Hemodynamic Monitoring Mixed Venous Oxygen Saturation (SvO2) Flashcards
Almost the same thing
Difference - where blood sample drawn from
Scvo2 (mixed venous gas) - blood sample - Mixed gas - blood from the superior vena cava = from regular central line because where is
Svo2 Mixed gas from the pulmonary artery (PA catheter)
Determined by oxygen extraction and oxygen consumption by the tissues
Factors that make up SVO2 are - 4 main ones
Normal values: 60 - 80%
Mixed venous and central venous oxygen saturation (SvO2)
Looking at calculation - what balance is between arterial oxygen supply and oxygen demand by the body
Svo2 Mixed gas from the pulmonary artery (PA catheter)
The amount of O2 remaining after tissue extraction.
Sampled obtained from the Pulmonary artery
Determined by oxygen extraction and oxygen consumption by the tissues
Cardiac output
Hemoglobin
SaO2 - arterial oxygen saturation
VO2 (oxygen consumption at the cellular level)
Factors that make up SVO2 are - 4 main ones
Any Critically ill patient who has potential to develop an imbalance between oxygen supply and metabolic tissue demand.
Can be anyone
Decreased Svo2 values
Indications - SVO2
4 factors that contribute SVO2 - 3 involve oxygen delivery
Decreased oxygen delivery
Increased oxygen demands
Decreased Svo2 values
Hemoglobin - oxygen transporter; low: affects O2 delivery
CO - not circulating RBC - not getting to where need to
SaO2 - 4 receptor sites for O2 and consistently have 2-3 filled not delivering oxygen because not saturating the RBC at all 4 sites on RBC
Decreased oxygen delivery
Anything that increases consumption at the cellular level - VO2
Increased oxygen demands
4 main reasons for decreased SVO2
↓O2 Delivery:
↓Oxygen saturation (SaO2/art sat):
↓ Cardiac Output - LV dysfunction (Cardiac disease, Drugs)
↑Oxygen consumption:
Decreased SVO2
All about RBC; RBC not present to circ O2 to tissue
↓ Hbg concentration (pt Anemia or Hemorrhage)
↓O2 Delivery:
Hypoxemia/hypoxic pt - something happening where not all 4 receptor sites on RBC occupied by O2: Lung Disease, ventilator settings: low FIO2 - stop weaning trial and increase FiO2
% of 4 spots on RBC that are occupied with O2
↓Oxygen saturation (SaO2/art sat):
All about LV and how well functioning
Cardiac diseases that affect CO
Medications - beta blocker or illicit drugs
Critically ill pop = cardiogeneic/Cardiac & late septic shock, Hypovolemia, Dysrhythmias - less filling time of LV affects CO
Low preload/hypovolemia
↓ Cardiac Output - LV dysfunction (Cardiac disease, Drugs)
Can control better = anything makes body demand more O2
Fever, infection, Seizures - increased O2 demand in brain and whole body esp if tonic clonic, agitation - all worked up - increases metabolic demand and O2 demand at cellular demand, Shivering, ↑Work of Breathing - weaning and now struggling and failing trial and draw ABG to determine that - can quantify SaO2 instead of how look and how fast breathing
What we do with them: Suctioning, bathing, repositioning, walking around the unit
↑Oxygen consumption:
Most common causes are:
Not good thing to see
Higher is not better
Need range betwee 60-80
When see increased, two most causes below
Sepsis
Wedged PA catheter: Leaving the balloon inflated after getting PAOP reading.
Increased SVO2
Problem not O2, Hgb level fine, CO fine
Oxygenating the blood and pumping the RBC with O2 on it just fine
Prob: bacteria in the way and O2 on RBC cannot offload into the tissue - keeps circulating
Sepsis
Get PA occlusive pressure reading - is an intermittent reading - inject air into balloon at distal tip of PA catheter and get reading and withdraw the air
Increased SVO2 when balloon inadvertently left inflated - not true SVO2/mixed venous gas - just pulling blood from PA and lungs - blood sample higher in O2 than should be
Dangerous - inaccurate readings for SVO2 - leaving balloon up - can harm/kill pt - can cause infarction in PA - where balloon inflated and pushing against wall of PA, higher risk infarction PA and infact in lung
Wedged PA catheter: Leaving the balloon inflated after getting PAOP reading.
Low
Normal range - 60-80%
The nurse is assessing a patient for a nurse on lunch who is on a weaning trial to determine if he can be extubated. After 30 minutes of the weaning trial the nurse draws a SvO2 and an ABG. The SvO2 are resulted: 55%.
Is this high, normal, or low?
Assess the patient and go to chart and see where started
What should the nurse do next?
Were normal - drop more than 10%; know pt struggling
End weaning trial and change ventilator settings to what the patient was originally on
HR elevated - trying circulate what oxygen do have through body and RR at 28 - elevated - trying oxygenate what have
Are struggling based on HR and RR
Supply and demand - mismatch - only at 55% and started at high end of normal at 78%
Ans: oxygen supply; failed their weaning trial; we need to stop the trial
The nurse decides to check the EMR to determine what the SvO2 was prior to the weaning trial. The SvO2 prior to the weaning trial was 78%. Current vital signs: 100/50, HR: 114 (irregular), RR: 28, Temp: 99.1o F.
What could be contributing to the drop in SvO2 in this patient?
Low
Know before central catheter or central line - low - Hgb low because in puddle at fest
Puddles - sig blood loss
ED admit report: Patient was stabbed in the left upper arm with a during a jousting demonstration at the Renaissance Festival. The joust severed the brachial artery; estimated blood loss at the scene was “a mid-sized puddle”.
Would you anticipate the Svo2 to be high, low, or normal?
Knowing had blood loss and SvO2 low (say 50%)
Fix prob: arterial bleed - sig blood loss
Give blood next - type and cross; units of blood sent up and admin
What intervention would the nurse anticipate next?
Know if gave enough blood - 2units to start - pts without central access - draw H&H - good start - can look at supply and demand; can draw SvO2 and see if supply and demand are =; 2units and SvO2 at 54% - need figure if bleeding somewhere else, need more blood, O2 delivery problem somewhere; do intervention: giving blood, change vent settings: test effectiveness of intervention by redrawing SvO2 and see if going up/down
Giving blood - anticipate go up
Weaning - hope not go down
How would the nurse determine the intervention was effective?
