Vasopressor Equivalents

Vasopressor Equivalent Dose

Calculates norepinephrine-equivalent dose (NED) to enable comparison across different vasopressor agents. Based on the Goradia et al. 2020 scoping review of vasopressor dose equivalence.

When to Use This Skill

• Comparing vasopressor exposure across different agents
• Shock severity quantification
• Vasopressor weaning studies
• Hemodynamic support burden calculation
• Cardiovascular SOFA component (uses vasopressor doses)

Equivalence Factors

*Vasopressin is converted: vasopressin_units_per_hr * 2.5 / 60

Pre-computed Table

SELECT
    stay_id,
    starttime,
    endtime,
    norepinephrine_equivalent_dose
FROM mimiciv_derived.norepinephrine_equivalent_dose;

Calculation Formula

norepinephrine_equivalent_dose = ROUND(
    COALESCE(norepinephrine, 0)
    + COALESCE(epinephrine, 0)
    + COALESCE(phenylephrine / 10, 0)
    + COALESCE(dopamine / 100, 0)
    + COALESCE(vasopressin * 2.5 / 60, 0),
    4
)

Source Tables

Individual vasopressor tables provide dose rates:

• mimiciv_derived.norepinephrine
• mimiciv_derived.epinephrine
• mimiciv_derived.dopamine
• mimiciv_derived.phenylephrine
• mimiciv_derived.vasopressin

All consolidated in:

• mimiciv_derived.vasoactive_agent

Critical Implementation Notes

1. Weight-Based Dosing: All doses are in mcg/kg/min (except vasopressin in units/hr). The underlying tables use patient weight for conversion.

2. Weight Estimation: When weight is not documented, it may be estimated. Check mimiciv_derived.weight_durations for weight source.

3. Vasopressin Units: Vasopressin is charted in units/hour, not units/min. The formula converts appropriately.

4. Excluded Agents:

   • Metaraminol: Not used at BIDMC
   • Angiotensin II: Rarely used (could add: angiotensin_ii * 10)
   • Dobutamine: Not a vasopressor (inotrope), excluded from NED

5. Time Intervals: Each row has a starttime/endtime representing when that dose was active.

6. Multiple Simultaneous Agents: NED sums all concurrent vasopressors.

Example: Maximum NED Per ICU Stay

SELECT
    stay_id,
    MAX(norepinephrine_equivalent_dose) AS max_ned
FROM mimiciv_derived.norepinephrine_equivalent_dose
GROUP BY stay_id
ORDER BY max_ned DESC;

Example: Vasopressor Duration

SELECT
    stay_id,
    SUM(TIMESTAMP_DIFF(endtime, starttime, HOUR)) AS vasopressor_hours
FROM mimiciv_derived.norepinephrine_equivalent_dose
WHERE norepinephrine_equivalent_dose > 0
GROUP BY stay_id;

Example: Time-Weighted Average NED

WITH weighted AS (
    SELECT
        stay_id,
        norepinephrine_equivalent_dose *
        TIMESTAMP_DIFF(endtime, starttime, MINUTE) AS dose_minutes,
        TIMESTAMP_DIFF(endtime, starttime, MINUTE) AS duration_minutes
    FROM mimiciv_derived.norepinephrine_equivalent_dose
)
SELECT
    stay_id,
    SUM(dose_minutes) / NULLIF(SUM(duration_minutes), 0) AS time_weighted_ned
FROM weighted
GROUP BY stay_id;

Example: Shock Severity Categories

WITH max_ned AS (
    SELECT
        stay_id,
        MAX(norepinephrine_equivalent_dose) AS max_ned
    FROM mimiciv_derived.norepinephrine_equivalent_dose
    GROUP BY stay_id
)
SELECT
    CASE
        WHEN max_ned = 0 THEN 'No vasopressors'
        WHEN max_ned < 0.1 THEN 'Low dose (<0.1)'
        WHEN max_ned < 0.3 THEN 'Moderate (0.1-0.3)'
        WHEN max_ned < 0.5 THEN 'High (0.3-0.5)'
        ELSE 'Very high (>=0.5)'
    END AS vasopressor_category,
    COUNT(*) AS n_stays
FROM max_ned
GROUP BY 1
ORDER BY 1;

References

• Goradia S et al. "Vasopressor dose equivalence: A scoping review and suggested formula." Journal of Critical Care. 2020;61:233-240.
• Brown SM et al. "Survival after shock requiring high-dose vasopressor therapy." Chest. 2013;143(3):664-671.