Journal of clinical monitoring and computing
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J Clin Monit Comput · Oct 2016
Does using two Doppler cardiac output monitors in tandem provide a reliable trend line of changes for validation studies?
The demise of the pulmonary artery catheter as a gold standard in cardiac output measurement has created the need for new standard. Doppler cardiac output can be measured suprasternally (USCOM) and via the oesophagus (CardioQ). Use in tandem they may provide a reliable trend line of cardiac output changes against which new technologies can be assessed. ⋯ The regression line between Doppler methods was offset with a slope of 0.9, thus CardioQ CI readings increased relative to USCOM. Both Doppler methods trended cardiac output reliably. Used in tandem they provide a new standard to assess cardiac output trending.
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J Clin Monit Comput · Oct 2016
The effect of head up tilting on bioreactance cardiac output and stroke volume readings using suprasternal transcutaneous Doppler as a control in healthy young adults.
To compare the performance of a bioreactance cardiac output (CO) monitor (NICOM) and transcutaneous Doppler (USCOM) during head up tilting (HUT). Healthy young adult subjects, age 22 ± 1 years, 7 male and 7 female, were tilted over 3-5 s from supine to 70° HUT, 30° HUT and back to supine. Positions were held for 3 min. ⋯ TFC decreased linearly with HUT. The NICOM does not provide linear changes in SV as predicted by physiology when patients are tilted. Furthermore there is a lack of agreement with USCOM measurements at baseline and during tilting.
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J Clin Monit Comput · Oct 2016
The effect of variable arterial transducer level on the accuracy of pulse contour waveform-derived measurements in critically ill patients.
We know that a 10 cm departure from the reference level of pressure transducer position is equal to a 7.5 mmHg change of invasive hemodynamic pressure monitoring in a fluid-filled system. However, the relationship between the site level of a variable arterial pressure transducer and the pulse contour-derived parameters has yet to be established in critically ill patients. Moreover, the related quantitative analysis has never been investigated. ⋯ On average, for every centimeter change of the transducer, there was a corresponding 0.014 L/min/m(2) CCI change and 0.36 % change rate, a 1.41 mmHg/s dP/dtmax change and 0.13 % change rate, and a 25 dyne/s/cm(5) SVRI change and 1.2 % change rate. The variation of arterial transducer position can result in inaccurate measurement of pulse contour waveform-derived parameters, especially when the transducer's vertical distance is more than 10 cm from the phlebostatic axis. These findings have clinical implications for continuous hemodynamic monitoring.
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J Clin Monit Comput · Oct 2016
Importance of re-calibration time on pulse contour analysis agreement with thermodilution measurements of cardiac output: a retrospective analysis of intensive care unit patients.
We assessed the effect of re-calibration time on cardiac output estimation and trending performance in a retrospective analysis of an intensive care unit patient population using error grid analyses. Paired thermodilution and arterial blood pressure waveform measurements (N = 2141) from 222 patient records were extracted from the Multiparameter Intelligent Monitoring in Intensive Care II database. Pulse contour analysis was performed by implementing a previously reported algorithm at calibration times of 1, 2, 8 and 24 h. ⋯ Shorter calibration times improved the agreement of cardiac output pulse contour estimates with thermodilution. Use of minimally invasive pulse contour methods in intensive care monitoring could benefit from prospective studies evaluating calibration protocols. The applied pulse contour analysis method and thermodilution showed poor agreement to monitor changes in cardiac output.
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J Clin Monit Comput · Oct 2016
Accuracy of inhaled agent usage displays of automated target control anesthesia machines.
Automated low flow anesthesia machines report how much inhaled anesthetic agent has been used for each anesthetic. We compared these reported values with the amount of agent that had disappeared by weighing the vaporizer/injectors before and after each anesthetic. The vaporizers/injectors of the Aisys, Zeus and FLOW-i were weighed with a high precision weighing scale before and after anesthesia with either desflurane in O2/air or sevoflurane in O2/N2O. ⋯ The differences may be due to either measurement error or cumulative agent display error. The current results can help the researchers decide whether the displayed amounts are accurate enough for their study purposes. The extent to which these discrepancies differ between different units of the same machine remains unstudied.