Christofer Stegmayr

Microemboli, developed during haemodialysis, pass the lung barrier and may cause ischaemic lesions in organs such as the brain

BACKGROUND Chronic haemodialysis (HD) may relieve some medical problems of terminal uraemia, but the life expectancy of patients is still significantly shortened, and there is a greatly increased morbidity. This includes pulmonary morbidity and chronic central nervous system (CNS) abnormalities. Previous studies have shown that a considerable amount of air microbubbles emanate within the blood lines of the dialysis device and pass the air detector without sounding an alarm. The aim of this study was to investigate whether microemboli can pass to the patient and whether they could be detected in the carotid artery. METHODS A total of 54 patients on chronic HD (16 with central dialysis catheter) were investigated with an ultrasound detector (Hatteland, Røyken, Norway) for the presence of microemboli at the arteriovenous (AV) fistula/graft and at the common carotid artery before and during HD. Measurements were taken for 2 and 5 min, respectively. Non-parametric paired statistics were used (Wilcoxon). RESULTS The median number (range) and mean +/- SD of microembolic signals detected at the AV access site before commencing dialysis and during HD were 0 (0-3) and 0.2+/- 0.5 versus 4 (0-85) and 13.5 +/- 20 (P = 0.000); at the carotid artery, 1 (0-14) and 1.7 +/- 2.9 versus 2 (0-36) and 3.5 +/- 5.8 (P = 0.008). CONCLUSIONS The infused and returning fluid from HD devices contains air microbubbles that enter the patient without triggering any alarms. These small emboli pass the lung and may cause ischaemic lesions in organs supported by the arterial circuit, such as the brain.

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

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 patients 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.

Microbubbles of air may occur in the organs of hemodialysis patients.

During hemodialysis (HD), blood that passes the dialysis device gets loaded with microbubbles (MB) of air that are returned to the patient without inducing an alarm. The aim with this study was to clarify if these signals are due to microembolies of air, clots, or artifacts, by histopathology of autopsy material of HD patients. These first results are from a patient on chronic HD. Due to pulmonary edema he was ultrafiltered. Within 30 minutes after the start, he suffered from a cardiac arrest and died. Autopsy verified the clinical findings. Microscopic investigation verified microembolies of air that were surrounded by fibrin in the lungs, brain, and heart. The study verified that MBs can enter the blood during HD and are trapped in the lungs. In addition, MBs pass the pulmonary capillaries and enter the arterial part of the body and are dispersed throughout the body. This can contribute to organ damage and be part of the poor prognoses seen in HD patients. Data support the importance to reduce MBs in the dialysis circuit.

A high blood level in the venous chamber and a wet-stored dialyzer help to reduce exposure for microemboli during hemodialysis

During hemodialysis (HD), microemboli develop in the blood circuit of the apparatus. These microemboli can pass through the venous chamber and enter into the patients circulation. The aim of this study was to investigate whether it is possible to reduce the risk for exposure of microemboli by altering of the treatment mode. Twenty patients on chronic HD were randomized to a prospective cross‐over study of three modes of HD: (a) a dry‐stored dialyzer (F8HPS, Fresenius, steam sterilized) with a low blood level in the venous chamber (DL), (b) the same dialyzer as above, but with a high level in the venous chamber (DH), and (c) a wet‐stored dialyzer (Rexeed, Asahi Kasei Medical, gamma sterilized) with a high blood level (WH). Microemboli measurements were obtained in a continuous fashion during 180 minutes of HD for all settings. A greater number of microemboli were detected during dialysis with the setting DL vs. WH (odds ratio [OR] 4.07, 95% confidence interval [CI] 4.03–4.11, P < 0.0001) and DH vs. WH (OR 1.18, 95% CI 1.17–1.19, P < 0.0001) and less for DH vs. DL (OR 0.290, 95% CI 0.288–0.293, P < 0.0001). These data indicate that emboli exposure was least when using WH, greater with DH, and most with DL. This study shows that using a high blood level in the venous chamber and wet‐stored dialyzers may reduce the number of microemboli.

