Journal of clinical monitoring and computing
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J Clin Monit Comput · Apr 2014
Comparative StudyEvaluation of point-of-care analyzers' ability to reduce bias in conductivity-based hematocrit measurement during cardiopulmonary bypass.
Most point-of-care testing analyzers use the conductivity method to measure hematocrit (hct). During open-heart surgery, blood-conductivity is influenced by shifts in electrolyte and colloid concentrations caused by infusion media used, and this may lead to considerable bias in the hct measurement. We evaluated to what extent different analyzers correcting for 0, 1, 2, or 3 factors, respectively, compensated for this electrolyte/colloid interference: (1) the conductivity method with no correction (IRMA), (2) with a [Na(+)]-correction (GEM Premier 3000), (3) with a [Na(+)]/[K(+)]-correction (i-STAT), and (4) with a [Na(+)]/[K(+)]-correction in combination with an algorithm that estimates the protein dilution [i-STAT in cardiopulmonary bypass (CPB)-mode]. ⋯ In order of high to low electrolyte/colloid interference: the analyzer with no correction, [Na(+)]-correction, [Na(+)/]/[K(+)]-correction, and [Na(+)/]/[K(+)]/estimated protein-correction showed a change of bias from stage I to stage III of -3.9 ± 0.5, -3.4 ± 0.4, -2.1 ± 0.5, -0.3 ± 0.5%. We conclude that correcting for more parameters (Na(+), K(+), estimated protein) gives less bias, but residual bias remains even after [Na(+)/]/[K(+)]/estimated protein-correction. This suggests that a satisfactory algorithm should also correct for other colloidal factors than protein.
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J Clin Monit Comput · Apr 2014
Reliable real-time calculation of heart-rate complexity in critically ill patients using multiple noisy waveform sources.
Heart-rate complexity (HRC) has been proposed as a new vital sign for critical care medicine. The purpose of this research was to develop a reliable method for determining HRC continuously in real time in critically ill patients using multiple waveform channels that also compensates for noisy and unreliable data. Using simultaneously acquired electrocardiogram (Leads I, II, V) and arterial blood pressure waveforms sampled at 360 Hz from 250 patients (over 375 h of patient data), we evaluated a new data fusion framework for computing HRC in real time. ⋯ Furthermore, the fusion of waveform sources produced better error density distributions than those derived from individual waveforms. The data fusion framework was shown to provide in real-time a reliable continuously streamed HRC value, derived from multiple waveforms in the presence of noise and artifacts. This approach will be validated and tested for assessment of HRC in critically ill patients.
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J Clin Monit Comput · Apr 2014
Practice guidelines for the supervising professional: intraoperative neurophysiological monitoring.
The American Society of Neurophysiological Monitoring (ASNM) was founded in 1988 as the American Society of Evoked Potential Monitoring. From the beginning, the Society has been made up of physicians, doctoral degree holders, technologists, and all those interested in furthering the profession. The Society changed its name to the ASNM and held its first Annual Meeting in 1990. ⋯ Adherence to a literature-based, formalized process characterizes the construction of all ASNM guidelines. The guidelines covering the Professional Practice of intraoperative monitoring were established by a committee of nearly 30 total participants and ultimately endorsed by the Board of Directors of ASNM on January 24th 2013. That document follows.
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J Clin Monit Comput · Apr 2014
Letter Case ReportsAn abrupt reduction in end-tidal carbon-dioxide during neurosurgery is not always due to venous air embolism: a capnograph artefact.
Venous air embolism (VAE) is a well recognized complication during neurosurgery. Pre-cordial doppler and trans-esophageal echocardiography are sensitive monitors for the detection of VAE. A sudden, abrupt reduction in the end-tidal carbondioxide (ETCO2) pressure with associated hypotension during neurosurgery might suggest VAE, when more sensitive monitors are not available. We describe an unusual cause for sudden reduction in ETCO2 during neurosurgery and discuss the mechanism for such presentation.
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J Clin Monit Comput · Apr 2014
FaceTime(®) for teaching ultrasound-guided anesthetic procedures in remote place.
In isolated area in Japan, only one anesthesiologist must often do new anesthetic techniques such as ultrasound-guided procedures without receiving any teaching. One solution to this problem may involve teleanesthesia, by which experienced anesthesiologists teach novices in remote places, by utilizing information communication technologies. FaceTime™ (Apple, USA), which provides 120p of the resolution and 30 frames per second (fps) is an application of free visual communications using iPod Touch™, iPhone™ or iPad™ (Apple, USA). ⋯ The delay time of iPhone5 was significantly longer than the others (iPod Touch; 0.14 ± 0.02 s, iPhone4; 0.13 ± 0.02 s, iPhone5; 0.19 ± 0.03 s), but clinically acceptable. The loss of the frames of iPhone5 (20; 1.1%) was significantly less than the others (iPhone4; 900, 50.0%, iPod Touch; 902, 50.1%). To teach anesthetic techniques in remote place by FaceTime, iPhone5 as the devise in isolate site was optimum compared with iPod Touch and iPhone4.