Ensuring sick patients receive the full dose of the medication they have been prescribed may sound like a basic prerequisite of medical care.
Yet underdosing — as it is medically known — is a significant problem in the NHS that could be putting patients at risk, according to some experts.
It can occur when hospital patients are given drugs intravenously.
Once the bag of solution has emptied, it is removed along with the tube through which the liquid is infused into the patient, and both are thrown away.
But, inevitably, some liquid containing the medication will remain inside the tube, especially when the IV kit (or set, as it is also known) relies on gravity — without liquid in the bag, there is nothing to push the remainder in the tube into the patient.
Underdosing — as it is medically known — is a significant problem in the NHS that could be putting patients at risk, according to some experts. It can occur when hospital patients are given drugs intravenously
Under guidelines, doctors and nurses are meant to ‘flush’ the tube with saline so the patient doesn’t miss out on the residual dose. This should be done for all intravenous (IV) drugs, including antibiotics and painkillers (but is not necessary for hydration fluids).
To flush the line once an IV infusion has finished, a new small bag of saline (50-100ml) should be attached to the drip and the infusion started again, to push any residual medication into the patient.
The National Infusion and Vascular Access Society (NIVAS), which represents healthcare workers involved in the administration of IV drugs and vascular access, issued the new guidance in February 2021 after two studies last year suggested up to a third of the dose of medication could be lost if the line is not flushed.
While line-flushing is standard practice in cancer care and paediatrics, on other wards ‘it is rarely done’, according to Rachel Dixon, an enteral nurse specialist and a former NHS infusion manager, who has brought the largely unrecognised issue of underdosing to the attention of NHS England.
‘The view seems to be that when the IV bag has emptied, the full dose has been given. But that isn’t the case,’ she says. ‘A proportion of it will still be in the tube and, if this is not flushed, the patient won’t get the full dose.
‘We should be giving drugs as prescribed, not as we fancy; we should be throwing away saline, not medication. This bad practice is a country-wide problem.’
A 2018 study across six departments in a large UK teaching hospital found that overall, 74 per cent of IV sets were not flushed over the course of a week. This rose to 99 per cent on surgical wards, 80 per cent on critical care and high-dependency units, and 89 per cent on the emergency admission unit.
None of the IV sets containing painkillers and antibiotics was flushed — and ‘almost one third’ had antibiotics still in them, with up to 21 per cent of the dose being thrown out, said the researchers.
Oncology was the only department where all IV sets were flushed, according to the study in the British Journal of Nursing.
Another UK study, published in the journal JAC — Antimicrobial Resistance in August last year, estimated up to 33 per cent of antibiotics may be lost; while a U.S. study, published in the Journal of Infusion Nursing also last year, found it was 35 per cent.
The potential impact of underdosing is far-reaching. ‘If patients don’t receive the prescribed dose of medication, it may impact on their recovery times, which means a longer, more costly stay in hospital,’ says Rachel Dixon, pointing to reports of underdosing being a cause of treatment failure in patients with malaria.
In its guidance, NIVAS admits that ‘flushing IV infusion sets in adult patients is rare’. Between 20ml and 30ml of drug solution may be lost, it says, which could be ‘half the dose of a 50ml bag’, adds Rachel.
Under the new guidelines, medical staff are advised to flush the lines and use a new IV set for each different drug.
In 2017, NHS England issued a Patient Safety Alert warning that a patient’s IV line should be flushed or removed at the end of each surgical procedure to prevent any residual anaesthetic or sedative drugs being inadvertently given to the same patient later, causing ‘muscle paralysis, unconsciousness and respiratory and cardiac failure’.
Between 2014 and 2017, 58 such incidents were reported.
In one case, a young woman, known only as Kathryn, was temporarily paralysed and went into respiratory arrest after residual anaesthetic drugs — given to her during an operation to remove her appendix in 2015 — were not flushed from the cannula before antibiotics were put through the same tube a few hours later.
‘When the nurse administered
