Acid Basae Flashcards
What accounts for pH
H+
Kidney compensates acid by producing…
ammonia
7.36 =
neutral (7.35-7.45)
pH = 7.25 and shows improvement ..
acidemic
order of ABG
pH/PCO2/O2/Bicarb
Indications for ordering ABG
resp failure severe dz which may lead to met acid vented pts sleep studies severely unwell pts
where are chemoreceptors located
internal carotids, aotic arch. detect change in pH
normal range and math value pH CO2 Bicarb AG Albumin
pH = 7.35-7.45 - 7.4 pCO2 = 35-45, 40 Bicarb = 22-26, 24 Anion Gap = 10-14, 12 Albumin = 4,4
renal compensation
- reabsorption of HCO3
- Formation of titratable acid (acid that can lose +)
- excretion of NH4+
Resp Acid
High CO2.
increase 10 CO2 = increase 1 HCO3= pH down 0.08
Chronic increase 4 HCO3 = pH down 0.03
Resp Alk
Low CO2.
Decrease 10 CO2 = decrease 2 HCO3= pH down 0.08
Chronic decrease 5 HCO3 = pH down 0.03
Met Alk
High HCO3
increase 10 HCO3 = increase 6 PCO2
Met Acid
Low HCO3
acute: PCO2=1.5*(HCO3) + 8
chronic: PCO2 = HCO3 + 15
These are the expected PCO2 change. if actual is > expected, then Resp Acid also
Henderson-Hasselbach equation
[H+] = 24 * PCO2/HCO3
45 H+ = 7.35 pH
35 H+ = 7.45 pH
Anion Gap
only for Met Acidosis
Na+ - (Cl + HCO3)
Normal = 0.2albumin + 1.5phos
___ contribuites almost the whole value of the AG
Association between __ and AG?
albumin
1 decrease of Albumin = 2.3 decrease AG
lactic acidosis
most common form of increased anion gap.
>4mg/dL
Eth Gly and Meth characterization
increased anion gap with an osmolal gap of 10+
osmolarity = 2*Na + glu/18 + BUN/2.8
Anion Gap Causes
methanol, uric acid, DKA, paraldehyde, iron tox, lactic acid, eth gly, rhabdo, salicylates
Non AG Met Acidosis
Renal tube failure
Acetazolamide/Addisons = high K+
GI
Delta Gap =
Delta Delta =
Delta Gap = AG-12
Delta Delta = DG + HCO3
What do we compare DD to?
if DD 26..
compare to normal Bicarb
26 = holding on to bicarb and there is an additional met alk occuring
Alveolar-arterial O2 difference formula
Normal value?
Does it increase with age?
How can we tell if its is normal?
AaO2D = PAO2 – PaO2 (from ABG)
about 10-15 mm Hg
yes
A normal A-a gradient should be less than the (patient’s age divided by 4) + 4.
Acidotic =
Acidemia =
Acidotic = final state Acidemia = process is still happening but within range
