by Jeremy Groves, Consultant in Anaesthesia and Critical Care
It is disheartening for all concerned when an arterial line stops working. The patient’s monitoring is compromised, re-siting a line takes up both medical and nursing time and it always seems to happen in the patient who is either desperately ill, or has such a poor arterial tree that the wire won’t thread.
An intervention that prolongs the life of a line must be a good thing. Everson and colleagues seem to think so. Their article in JICS¹ points to one such intervention that the majority of critical care units have moved away from in recent years, namely using heparinised saline to flush arterial lines rather than 0.9% saline.
Everson and colleagues comment that, despite the NPSA recommendation, administration of incorrect flush solutions continue to occur.
The change away from heparinised saline related to a 2008 NPSA report and recommendation.² This identified two deaths occurring from arterial line flush solutions: one (described in a case report) due to 5% glucose being used leading to a presumption of hyperglycaemia and consequent overdose of insulin, the cause of the other was not clear to me from the report but there is reference to a glucose/saline solution being involved. There were 82 less serious incidents where incorrect infusions were connected. Everson and colleagues comment that, despite the NPSA recommendation, administration of incorrect flush solutions continue to occur.
In their study arterial line life, and associate costs, were monitored during the change over from heparinised saline to 0.9% saline. In the 337 patients monitored, 447 lines were inserted, 244 with heparinised saline and 227 with 0.9% saline. When the median lifespan of lines on first insertion were compared, the lines flushed with heparinised saline fared significantly better (median life 2.5 days vs 2 days p<0.004). This came at a financial cost. Using 0.9% saline was cheaper to the tune of £4,800 a year, although this didn’t factor in the extra staff time or disruption to patients that replacing lines entailed.
The authors argue that, despite perceived risks such as heparin induced thrombocytopenia and contamination of coagulation tests that heparinised saline may be the safest option.
The authors argue that, despite perceived risks such as heparin induced thrombocytopenia and contamination of coagulation tests that heparinised saline may be the safest option. Its use avoids the clinical impact and wasted resources due to blocked lines when using 0.9% saline.
I have a certain sympathy with this view, though one needs to be very cautious when departing from NPSA guidance. The NPSA seem to have made a significant jump from errors caused by attaching incorrect solutions with glucose in them, to the risks of adding drugs (heparin) to solutions for flushing arterial lines. The last paragraph of the NPSA report alludes to manufacturers engineering the problem away. Unfortunately, I haven’t seen evidence that this is on the cards. I think it would be really positive to see clearly labelled bags of arterial flush solutions and dedicated, non-interchangeable connectors on arterial line giving sets & catheters that prevent inappropriate solutions being attached.
An engineering solution would enable us to use the right solution.
- Matthew Everson, Lucy Webber, Chris Penfold, Sanjoy Shah, Dan Freshwater-Turner. Finding a solution: Heparinised saline versus normal saline in the maintenance of invasive arterial lines in intensive care. JICS ,17(4): 284-289
Access the Journal of the Intensive Care Society here: http://journals.sagepub.com/home/inc