3. Acid Base Management Flashcards
venous CO2 normal value
24-30 mEq/L
(CO2 + HCO3-)
arterial CO2 normal value
22-26 mEq/L
(HCO3-)
PaCO2 normal
35-45 mmHg
PvCO2 normal
40-50 mmHg
PvCO2 is normally _______ compared to PaCO2
PvCO2 is 5 mmHg higher than PaCO2
if a pt is poorly perfused, what happens to the PvCO2:PaCO2 gradient
increases
PaO2 of atmosphere normal
160 mmHg (sea level)
PaO2 normal value
70-100 mmHg
what happens to PaO2 as you age?
it decreases
PvO2 normal value
30-40 mmHg
CaO2 normal value
16-20 mL/dL
CvO2 normal value
12-16 mL/dL
DO2
total delivery of O2 per minute
DO2 normal
1000 mL of O2 delivered per minute
normal Hb
15 g/dL
normal SaO2
93-98%
normal CO
5 L/min
mvO2 normal
60-80%
(up to 90%)
ScvO2 normal
70-75%
difference between PAO2 and PaO2
A-a gradient
A-a gradient: room air
5-15 mmHg
A-a gradient: elderly
15-25 mmHg
A-a gradient: 100% FiO2
10-110 mmHg
normal MV
7-8 L/min
Va =
2/3 of MV
Vd =
1/3 of MV
VCO2
200 mL/min
what happens to VCO2 under GA
decreased by up to 60%
VO2: normothermic adult
250 mL/min
VO2: infants
6-8 mL/kg/min
VO2: adults
3-4 mL/kg/min
pH
7.35-7.45
%MetHB on ABG
<2%
%COHb on ABG
<3%
HCO3-/PaCO2 ratio
20:1
PaO2/Fio2 ratio
480
Anion Gap
8-16 mEq/L
Base Excess
-2.0 - 2.0 mEq/L
serum lactate concentration
< 2 mmol/L
lactic acidosis
serum lactate > 5 mmol/L
Vt
volume of air expired in 1 breath
including dead space
MV
total volume of air breathed in 1 min
including dead space
MV =
MV = RR*Vt
Vd
volume of dead space in 1 breath
Vd: pulmonary dz
> 1/3 of Vt
Vd/Vt
amount of dead space ventilation that occurs in 1 min
Vd/Vt =
Vd/Vt = Vd*RR
alveolar volume
amount of air in 1 breath that reaches the alveoli and participates in gas exchange
alveolar volume =
alveolar vol = Vt - Vd
Va
amount of air in 1 min that reaches the alveoli and participates in gas exchange
Va =
Va = (Vt - Vd) *RR
blood gas: technically
gas under ordinary conditions
dissolved in our blood
blood gas: clinically
collection of values that may include actual blood gases but also include other values
ABG measures (6)
- pH
- PaCO2
- HCO3-
- PaO2
- SaO2
- Base excess
ABG additional values (6)
- Hb/Hct
- K+
- Glu
- Ca2+
- COHb
- MetHb
3 forms of CO2 in the body
- PaCO2
- HCO3- (plasma)
- HCO3- (Hb-bound)
PaCO2 accounts for ________ of all CO2
5-10%
HCO3- in plasma accounts for _______
60-65%
HCO3- bound to Hb accounts fo
30%
HCO3- total in body
90-95% of all CO2
lechatlier principle: drive RIGHT
incr CO2
or
decr HCO3-
lechatlier principle: drive LEFT
decr CO2
or
incr HCO3-
acids drive reaction
RIGHT
acids ____ H+
incr H+ ions
bases drive reaction
LEFT
bases ____ H+
decr H+ ions
respiratory acidosis cause
hypoventilation
incr PaCO2
respiratory acidosis diagnosis
low pH
high PaCO2
respiratory alkalosis cause
hyperventilation
decr PaCO2
respiratory alkalosis diagnosis
high pH
low PaCO2
metabolic acidosis cause
decr HCO3-
metabolic acidosis diagnosis
low pH
low HCO3-
metabolic alkalosis cause
incr HCO3-
metabolic alkalosis diagnosis
high pH
high HCO3-
pH is determine by
HCO3- to PaCO2 ratio
acidosis SE (6)
- decr contractility
- decr catecholamine response
- decr coag / incr bleeding
- incr PVR
- incr risk of Vfib
- incr plasma K+
alkalosis SE (6)
- shifts O2-Hb LEFT
- incr SVR
- cerebral vasoconstriction
- decr pVR
- decr plasma K+
pH ~
pH ~ HCO3- / PaCO2
base excess: technically
amount of acid or base needed to return the blood to pH 7.4 and PaCO2 to 40 mmHg
base excess: clinically
tells us if pt has too much or too little base in the blood
normal Base excess
-2 to 2 mmol/L
base excess > 2mmol/L
too much base
metabolic alkalosis
base excess < -2 mmol/L
not enough base
metabolic acidosis
what indicates metabolic acid/base status
base excess
what indicates respiratory acid/base status
PaCO2
PaCO2 should be _______ to EtCO2
PaCO2 should be 3-5 mmhg higher than EtCO2
if PaCo2 is significantly higher than EtCO2, then what might that suggest?
- lung disease
- hypotension
- low CO
PaCO2 =
PaCO2 = [(VCO2)*0.863]/Va
PaCO2 is proportional to
VCO2
PaCO2 is inversely proportional to
Va
with each subsequent minute of apnea
CO2 will increase exponentially
venous labs names
BMP
Chem 7
Electrolyte panel
venous sample includes which form of CO2
CO2
HCO3-
tCO2
venous CO2 (CO2 + HCO3-)
normal Venous CO2/HCO3-
24-30 mEq/L
normal arterial HCO3-
22-26 mEq/L
PAO2
partial pressure of O2 in the alveoli
PAO2 is determined by
FiO2
barometric pressure