Exam 2 Oxygen Indices & ICU Assessment Flashcards
what does P50 indicate
hemoglobin is 50% saturated with oxygen
normal P50 is 27 mmHg
how is P50 affected when curve shifts left
increase Hb affinity for O2 increase pH decrease CO2 decrease temperature decrease 23DPG P50 decrease
how is P50 affected when curve shifts right
decrease Hb affinity for O2 decrease pH increase CO2 increase temperature increase 23DPG P50 increase
what is the significance of utilization of monitoring systems in ICU
continuous assessment
measures values caregivers cant detect
what is the significance of P/F ratio
determine if dealing with ALI or ARDS
identify acute hypoxemic failure
what is the significance of
P(A-a)O2 difference
indicates gas exchange efficiency
help narrow the cause of hypoxemia
what is the significance of PaO2/PAO2 ratio
useful for gas exchange index with changing FiO2
what is the significance of
C(a-v)O2
how much oxygen is removed from blood in capillaries as it circulates into the body
what is the significance of O2 ER
assess the adequacy of systemic oxygen delivery
what can affect SpO2 readings
motion artifact environmental light anemia deeply pigmented skin carboxyhemoglobin methemoglobin nail polish blood-borne dyes (cyanide)
define anemia
lack of healthy RBC to carry oxygen to tissues
when is cyanosis noted on a patient
5g/dL desaturation of hemoglobin
what is the importance of assessing a patients baseline prior to diagnostic procedures
to compare and see how the patient is tolerating the procedure
how is a shunt determined using P(A-a)O2 and P/F ratio
for every 50 mmHg difference in A-a gradient, a 2% shunt is approximated
how is a ALI determined using P(A-a)O2 and P/F ratio
if the P/F ratio is < 300 its ALI, < 200 its ARDS
how is a V/Q mismatch determined using P(A-a)O2 and P/F ratio
an elevated A-a gradient indicated V/Q mismatch
how is a ARDS determined using P(A-a)O2 and P/F ratio
if the P/F ratio is < 200 its ARDS
what is Qs/Qt indication of
effectiveness of pulmonary oxygenation
what increased the Qs/Qt value
atelectasis pneumonia ARDS pulmonary edema pulmonary vasodilation inotropic agents
when does the body’s compensatory mechanism or increased C.O. get triggered
your body will shunt blood to vital organs if C.O. drops
what increases C(a-v)O2
2 things
low C.O.
increased VO2
what increases SvO2
3 things
decrease O2 ER
decrease VO2
decrease C(a-v)O2
what increases PvO2
4 things
increase C.O.
increase Hb
increase SaO2
decrease VO2
what increases VO2
5 things
exercise trauma inflammation sepsis shivering
what increases DO2
1 thing
septic shock
what increases O2ER
3 things
low C.O.
increased VO2
decreased CaO2
what decreases C(a-v)O2
4 things
septic shock
increased C.O.
anemia
left shift on curve
what decreases SvO2
5 things
suctioning shivering extubation weaning PPV
what decreases PvO2
4 things
decrease C.O.
decrease Hb
decrease SaO2
increase VO2
what decreases VO2
4 things
skeletal muscle relaxation (drug induced)
peripheral shunting (sepsid, trauma)
cyanide poisoning
hypothermia
what decreases DO2
2 things
decreased C.O.
decreased CaO2
what decreases O2ER
2 things
high C.O.
sepsis
what are normal/(acceptable) values of C(a-v)O2
4 to 6 mL/100 mL blood or vol%
5 vol%, <7 ml/dL
what are normal/(acceptable) values of SvO2
65 to 75%
minimal >60%, >65%
what are normal/(acceptable) values of PvO2
38 to 42 mmHg
40 mmHg, >32 mmHg
what are normal/(acceptable) values of VO2
100 to 140 mL/min
250 mL/min
what are normal/(acceptable) values of DO2
550 to 650 mL/min
1000 mL/min
what are normal/(acceptable) values of O2ER
75%
750 mL
how do you calculate OI
FiO2 x (MAP/PaO2) x 100
if on conventional ventilation what is the number to switch to HFV or iNO
> 25
if on conventional ventilation what is the number to switch to ECMO
> 40
what is a normal value of OI
< 25 (20)
how do you calculate P(A-a)O2
PAO2 = [(Pb - PH2O) x FiO2] - (PaCO2 x 1.25)
PAO2 - Pao2
how do you calculate estimated shunt
(CcO2 - CaO2) / (CcO2 - CvO2)
CcO2 = (Hb x 1.34) + (PaO2 x 0.003)
CaO2 = (SaO2 x Hb x 1.34) + (PaO2 x 0.003)
CvO2 = (SvO2 x Hb x 1.34) + (PvO2 x 0.003)
how do you calculate CaO2
(Hb x 1.34 x SaO2)+(PaO2 x 0.003)
how do you calculate C(a-v)O2
CaO2 = (Hb x 1.34 x SaO2) + (PaO2 x 0.003)
CvO2 = (Hb x 1.34 x SvO2) + (PvO2 x 0.003)
how do you calculate VO2
C.O. x (CaO2 - CvO2) x 10
how do you calculate DO2
C.O. x CaO2 x 10
CaO2 = (SaO2 x Hb x 1.34) + (PaO2 x 0.003)
how do you calculate O2ER
[C(a-v)O2 / CaO2]
CaO2 = (SaO2 x Hb x 1.34) + (PaO2 x 0.003)
CvO2 = (SvO2 x Hb x 1.34) + (PvO2 x 0.003)
how is ICP assessed in ICU patients
fluid filled system with external transducer
solid state system with miniature pressure transducers
how is nutrition assessed in ICU patients
obtain history
perform physical exam
appraisal of muscle and organ function
how is renal function assessed in ICU patients
assessing BUN
assessing creatinine
assessing urine volume
how is neurological status assessed in ICU patients
obtain history
exam: mental status, pupillary response and eye movement, corneal and gag reflex, respiratory rate and pattern, ICP monitoring (10-15 normal), Glasgow coma scale
how is hemodynamic stability assessed in ICU patients
ECG for arrhythmias
arterial blood pressure for integrity of cardiovascular tone