Quiz 3 (Mike Ch. 9).txt
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Quiz 3 (Mike Ch. 9).txt
CRAFTON HILLS COLLEGE RESP 139 Mike
CRAFTON HILLS COLLEGE RESP 139 (Mike Ch. 9)
What are the Acceptable Sites for Arterial Puncture?
Radial Artery ( most preferred)
Why is the Radial Artery the Preferred Site?
Artery is superficial
Not adjacent to large veins
Easy to palpate
Presence of collateral blood flow
Relative safety by being so distal on the limb
Why is the Brachial Artery is NOT the Preferred Site?
Relative proximity to a large vein and nerve
Contact with nerve can be very painful
Inadvertent venous sampling
Limited collateral circulation
Why draw from the Femoral Artery?
The femoral artery is very large
It is easy to find
It is the only site available:
- During CPR
- Low QT
- Hypotension / Hypovolemia
Why is the Femoral Artery is NOT the Preferred Site for blood draw?
Potential trauma to the major arterial blood supply to the lower extremity
Vessel Relative proximity to a large vein.
It may be deep and difficult to locate.
Lacks sufficient collateral circulation.
What readings will Air bubbles in sample give?
Will normally decreased PaCO2
Will normally increased pH
Will normally increased PaO2
What readings will a Delay in analysis give?
Will normally increased PaCO2
Will normally decreased PaO2
Will normally decreased pH
If properly iced, a blood gas sample will have little changed in values if analyzed within how long?
What will too much heparin left in the syringe cause to the readings of a blood gas?
Will normally decreased pH
Make sure expel all liquid from syringe
Why might we accidentally draw venous blood when sampling a blood gas?
sometimes hard to distinguish arterial from venous in hypoxic pt.
Sometimes the blood will not pulsate in the hypotensive pt.
What will Patient Anxiety cause to the result of a blood gas?
Can lead to hyperventilation
What may clots cause to a blood gas reading?
Loss of blood gas sample
Delays in running samples
Delays in recording the blood gas results
Causing the analyzer to �go down� for maintenance, further delaying blood gas analysis
What is the proper process of drawing an arterial blood gas?
confirm the order and chart review
Determine if the patient is anticoagulated
- Normal platelet count 150,000-400,000/mm3
- Rule of thumb
: Normal clotting time 1-7 minutes
Obtain needed equipment
Perform Allen�s test
If the radial artery is unsuitable as a puncture site:
- The dorsalis pedis artery is the second choice
- Followed by the posterior tibial artery
Femoral artery punctures are performed only in emergency situations in children.
Femoral artery punctures are never performed in neonates.
What are Contraindications to an ABG puncture?
Abnormal modified Allen�s test
should not be performed through a lesion or through or distal to a surgical shunt (e.g., as in a dialysis patient)
evidence of infection or peripheral vascular disease involving the selected limb, an alternate site should be selected
coagulopathy or medium-to-high-dose anticoagulation therapy
How are capillary sample sites choosen?
A highly vascularized capillary bed:
- Big Toe
: do not use on infants
For a heel, only stick on the _________ side of the heel never over the ________ tendon, this will scar and cause painful walking later in life.
What is the proper process for drawing a capillary blood gas?
Arterialize the heel by warming it to 42-45 degrees for 5-15 minutes prior to the stick via:
- heat lamp
- warm bath
- chemical heat pack
After the site is cleaned and prepped, a lancet is used to punch a single 2.5 mm deep hole in the heel, establishing a free flow of blood
Do NOT squeeze of milk the site
First amount of blood that comes out should be wiped away due to serous fluid
A pre-heparinized capillary tube is inserted into the drops of blood and allowed to fill to the predetermined volume
hand carry the sample to the ABG lab
If the sample can not be hand carried to blood gas lab:
- Both ends of the tube are capped or sealed after a flea is inserted.
- The flea is used to mix the sample and prevent clotting.
