Journal of clinical monitoring and computing
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J Clin Monit Comput · Aug 2014
Case ReportsImpact of changes in systemic vascular resistance on a novel non-invasive continuous cardiac output measurement system based on pulse wave transit time: a report of two cases.
The inaccuracy of arterial waveform analysis for measuring continuos cardiac output (CCO) associated with changes in systemic vascular resistance (SVR) has been well documented. A new non-invasive continuous cardiac output monitoring system (esCCO) mainly utilizing pulse wave transit time (PWTT) in place of arterial waveform analysis has been developed. However, the trending ability of esCCO to measure cardiac output during changes in SVR remains unclear. ⋯ In each case, the trending ability of esCCO to measure cardiac output and time component of PWTT were analyzed. Recorded data suggest that the time component of PWTT may have a significant impact on the accuracy of estimating stroke volume during changes in SVR. However, further prospective clinical studies are required to test this hypothesis.
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J Clin Monit Comput · Aug 2014
Comparative StudyPrognostic value of EEG indexes for the Glasgow outcome scale of comatose patients in the acute phase.
The purpose of this work is the estimation of the Glasgow outcome scale (GOS) from a single continuous electroencephalogram (c-EEG) routinely recorded to monitor comatose patients in the neurosurgical intensive care unit. c-EEG was recorded from 13 patients in the acute phase: five with GOS = 5, four with GOS = 3 and four with GOS = 1. Different indexes were extracted from epochs of c-EEG (classical: amplitude and spectral estimators; non classical: from recurrence quantification analysis-RQA-and approximate entropy). Descriptors of different indexes (temporal variation and mean, standard deviation, skewness of the distribution across epochs) were used to train support vector machines to identify the correct GOS. ⋯ Spectral indexes allowed to get optimal performances in classifying GOS 1 and 3. Nonlinear indexes (especially determinism from RQA) were optimal for identifying GOS = 5. Thus, the integration of information from classical/linear and nonlinear c-EEG descriptors in a multi-index classifier is important for GOS estimation.
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Intense neuromuscular blockade (NMB) measured by post tetanic count (PTC) was monitored, reversed and verified in this pig model. In a cross-over assessor blinded design six pigs were randomized to either no NMB followed by intense NMB, or intense NMB followed by no NMB. Neuromuscular measurements were performed with acceleromyography [train-of-four (TOF) Watch SX]. ⋯ We established a pig model for monitoring intense NMB with surface stimulation electrodes and acceleromyography. We verified total relaxation of the diaphragm and the abdominal muscles at the PTC 0-1 by suction test and with surface electromyography. This pig model is suitable for studies with experimental abdominal surgery with monitoring of intense NMB, and where relaxation of the diaphragm and the abdominal muscles are required.
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J Clin Monit Comput · Aug 2014
Variations in the pre-ejection period induced by ventricular extra systoles may be feasible to predict fluid responsiveness.
Monitoring that can predict fluid responsiveness is an unsettled matter for spontaneously breathing patients. Based on the convincing results with dynamic monitoring based on preload variations induced by mechanical ventilation, we hypothesised that the extra systolic post-ectopic beat could constitute a similar intermittent preload shift inducing a brief variation in blood pressure and that the magnitude of this variation could predict the hemodynamic response to volume expansion in sedated pigs. Ten pigs were sedated and hemodynamically monitored and four intravascular volume shifts were made: blood depletion (25% of estimated blood volume; 660 ml), retransfusion (of 500 ml depleted blood), and two sequential volume expansions (500 ml colloid each). ⋯ Ventricular extra systoles were generally useful for fluid responsiveness prediction (ROC areas >0.65). ∆PEP variables best predicted fluid responsiveness: ∆PEP derived from arterial pressure curve and ECG had ROC area of 0.84 and sensitivity of 0.77 and specificity of 0.71; ∆PEP derived from plethysmographic curve and ECG had ROC area of 0.79 and sensitivity of 0.71 and specificity of 0.70. However, ∆PP was not a useful variable in this study (ROC area <0.65). Hemodynamic analysis of post ectopic beats may be a feasible method for fluid responsiveness prediction.