Concepts
We have gathered concepts commonly used in the context of ECLS. These should assist you in implementing the OMOP CDM and the ECLS CDM expansion more quickly and efficiently within your local infrastructure.
Observations with an unknown timestamp
Sometimes, the exact timing of medical procedures, lab measurements, or disease onset is unknown. By OMOP CDM conventions you can capture these data using the observation table with two concepts:
- 1340204, History of event as observation_concept_id
- The actual observation as value_as_concept_id
Info
You can limit the timeframe by using any History of event child that is more precise. Click here for more concepts.
Diagnoses
Capturing the right diagnoses is an important task, especially for patients supported by an extracorporeal circuit. Diagnoses should be captured in the condition_occurrence table. When entering conditions, make sure to set a proper condition_status_concept_id. Typical concepts are:
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 32890 | Admission diagnosis | condition_occurrence | |
| 32896 | Discharge diagnosis | condition_occurrence | |
| 32902 | Primary diagnosis | condition_occurrence | |
| 32908 | Secondary diagnosis | condition_occurrence |
Info
In line with standard mapping rules, pre-existing conditions will be captured in the observation table. Click here for more types of diagnosis.
ECLS-specific concepts
Congenital diaphragmatic hernia (CDH)
A typical condition seen in neonatal patients is a congenital diaphragmatic hernia, where abdominal organs protrude into the thoracic cavity, potentially impacting lung function and cardiac output.
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717796 | Left congenital diaphragmatic hernia | condition_occurrence | |
| 36717797 | Right congenital diaphragmatic hernia | condition_occurrence |
Info
The repair is captured using 4147525, Repair of neonatal diaphragmatic hernia as procedure or observation, if the exact point in time is not known (see above).
ECLS as bridge to...
The intention to treat is different for every patient. Choose accordingly:
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717798 | Extracorporeal life support as bridge to recovery | observation | |
| 36717799 | Extracorporeal life support as bridge to transplant | observation | |
| 36717800 | Extracorporeal life support as bridge to lung transplant | observation | |
| 36717801 | Extracorporeal life support as bridge to heart transplant | observation | |
| 36717802 | Extracorporeal life support as bridge to combined heart-lung transplant | observation | |
| 36717803 | Extracorporeal life support as bridge to decision | observation | |
| 36717804 | Extracorporeal life support as bridge to destination | observation | |
| 36717805 | Extracorporeal life support as bridge to long-term mechanical circulatory support | observation | |
| 36717806 | Extracorporeal life support as periprocedural support | observation | |
| 36717807 | Extracorporeal life support as interval support for organ retrieval | observation |
Blood samples drawn from the ECLS circuit
The OMOP CDM provides multiple methods for storing blood sample data. The measurement table can be populated using either pre-coordinated concepts (usually LOINC-based) or concepts combined with the specimen table. The specimen table is designed to identify the origin of a biological sample. Both entries must be linked via the fact_relationship table (many-to-many relationship).
We recommend using the specimen table approach, as it allows for a more nuanced way to store results, despite being potentially more cumbersome for users.
The ECLS CDM introduced two new concepts to denote the exact origin when drawing blood from an extracorporeal circuit.
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717874 | Pre-membrane lung blood specimen | specimen | |
| 36717875 | Post-membrane lung blood specimen | specimen |
Info
A pre-pump head blood specimen is intentionally missing as it is equal to Pre-membrane lung blood specimen.
Typical other sites of origin are:
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 4047496 | Arterial blood specimen | specimen | |
| 4045667 | Venous blood specimen | specimen |
Info
If laterality is important (V-A ECMO with possible differential oxygenation), use the anatomic_site_concept_id:
For example:
4284463, Structure of left radial artery
4276858, Structure of right radial artery
ECLS-related measurements
Since settings and actual measurements can differ, we provide both concept types. In most cases, the setting and the actual measurement might be the same.
