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BACKGROUND: In rare instances, hemodialysis venous needles may become dislodged, and when left undetected can lead to severe injury or death. Although dialysis machines have alarms to detect venous needle dislodgment, their range of detection is limited. An understanding of the clinical conditions that may lead to missed needle dislodgments is needed for development of more robust detection systems.

METHODS: We created a sham dialysis circuit with a Fresenius 2008 K dialysis machine for in vitro simulation testing of machine alarm behavior under variable conditions. The circuit used a blood substitute and mimicked a patient's venous access site. We varied blood flow rate, venous pressure, and upward drift in venous pressure and analyzed the time to alarm for the machine and an improved alarm algorithm. We also performed a cross-sectional retrospective study to identify the clinical occurrence of venous pressure upward drift between September 1, 2016, and November 1, 2016 in patients on hemodialysis with an arteriovenous fistula.

RESULTS: Of 43,390 venous pressure readings for 147 patients on hemodialysis, 16,594 (38%) showed an upward drift in venous pressure (range 20-79 mmHg), with a mean ± SD increase of 11±18 mmHg within 20±14 minutes. A total of 19 venous needle dislodgment simulations under different venous pressure and blood flow parameters resulted in 19 (100%) algorithm alarm activations. Only 8 simulations (42%) activated a machine alarm, and machine alarm activation time was longer than the algorithm activation time for all 8 machine alarms (range 1-13 seconds).

CONCLUSIONS: Patients can experience changes in venous pressure during hemodialysis which may not trigger a machine alarm in the case of a venous needle dislodgment. Our simulations showed that current dialysis machine alarm systems may not compensate for upward drift in venous pressure, and improved algorithms for detecting needle dislodgment during hemodialysis are needed.

Medical Subject Headings

Veins; Venous Pressure; Renal Dialysis

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ePub ahead of print





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