Clinical applications of photoplethysmography in paediatric intensive care

Objective: The photoplethysmographic wave is displayed by most pulse oximeters. It may be used as anon-invasive alternative to invasive arterial blood pressure trace analysis for continuous haemodynamic monitoring in selected situations. Patients and setting: Four cardiac patients treated in atertiary neonatal-paediatric intensive care unit. Measurements: Simultaneous monitoring of the photoplethysmographic wave, ECG, and invasive blood pressure. Results and conclusions: Photoplethysmography allows for monitoring pulse rate in patients with (possible) heart rate/pulse rate dissociation (pacemaker dependency, pulsatile ventricular assist device); monitoring sudden changes in heart beat volume, which are unrelated to respiration (pulseless electrical activity, pulsus alternans); and monitoring respiratory-dependent fluctuations of the plethysmographic wave (heart failure, hypovolaemia, asthma, upper airway obstruction, pericardial effusion). Deterioration, slowly evolving over time, may be detected by this metho

On the development of a harmonic balance method for aeroelastic analysis

To efficiently simulate time-periodic, non-linear flows in turbomachinery a Harmonic Balance (HB) method has recently been developed within the framework of DLR’s compressible, Unsteady Reynolds Averaged Navier- tokes (URANS) solver TRACE. As a hybrid time- and frequency-domain method, that solves directly for the complex valued solution harmonics of the URANS equations, the approach allows both the integration of highly accurate non-reflecting boundary conditions and the efficient resolution of non-linear flow phenomena. In the current work the HB-solver is extended and applied to investigate the aeroelastic problem of flutter in turbomachinery. Within this context the HB-method is developed, under consideration of the Geometric Conservation Law (GCL), to support deforming meshes. To validate the approach the well documented aeroelastic test case Standard Configuration 10 is simulated and results are compared to those obtained with an inhouse time-linearized solver and reference datafrom the literature

Multivariate Regression Analysis of Gravitational Waves from Rotating Core Collapse

We present a new multivariate regression model for analysis and parameter estimation of gravitational waves observed from well but not perfectly modeled sources such as core-collapse supernovae. Our approach is based on a principal component decomposition of simulated waveform catalogs. Instead of reconstructing waveforms by direct linear combination of physically meaningless principal components, we solve via least squares for the relationship that encodes the connection between chosen physical parameters and the principal component basis. Although our approach is linear, the waveforms' parameter dependence may be non-linear. For the case of gravitational waves from rotating core collapse, we show, using statistical hypothesis testing, that our method is capable of identifying the most important physical parameters that govern waveform morphology in the presence of simulated detector noise. We also demonstrate our method's ability to predict waveforms from a principal component basis given a set of physical progenitor parameters

Single-electron Double Quantum Dot Dipole-coupled to a Single Photonic Mode

We have realized a hybrid solid-state quantum device in which a single-electron semiconductor double quantum dot is dipole coupled to a superconducting microwave frequency transmission line resonator. The dipolar interaction between the two entities manifests itself via dispersive and dissipative effects observed as frequency shifts and linewidth broadenings of the photonic mode respectively. A Jaynes-Cummings Hamiltonian master equation calculation is used to model the combined system response and allows for determining both the coherence properties of the double quantum dot and its interdot tunnel coupling with high accuracy. The value and uncertainty of the tunnel coupling extracted from the microwave read-out technique are compared to a standard quantum point contact charge detection analysis. The two techniques are found to be consistent with a superior precision for the microwave experiment when tunneling rates approach the resonator eigenfrequency. Decoherence properties of the double dot are further investigated as a function of the number of electrons inside the dots. They are found to be similar in the single-electron and many-electron regimes suggesting that the density of the confinement energy spectrum plays a minor role in the decoherence rate of the system under investigation.Comment: 8 pages, 5 figure

Determinants of arterial and central venous blood pressure variation in ventilated critically ill children

Purpose: Ventilation-induced arterial pressure variation predicts volume responsiveness in adults. Several factors are known to influence the interpretability of these variations. We analysed ventilation-induced variations in critically ill children with reference to ventilatory and circulatory parameters. Methods: We prospectively included 20 paediatric patients. Variation of systolic pressure (SPV), pulse pressure (PPV) and central venous pressure (CVP) were assessed during pressure-controlled ventilation with inspiratory pressures (P insp) of 20 and 28cmH2O. Blood gases were analysed and echocardiography was performed. Results: SPV, PPV and CVP variation significantly increased with elevated P insp (p<0.001, p=0.008 and p=0.003). Baseline CVP and shortening fraction were significant negative predictors of PPV and SPV. Conclusion: This preliminary study identified P insp as a determinant of SPV, PPV and CVP variation in children. Further independent determinants of SPV and PPV were baseline CVP and ventricular performance, both of which must be considered when interpreting pressure variation