Venous Needle Dislodgement – A Universal Concern
• seizures; • low oxygen level; • VND.
Venous Needle Dislodgement
Without a doubt, VND is the most unexpected and potentially life-threatening complication in dialysis. If the venous needle becomes dislodged or disconnected from the vascular access, large amounts of the patient’s blood may be pumped outside of the patient’s body in a matter of minutes. To put it into perspective, if a dialysis machine is set to pump the blood at 375 ml/min, the patient may lose the equivalent of half a bottle of wine every minute. This can have tragic results if the dislodgement is not recognised immediately. Unfortunately, once the end of the needle is out of the patient’s access and the blood is being pumped into the bed or chair, there is very little leeway in time before the patient experiences a massive haemorrhage or dies from exsanguination. The urgency of the situation cannot be overemphasised. In less than 7.5 minutes, an average sized man receiving a dialysis treatment can lose over 40 % of his blood volume5 from an undetected VND, while an average sized woman can lose over 40 % of her blood volume6
in less than five minutes. Haemorrhage
attributable to a VND is considered a class IV haemorrhage and can be fatal without a rapid response.7
VND can occur without warning. The problem is not unique to larger, busier clinics or a specific brand of dialysis machine, needles or tubing, and does not occur only in confused or disorientated patients or as a result of not taping the needle down just right. That is what makes VND daunting: it is unpredictable and potentially devastating not only for the patient but also for caregivers and at an administration and corporate level.
Safety of Dialysis Machines
Since the mid-1980s, mandatory safety features for dialysis machines have been imposed and dialysis machines are the subject of various national and international standards. The most important are the International Electrotechnical Commission standards and the very similar American Association of Medical Instrumentation standards. The latter apply to the US only. For every machine sold after the mid-1980s, the user is assured that these devices comply with the respective standards. Compliance is enforced by the various approval and certification procedures. However, these standards define only minimum safety requirements. Every manufacturer is free to do more than the safety standards require.8
Ideally, the venous pressure alarm should sound if the venous needle disconnects, alerting the staff to the fact there is a problem. However, there are problems with reliability. There can be a significant delay from the time the needle disconnects until the alarm sounds. With pump pressures set anywhere from 350 to 500 ml/min, the patient may lose a considerable amount of blood before the alarm sounds. Dialysis staff report that machine venous pressure alarms have a reputation of sounding nuisance alarms (an alarm that sounds for no apparent reason). In busy dialysis clinics, there is a danger of alarm fatigue. Alarms are intended to alert clinicians to deviations from a pre-determined ‘normal’ status. However, alarm fatigue may occur when the sheer number of monitor alarms overwhelms clinicians, possibly leading to alarms being disabled, silenced or ignored.9
In
addition to re-setting the nuisance alarms to silence them, dialysis staff may not visually check the access site. In the US, it is policy that
EUROPEAN NEPHROLOGY
all access sites remain uncovered to expose the area, making it easier for the site to be monitored,10
venous pressure alarms have not sounded at all with VNDs.
The Emergency Care Research Institute (ECRI), a watchdog group in the US, tracks and evaluates segments of the healthcare industry and its products and issues medical device incident and hazard information. In 1998, ECRI released a paper in response to two reports of VND in patients during dialysis without the venous pressure alarm being triggered.11
New Statistics
A review of the literature yields relatively little information on VND before 2008, when an article outlining the recommended methods to minimise the risk of VND was published.12
Medical textbooks describe
VND as a serious but rare complication of dialysis. Since 2008, more information has been published indicating that VND is not the rare, exceptional occurrence it was once thought. New information on the incidence of VND, based on recent statistics, indicates that:
• more than two patients have a VND with a serious outcome every day;13
• •
more than two patients die every week as a result of VND;14 more than 200 needles dislodge every day.15
and
If dislodgement is recognised early, the patient may not lose enough blood to warrant any additional treatment; however, VND is such a rapidly occurring incident that large amounts of blood may be lost very quickly if intervention is not begun almost immediately.
Home Dialysis
Home dialysis, as opposed to in-centre dialysis, is a growing trend. Home dialysis allows patients to dialyse at home instead of having to travel to a dialysis centre. Patients who choose home dialysis enjoy many benefits, including the flexibility to have more control over when they receive their treatments, being able to spend more time with their family and having the ability to continue to work. Home dialysis also allows patients to learn more about their disease and how it is treated.16
Patients who dialyse at home face the risk of
VND as well as patients who attend a medical centre. VND is one of the most frequent concerns among home dialysis patients, as they worry that they may not immediately detect a dislodgement.
Prevention
Considering that VND can occur at any time and anywhere, increased awareness and vigilance needs to be exercised by anyone who receives dialysis and their caregivers.
Studies have been performed to look at when a VND is most likely to occur.1,17
There are some clear risk factors, which include:
• confused and restless patients; • patients in private or secluded rooms; the last two hours of dialysis; •
However, there are studies that indicate that the typical scenario of VND is in apparently routine treatments and with fully staffed units. In most reported episodes, there was no observed event that led to dislodgement of the needle.13
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but there have been instances when
access sites that are covered and cannot be visually observed; • nocturnal dialysis, where the lights are off and the patient is sleeping.
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