RPM is a unit
Revolutions per minute (RPM), although frequently misused as a proxy for the blood pump speed, is a unit.
| concept_id | concept_name | table | proposed UOM | comment |
|---|---|---|---|---|
| 36717866 | Extracorporeal life support pump flow rate setting | observation | L/min | |
| 36717867 | Extracorporeal life support pump rotational speed setting | observation | /min | |
| 36717868 | Extracorporeal life support temperature regulation device target setting | observation | Cel | |
| 36717869 | Extracorporeal life support pump flow rate | measurement | L/min | |
| 36717870 | Extracorporeal life support pump rotational speed | measurement | /min | |
| 36717871 | Extracorporeal life support temperature regulation device temperature | measurement | Cel |
Measurements about the performance of the membrane lung in respect to the patient’s status are of high interest.
| concept_id | concept_name | table | proposed UOM | comment |
|---|---|---|---|---|
| 36717879 | Device inlet carbon dioxide fraction | measurement | % | |
| 36717880 | Device inlet oxygen fraction | measurement | % | |
| 36717881 | Sweep gas flow rate | measurement | L/min | |
| 36717882 | Sweep gas inlet carbon dioxide fraction | measurement | % | |
| 36717883 | Sweep gas inlet oxygen fraction | measurement | % | |
| 36717884 | Effective extracorporeal flow | measurement | % | |
| 36717885 | Extracorporeal flow fraction | measurement | % | |
| 36717886 | Outlet blood oxygen saturation | measurement | % | |
| 36717887 | Inlet blood oxygen saturation | measurement | % | |
| 36717888 | Pre-membrane lung carbon dioxide tension | measurement | mmHg | |
| 36717889 | Pre-membrane lung oxygen tension | measurement | mmHg | |
| 36717890 | Pre-membrane lung pressure | measurement | mmHg | |
| 36717891 | Pre-membrane lung oxygen saturation | measurement | % | |
| 36717892 | Post-membrane lung carbon dioxide tension | measurement | mmHg | |
| 36717893 | Post-membrane lung oxygen tension | measurement | mmHg | |
| 36717894 | Post-membrane lung pressure | measurement | mmHg | |
| 36717895 | Post-membrane lung oxygen saturation | measurement | % | |
| 36717896 | Pump inlet pressure | measurement | mmHg | |
| 36717897 | Membrane lung pressure drop | measurement | mmHg | |
| 36717898 | Recirculation fraction | measurement | % |
Procedures on the circuit
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717862 | Water change of extracorporeal life support temperature regulation device | procedure | |
| 36717863 | Manual operation of extracorporeal life support device | procedure | Using the hand crank |
| 36717848 | Sighing of extracorporeal membrane lung | procedure | Sighing is the official term. Other typical terms used are flushing or sneezing. |
Differential oxygenation and CO2 tension
In venoarterial ECMO, blood can be differentially oxygenated and decarboxylated depending on the intrinsic cardiac output.
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717859 | Differential oxygenation | observation | In a clinical setting, synonyms such as Harlequin syndrome or North-South phenomenon are typically used. |
| 36717861 | Differential carbon dioxide tension | observation |
Info
36717860, Differential hypoxemia is the resulting condition. Do not forget to create an entry for it in the condition_occurrence table.
Recirculation
Recirculation is only observable in venovenous configurations. Do not forget about the recirculation fraction as measureable parameter.
Info
Recirculation can also be a reason to exchange parts of your circuit. If it is the primary reason it is considered a complication. Make sure to use the concept for stop_reason_concept_id if this is the case.
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717821 | Recirculation | observation |
Continuous renal replacement therapy (CRRT) using the ECLS circuit
Continuous renal replacement therapy (CRRT) machines can be connected to the ECLS circuit in different ways.
Info
Make sure to create at least a procedure_occurrence entry for the therapy itself. E.g., 37018292, Continuous renal replacement therapy.
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717911 | Configuration of renal replacement therapy attached to extracorporeal life support circuit | observation | observation_concept_id + one of the following as value_as_concept |
| 36717912 | Pre-membrane lung drainage; pre-membrane lung return | ||
| 36717913 | Pre-membrane lung drainage; pre-blood pump return | ||
| 36717914 | Post-membrane lung drainage; pre-membrane lung return | ||
| 36717915 | Post-membrane lung drainage; pre-blood pump return |
ECLS-related devices
ECLS circuits can be modified by introducing different devices. If these devices are present in your system, create an entry for them. Storing these in the device_exposure table was a deliberate design choice for the first version of the ECLS CDM, but this may change in a future update.
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717855 | Extracorporeal air bubble/foam detector | device_exposure | |
| 36717856 | Extracorporeal filter | device_exposure | |
| 36717857 | Extracorporeal bladder | device_exposure | |
| 36717858 | Extracorporeal loop | device_exposure |
Discontinuation trial
When the ECLS circuit is temporarily stopped (without decannulation) to assess if the patient can survive without support, you can use this concept to record the exact timing.
