Arterial Blood Gases
What are some characteristics of arterial blood gasses (ABGs)?
results give us information on how well the lungs and the kidneys are functioning.
lungs regulate the CO2: respiratory rate
kidneys regulate the HCO3: producing HCO3 and excreting H+ ions
Acid-base balance equation
H+ + HCO3- (kidneys) <-> H2CO3 (carbonic acid) <-> H2O + CO2 (lungs)
body tries to maintain a 20:1 ratio btwn HCO3 and H2CO3.
Ex: pt is hypoventilating so their CO2 decreases. carbonic acid will then breakup to make H2O and CO2.
The ratio is now 20:0.5, so H+ and HCO3- will combine to form carbonic acid to get the ratio back up.
What are the different normals for ABGs?
pH: 7.35-7.45
PaCO2: 35-45 mmHg
HCO3: 22-26 mEq/L
What are some characteristics of respiratory acidosis?
caused by hypoventilation: could be from sedation or poor gas exchange (COPD, pneumonia, CHF).
causes you to retain CO2, which increases your PaCO2.
CO2 then combines w/ H2O to form carbonic acid, and the pH becomes more acidotic (<7.35).
carbonic acid will then start to dissociate: H+ will be excreted from the urine. HCO3 will be reabsorbed
(body is trying to take care of it), to maintain a 20:1 ratio. this will take 24-48 hrs though, which is too
long when resp issues are present.
corrected by: hyperventilation. intubate or decrease narcotics.
, What are some characteristics of respiratory alkalosis?
caused by hyperventilation: anxiety and pain. also like when you climb stairs and your lips tingle a little.
can have carpopedal spasms where your hands and feet tingle, causes the pt to freak out and
hyperventilate more.
causes you to blow off CO2, which causes decreased PaCO2 and the pH becomes alkalotic. carbonic acid
must then break down in order to produce more CO2; H2 released from the cells and kidneys produce
more HCO3.
corrected by: hypoventilation. reduce anxiety or control pain (not too much tho bc don't want them to
be too sedated and end up in resp acidosis).
What are some characteristics of metabolic acidosis?
caused by increased H+ ions: can be from renal failure (unable to excrete H+), DKA and starvation
(increased H+ production), and diarrhea (loss of HCO3).
H+ then has nothing to bind to, so the brain is stimulated to breath faster to decrease the PaCO2 (only
works for a short time tho). if producing more H+ w/ nothing to bind to, carbonic acid tries to break
apart to produce HCO3. person has to slow down their breathing to retain the CO2 so it can bind w/ the
water to make more carbonic acid. this is why ppl in DKA have Kussmaul respirations, trying to breathe
fast and deep to blow off CO2.
kidneys then excrete more H+ (if they have nothing to bind to) OR reabsorb more HCO3 (to bind w/ the
excess H+, decreased free HCO3).
correct the problem: reverse DKA, tx diarrhea (esp in children!), and dialysis (if pt can't get rid of H+ bc
they're in renal failure, dialysis will get the H+ out).
What are some characteristics of metabolic alkalosis?
causes: vomiting (loss of HCl from stomach causes a loss of H+ ions), antacids (like mylanta, bc they bind
to and neutralize H+ and make everything more alkalotic), diuretic use (excretes H+ from kidneys), and
increased pH (from decrease in H+).
quick fix: slow down respirations to retain CO2 (only works for short time).
kidneys: excrete HCO3 AND retain H+
correct the problem: antiemetics, decrease antacid use, and decrease diuretic use (why it's so important
to do a thorough med hx).
What are some characteristics of arterial blood gasses (ABGs)?
results give us information on how well the lungs and the kidneys are functioning.
lungs regulate the CO2: respiratory rate
kidneys regulate the HCO3: producing HCO3 and excreting H+ ions
Acid-base balance equation
H+ + HCO3- (kidneys) <-> H2CO3 (carbonic acid) <-> H2O + CO2 (lungs)
body tries to maintain a 20:1 ratio btwn HCO3 and H2CO3.
Ex: pt is hypoventilating so their CO2 decreases. carbonic acid will then breakup to make H2O and CO2.
The ratio is now 20:0.5, so H+ and HCO3- will combine to form carbonic acid to get the ratio back up.
What are the different normals for ABGs?
pH: 7.35-7.45
PaCO2: 35-45 mmHg
HCO3: 22-26 mEq/L
What are some characteristics of respiratory acidosis?
caused by hypoventilation: could be from sedation or poor gas exchange (COPD, pneumonia, CHF).
causes you to retain CO2, which increases your PaCO2.
CO2 then combines w/ H2O to form carbonic acid, and the pH becomes more acidotic (<7.35).
carbonic acid will then start to dissociate: H+ will be excreted from the urine. HCO3 will be reabsorbed
(body is trying to take care of it), to maintain a 20:1 ratio. this will take 24-48 hrs though, which is too
long when resp issues are present.
corrected by: hyperventilation. intubate or decrease narcotics.
, What are some characteristics of respiratory alkalosis?
caused by hyperventilation: anxiety and pain. also like when you climb stairs and your lips tingle a little.
can have carpopedal spasms where your hands and feet tingle, causes the pt to freak out and
hyperventilate more.
causes you to blow off CO2, which causes decreased PaCO2 and the pH becomes alkalotic. carbonic acid
must then break down in order to produce more CO2; H2 released from the cells and kidneys produce
more HCO3.
corrected by: hypoventilation. reduce anxiety or control pain (not too much tho bc don't want them to
be too sedated and end up in resp acidosis).
What are some characteristics of metabolic acidosis?
caused by increased H+ ions: can be from renal failure (unable to excrete H+), DKA and starvation
(increased H+ production), and diarrhea (loss of HCO3).
H+ then has nothing to bind to, so the brain is stimulated to breath faster to decrease the PaCO2 (only
works for a short time tho). if producing more H+ w/ nothing to bind to, carbonic acid tries to break
apart to produce HCO3. person has to slow down their breathing to retain the CO2 so it can bind w/ the
water to make more carbonic acid. this is why ppl in DKA have Kussmaul respirations, trying to breathe
fast and deep to blow off CO2.
kidneys then excrete more H+ (if they have nothing to bind to) OR reabsorb more HCO3 (to bind w/ the
excess H+, decreased free HCO3).
correct the problem: reverse DKA, tx diarrhea (esp in children!), and dialysis (if pt can't get rid of H+ bc
they're in renal failure, dialysis will get the H+ out).
What are some characteristics of metabolic alkalosis?
causes: vomiting (loss of HCl from stomach causes a loss of H+ ions), antacids (like mylanta, bc they bind
to and neutralize H+ and make everything more alkalotic), diuretic use (excretes H+ from kidneys), and
increased pH (from decrease in H+).
quick fix: slow down respirations to retain CO2 (only works for short time).
kidneys: excrete HCO3 AND retain H+
correct the problem: antiemetics, decrease antacid use, and decrease diuretic use (why it's so important
to do a thorough med hx).
