Week 2 ABGs ✅ Flashcards
When do you do an ABG?
Respiratory disorders e.g. asthma, COPD
Resuscitation
Sepsis
Metabolic acidosis
Why is lactate produced?
Anaerobic respiration
What is met-Hb?
Methoglobin
What is co-Hb?
Carboxyhemoglobin
What is acid?
concentration of hydrogen ions
How do you do an ABG?
Wash hands
Get sharps bin
LA might be appropriate
Allen test
Take blood from radial artery
How do you do an Allen test?
Occlude radial artery
What are the by-products of metabolism?
H+
H20
CO2
How is acid disposed of?
Gaseous exchange in lungs
Carbonic anhydrase converts CO2 and H2O into H2CO3
How is CO2 and H2O converted into H2CO3?
Carbonic anhydrase
What is the buffer system?
H+ + HCO3- <-> H2CO3 <-> H2O + CO2
How long does it take for kidneys to compensate?
6-12 hours
What is respiratory compensation?
Breathe out more or less CO2
How do you diagnose respiratory acidosis/alkalosis? (not aemia!)
CO2 below or above normal
How do you diagnosis metabolic acidosis/alkalosis? (not aemia!)
HCO3 below or above normal
Why might a pH still be normal in an acid-base balance?
Not an acid base problem!
Chronic COPD - chronic metabolic compensation
Both acid AND alkaline problem
What does SBE stand for and what does it mean?
Standard base excess
Measure of other buffers - correlates with HCO3
What do you need to consider when interpreting ABGs?
History - risk and signs/symptoms
Data - pH, O2, CO2, HCO3, single or multiple acid-base disturbance?
Integration - do the suspicions agree with the data?
How do you work out the expected kPa from FiO2?
FiO2 - 10 = kPa