- The sample is iced until analyzed
Why should we not squeeze or milk a capillary blood gas puncture site?
It de-arterializes the site.
Will cause the sample to clot
What are the advantages of Arterial Catheter (A-Line) Sampling?
Minimal trauma to patient
Allows for repeated sampling
Ability to monitor blood pressure in �real time�
What are the disadvantages of Arterial Catheter (A-Line) Sampling?
Loss of volume
Continuous, non-invasive monitoring of carbon dioxide and oxygen levels is an example of what?
How Does Transcutaneous Monitoring Work?
The major resistance to transcutaneous gas diffusion is the lipid structure of the skin.
Heating an area of the skin to 41- 45o liquefies the lipid structure allowing the molecules to line up and creating the channels for gas diffusion.
- Heat shifts the oxygen dissociation curve to the right, releasing O2.
- Heat also causes vasodilation, arterializing the blood.
- Adaptations of the Clark and Severinghaus electrodes are utilized.
Heat shifts the oxygen dissociation curve to the _______, releasing O2
Heat will cause vasodilation or vasoconstriction, which in turn arterializes the blood?
Pt___ tends to correlate better to arterial values than Pt__.
Why does PtCO2 tend to correlate better to arterial values than PtO2?
CO2 diffuses easier than O2
CO2 electrode has a larger surface area for diffusion
PtO2 usually tends lower than PAO2
Why are transcutaneous monitors used (clinical application)?
Changes in vascular blood flow
Monitor for ROP
To reduce the number of blood gas �sticks"
Ventilator management, especially during HFO
What are the limitations of transcutaneous monitors?
Insufficient heat applied to skin
Blistering of skin
Poor perfusion to skin, especially if placed over bony prominences, or distal extremities.
Be sure to select fleshly sites with good capillary refill (<2 sec.)
What is another major limitaion of transcutaneous monitors?
Can also be labor intensive:
Requires frequent site changes (q 2-4 hours, minimum)
Calibration q 8-12 hours
Electrode will need to be cleaned, re-membraned, and re-calibrated between pts
How do we troubleshoot a transcutaneous monitor is they do not correlate to blood gas values?
Check for air-leak around electrode site
Need to change membrane
Need to change site
Edematous site and/or patient
Check for vasoactive drugs (e.g. epinephrine)
Where is Conjunctival Transcutaneous Electrode placed?
under the eye lid
What is Capnography/Capnometry?
Measurement of exhaled or end tidal PaCO2 (PetCO2)
Provides continuous, accurate monitoring of PaCO2
What does Capnography/Capnometry use?
spectrophotometric infrared analyisis of Exhaled CO2
What are the two methods used to collect and analyze gas in Capnography/Capnometry?
What are the advantages and disadvantages of a Sidestream analyzer?
Removes sample continuously through a small tube
- Measurements are delayed
Light weight, less likely to cause inadvertent extubation
What are the advantages and disadvantages of a Mainstream analyzer?
Analyzes at the airway
- Measurements are current
Accidental extubation is a hazard
What tends to alter exhaled PaCO2?
End tidal CO2 monitors show changes in function, not condition. Some examples that help demonstrate this are things suchas?
: Causes decreased PetCO2 levels. PetCO2 will be lower than arterial levels
: Often shows no change. CO2 diffuses 20 times faster than O2. ONLY decreases with SIGNIFICANT shunting.
What are some Conditions that increase deadspace?
High pressures from mechanical ventilation
What are some Conditions that cause shunting?
Tetrology of Fallot (diseases that cause cardiac problems)
Atrial Septal Defect
What are Limitations to PetCO2 monitoring?
Can only show changes in ventilaotry condition, not improvement or deterioration
An increase in PetCO2 during PetCO2 monitoring may be due to?
A decrease in PetCO2 during PetCO2 may be due to?
Improvement in ventilation
Increased deadspace ventilation