In vitro testing of prevailing materials and initial clinical findings

Evaluation of air contamination incidences and in vitro settings and experiences of micro bubblesThe use of citrate-containing dialysate for anticoagulation in hemodialysis (hd). report of clinical experienceK1 (EI0154) AGES IN HEMODIALYSIS: TISSUEAND PLASMAAUTOFLUORESCENCE R. Graaff1, S. Arsov1, L. Trajceska4, P. Dzekova4, G.E. Engels1, M. Koetsier1, W. van Oeveren1, L Lundberg5, S. Assa2, C.F.M. Franssen2, A.J. Smit3, G. Rakhorst1, A. Sikole2, B. Stegmayr5 1Dept. of Biomedical Engineering, 2Internal Medicine, Div. Nephrology and 3Div. Vascular Medicine, University Medical Center Groningen, Groningen, The Netherlands; 4Department of Nephrology, University Clinic of Nephrology, Skopje, R. Macedonia; 5Department of Internal Medicine, University Hospital, Umea, SwedenObjectives: During HD previous studies have shown that especially micro bubbles of air may pass the air detector. These studies focused to analyse in vitro if the air trap of various producers may ...Artificial Kidney – Uremic Toxins – SYMPOSIUM, 606 Smart and Responsive Biomaterials – SYMPOSIUM, 607 Cardiovascular General 1: Devices – GENERAL SESSION, 608 Ambulatory Blood Processing – SYMPOSIUM, 610 Animal Models for Tissue Engineering – SYMPOSIUM, 610 Cardiovascular General 2: Devices Interaction – GENERAL SESSION, 612 Artificial Muscle for Internal Organ – SYMPOSIUM, 613 Functionalized Biomaterials – SYMPOSIUM, 614 Cardiovascular General 3: Physiology and Pump Control – GENERAL SESSION, 615 Vascular Access in Hemodialysis – SYMPOSIUM, 617 Polymeric Membranes/Blood Interfaces – SYMPOSIUM, 618 Nano and Micro Technology: Driving the Future of Organ Recovery & Development – SYMPOSIUM, 619 Roadbumps for Tissue-Engineering Artificial Organs – SYMPOSIUM, 621 Artificial Liver GENERAL SESSION, 621 Tissue Engineering Approaches – SYMPOSIUM, 622 Cardiovascular General 4: Cardiopulmonary – GENERAL SESSION, 624 Artificial Kidney Dialysis – SYMPOSIUM, 625 Tissue Engineering of Skin: Creating a New Bio-Artificial Organ for Clinical Application – SYMPOSIUM, 627 Cardiovascular General 5: Device & Biology – GENERAL SESSION, 628 Citrate Anticoagulation A Future Option for Extracorporeal Blood Purification – SYMPOSIUM, 629 Latest Advances in Preventive and Regenerative Medicine Technologies – SYMPOSIUM, 630 Intra-Aortic Balloon Pump as a Cardiac Assist Device – SYMPOSIUM, 631 Artificial Organ Transplantation – SYMPOSIUM, 632 New Biomaterials and Scaffolds – SYMPOSIUM, 633 Modelling of Cardiovascular and Pulmonary Function in Regard to Clinical Applications – SYMPOSIUM, 634 Artificial Kidney Dialysis Techniques – SYMPOSIUM, 635 Natural Based Polymeric Biomaterials and Composites for Regenerative Medicine – SYMPOSIUM, 637 Partial Cardiac Support in Shortand Long-Term Application – SYMPOSIUM, 638 Artificial Organs – Practical Applications – GENERAL SESSION, 639 Non-Destructive Techniques to Monitor 3D In Vitro Tissue Engineering Constructs – SYMPOSIUM, 640 Stent and Vascular Prosthesis – GENERAL SESSION, 641 Dialysis Techniques Access – GENERAL SESSION, 643 Scaffolds for TE Via Electrospinning-Structures and Biomaterials – SYMPOSIUM, 644 Drug Delivery Systems – GENERAL SESSION, 646 “Approval Procedures for Medical Devices: Facts, Figures and Basic Rules Seen from Different Continental Perspectives – Artificial Organs and Society: Recent Trends in Japan”, 647K1 (EI0154) AGES IN HEMODIALYSIS: TISSUEAND PLASMAAUTOFLUORESCENCE R. Graaff1, S. Arsov1, L. Trajceska4, P. Dzekova4, G.E. Engels1, M. Koetsier1, W. van Oeveren1, L Lundberg5, S. Assa2, C.F.M. Franssen2, A.J. Smit3, G. Rakhorst1, A. Sikole2, B. Stegmayr5 1Dept. of Biomedical Engineering, 2Internal Medicine, Div. Nephrology and 3Div. Vascular Medicine, University Medical Center Groningen, Groningen, The Netherlands; 4Department of Nephrology, University Clinic of Nephrology, Skopje, R. Macedonia; 5Department of Internal Medicine, University Hospital, Umeå, SwedenDoes the advanced glycation end-products (ages) food intake influence mortality in dialysis patients?