Office Hours & Recorded Sessions


CHoRUS Bridge2AI Standards Office Hours

The Waveform Extension has been discussed extensively in CHoRUS Bridge2AI Standards Office Hours. These sessions provide valuable implementation context, live demonstrations, and Q&A with the development team.


Recorded Sessions

[03-13-25] Linking waveform and EHR data - Part 1

Focus: Introduction to waveform and EHR data linkage methodology

Topics Covered: - Overview of challenges in linking multimodal data - Introduction to the waveform_registry concept - Temporal alignment strategies - Patient privacy considerations

Resources: - Video Recording - Transcript


[03-20-25] Linking waveform and EHR data - Part 2

Focus: Continued discussion on waveform-EHR data integration

Topics Covered: - Deep dive into linkage table schemas - Handling multi-file waveform sessions - File format considerations - Metadata extraction best practices

Resources: - Video Recording - Transcript


[04-17-25] Waveform linkage and site updates

Focus: Updates on waveform linkage implementation across sites

Topics Covered: - Implementation progress at CHoRUS sites - Lessons learned from early implementations - Common pitfalls and solutions - Site-specific challenges and adaptations

Resources: - Video Recording - Transcript


[06-26-25] Implementation of OMOP CDM Waveform Extension SOP

Focus: Comprehensive session on implementing the 4-table waveform extension

Topics Covered: - Complete walkthrough of the 4-table schema - Table population order and rationale - Field-by-field implementation guidance - ETL pipeline architecture - Quality assurance and validation - Common edge cases and solutions

Resources: - Video Recording - Transcript

Highly Recommended: This session provides the most comprehensive overview of the current Waveform Extension specification.


[10-16-25] CHoRUS Bridge2AI Standards Office Hours Continued

Focus: Continued discussions on waveform standards and implementation

Topics Covered: - Updates on vocabulary development - Feature extraction standardization - Multi-site data quality comparison - Integration with AI/ML pipelines

Resources: - Transcript


[11-20-25] CHoRUS Bridge2AI Standards Office Hours Continued

Focus: Recent discussions on waveform extension updates and implementation challenges

Topics Covered: - Latest schema refinements - Community feedback integration - Real-world implementation examples - Future roadmap discussion

Resources: - Transcript


Key Themes Across Sessions

Temporal Alignment

A recurring theme across sessions is the challenge of temporal alignment between waveform data and EHR data: - Clock synchronization between acquisition devices and EHR systems - Timezone handling and UTC standardization - Handling daylight saving time transitions - Temporal precision requirements (second vs. millisecond)

File Management

Multiple sessions discuss practical file management considerations: - Storage location strategies (filesystem, object storage, database BLOBs) - Naming conventions for traceability - Handling large file volumes - De-identification of file metadata

Metadata Extraction

Signal metadata extraction is critical and discussed extensively: - Parsing diverse file formats (EDF, WFDB, vendor-specific) - Handling missing or inconsistent metadata - Standardizing channel names across devices - Sampling rate and calibration factor preservation

Vocabulary Mapping

Developing and maintaining vocabulary mappings: - Waveform type concepts (ECG, EEG, ABP, etc.) - Channel/lead concepts (Lead II, FP1-FP2, etc.) - Feature algorithm concepts (Bazett’s formula, SDNN, etc.) - Device concepts (Phillips IntelliVue, GE CARESCAPE)

Feature Derivation

Best practices for extracting features from waveforms: - Selecting appropriate time windows - Handling artifacts and low-quality segments - Standardizing algorithm implementations - Linking features to MEASUREMENT/OBSERVATION tables


Implementation Examples

Several sessions include live demonstrations and code walkthroughs:

  • ETL Pipeline Architecture (06-26-25): Step-by-step walkthrough of a Python-based ETL pipeline
  • EDF Parsing (03-20-25): Example code for extracting metadata from EDF files
  • Temporal Joins (03-13-25): SQL examples for joining waveform features with clinical events


Community Q&A Highlights

Q: How do we handle waveform files that span multiple visits?

A: This is a known edge case. The recommended approach is to: 1. Split the file into visit-specific segments if possible 2. If splitting is not feasible, link to the primary visit where most of the acquisition occurred 3. Use visit_detail_id to capture sub-visit granularity if available 4. Document the decision in your ETL documentation

Q: What if our device doesn’t provide sampling rate metadata?

A: You have several options: 1. Use the manufacturer’s specification if the device model is known 2. Infer from the signal (count samples over a known time period) 3. Flag as “unknown” with a quality indicator 4. Reach out to the vendor for technical specifications

Q: Should we store raw waveforms or just features?

A: This depends on your use case and storage constraints: - Raw waveforms: Required for exploratory analyses, novel feature development, reprocessing - Features only: Sufficient for many observational studies if features are well-defined - Hybrid: Store raw for a subset (e.g., recent data, interesting cases) and features for all

The Waveform Extension supports both approaches.

Q: How do we handle continuous vs. intermittent monitoring?

A: Use the waveform_occurrence_start_datetime and waveform_occurrence_end_datetime fields: - Continuous monitoring: One occurrence spanning the entire monitoring period - Intermittent: Multiple occurrences with gaps in between - Use preceding_waveform_occurrence_id to link sequential monitoring sessions


Upcoming Sessions

The working group continues to hold regular meetings and office hours. To join:


Contributing to Office Hours

We welcome presentations and demos from the community:

  • Share your implementation: Present your ETL approach and lessons learned
  • Demo your tools: Show off ETL utilities, visualization tools, or analysis pipelines
  • Propose topics: Suggest discussion topics or specific challenges to address
  • Ask questions: Submit questions in advance for dedicated Q&A sessions

Contact to schedule a presentation.