Volume 36, Issue 6 pp. 525-529

A High Blood Level in the Air Trap Reduces Microemboli During Hemodialysis

Ulf Forsberg

Corresponding Author

Ulf Forsberg

Department of Internal Medicine, Skellefteå County Hospital, Skellefteå

Dr. Ulf Forsberg, Department of Internal Medicine, Skellefteå County Hospital, Skelleftea 931 86, Sweden. E-mail: [email protected]Search for more papers by this author
Per Jonsson

Per Jonsson

Institute of General Health and Medicine, Department of Medicine, Norrland University Hospital

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Christofer Stegmayr

Christofer Stegmayr

Institute of Technology, University of Umeå

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Bernd Stegmayr

Bernd Stegmayr

Department of Nephrology, Norrland University Hospital, Umeå, Sweden

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First published: 23 February 2012
Citations: 27

Abstract

Previous studies have demonstrated the presence of air microemboli in the dialysis circuit and in the venous circulation of the patients during hemodialysis. In vitro studies indicate that a high blood level in the venous air trap reduces the extent of microbubble formation. The purpose of this study was to examine whether air microbubbles can be detected in the patient's access and if so, whether the degree of microbubble formation can be altered by changing the blood level in the venous air trap. This was a randomized, double-blinded, interventional study of 20 chronic hemodialysis patients. The patients were assigned to hemodialysis with either an elevated or a low blood level in the air trap. The investigator and the patient were blinded to the settings. The numbers of microbubbles were measured at the site of the arteriovenous (AV) access for 2 min with the aid of an ultrasonic Doppler device. The blood level in the air trap was then altered to the opposite setting and a new measurement was carried out after an equilibration period of 30 min. Median (range) for the number of microbubbles measured with the high air trap level and the low air trap level in AV access was 2.5 (0–80) compared with 17.5 (0–77), respectively (P = 0.044). The degree of microbubble formation in hemodialysis patients with AV access was reduced significantly if the blood level in the air trap was kept high. The exposure of potentially harmful air microbubbles was thereby significantly reduced. This measure can be performed with no additional healthcare cost.

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