Analyses overview

In the following a brief overview of the ANSLAB modules available will be given.

Cardiovascular measures

ANSLAB has efficient procedures for the editing and analysis of continuous

  • electrocardiography (ECG)
  • impedance cardiography
  • pulse plethysmography
  • blood pressure
  • skin temperature.

  It includes powerful spectral and other variability analyses relevant for, e.g.,

  • heart rate variability / respiratory sinus arrhythmia
  • baroreflex sensitivty
  • respiratory variability.

Advanced options include chaos measures (e.g. detrended fluctuation analysis), crossspectral analysis, and time-frequency analysis such as complex demodulation.

Electrodermal measures

This module allows for visual editing of artifacts and extraction of skin conductance level. In addition, automatic identification of non-specific skin conductance responses (SCRs) is performed. Per non-specific SCR, several waveform parameters are available (amplitude, rise time, half recovery time, etc.). The module further allows for customized high-pass or low-pass filtering and calibration (linear transformation) of the raw signal. Analyses can be performed on a file-by-file and task-by-task basis or in batch mode across files/tasks/subjects.

Stimulus-related SCRs can be edited for artifacts and subsequently analyzed using the event related analysis tool.

Some of the analysis options are depicted in this video.

Reflexive startle analysis tool

This module allows automatic filtering, rectification and smoothing of the raw EMG signal and extraction of event-marker based EMG parameters. A response plot allows identification of inadequate baseline or response scores, drag-and-drop editing of artefactual data and extraction of onset latency, response latency, and response magnitude for each startle response. See this video for a brief overview.

Heart rate variability

ANSLAB is very powerful with respect to the analysis of HRV. Besides widely used variability indices such as spectral analysis-derived HRV and root mean square of successive differences, ANSLAB outputs a range of more advanced variability measures:

  • Complex demodulation (a time-frequency analysis method allowing a high temporal resolution of extracted variability indices)
  • Steven Porges' method (V-hat, including cubic polynomial detrending)
  • Stationarity indices
  • Nonlinear parameters (approximative and sample entropy, detrended fluctuation analysis (DFA), Hurst exponent, embedding dimension, and (Largest) Lyapunov exponent (optionally based on embedding parameters)).

Batch processing and batch plotting options allow semi- or full automatized analysis of HRV. This video demonstrates some of the analysis features.

Impedance cardiography

This module includes programs for ensemble averaging with statistical autoediting of outlier beats, drag-and-drop editing of B-, Z-, and X-points, and the extraction of preejection period (PEP), left ventricular ejection time (LVET), stroke volume, cardiac output, Heather index, etc.

Respiration

This module allows editing of raw respiratory signals, automatic inspiration/expiration start/end detection, drag-and-drop editing of breath onset/offset points, computation of respiratory rate, tidal volume, minute ventilation, fractional inspiratory ratio, inspiratory and expiratory times and pauses, inspiratory flow rate, tidal volume instability and respiratory rate instability.

Electromyography

This module allows automatic filtering, rectification, and smoothing of EMG signals and extraction of EMG amplitude.

Pulse plethysmography

This module allows ECG-based and stand-alone pulse analysis, computation of pulse amplitude, pulse rate, and (if ECG-based) pulse transit time.

Continuous blood pressure

This module creates a batch-compliant interface to integrate the Finapres Medical Systems BeatScope software in the ANSLAB environment (a Beatscope license is required). Raw data can be edited before starting the Beatscope analysis, and extracted parameters can be browsed, edited and exported using the ANSLAB user interface. Extracted parameters are systolic blood pressure, diastolic blood pressure, true mean blood pressure, heart rate, total peripheral resistance, left ventricular ejection time, cardiac oxygen supply (demand ratio), cardiac output, stroke volume, aortic characteristic impedance, total arterial compliance, etc.

Accelerometry

This module allows the editing, decomposition and quantification of angle/posture (low frequency) and motion (high frequency) components of an accelerometer signal. For ambulatory monitoring data files, an elaborated activity analysis is available to allow for the identification and stratification of activity levels across the day as a basis for the analysis of other physiological signals (activity stratification as control of activity confounds).

Capnography analysis

This module includes automatic end-tidal pCO2 plateau identification, visual plateau marking and editing, outlier identification and the extraction of pCO2 and respiratory rate.

Temperature analysis

This module allows filtering and visual editing of artifacts of a (skin) temperature signal and its mathematical derivative and extraction of temperature and temperature slope values.

Respiration calibration

This module extracts calibration coefficients for respiratory signals based on fixed-volume bag or spirometric comparison data. Combined with respiratory pattern analysis these allow calibrated analysis of respiratory pattern (e.g., tidal volume in units of liters).

Crossspectral analysis

This module includes programs for the calculation, display and editing of the crossspectrum, transfer function, spectral coherence and crossspectral phase angle at specified frequencies of any two signals analyzed and saved with ANSLAB. This allows, e.g., the computation for baroreflex sensisitivy from ECG and blood pressure signals, or computation of sufficient cardio-respiratory coherence (>0.5) at respiratory frequencies to assure reliable interpretation of high-frequency HRV as truly respiratory driven and thus reliable index of vagal activity.

Vocal response analysis

This module extracts response latency (vocal reaction time) and response magnitude from recorded sound signals. A response plot successively displays each vocal resonse and allows identification of inadequate responses and drag-and-drop editing of baseline level, onset latency, and response level. Sound can be played back for verification during scoring or written to WAV-files for playback in sound editing programs. This tool allows, e.g., exact and reliable scoring of computerized Stroop color naming tests.

Response coherence analysis

The ANSLAB coherence analysis module allows to estimate parameters describing the coherence between two signals which have previously been extracted using other analyses in ANSLAB. This allows to investigate to which extent two signals are coherent.

The analysis is carried out by computing the cross-correlation between the two signals of interest at different time lags (configurable in the options dialog). Among other variables, the time lag corresponding to the maximum cross-correlation along with the correlation coefficient at this lag is returned by the analysis.