PubMed Health⌕ Search

Biomedical subjects

Andreas Nilsson

Publications and source records attributed to Andreas Nilsson.

10 recordsLinked to original sources
PubMed2006

Postoperative urinary continence after robot-assisted laparoscopic radical prostatectomy.

OBJECTIVE: Laparoscopic radical prostatectomy has shown excellent results concerning patient morbidity, with less blood loss compared to conventional surgery. Robot-assisted laparoscopy offers several additional important technical improvements and therefore it might be suggested that robotic radical prostatectomy would also offer surgical advantages. The objective of this study was to evaluate urinary continence for the first 72 cases of robot-assisted radical prostatectomy performed by a single surgical team. MATERIAL AND METHODS: We analysed the outcomes of the first 72 consecutive patients to undergo robot-assisted prostatectomy for localized prostate cancer at our hospital between January 2002 and May 2004. A self-administered questionnaire concerning urinary status was mailed to the patients 3 and 6 months after surgery. Pre- and peroperative characteristics were obtained from patient medical records. The mean age was 61.2 years (range 36-71 years) and the mean preoperative prostate-specific antigen level was 6.3 ng/ml (range 2.3-10.7 ng/ml). The preoperative clinical stage was T1c, 67%, T2, 28% and T3, 5% and the mean Gleason sum was 6 (range 5-9). RESULTS: Sixty-one of the 68 patients (90%) reported no use of pads and 6 (9%) used a maximum of 1 pad/day 3-6 months after surgery. One patient reported use of >1 pad/day 6 months after surgery. Three significant complications were noted: ureter injury, haemorrhage and femoral nerve injury. CONCLUSIONS: In this series, which represents the learning curve for one surgical team, only a tenth of the patients still required pads 3-6 months after surgery. Considering the short follow-up period, the results in this series will probably improve over time.

Adult↗
PubMed2005

Carrier medium exchange through ultrasonic particle switching in microfluidic channels.

This paper describes a method, utilizing acoustic force manipulation of suspended particles, in which particles in a laminar flow microchannel are continuously translated from one medium to another with virtually no mixing of the two media. During the study, 5-microm polyamide spheres suspended in distilled water, spiked (contaminated) with Evans blue, were switched over to clean distilled water. More than 95% of the polyamide spheres could be collected in the clean medium while removing up to 95% of the contaminant. Preliminary experiments to use this method to wash blood were performed. Red blood cells were switched from blood, spiked with Evans blue, to clean blood plasma. At least 95% of the red blood cells (bovine blood) could be collected in clean blood plasma while up to 98% of the contaminant was removed. The obtained results indicate that the presented method can be used as a generic method for particle washing and, more specifically, be applied for both intraoperative and postoperative blood washing.

Journal Article↗
PubMed2005

Particle separation using ultrasound can be used with human shed mediastinal blood.

BACKGROUND: Shed mediastinal blood collected by cardiotomy suction has been shown to be a large contributor to lipid microemboli ending up in different organs. The aim of this study was to test the separation efficiency on human shed blood of a new separation method developed to meet this demand. METHODS: Shed mediastinal blood collected from the pericardial cavity of 13 patients undergoing cardiac surgery with cardiopulmonary bypass was collected. The blood was processed in an eight-channel parallel PARSUS separator, and separation efficiency was determined. RESULTS: Erythrocyte recovery, in terms of a separation ratio, varied between 68% and 91%. Minor electrolyte changes took place, where levels of sodium increased and levels of potassium and calcium decreased. CONCLUSION: This study demonstrates that PARSUS technology can be used on human shed mediastinal blood with good separation efficiency. The technology is, thereby, suggested to have future clinical relevance.

Blood Transfusion, Autologous↗
PubMed2004

Separation of lipids from blood utilizing ultrasonic standing waves in microfluidic channels.

A method to continuously separate different particle types in a suspension is reported. Acoustic forces in a standing wave field were utilized to discriminate lipid particles from erythrocytes in whole blood. The presented technology proposes a new method of cleaning, i.e. removing lipid emboli from, shed blood recovered during cardiac surgery. Blood contaminated with lipid particles enter a laminar flow micro channel. Erythrocytes and lipid particles suspended in blood plasma are exposed to a half wavelength standing wave field orthogonal to the direction of flow as they pass through the channel. Because of differences in compressibility and density the two particle types move in different directions, the erythrocytes towards the centre of the channel and the lipid particles towards the side walls. The end of the channel is split into three outlet channels conducting the erythrocytes to the centre outlet and the lipid particles to the side outlets due to the laminar flow profile. The separation channel was evaluated in vitro using polyamide spheres suspended in water, showing separation efficiencies approaching 100%. The system was also evaluated on whole blood using tritium labelled lipid particles added to bovine blood. More than 80% of the lipid particles could be removed while approximately 70% of the erythrocytes were collected in one third of the original fluid volume. The study showed that the further reduced micro channel dimensions provided improved performance with respect to; (i) separation efficiency, (ii) actuation voltage, and (iii) volumetric throughput as compared to earlier work.

