pobm.obm package

pobm.obm.burden

class pobm.obm.burden.HypoxicBurdenMeasures(begin: numpy.array, end: numpy.array, CT_Threshold: float = 90, CA_Baseline: float = None)

Bases: object

Class that calculates hypoxic burden features from SpO2 time series.

Parameters:

• begin (Numpy array) – Numpy array of indices of beginning of each desaturation event.
• end (Numpy array) – Numpy array of indices of end of each desaturation event. begin and end should have the same length.
• CT_Threshold (float, optional) – Percentage of the time spent below the “CT_Threshold” % oxygen saturation level.
• CA_Baseline (float, optional) – Baseline to compute the CA feature. Default value is mean of the signal.

compute(signal)

Computes all the biomarkers of this category.

Parameters:signal – 1-d array, of shape (N,) where N is the length of the signal Returns:HypoxicBurdenMeasuresResults class containing the following features:

• CA: Integral SpO2 below the xx SpO2 level normalized by the total recording time
• CT: Percentage of the time spent below the xx% oxygen saturation level
• POD: Percentage of oxygen desaturation events
• AODmax: The area under the oxygen desaturation event curve, using the maximum SpO2 value as baseline and normalized by the total recording time
• AOD100: Cumulative area of desaturations under the 100% SpO2 level as baseline and normalized by the total recording time

Example:

from pobm.obm.burden import HypoxicBurdenMeasures

# Initialize the class with the desired parameters
hypoxic_class = HypoxicBurdenMeasures(results_desat.begin, results_desat.end, CT_Threshold=90, CA_Baseline=90)

# Compute the biomarkers
results_hypoxic = hypoxic_class.compute(spo2_signal)

comp_ca(signal)

Compute the cumulative area biomarker

Parameters:signal – 1-d array, of shape (N,) where N is the length of the signal Returns:CA, the cumulative area (float)

comp_ct(signal)

Compute the cumulative time biomarker

Parameters:signal – 1-d array, of shape (N,) where N is the length of the signal Returns:CT, the cumulative time (float)

pobm.obm.complex

class pobm.obm.complex.ComplexityMeasures(CTM_Threshold: float = 0.25, DFA_Window: int = 20, M_Sampen: int = 3, R_Sampen: float = 0.2, M_ApEn: int = 2, R_ApEn: float = 0.25)

Bases: object

Class that calculates complexity features from SpO2 time series.

Parameters:

• CTM_Threshold (float, optional) – Radius of Central Tendency Measure.
• DFA_Window (int, optional) – Length of window to calculate DFA biomarker.
• M_Sampen (int, optional) – Embedding dimension to compute SampEn.
• R_Sampen (float, optional) – Tolerance to compute SampEn.
• M_ApEn (int, optional) – Embedding dimension to compute ApEn.
• R_ApEn (float, optional) – Tolerance to compute ApEn.

compute(signal) → pobm._ResultsClasses.ComplexityMeasuresResults

Computes all the biomarkers of this category. :param signal: 1-d array, of shape (N,) where N is the length of the signal :return: ComplexityMeasuresResults class containing the following features:

• ApEn: Approximate Entropy.
• LZ: Lempel-Ziv complexity.
• CTM: Central Tendency Measure.
• SampEn: Sample Entropy.
• DFA: Detrended Fluctuation Analysis.

Example:

comp_apen(signal)

Compute the approximate entropy, according to [1]_ :param signal: 1-d array, of shape (N,) where N is the length of the signal :return: ApEn (float) .. [1] Pincus, S. M. Approximate entropy as a measure of system complexity. Proc. Natl. Acad. Sci. U. S. A. 88, 2297–2301 (1991).

comp_lz(signal, dual_quantization=True)

Compute Lempel-Ziv, according to [2]_ :param signal: 1-d array, of shape (N,) where N is the length of the signal :param dual_quantization: if True, the signal is converted into a binary signal, according to the original algorithm [2]_. If False, the signal is quantized in 4 levels. :return: LZ (float) .. [2] Lempel, A. & Ziv, J. On the Complexity of Finite Sequences. IEEE Trans. Inf. Theory 22, 75–81 (1976).

