratory alkalosis


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


Causes of metabolic acidosis

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)


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

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


Management of metabolic acidosis

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


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

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


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

1. CNS:
-lethargy disorientation,

2. M/S:
-muscle twitching,
-muscle cramps

-Nausea, vomiting and
-respiratory depression
Difficult to treat


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

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


Base Excess:
1. Calculated value estimates what?

2. It is an estimate of the what?

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)


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

1. Cl–

2. Helps maintain the osmotic pressure of the blood


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?

1. 99

2. fewer

3. in urine


What is the anion gap?


Normal range?

unmeasured anions = protein, phosphate, citrate, sulfate

AG= Na - (Cl- + Bicarbonate)

7-13 mmol/L


ABG step one?

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


1. ABG analysis Step 2

2. IN primary respiratory disorders?

3. In primary metabolic disorders?

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


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?

1. Is there compensation?

2. Going up

3. Going up


ABG analysis Step 4?

Assess the PaO2
Hypoxemia if


ABG analysis Step 5?


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


Do problems in Slide show starting on slide 51