LECTURE 1: Acid Base Balance & Ventilator
Interpreting blood gases
(remember the rules of the B’s)
• If the pH and the bicarb are both in the same direction then it’s metaBolic (Bicarb Both Bolic), if they are in different directions then it is respiratory
• If bicarb is normal and th...
Mark Klimek Lecture Notes
Mark Klimek Lecture Notes
LECTURE 1: Acid Base Balance & Ventilator
Interpreting blood gases
(remember the rules of the B’s)
If the pH and the bicarb are both in the same direction then it’s metaBolic
(Bicarb Both Bolic), if they are in different directions then it is
respiratory
If bicarb is normal and the pH is low or high then its respiratory
You will be given 8 values for arterial blood gas, always first look at the
pH and the bicarb first
You get acidosis and alkalosis from the pH
LABS: ABG’s
The normal pH is 7.35-7.45
The normal bicarb is 22-26 (the bicarb years where you make all the
decisions [22-26 years old], or 2+2+2=6)
The normal CO2 is 35-45 (same as pH)
Signs and Symptoms with ABG’s
As the pH goes up so does my patient
o If the pH goes up, every system in your body gets
more irritable/hyperexcitable
As the pH goes down so does my patient
o If the pH goes down, systems in your body shut down
Except for potassium- When pH goes down, potassium goes up
If the pH goes up (alkalosis): you will find irritability, hyperreflexia (3&4),
tachypnea, tachycardia, borborygmi (increased bowel sounds), seizure (need
suctioning at the bed side because they can seize and aspirate)
If pH goes down (acidosis): hyporeflexia, bradycardia, lethargy, obtunded,
paralytic ileus, coma, respiratory arrest (need bag-mask ventilation bag at
bedside for respiratory arrest), +1 reflexes
MACkussmal- compensatory and respiratory pattern for only acid base
disorder: MAC- Metabolic ACidosis
,Mark Klimek Lecture Notes
Respiratory Acidosis multiple choice example: What would you see with a
patient who is in respiratory acidosis?
a. +1 reflex,
b. diarrhea,
c. adynamic ileus (no movement),
d. spasm,
e. urinary retention,
f. paraxysmol atrial tachycardia,
g. second degree lovitz, type 2 heart block (impulse is being slowed),
h. hypokalemia
EXAMPLE: (In general what do pain meds do?
ANSWER: They sedate you, they are CNS depressants: lethargy, lucidity, reflexes at
+1, hyporeflexia, obtundent
Causes of Acid Base Imbalance
Don’t get signs and symptoms mixed up with causation!!!
What causes something is the opposite of what the signs and symptoms are
o EXAMPLE: diarrhea will cause a metabolic acidosis but once you get
acidotic, it will shut your bowels down and you will get a paralytic
ileus.
The first question you should ask yourself if the scenario involves a lung
problem.
o Is it a respiratory problem? BUT remember it can still be
respiratory acidosis/alkalosis…
Next question you ask yourself…
o is the client overventilating or underventilating?
o If the patient is overventilating pick alkalosis
o If they are underventilating pick acidosis
If the client is overventilating.. it has an attachment to the word- alkalosis
(because they are both OVER)… ventilating OVER becomes respiratory
ALKALOSIS
,Mark Klimek Lecture Notes
If the client is undeventilating.. it has an attachment to the word- acidosis
(because they are both UNDER)- ventilating UNDER becomes
respiratory ACIDOSIS
Examples:
1) A woman is overzealously using her breathing techniques during labor,
what acid base disorder will she exhibit? Overventilation
o Respiratory Alkalosis
2) A child is near drowning, what acid base disorder would it be?
Underventilating
o Respiratory Acidosis
3) Your patient has emphysema, what acid base disorder would it be?
Underventilating
o Respiratory Acidosis
Ventilating does not mean respiratory rate.. respiratory rate is irrelevant-
ventilation has to do with gas exchange!!
Examples:
1) Patient has pneumonia in 4 lobes of the lung, breathing at 50/min and their
SO2 is at 78 on 8 liters per max
o Explanation: Breathing really fast while still having a low O2 level
means that the patient is still underventilating because respiratory
rate has nothing to do with it. Everyone pays so much attention to
rate when they should be paying closer attention to the SO2.
o If your SO2 is good and you are breathing slow, you are fine but if
your SO2 is low and you’re breathing fast, you are actually
underventilating. A lot of times the respiratory rate
compensates- pay attention to SO2!!!
2) Patient is on a PCA pump, what acid base imbalance would tell you they
need to come off that thing?
o A PCA pump depresses respirations. So, patients need to come off
of it as soon as possible because if they were getting too much it
would make their respiratory rate go really down which would
, Mark Klimek Lecture Notes
make the patient underventilate so the answer would be
respiratory acidosis.
o So respiratory acidosis would tell you that you need to come off
the PCA pump.
What if its not lung?
It would be Metabolic.
Only one scenario that you will answer metabolic alkalosis: if the patient has
prolonged gastric vomiting or suctioning
pick metabolic alkalosis.. Why?
o Pt is losing acid... pt will become basic
Otherwise everything else that is not lung or the above, pick metabolic
acidosis
Ex.
1) Patient had GI surgery and has had an NG tube to low intermittent gone
post suctioning for 3 days, what acid base disorder would he most likely
exhibit?
o Metabolic alkalosis
2) Patient has hyper emesis gravidarum , what acid base disorder are
they going to exhibit
o Metabolic alkalosis
3) Continuation: Pt is going to be dehydrated- what acid base disorder would
they have?
o Metabolic acidosis
4) Pt has acute renal failure, what acid base disorder would this be?
o Metabolic acidosis- its not lung or vomiting or suctioning so it has
to be metabolic acidosis
5) A pt with infantile diarrhea would have what acid base disorder?
o Metabolic acidosis
6) A pt with third degree burns over 60 percent of the body?
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