ABSTRACT
OBJECTIVES: Ventricular fibrillation (VF) is a life-threatening cardiac arrhythmia and within of minutes of its occurrence, optimal timing of countershock therapy is highly warranted to improve the chance of survival. This study was designed to investigate whether the autoregressive (AR) estimation technique was capable to reliably predict countershock success in VF cardiac arrest patients. METHODS: ECG data of 1077 countershocks applied to 197 cardiac arrest patients with out-of-hospital and in-hospital cardiac arrest between March 2002 and July 2004 were retrospectively analyzed. The ECG from the 2.5 s interval of the precountershock VF ECG was used for computing the AR based features Spectral Pole Power (SPP) and Spectral Pole Power with Dominant Frequency weighing (SPPDF) and Centroid Frequency (CF) and Amplitude Spectrum Area (AMSA) based on Fast Fourier Transformation (FFT). RESULTS: With ROC AUC values up to 84.1% and diagnostic odds ratio up to 19.12 AR based features SPP and SPPDF have better prediction power than the FFT based features CF (80.5%; 6.56) and AMSA (82.1%; 8.79). CONCLUSIONS: AR estimation based features are promising alternatives to FFT based features for countershock outcome when analyzing human data.
Subject(s)
Electric Countershock/methods , Ventricular Fibrillation/therapy , Humans , Models, Theoretical , Predictive Value of Tests , ROC Curve , Retrospective Studies , Risk Assessment , Signal Processing, Computer-Assisted , Time Factors , Ventricular Fibrillation/pathologyABSTRACT
Adoptive immunotherapy with tumour-reactive CD8(+) cytotoxic T lymphocytes (CTLs) requires efficient in vitro approaches allowing the expansion of CTLs to large numbers prior infusion. Here, we investigated the antigen-independent activation and the expansion of human T cells in peripheral blood mononuclear cells (PBMCs) and in tumour-reactive CTLs using Dynabeads coated with monoclonal antibodies to CD3 and to the costimulatory molecules CD28 and CD137 (4-1BB). T cells in PBMCs showed an increased expansion rate of 15- to 17-fold during a 2-week culture period using antibody-conjugated beads with interleukin-2 (IL-2) added versus IL-2 alone. No significant difference between CD3/CD28 beads and CD3/CD28/CD137 beads was observed (P = 0.4). In contrast, expansion of tumour-reactive CD8(+) CTLs over 2 weeks was more efficient using CD3/CD28/CD137 beads (14.4-fold ± 1.2) compared with CD3/CD28 beads (10.6-fold ± 0.7) (P = 0.03) and matched well to the control arm using weekly stimulation with tumour cells. Although all modes of in vitro stimulation decreased the expression of central memory markers CD62L and CCR7 on CTLs, bead-activated cultures expressed consistently higher levels than tumour-stimulated cultures. CTLs analysed after bead-induced expansion versus weekly tumour stimulation showed equal IFN-γ production in ELISPOT assay. Furthermore, cytotoxicity assays demonstrated an either unchanged or slightly reduced capability of tumour cell lysis for antigen-independent stimulated CTLs versus those that maintained on weekly tumour stimulation, regardless of which type of beads was used. Our data suggest that the conjugation of anti-CD137 antibodies to conventional CD3/CD28 beads results in a minor but significant increase in the expansion capacity for tumour-reactive CD8(+) CTLs.
Subject(s)
CD28 Antigens/immunology , CD3 Complex/immunology , Immunotherapy, Adoptive/methods , Lymphocyte Activation/immunology , Neoplasms/immunology , T-Lymphocytes, Cytotoxic/immunology , Tumor Necrosis Factor Receptor Superfamily, Member 9/immunology , Cells, Cultured , Humans , Immunomagnetic Separation , Interferon-gamma/biosynthesis , Interferon-gamma/immunology , Interleukin-2/immunology , L-Selectin/immunology , Receptors, CCR7/immunologyABSTRACT
OBJECTIVES: Spectral analysis of the ventricular fibrillation (VF) ECG has been used for predicting countershock success, where the Fast Fourier Transformation (FFT) is the standard spectral estimator. Autoregressive (AR) spectral estimation should compute the spectrum with less computation time. This study compares the predictive power and computational performance of features obtained by the FFT and AR methods. METHODS: In an animal model of VF cardiac arrest, 41 shocks were delivered in 25 swine. For feature parameter analysis, 2.5 s signal intervals directly before the shock and directly before the hands-off interval were used, respectively. Invasive recordings of the arterial pressure were used for assessing the outcome of each shock. For a proof of concept, a micro-controller program was implemented. RESULTS: Calculating the area under the receiver operating characteristic (ROC) curve (AUC), the results of the AR-based features called spectral pole power (SPP) and spectral pole power with dominant frequency (DF) weighing (SPPDF) yield better outcome prediction results (85%; 89%) than common parameters based on FFT calculation method (centroid frequency (CF), amplitude spectrum area (AMSA)) (72%; 78%) during hands-off interval. Moreover, the predictive power of the feature parameters during ongoing CPR was not invalidated by closed-chest compressions. The calculation time of the AR-based parameters was nearly 2.5 times faster than the FFT-based features. CONCLUSION: Summing up, AR spectral estimators are an attractive option compared to FFT due to the reduced computational speed and the better outcome prediction. This might be of benefit when implementing AR prediction features on the microprocessor of a semi-automatic defibrillator.
Subject(s)
Electric Countershock/methods , Electrocardiography/methods , Fourier Analysis , Neural Networks, Computer , Signal Processing, Computer-Assisted , Ventricular Fibrillation/therapy , Algorithms , Animals , Area Under Curve , Disease Models, Animal , Humans , Microcomputers , ROC Curve , Regression Analysis , Swine , Treatment OutcomeABSTRACT
AIM: Biomechanical study to examine the stability of a stand-alone cage (SAC; Topaz, Ulrich Medizintechnik, Ulm) incorporating integrated anterior fixation with and without additional posterior fixation. METHOD: Six human spinal specimens (L4/5) were loaded in a spine tester in the three main motion planes in the following states: (a) intact, (b) defect (nucleotomy), (c) SAC, (d) SAC+internal fixator (IF), and (e) SAC+translaminar facet screws (TFS). Facet joint translation (FJT) and range of motion (ROM) were measured and used to evaluate the stability of the tested states. RESULTS: The SAC stabilized the segment in comparison to the intact (a) and defect-containing (b) segments. The most rigid fixation was found for SAC+IF compared with the other states (a, b, c, e). The ROM and FJT of the SAC with the additional IF (d) showed a significant higher stability in all three motion planes. All differences in ROM and FJT between the tested states were statistically significant (p<0.05) except for the FJT SAC and SAC+TFS. CONCLUSION: The ventral Topaz SAC is a stable implant for the lumbar spine. Additional dorsal stabilization is an option to increase the stability.