Acoustics↗
PubMed2004

Acoustic control of suspended particles in micro fluidic chips.

A method to separate suspended particles from their medium in a continuous mode at microchip level is described. The method combines an ultrasonic standing wave field with the extreme laminar flow properties obtained in a silicon micro channel. The channel was 750 microm wide and 250 microm deep with vertical side walls defined by anisotropic wet etching. The suspension comprised "Orgasol 5 microm" polyamide spheres and distilled water. The channel was perfused by applying an under pressure (suction) to the outlets. The channel was ultrasonically actuated from the back side of the chip by a piezoceramic plate. When operating the acoustic separator at the fundamental resonance frequency the acoustic forces were not strong enough to focus the particles into a well defined single band in the centre of the channel. The frequency was therefore changed to about 2 MHz, the first harmonic with two pressure nodes in the standing wave, and consequently two lines of particles were formed which were collected via the side outlets. Two different microchip separator designs were investigated with exit channels branching off from the separation channel at angles of 90 degrees and 45 degrees respectively. The 45 degrees separator displayed the most optimal fluid dynamic properties and 90% of the particles were gathered in 2/3 of the original fluid volume.

Acoustics↗
PubMed2004

Particle separation using ultrasound can radically reduce embolic load to brain after cardiac surgery.

BACKGROUND: Microembolism during cardiopulmonary bypass has been suggested as being the predominant cause of neurocognitive disorders after cardiac surgery. Shed blood, normally retransfused into the patient during cardiopulmonary bypass, is a major source of lipid microemboli in the brain capillaries. A newly developed technique based on acoustic standing-wave separation of particles in fluid in microchannels, with the capacity to remove lipid particles in blood, is presented. METHODS: A separator consisting of eight parallel, high-fidelity microfabricated channels was actuated with an ultrasound field to create a standing wave. Three different concentrations of lipid particles (diameter, 0.3 microm) were added to blood samples with increasing hematocrits and introduced into the separator channels to separate lipid particles and erythrocytes. RESULTS: The mean separation rates for lipid particles were 81.9% +/- 7.6% and for erythrocytes 79.8% +/- 9.9%, and both were related to the hematocrit level of the incoming blood sample. The procedure was atraumatic and did not cause hemolysis. CONCLUSIONS: Particle separation by means of an acoustic standing-wave technique can be used for atraumatic and effective removal of lipid particles from blood, with the possible clinical implication of reducing neurocognitive complications after cardiopulmonary bypass.

Animals↗
PubMed2003

Effect of monitor placement and of activity setting on the MTI accelerometer output.

PURPOSE: To examine the effect of monitor placement (hip vs back) and of activity setting (treadmill vs track) on the output from the Manufacturing Technology Inc. (MTI), activity monitor (model WAM 7164). METHODS: In a laboratory study, 28 subjects (14 men, 14 women) walked at a normal pace, walked at a fast pace, and jogged at a comfortable pace on an indoor track. These activities were repeated on a treadmill using the individual speeds from the track locomotion. Oxygen uptake was measured simultaneously using a portable metabolic system. One activity monitor was worn on the hip and one on the lower back. In a field study, 34 subjects (18 men, 16 women) each wore two monitors (hip and low back placement) for seven consecutive days. In the laboratory study, ANOVA showed significant effects of placement ( P = 0.009) and setting ( P < 0.001), indicating that activity counts differ between different body sites and different settings (track vs treadmill). Gross energy expenditure predictive equations were developed and thereafter evaluated in the field study. Time spent at moderate and vigorous intensity of physical activity was 38% and 85% ( P < 0.001) higher when calculated from the treadmill-based equations as compared to the track-based equations. Free-living physical activity estimates were not affected by the placement. CONCLUSION: The relationship between activity counts and energy expenditure during laboratory locomotion is placement and setting-specific. When habitual physical activity is assessed in free-living subjects, the treadmill derived relationship between energy expenditure and activity counts may overestimate time spent at moderate intensity of physical activity, whereas the placement of the monitor does not influence on the interpretation of the data.

Adult↗