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717921 | Extracorporeal life support discontinuation trial | procedure |
General concepts
General patient characteristics
| concept_id | concept_name | table | proposed UOM | comment |
|---|---|---|---|---|
| 3036277 | Body height | measurement | centimeter | |
| 3025315 | Body weight | measurement | kilogram | |
| 3011043 | Birth weight Measured | measurement | kilogram | |
| 3012266 | Gestational age | measurement | week |
Race, ethnicity and gender
The collection of a patient’s race, ethnicity, and gender is a controversial topic. For example, due to historical reasons, race and ethnicity are not collected on a regular basis in Germany or Austria when patients are admitted to the hospital. If you need data regarding gender, race, or ethnicity, follow the official documentation on how to store such information: https://ohdsi.github.io/CommonDataModel/cdm54.html#PERSON
Units of measurement
Conventions
| Physical concept | Units |
|---|---|
| Pressure | mmHg [conversion: 1 kPa ≙ 7.5 mmHg] |
| Volumetric flow | l/min |
| Length | cm: cannula length, cannula insertion depth, device dimensions measurements |
| m: tubing length > 50cm | |
| in: circuit tubing diameter | |
| Fr: cannula (outer) diameter | |
| Area | m² |
| Temperature | °C [conversion: (°F - 32) * 5/9 = 0 °C] |
| Respiratory | mbar or cmH2O [they are virtually identical: 1mbar = 1.01972 cmH₂O] |
The following units are often encountered in the field of ECLS.
| concept_id | concept_code | concept_name |
|---|---|---|
| 8876 | mm[Hg] | millimeter mercury column |
| 8541 | /min | per minute |
| 8698 | L/min | liter per minute |
| 32710 | L/min/m2 | liter per minute per square meter |
| 586323 | Cel | degree Celsius |
| 8582 | cm | centimeter |
| 9529 | kg | kilogram |
| 8554 | % | percent |
| 8617 | m2 | square meter |
| 720858 | mbar | millibar |
| 44777602 | kPa | kilopascal |
| 44777590 | cm[H2O] | centimeter watercolumn |
| 720865 | ml/mbar | milliliter per millibar |
| 9586 | mol/L | mole per liter |
| 9579 | mmol/mol | millimole per mole |
| 9570 | mL/dL | milliliter per deciliter |
| 8840 | mg/dL | milligram per deciliter |
| 8576 | mg | milligram |
| 8504 | g | gram |
| 9546 | m | meter |
| 9327 | [in_i] | inch (international) |
| 9655 | ug | microgram |
| 8511 | wk | week |
Info
For a complete list, check out the UCUM vocabulary here.
Vital parameters
| concept_id | concept_name | table | proposed UOM | comment |
|---|---|---|---|---|
| 3027018 | Heart rate | measurement | /min | |
| 21490670 | Heart rate Intra arterial line by Invasive | measurement | /min | |
| 21490853 | Invasive Systolic blood pressure | measurement | mmHg | |
| 21490852 | Invasive Mean blood pressure | measurement | mmHg | |
| 21490851 | Invasive Diastolic blood pressure | measurement | mmHg | |
| 36032120 | Systolic blood pressure mean | measurement | mmHg | |
| 3027598 | Mean blood pressure | measurement | mmHg | |
| 36031214 | Diastolic blood pressure mean | measurement | mmHg | |
| 3005606 | Pulmonary artery Systolic blood pressure | measurement | mmHg | |
| 3028074 | Pulmonary artery Mean blood pressure | measurement | mmHg | |
| 3017188 | Pulmonary artery Diastolic blood pressure | measurement | mmHg | |
| 3020891 | Body temperature | measurement | Cel | |
| 44809207 | Target body temperature | measurement | Cel | |
| 4196147 | Peripheral oxygen saturation | measurement | % |
Proning
Placing a patient in a prone or semi-prone position is often useful in severe acute respiratory distress syndrome. If you want to capture a patient in a prone position, use the following concepts:
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 4196006 | Placing subject in prone position | procedure | plus |
| 4050473 | Prone body position | observation | = 180° |
| 4189315 | Left lateral tilt | observation | = right side up |
| 4213916 | Right lateral tilt | observation | = left side up |
Impella
A new approach in ECLS therapy involves combining ECLS with Impella. You can use the below concepts for the implantation strategy (procedure_occurrence) and use one of the available devices in device_exposure.
| concept_id | concept_name | table | comment |
|---|---|---|---|
| 36717917 | Implantation of transvalvular microaxial flow pump | procedure | |
| 36717918 | Open implantation of transvalvular microaxial flow pump | procedure | |
| 36717919 | Percutaneous implantation of transvalvular microaxial flow pump | procedure |