Blood Gas Interpretation
Blood Gas Interpretation
Blood Gas Interpretation
Blood Gases
Important diagnostic tool
Reveals:
1. acid-base balance
2. oxygenation status
**arterial gases only**
3. abnormalities of ventilation
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Acid- base balance
The body is designed for optimum performance at a
specific pH level
Cell division
Metabolism
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Components of Acid- Base Balance
pH- measures the bloods acidity
Normal range 7.35- 7.45
Overall H+ from both respiratory and metabolic factors
pCO2- partial pressure of carbon dioxide in the blood
Normal range 35-45 mmHg
Snapshot of adequacy of alveolar ventilation
HCO3- the amount of bicarbonate in the blood
Normal range 22- 26 mEq/L
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Acid Base Balance
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Acid Base Balance
Lungs Kidneys
Respiratory Metabolic
CO2 (acid) HCO3 ( base/alkaline)
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Making sense of it
pH
7.35 7.45
Respiratory Metabolic
CO2=Acidosis HCO3=Acidosis
CO2=Alkalosis HCO3=Alkalosis
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Interpretation: 4 steps
Normal Values
pH 7.35 7.45
pCO2 35 45 mmHg
HCO3 22 - 26 mEq/L
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Step 1
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Step 2
35 40 45
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Step 3
22 24 26
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Step 4
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ABG Analysis
pH pCO2 HCO3
Resp. Acidosis A A N
(<7.35) (>45) (22-26)
Resp. B B N
Alkalosis (>7.45) (<35) (22-26)
Metabolic A N A
Acidosis (<7.35) (35-45) (<22)
Metabolic B N B
Alkalosis (>7.45) (35-45) (>26)
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Lets practice
pH pCO2 HCO3
A A N Respiratory Acidosis
7.26 55 23
B N B Metabolic Alkalosis
7.54 43 39
N N N Normal
7.39 41 25
B B N Respiratory Alkalosis
7.51 29 24
A N A Metabolic Acidosis
7.29 40 17
A A A Mixed Acidosis
7.28 61 18
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Compensation
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Understanding Compensation
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Understanding Compensation
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Understanding Compensation
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Lets Practice Compensation
pH pCO2 HCO3
Metabolic Alkalosis partially
B A B compensated
7.51 49 40
A A N Respiratory Acidosis uncompensated
7.29 53 22
N B A
Metabolic Acidosis fully compensated
7.37 25 18
N A B Respiratory Acidosis fully compensated
7.35 65 28
B B A
Respiratory Alkalosis partially
compensated
7.46 22 20 Respiratory Acidosis partially
A A B compensated
7.34 52 27
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A Final Step
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Respiratory Acidosis
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Respiratory Acidosis
Clues
Confusion, restlessness
Headache, dizziness
Lethargy
Dyspnea
Tachycardia
Dysrhythmias
Coma leading to death
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Respiratory Acidosis
Solutions
Improve ventilation
Ensure adequate airway; positioning,
suctioning
Encourage deep breathing and coughing
Frequent repositioning
Chest physio/ postural drainage
Bronchodilators
Decrease sedation/analgesia
Oxygen therapy
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Respiratory Alkalosis
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Respiratory Alkalosis
Clues
Light headedness
Confusion
Decreased concentration
Tingling fingers and toes
Syncope
Tetany
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Respiratory Alkalosis
Solutions
Decrease respiratory rate and depth
Sedation/analgesia as appropriate
Rebreather mask
Paper bag
Emotional support/encourage patient to slow
breathing
Calm, soothing environment
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Metabolic Acidosis
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Metabolic Acidosis
Clues
Stupor
Restlessness
Kussmauls respirations (air hunger)
Seizures
Coma leading to death
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Metabolic Acidosis
Solutions
Replace HCO3 while treating underlying cause
Monitor intake and output
Monitor electrolytes, especially K+
Seizure precautions
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Metabolic Alkalosis
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Metabolic Alkalosis
Clues
Weakness, dizziness
Disorientation
Hypoventilation
Muscle twitching
Tetany
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Metabolic Alkalosis
Solutions
Control vomiting
Replace GI losses
Eliminate overuse of antacids
Monitor intake and output
Monitor electrolytes
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