Description
Zero-time intercept of a supplied waveform tangent, without selecting a tangent or judging spirometry acceptability.
A bench or research calculation starts from supplied measurements, reference values, and unit conventions. A transformed value, timing difference, or support fraction describes that model; its clinical meaning depends on measurement validity and a separate professional assessment.
Zero-time intercept of a supplied waveform tangent, without selecting a tangent or judging spirometry acceptability.
When to use this tool
Use it for spirometry start time back extrapolated offset when the required inputs and conventions are already available.
How to use the tool and how it works
- Enter tangentSlope, tangentTime, tangentVolume, recordedStart. Use the stated units and boundary conventions.
- Run the calculation. Correct any input error before interpreting a result.
- Read extrapolatedZeroTime, startOffset, extrapolatedVolumeAtStart. Inspect any known, defined, inclusion, or boundary flags before interpreting numeric values.
Require nonzero tangentSlope. Calculate extrapolatedZeroTime=tangentTime-tangentVolume/tangentSlope, startOffset relative to recordedStart, and the tangent's extrapolatedVolumeAtStart.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| tangentSlope | Tangent Slope | Required. Finite number. |
| tangentTime | Tangent Time | Required. Finite number. |
| tangentVolume | Tangent Volume | Required. Finite number. |
| recordedStart | Recorded Start | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| extrapolatedZeroTime | Extrapolated Zero Time | Required. Finite number. |
| startOffset | Start Offset | Required. Finite number. |
| extrapolatedVolumeAtStart | Extrapolated Volume At Start | Required. Finite number. |
{
"input": {
"tangentSlope": 4,
"tangentTime": 0.5,
"tangentVolume": 1,
"recordedStart": 0
},
"output": {
"extrapolatedZeroTime": 0.25,
"startOffset": 0.25,
"extrapolatedVolumeAtStart": -1
}
}Limitations and assumptions
- The tangent is supplied rather than fitted from data. Consistent volume and time units are required, and these terms do not establish maneuver acceptability or select a clinical time-zero convention.
- The field tables describe structural bounds; the mechanics also state cross-field requirements. Malformed input shapes, disallowed keys, and invalid domains cause input errors. Results must remain finite and within the declared output contract. A successful false flag or zero placeholder is distinct from an error.
- Numeric arithmetic uses binary floating point. Exact comparisons have no hidden tolerance or decimal rounding; negative zero is exported as zero. Decimal-text integer operations retain the exactness specifically stated above.
Alternative or Complementary methods
For spirometry start time back extrapolated offset, check the source records and the supplied rule before comparing the result with another method. Use an appropriately validated measurement or analysis method for clinical interpretation.
References
Similar or alternative tools
- Spirometry Time Volume Increment
Compute one supplied research trace increment and mean flow without a maneuver quality or clinical interpretation.
- Spirometry Time Zero Shift
Shift a supplied research recording clock without assessing test quality.