Blood Collection

Question 1

Sample Collection

Answer 1

• Refrain from collecting from catheters unless severely compromised
• Use of needle smaller than 21g could lyse the blood and cause erroneous results
• Add up the total blood needed, and use the closest sized syringe
• Refrain from excessive suction (could lyse or introduce fat cells)
• Always fill to line on tube
• Check expiry dates
• Sample should be labeled, times and dated if being refrigerated for later testing (within 3-4h)
• Coagulation (unless being sent to lab) and arterial samples assessing PaO2 should be done immediately
• Invert tube 5-10 times post draw

Question 2

Tube Selection

Answer 2

• Green/orange lithium heparin = blood gas
• Blue sodium citrate = coagulation
• Purple EDTA = CBC
• Microhematocrit tubes = PCV, TP, serum colour
• Red/plain serum = external lab tests

Question 3

Basic Blood Gas

Answer 3

• Can assess underlying disease processes and severity of illness to guide emergency intervention
• Arterial blood gases primarily provide info on oxygenation, ventilation and acid base status
• Venous blood gases provide info on electrolytes, ventilation and acid base status

Question 4

Typical Analyses Provided by Point of Care Blood Gas Analyser: Venous

Answer 4

pH > PcO2 > TCO2a > HCO3-a > BEecf-

Question 5

Typical Analyses Provided by Point of Care Blood Gas Analyser: Arterial

Answer 5

pH > PcO2 > PaO2 > TCO2a > HCO3-a > BEecf- > SaO2

Question 6

Complete Blood Count (CBC)

Answer 6

• Measures inflammatory cells, red blood cells and platelets
• Good to assess for anaemia, thrombocytopenia and the current status of the patient

Question 7

Biochemistry

Answer 7

• Mainly assess liver and kidney parameters

Question 8

Coagulation

Answer 8

• Clotting factors help prevent haemorrhaging
• If not enough clotting factors or they are not functioning, the patient can be prone to sudden bleeding
• Venoms (e.g snake venom) can cause acute consumption of clotting factors
• an ACT is a crude measurement of clotting factors (requires 95% of clotting factors to be lost to cause a prolongation)
• pT and APTT are more sensitive