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White Paper: Standard Issues Relating to the Detection of Venous Needle Dislodgement

This document deals with how the risk of venous needle dislodgement is treated under US and European Medical Standards. In both sets of standards, it is acknowledged that venous needle dislodgement can cause potentially lethal situations and that there is currently no optimal system available for detection.

Various organisations and other sources confirm the lack of an optimal alarm, adding proof of incidents where an adequate alarm could have changed the fatal course of events. Redsense is the first clinically tested monitoring system for venous needle dislodgement in hemodialysis.

 

Venous Pressure Monitoring: Acceptable But Not Optimal

The American National Standard for Hemodialysis Systems [1] insists on requirements which will; "at a minimum, help ensure the effective, safe performance of hemodialysis systems, devices, and related materials".

Accoding to this standard, the dialysis machines must be equipped with venous pressure monitoring. However, it is also acknowledged that this method is not optimal for detecting venous needle dislodgement. It says:

Blood line separation or needle pullout is uncommon but does occur, and can cause potentially lethal situations enabling a -- significant blood loss from venous disconnection. No system in current use will reliably detect such a venous separation or needle pullout".[2]

The newly revised German guidelines document [3] states that "one of the most frequent incidents during a dialysis treatment is an unnoticed blood loss to the environment, caused by minute leaks or by a slipped-out venous cannula". These guidelines continue by recommending considerable caution when setting alarm limits for venous pressure monitoring and that:

"--the puncture site must always be visible during the entire treatment. This is the only way to ensure that the operator will detect such a problem visually because, otherwise, blood might ooze away unnoticed in an absorbing covering after the cannula has slipped out."


 

Safety Even More Important in Home Dialysis

Nocturnal Home Hemodialysis (NHHD) takes place in the home while the patient is sleeping, typically at night, up to seven times per week, for approximately six to ten hours per treatment. It is administered by the patient or a trained partner, rather than by a trained medical professional. According to FDA guidelines [4], in NHHD; "safety becomes a primary concern" and:

"Any device malfunction, access problems, or break in the seal of the hemodialysis circuit (e.g., dislodged access needle, blood leaks) would be life threatening, even with the lower blood flows used in nocturnal home hemodialysis."

The FDA guidelines also identify the risk of inadvertent disconnections:

"Most current systems rely on the venous return pressure to monitor for vascular disconnect, since disconnection should result in a noticeable drop in venous pressure. However, inherent resistance in the blood tubing and small gauge needles can cause enough back-pressure in the system to prevent the venous return pressure alarm from triggering. This situation could result in significant blood loss and eventual exsanguination of a patient."

These guidelines recommend alarms to detect fluid (blood or dialysate) leaks, and a moisture detector (until now, the only alternative detection method) at the site of hemodialysis access.

Note: The Redsense alarm is currently approved for use in home dialysis in Europe, Canada and the US only.


 

Venous Pressure Monitoring and Needle Dislodgement

In 1998, the ECRI Institute [5] received two reports of hemodialysis machine venous line needles dislodging from patients during treatment without triggering a venous pressure alarm. Their conclusion:

"ECRI believes that the venous pressure monitor is not a reliable means of detecting needle dislodgments and agrees with manufacturers that visually monitoring the status of blood lines appears to be the only sure way to spot these problems."[6]

Instances in which the venous pressure alarm may not activate are described in an article from 2006 [7]. These instances are confirmed by reports of incidents from the MAUDE Database [8]:

1. If the venous pressure alarm limit is not properly set. Even complete disconnections of blood lines from catheters or cannulas resulting in total loss of the extracorporeal blood flow may go undetected. (MAUDE 515860)

2. Even with properly set alarm limits, the venous pressure monitor may not alarm if the venous cannula slips from the fistula or graft, which may happen if the cannula is not properly fixated. (MAUDE 557216)


 

Risk Reduction & Intended Use

The European Council Directive concerning medical devices [9] state that manufacturers must – when a risk cannot be eliminated or reduced – take adequate protection measures including alarms if necessary. The manufacturer must also inform users of the residual risks due to any shortcomings of the protection measures adopted.
Risk Reduction also includes ensuring that any equipment, disposables or systems in dialysis is used according to its Intended Use. For example, moisture detectors such as enuresis pads are sometime used to detect needle disconnections during haemodialysis though it is not their intended use. As stated by the German guidelines:

"If a clinic, knowingly or unknowingly, uses devices or disposables that are not approved, this is considered to be Non-Intended Use. In such cases, the organisation bears the responsibility for any resulting damage".


 

Awareness

According to standards, manufacturers (of dialysis machines) are required to inform users about risk. To what extent dialysis professionals are aware of the risk is not known.

In a minor survey conducted by Redsense Medical among 77 nephrology nurses [10], more than half of them had experienced venous needle dislodgement in their own unit but 69% of them believed that venous pressure monitoring will detect venous needle dislodgement. However, a few of these were aware of its uncertainty, adding comments like "I think it will alarm", "perhaps too late", or "just sometimes".

Redsense Medical works together with the European Dialysis & Transplant Nurses Association/European Renal care Association[11] to develop educational guidelines on the prevention and detection of venous needle dislodgement.


[1] AANSI/AAMI RD5:2003
[2] AANSI/AAMI RD5:2003, Section A.4.2.4.1, General
[3] Principles for Safe Application of Medical Devices in Extracorporeal Renal Replacement Therapy, Deuthsche Norm VDE 0753-4,
[4]On June 8, 2003, The Medical devices advisory committee held an open public hearing for the purposes of evaluating devices and guidelines for nocturnal home dialysis
[5] An independent international organisation focusing on medical device safety:www.ecri.org
[6] Undetected Venous Line Needle Dislodgment during Hemodialysis, Health Devices Nov 1998;27(11):404-6
[7] Neglected Safety Aspects in Hemodialysis and Their Related Problems, H-D Polaschegg, Hemodialysis Horizons, AAMI, 2006
[8] MAUDE Manufacturer and User Facility Device Experience Database, hosted by FDA/US. MAUDE data represents reports of adverse events involving medical devices
[9]93/42 EEC, from 14 June 1993
[10] EDTNA/ERCA International Conference, Florence 15-18 September 2007
[11] EDTNA/ERCA, www.edtnaerca.org