comp_ctm(signal)

Compute CTM, according to [3]_ :param signal: 1-d array, of shape (N,) where N is the length of the signal :return: CTM (float) .. [3] Cohen, M. E., Hudson, D. L. & Deedwania, P. C. Applying continuous chaotic modeling to cardiac signal analysis. IEEE Eng. Med. Biol. Mag. 15, 97–102 (1996).

comp_sampen(signal)

Compute the sample entropy, according to [4]_ :param signal: 1-d array, of shape (N,) where N is the length of the signal :return: SampEn (float) .. [4] Richman, J. S. & Moorman, J. R. Physiological time-series analysis using approximate entropy and sample entropy. Am J Physiol-Heart C 278, H2039–H2049 (2000).

comp_dfa(signal)

Compute DFA, Detrended Fluctuation Analysis according to [5]_ :param signal: 1-d array, of shape (N,) where N is the length of the signal :return: DFA (float) .. [5] Peng, C. ‐K., Havlin, S., Stanley, H. E. & Goldberger, A. L. Quantification of scaling exponents and crossover phenomena in nonstationary heartbeat time series. Chaos An Interdiscip. J. Nonlinear Sci. 5, 82–87 (1995).

pobm.obm.desat

class pobm.obm.desat.DesaturationsMeasures(ODI_Threshold: int = 3, hard_threshold: int = 90, relative: bool = True, desat_max_length: int = 90, min_dist_meta_event: int = 0, desat_min_length: int = 0)

Bases: object

Class that calculates the desaturation features from SpO2 time series.

Parameters:

• ODI_Threshold (int, optional) – Threshold to compute Oxygen Desaturation Index.
• hard_threshold (int, optional) – Hard threshold to detect desaturations.
• relative (bool, optional) – Whether to use a relative or hard threshold to detect desaturations.
• desat_max_length (int, optional) – The maximum length of desaturations.
• min_dist_meta_event (int, optional) – The maximal distance between 2 desaturations to convert them into a meta desat

compute(signal) → pobm._ResultsClasses.DesaturationsMeasuresResults

Computes all the biomarkers of this category.

Parameters:signal – 1-d array, of shape (N,) where N is the length of the signal Returns:DesaturationsMeasuresResults class containing the following features:

• ODI: Oxygen Desaturation Index
• DL_u: Mean of desaturation length
• DL_sd: Standard deviation of desaturation length
• DA100_u: Mean of desaturation area using 100% as baseline.
• DA100_sd: Standard deviation of desaturation area using 100% as baseline
• DAmax_u: Mean of desaturation area using max value as baseline.
• DAmax_sd: Standard deviation of desaturation area using max value as baseline
• DD100_u: Mean of depth desaturation from 100%.
• DD100_sd: Standard deviation of depth desaturation from 100%.
• DDmax_u: Mean of depth desaturation from max value.
• DDmax_sd: Standard deviation of depth desaturation from max value.
• DS_u: Mean of the desaturation slope.
• DS_sd: Standard deviation of the desaturation slope.
• TD_u: Mean of time between two consecutive desaturation events.
• TD_sd: Standard deviation of time between 2 consecutive desaturation events.
• begin: List of indices of beginning of each desaturation event
• end: List of indices of end of each desaturation event

Example:

from pobm.obm.desat import DesaturationsMeasures

# Initialize the class with the desired parameters
desat_class = DesaturationsMeasures(ODI_Threshold=3)

# Compute the biomarkers
results_desat = desat_class.compute(spo2_signal)

group_meta_desat(signal)

remove_small_desats()

desaturation_detector(signal)

Runs desaturation detector, compute the ODI biomarker according to [6]

Parameters:signal – The SpO2 signal, of shape (N,) Returns:ODI: the average number of desaturation events per hour (int).

