What disorder can venipuncture be used to treat?
Indication for venipuncture
Sample of venous blood is needed in larger amounts than finger stick can provide
MC used veins for venipuncture
Superficial veins in antecubital fossa (median cubital vein)
Why is the median cubital vein MC used for venipuncture?
- Less likely to roll
- Lies more superficially
- Skin over it is less sensitive than other veins
Light blue venipuncture tube
- 3.2% Na citrate
- Used for coagulation studies
Red or gold venipuncture tubes
- Serum tube with or w/o clot activator or gel
- Promotes blood clotting with glass or silica particles
- Used for chemistry, serology, immunology
Which blood tubes promote clotting?
Red or gold tops
Green venipuncture tubes
- Na or Li heparin with or w/o gel
- Stat and routine chemistry
Lavender or pink venipuncture tubes
- Potassium EDTA
- Hematology and blood bank
Gray venipuncture tubes
Used for glucose testing, blood alcohol, lactic acid
Blood culture contraindications
- Warfarin patients
- Site of an active skin infection
- Failure of previous blood cultures to identify infecting agent
When should a contaminated blood culture sample be suspected?
- Common skin flora (S. epidermis)
- Mix of several kinds of bacteria
- Growth found in only 1 of several specimens from separate venipunctures
What does S. epidermis indicate in a blood culture sample?
Standard blood culture bottles consist of what?
- 1 aerobic culture media bottle
- 1 anaerobic culture media bottle
How should skin be prepped for blood culture?
- Sterile 70% isopropyl alcohol starting at site and moving out in circles
- Repeat twice using new wipes each time
- Apply chlorhexidine in same manner
If 2 blood cultures must be drawn from the same site, how long should you wait in between samples?
At least 10 minutes
Where are ABGs usually performed?
What must be done prior to ABG?
Allen’s test to show adequate collateral circulation
What is the Allen’s test?
- Performed prior to ABG
- Shows adequate collateral circulation
What does an ABG reliably determine?
Ventilation (CO2 content)
What is the only to accurately determine alveolar-arterial oxygen gradient?
Absolute contraindications to ABG
- Abnormal Allen’s test
- Local infection or distorted anatomy at potential puncture site
- AV fistula or vascular graft
- Known or suspected severe PVD of limb involved
Relative contraindications to ABG
- Severe coagulopathy
- Anticoag therapy
- Use of thrombolytics
MC complication of ABG
Hemorrhage or hematoma formation at puncture site (MC in femoral and brachial arteries)
When do errors in ABG analysis occur?
- Excess or incomplete removal of air bubbles (falsely high PO2)
- Excess heparin in syringe (falsely low PCO2)
- Delays in placing sample on ice
What error can cause falsely elevate PO2 levels in ABG?
Excess or incomplete removal of air bubbles
What error can falsely lower PCO2 values in ABG?
Excess heparin in syringe
How does excess heparin in syringe affect ABG results?
Falsely low PCO2
What is the least preferred site of ABG?
Brachial artery (runs deeper and is relatively small)
Why is the brachial artery a less desired ABG site?
- Runs deeper (harder to identify and achieve hemostasis after)
- Small and does not have extensive collateral circulation
MC used antiseptic skin solutions for ABG?
What results does an ABG provide?
- Blood pH
- PCO2 and PO2
- Calculated serum HCO3 and base excess
PO2 less than 11 kPa on room air (not usually clinically important unless below 8 kPa)
What is considered respiratory failure?
PO2 less than 8 kPa
Define Type I respiratory failure
Hypoxemia WITHOUT hypercapnia
Define Type II respiratory failure
Hypoxemia AND hypercapnia (indicating hypoventilation)
Examples of intradermal injection
- TB PPD testing
- Allergy testing
- Sentinel node biopsies
What type of injection is TB PPD testing?
When are subcutaneous injections used?
For drugs requiring slow absorption and long duration of action (insulin, hormones, vaccines, heparin)
Risks of subcutaneous injections
Where are SQ injections given?
- Infants: thighs
- Older children and adults: deltoid, upper outer thighs, abdomen
When are IM injections indicated?
-Drugs not easily absorbed
-Intermediate rate of onset and duration of action
(abx, narcotics, hormones, vaccines)
IM injection sites
- Children: UOQ of buttocks, deltoid
- Adults: anterior thigh, UOQ of buttocks, deltoid
Why are IM injections given in UOQ of buttocks?
To avoid sciatic nerve
Where is the MC choice for IO placement?
Antero-medial aspect of upper tibia
How long can an IO be left in place?
Up to 72-96 hours