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Safety and biological aspects of present techniques of haemodialysis
Umeå University, Faculty of Medicine, Public Health and Clinical Medicine.
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Introduction: Haemodialysis (HD) is a treatment in which blood from the patient is lead through a tubing system into a dialysis device in a extracorporeal circuit. This circuit contains semipermeable membranes (dialyzer). Blood with uraemic toxins flows on one side, and a salt solution flows on the other side. The salt solution flushes away waste products that have passed the membrane by diffusion or convection through small pores. From there the blood returns to the patient through a tubing system that contains an air-trap and a sensor to avoid air contamination in the blood. Besides air contamination, this treatment is burdened with safety problems such as biocompatibility, electrical safety and mechanical safety. The aim of this thesis was to investigate the safety issues in haemodialysis devices regarding leakage current and air contamination during standard procedures and simulated fault conditions. Does the dialysis device constitute a risk for the patient?

Methods: To determine the extent of leakage current in HD machines, measurements at the filter-coupling site were performed in vitro according to the safety standard, IEC 601-1, in 5 types of dialysis machines. To determine, in vitro, to what extent blood and priming fluid allowed leakage current to pass to the patient, leakage current were also measured in the blood lines. The blood line was filled with blood from donors or priming fluid in eight different runs. To determine if leakage current could influence biocompatibility, a Fresenius 2008C dialysis machine and 8 hemophan dialyzers were used. Blood lines contained about 400 ml heparinized blood from each of 8 different donors (in vitro). C3d was measured, in vitro, before start of a simulated dialysis and at 15, 30, 45 and 60 min. during standard dialysis procedure. Then 1.5 mA current was switched on and additional samples were drawn at 75 and 90 min. Some patients need a central dialysis catheter (CDC) for access, placed close to or within the heart. To analyze if leakage current during standard HD would influence the ECG, patients with CDC or with AV-fistula as access were investigated. To analyse if air contamination could occur without activating security alarms in the dialysis device, various modes of in vitro dialysis settings were studied, some using a dextran solution to mimic blood viscosity. Besides visual inspection an ultrasound detector for microemboli and microbubbles was also used.

Results: The data showed leakage current at the filter coupling site that was significantly higher for some devices than for others. The leakage current could pass through blood and priming fluid. It exceeded the cardiac floating (CF)-safety limit (<50μA) at the top of the CDC using the test mains on applied part for saline (median 1008μA), for blood (median 610μA) and for a single fault condition using saline (median 68 μA) or blood (47 μA). The leakage current experiments showed that complement activation worsened as the leakage current increased. During standard dialysis arrhythmia could occur. Microbubbles were visible at the bottom of the air-trap and bubbles could pass the air-trap towards the venous line without triggering the alarm. During recirculation, several ml of air could be collected in an intermediate bag after the venous line. Ultrasound showed the presence of bubbles of sizes 2.5-50 μm as well as more than 50 μm silently passing to the venous line in all runs performed.

In conclusion, the data showed that a leakage current in HD devices can be high enough to be a safety risk for the patient. This risk is greater if a single fault arises in the dialysis machine or another device connected to the same patient, or during mains contact to the patient. Then the current flow may be high enough to cause arrhythmia for the patient, especially when using a CDC. There is also reason for concern that micro bubble transmission may occur without inducing an alarm. These factors need to be looked over to improve safety regulations and optimize HD treatment and service schedules.

Place, publisher, year, edition, pages
2006. , 99 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1071
Keyword [en]
haemodialysis, safety, leakage current, central dialysis catheter, microbubbles, microemboli, air contamination
Research subject
transfusionsmedicin
Identifiers
URN: urn:nbn:se:umu:diva-941ISBN: 91-7264-226-2 (print)OAI: oai:DiVA.org:umu-941DiVA: diva2:145138
Public defence
2006-12-08, Sal B, 9 tr, Tandläkarhögskolan, NUS, Umeå, 13:00 (English)
Opponent
Available from: 2006-11-20 Created: 2006-11-20 Last updated: 2009-10-09Bibliographically approved
List of papers
1. Current leakage in hemodialysis machines may be a safety risk for patients.
Open this publication in new window or tab >>Current leakage in hemodialysis machines may be a safety risk for patients.
2000 (English)In: Artificial Organs, ISSN 0160-564X, E-ISSN 1525-1594, Vol. 24, no 12, 977-981 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-5577 (URN)10.1046/j.1525-1594.2000.06557.x (DOI)11121978 (PubMedID)
Available from: 2006-11-20 Created: 2006-11-20 Last updated: 2017-12-14Bibliographically approved
2. Blood lines conduct leakage current during haemodialysis: a potential safety risk during first failure, especially for patients with central dialysis catheter as access.
Open this publication in new window or tab >>Blood lines conduct leakage current during haemodialysis: a potential safety risk during first failure, especially for patients with central dialysis catheter as access.
2005 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, no 6, 731-738 p.Article in journal (Refereed) Published
Keyword
Catheterization; Central Venous/*adverse effects, Electric Conductivity, Equipment Failure, Equipment Safety, Humans, Renal Dialysis/*instrumentation, Risk Assessment/methods
Identifiers
urn:nbn:se:umu:diva-14775 (URN)16594299 (PubMedID)
Available from: 2007-06-18 Created: 2007-06-18 Last updated: 2017-12-14Bibliographically approved
3. Electrical current leakage during hemodialysis may increase blood-membrane interaction
Open this publication in new window or tab >>Electrical current leakage during hemodialysis may increase blood-membrane interaction
2001 (English)In: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 24, no 3, 136-139 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-5579 (URN)11314806 (PubMedID)
Available from: 2006-11-20 Created: 2006-11-20 Last updated: 2017-12-14Bibliographically approved
4. Measurement of cardiac rhythm in connection to haemodialysis with focus on a possible interference due to leakage current: a pilot study of patients in chronic haemodialysis
Open this publication in new window or tab >>Measurement of cardiac rhythm in connection to haemodialysis with focus on a possible interference due to leakage current: a pilot study of patients in chronic haemodialysis
Show others...
(English)Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:umu:diva-5580 (URN)
Available from: 2006-11-20 Created: 2006-11-20 Last updated: 2013-03-18Bibliographically approved
5. Air bubbles pass the security system of the dialysis device without alarming.
Open this publication in new window or tab >>Air bubbles pass the security system of the dialysis device without alarming.
Show others...
2007 (English)In: Artificial Organs, ISSN 0160-564X, E-ISSN 1525-1594, Vol. 31, no 2, 132-139 p.Article in journal (Refereed) Published
Keyword
Embolism; Air/*diagnosis/*prevention & control, Equipment Failure Analysis, Filtration/instrumentation, Humans, Microbubbles, Renal Dialysis/*adverse effects
Identifiers
urn:nbn:se:umu:diva-8298 (URN)10.1111/j.1525-1594.2007.00352.x (DOI)17298402 (PubMedID)
Available from: 2008-03-06 Created: 2008-03-06 Last updated: 2017-12-14Bibliographically approved

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