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No science, but if I put a cannula in myself take blood from it. If one in pre-hospital either another cannula if indicated or venepuncture. I suppose if pre-hospital cannula theoretically maybe thrombus around end of cannula which might cause mechanical haemolysis.
Andy Webster
-----Original
Message-----
From: Accident and Emergency
Academic List [mailto:[log in to unmask]] On Behalf Of Ray McGlone
Sent: 26 January 2004 16:16
To: [log in to unmask]
Subject: Haemolysed blood
specimens
One of our SHO's has just completed an audit into haemolysed blood specimens. When we started using vacutainers several years ago our haemolysis rate on samples increased. I wondered whether other departments had also experienced this? Has anyone else audited this? I'm enclosing an extract from the audit..... I'm sorry about the large font but it's stuck on this setting.
On a second point does anyone routinely take samples from the venflon put in by the paramedics...... as they always use at least an 18G and often in a large vein like the cubital fossa it seems a shame not to use that site... for the patient's sake. I discard the first 5 ml of blood. Anyone done a study on this?
Ray McGlone
A randomized, prospective study conducted at the emergency dept in Columbus, Georgia2 where a total of 165 patients were randomized into the IV group (87pts) or the venepuncture group(78pts) also showed a statistical significant difference (p=0.03) where more blood was haemolysed when drawn from the IV catheters ( 13.7% versus 3.8%). The study also showed a a lower in incidence of haemolysis with larger catheter diameters (p=0.047); 24 gauge(100%), 22 gauge(25%), 20 gauge(15%), 18 gauge(10%), 16 and 14 gauges(0%).
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Compared to other A&E departments, RLI has slightly lower or comparable rates of haemolysis. For instance, when looking at the 598 questionnaire based study at the John Hopkins Hospital 1 , Baltimore; 32% of their samples had some degree of haemolysis (compared to 4% shown here); the study also showed that blood drawn through IV catheters resulted in significantly more haemolysis than using the needle technique (p<.001). The survey also demonstrated that the predominant method of drawing blood was by IV catheters (69%) which was similar to our rate here(72%). The study also showed that IV catheter haemolysis was higher when a vacutainer was used versus a syringe ( 22% versus 9%); this was significant at p=0.02
1. Grant M. The effect of blood drawing techniques and equipment on the haemolysis of ed laboratory samples. J Emerg Nurs 2003;29:116-21.
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• 2. Kennedy C et al. A comparison of haemolysis rates using intravenous catheters versus venipuncture tubes for obtaining blood samples. J Emerg Nurs 1996;22: 566-9.
Ray McGlone
Morecambe Bay Hospitals NHS Trust
http://www.baem.org.uk/aedepartment.htm