[6]	Jung, D. W. et al. Real-Time Automatic Apneic Event Detection Using Nocturnal Pulse Oximetry. IEEE Trans. Biomed. Eng. 65, 706–712 (2018).

pobm.obm.general

class pobm.obm.general.OverallGeneralMeasures(ZC_Baseline: float = None, percentile: int = 1, M_Threshold: int = 2, DI_Window: int = 12)

Bases: object

Class that calculates overall general features from SpO2 time series.

Parameters:

• ZC_Baseline (int, optional) – Baseline for calculating number of zero-crossing points.
• percentile (int, optional) – Percentile to perform. For example, for percentile 1, the argument should be 1
• M_Threshold (int, optional) – Percentage of the signal M_Threshold % below median oxygen saturation. Typically use 1,2 or 5
• DI_Window (int, optional) – Length of window to calculate the Delta Index.

compute(signal) → pobm._ResultsClasses.OverallGeneralMeasuresResult

Computes all the biomarkers of this category.

Parameters:signal – 1-d array, of shape (N,) where N is the length of the signal Returns:OveralGeneralMeasuresResult class containing the following features:

• AV: Average of the signal.
• MED: Median of the signal.
• Min: Minimum value of the signal.
• SD: Std of the signal.
• RG: SpO2 range (difference between the max and min value).
• P: percentile.
• M: Percentage of the signal x% below median oxygen saturation.
• ZC: Number of zero-crossing points.
• DI: Delta Index.

Example:

from pobm.obm.general import OverallGeneralMeasures

# Initialize the class with the desired parameters
statistics_class = OverallGeneralMeasures(ZC_Baseline=90, percentile=1, M_Threshold=2, DI_Window=12)

# Compute the biomarkers
results_statistics = statistics_class.compute(spo2_signal)

pobm.obm.periodicity

class pobm.obm.periodicity.PRSAMeasures(PRSA_Window: int = 10, K_AC: int = 2)

Bases: object

Class that calculates PRSA features from SpO2 time series.

Parameters:

• PRSA_Window (int, optional) – Fragment duration of PRSA.
• K_AC (int, optional) – Number of values to shift when computing autocorrelation

compute(signal) → pobm._ResultsClasses.PRSAResults

Computes all the biomarkers of this category.

Parameters:signal – 1-d array, of shape (N,) where N is the length of the signal Returns:PRSAResults class containing the following features:

• PRSAc: PRSA capacity.
• PRSAad: PRSA amplitude difference.
• PRSAos: PRSA overall slope.
• PRSAsb: PRSA slope before the anchor point.
• PRSAsa: PRSA slope after the anchor point.
• AC: Autocorrelation.

Example:

from pobm.obm.periodicity import PRSAMeasures

# Initialize the class with the desired parameters
prsa_class = PRSAMeasures(PRSA_Window=10, K_AC=2)

# Compute the biomarkers
results_PRSA = prsa_class.compute(spo2_signal)

class pobm.obm.periodicity.PSDMeasures(frequency_low_threshold: float = 0.014, frequency_high_threshold: float = 0.033)

Bases: object

Class that calculates PSD features from SpO2 time series.

Parameters:

• frequency_low_threshold (float, optional) – Low threshold for the PSD_band biomarker.
• frequency_high_threshold (float, optional) – High threshold for the PSD_band biomarker.

compute(signal) → pobm._ResultsClasses.PSDResults

Computes all the biomarkers of this category.

Parameters:signal – The SpO2 signal, of shape (N,) Returns:PSDResults class containing the following features:

• PSD_total: The amplitude of the spectral signal.
• PSD_band: The amplitude of the signal multiplied by a band-pass filter in the desired band.
• PSD_ratio: The ratio between PSD_total and PSD_band.
• PDS_peak: The max value of the FFT into the desired band.

Example:

from pobm.obm.periodicity import PSDMeasures

# Initialize the class with the desired parameters
psd_class = PSDMeasures()

# Compute the biomarkers
results_PSD = psd_class.compute(spo2_signal)

Module contents