Journal of clinical monitoring and computing
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J Clin Monit Comput · Dec 2020
Randomized Controlled TrialHierarchical Poincaré analysis for anaesthesia monitoring.
Although the degree of dispersion in Poincaré plots of electroencephalograms (EEG), termed the Poincaré-index, detects the depth of anaesthesia, the Poincaré-index becomes estranged from the bispectral index (BIS) at lighter anaesthesia levels. The present study introduces Poincaré-index20-30 Hz, targeting the 20- to 30-Hz frequency, as the frequency range reported to contain large electromyogram (EMG) portions in frontal EEG. We combined Poincaré-index20-30 Hz with the conventional Poincaré-index0.5-47 Hz using a deep learning technique to adjust to BIS values, and examined whether this layered Poincaré analysis can provide an index of anaesthesia level like BIS. ⋯ We then evaluated the trained MLPNN model using the test dataset, by comparing the measured BIS (mBIS) with BIS predicted from the model (PredBIS). The relationship between mBIS and PredBIS using the two Poincaré-indices showed a tight linear regression equation: mBIS = 1.00 × PredBIS + 0.15, R = 0.87, p < 0.0001, root mean square error (RMSE) = 7.09, while the relationship between mBIS and PredBIS simply using the original Poincaré-index0.5-47 Hz was weaker (R = 0.82, p < 0.0001, RMSE = 7.32). This suggests the 20- to 30-Hz hierarchical Poincaré analysis has potential to improve on anaesthesia depth monitoring constructed by simple Poincaré analysis.
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J Clin Monit Comput · Dec 2020
Reliability of B-line quantification by different-level observers and a software algorithm using point-of-care lung ultrasound.
Quantification of B-lines on lung ultrasonographs is operator-dependent and considered a semi-quantitative method. To avoid this variability, we designed a software algorithm for counting B-lines. We compared the number of B-lines obtained in real-time by observers with three different levels of experience and by the software algorithm, and analyzed intra-rater variability in terms of the estimated number of B-lines in two successive examinations. ⋯ For all lung zones, the intraclass correlation for B-lines counting between OB1 and OB2 was 0.663; between OB1 and OB3, 0.559; and between OB1 and OBS, 0.710. OBS had a better concordance coefficient (0.752) between the first and the second measurements than did the human observers. Our results show that the software algorithm for B-lines counting is a potentially promising alternative when observers have little lung ultrasound experience.
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J Clin Monit Comput · Dec 2020
Do changes in perfusion index reflect changes in stroke volume during preload-modifying manoeuvres?
Changes in stroke volume (deltaSV) induced by a lung recruitment manoeuvre (LRM) have been shown to accurately predict fluid responsiveness during protective mechanical ventilation. Cardiac output monitors are used in a limited number of surgical patients. In contrast, all patients are monitored with a pulse oximeter, that may enable the continuous monitoring of a peripheral perfusion index (PI). ⋯ A deltaPI ≥ 26% predicted a deltaSV > 30% with a sensitivity of 83% and a specificity of 78% (AUC = 0.84, 95%CI 0.71-0.93). 24 patients experienced a deltaSV > 30% and subsequently received fluid. Fluid loads induced a 16% increase in SV and a 17% increase in PI, but fluid-induced deltaPI and deltaSV were weakly correlated (r2 = 0.19). In neurosurgical patients, we conclude that deltaPI may be used as a surrogate for deltaSV during LRMs but not during fluid loading.
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J Clin Monit Comput · Dec 2020
Validation of an automated system for detecting ineffective triggering asynchronies during mechanical ventilation: a retrospective study.
We compare the sensitivity and specificity of clinician visual waveform analysis against an automated system's waveform analysis in detecting ineffective triggering in mechanically ventilated intensive care unit patients when compared against a reference label set based upon analysis of respiratory muscle activity. Electrical activity of the diaphragm or esophageal/transdiaphragmatic pressure waveforms were available to a single clinician for the generation of a reference label set indicating the ground truth, that is, presence or absence of ineffective triggering, on a breath-by-breath basis. Pressure and flow versus time tracings were made available to (i) a group of three clinicians; and (ii) the automated Syncron-E™ system capable of detecting patient-ventilator asynchrony in real-time, in order to obtain breath-by-breath labels indicating the presence or absence of ineffective triggering. ⋯ Specificity for clinicians and the automated system were high (99.3% for clinician and 98.5% for the automated system). The automated system had a significantly higher sensitivity (83.2%) compared to clinicians (41.1%). Ineffective triggering detected by the automated system, which has access only to airway pressure and flow versus time tracings, is in substantial agreement with a reference detection derived from analysis of invasively measured patient effort waveforms.
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J Clin Monit Comput · Dec 2020
Observational StudyPerioperative measurement of core body temperature using an unobtrusive passive heat flow sensor.
Clinicians strive to maintain normothermia, which requires measurement of core-body temperature and may necessitate active warming of patients. Monitoring temperature currently requires invasive probes. This work investigates a novel foam-based flexible sensor worn behind the ear for the measurement of core body temperature. ⋯ The error bias and limits of agreement over these segments were on average of - 0.05 ± 0.28 °C (95% limits of agreement) overall. The dynamic model outperformed the simple heat-flow model for periods of surrounding temperature changes (12.7% of total time) while it had a similar, high, performance for the temperature-stable periods. The results suggest that our proposed topical sensor can replace invasive core temp sensors and provide a means of consistently measuring core body temperature despite surrounding temperature shifts.