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Impedance Signal (impedance + signal)
Selected AbstractsRed blood cell quantification microfluidic chip using polyelectrolytic gel electrodesELECTROPHORESIS, Issue 9 2009Kwang Bok Kim Abstract This paper reports on a novel microfluidic chip with polyelectrolytic gel electrodes (PGEs) used to rapidly count the number of red blood cells (RBCs) in diluted whole blood. The proposed microdevice is based on the principle that the impedance across a microchannel between two PGEs varies sensitively as RBCs pass through it. The number and amplitude of impedance peaks provide the information about the number and size of RBCs, respectively. This system features a low-voltage dc detection method and non-contact condition between cells and metal electrodes. Major advantages include stable detection under varying cellular flow rate and position in the microchannel, little chance of cell damage due to high electric field gradient and no surface fouling of the metal electrodes. The performance of this PGEs-based system was evaluated in three steps. First, in order to observe the size-only dependence of the impedance signal, three different sizes of fluorescent microbeads (7.2, 10.0, and 15.0,,m; Bangs laboratories, USA) were used in the experiment. Second, the cell counting performance was evaluated by using 7.2,,m fluorescent microbeads, similar in size to RBCs, in various concentrations and comparing the results with an animal hematoanalyzer (MS 9-5; Melet schloesing laboratories, France). Finally, in human blood sample tests, intravenously collected whole blood was just diluted in a PBS without centrifuge or other pretreatments. The PGE-based system produced almost identical number of RBCs in over 800-fold diluted samples to the results from a commercialized human hematoanalyzer (HST-N402XE; Sysmex, Japan). [source] Clinical Use of Intracardiac Impedance: Current Applications and Future PerspectivesPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2001WAYNE ARTHUR ARTHUR, W., et al.: Clinical Use of Intracardiac Impedance: Current Applications and Future Perspectives. For over 40 years the measurement of intracardiac impedance has been proposed as a method of assessing the contractile state of the heart muscle. This technique requires the positioning of one or more intracavitary electrodes and the generation of an electric field from an alternating current source. Variations in the calculated impedance signal reflect changes in the ventricular blood pool volume adjacent to the electrodes. Intracardiac impedance measurement has been successfully developed as a research tool to assess myocardial contractility, and from this, clinical uses have evolved. Commercial rate responsive pacing systems use intracardiac impedance to assess the inotropic state of the heart. Further development of this technology might allow hemodynamic discrimination of cardiac arrhythmias. [source] Regional ventilation distribution in non-sedated spontaneously breathing newborns and adults is not differentPEDIATRIC PULMONOLOGY, Issue 9 2009Andreas Schibler MD Abstract Background: In adults, ventilation is preferentially distributed towards the dependent lung. A reversal of the adult pattern has been observed in infants using radionuclide ventilation scanning. But these results have been obtained in infants and children with lung disease. In this study we investigate whether healthy infants have a similar reverse pattern of ventilation distribution. Study Design: Measurement of regional ventilation distribution in healthy newborn infants during non-REM sleep in comparison to adults. Methods: Twenty-four healthy newborns and 13 adults were investigated with electrical impedance tomography (EIT) in supine and prone position. Regional ventilation distribution was assessed with profiles of relative impedance change. The phase lag between dependent and non-dependent ventilation was calculated as a measure of asynchronous ventilation. Results: In newborns and adults the geometric center of ventilation was centrally located in the lung at 52.2,±,6.2% from anterior to posterior and at 50.5,±,14.7%, respectively. Using impedance profiles, ventilation was equally distributed to the dependent and non-dependent lung regions in newborns. Ventilation distribution in adults was similar. Phase lag characteristics of the impedance signal showed that infants had slower emptying of the dependent lung than adults. Conclusion: The speculated reverse pattern of regional ventilation distribution in healthy infants compared to adults could not be demonstrated. Gravity had little effect on ventilation distribution in both infants and adults measured in supine and prone position. Pediatr Pulmonol. 2009; 44:851,858. © 2009 Wiley-Liss, Inc. [source] Monitor-induced tachycardia in a patient with a rate-responsive pacemakerANAESTHESIA, Issue 4 2006S. Houtman Summary A patient with a ventricle-paced, ventricle-sensed and inhibited, respiratory rate-responsive pacemaker presented for orthopaedic surgery. She had been operated upon recently without any adverse effects. In the recovery unit her electrocardiograph showed a paced ventricular tachycardia of about 140 beats.min,1 without any other adverse sign or symptom. Although this tachycardia initially decreased to 70 beats.min,1 after about 30 min, it later rose again to 140 beats.min,1. A pacemaker technician was consulted, who suggested that there may be interference between the bioelectric impedance signals of the patient monitoring system that was being used to measure respiratory rate and the pacemaker's own measurement systems. [source] Prospective Clinical Trial, DEFI 2005: Does an AED Algorithm with More CPR Impact Out-of-Hospital Cardiac Arrest Prognosis?ACADEMIC EMERGENCY MEDICINE, Issue 2008Herve Degrange Background:, Level 1 evidence is lacking for the Guidelines 2005 recommended changes in CPR and automated external defibrillator (AED) protocols. Objectives:, We conducted a block-randomized controlled trial to evaluate if changes to CPR during AED use could improve return of spontaneous circulation (ROSC) and hospital admission rates. Methods:, From September 2005 to March 2007, 200 biphasic LIFEPAKs, 500 AEDs, used by firefighters, were randomized every 2 months by fire station (clinicaltrials.gov NCT00139542). The 100 CONTROL AEDs conformed to Guidelines 2000. The 100 STUDY AEDs added pre-shock CPR and removed stacked shocks and post-shock pulse checks. In both groups, firefighters received weekly CPR training. ECG and impedance signals recorded by AEDs were reviewed to quantify CPR delivery. Median [interquartile range], *p < 0.05. Results:, Informed consent was obtained for 840 defibrillated patients (420 CONTROL vs. 420 STUDY). There were no differences in patient characteristics (age, sex, location, etiology, witnessed, bystander CPR, chest compression (CC) rate) and time from call to AED power on. The STUDY AEDs prompted for more CPR during AED use (81% [80, 83] vs. 62% [55, 67]*), resulting in more hands-on time (62% [54, 69] vs 49% [39, 57]*), more patients receiving only one shock (40 vs 33%*), and shorter pauses in CC before (9s [7, 13] vs 19s [16, 21]*) and after (11s [8, 14] vs 32s [26, 38]*) the shock. There was no difference in the rates of ROSC (48% [44, 53] vs 50% [45, 55], p = 0.63) and hospital admission (44% [40, 49] vs 45% [40, 49], p = 0.94) for the STUDY vs CONTROL groups. Conclusions:, Increasing CPR, shortening CC pauses and delivering fewer shocks resulted in no observed difference in ROSC or survival to hospital admission. The overall rate of hospitalization was higher than the historical expectation (34% hospital admission before study), possibly due to the increased emphasis on training and importance of CPR in both groups. [source] | ||||||||||