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Bolus drugs as unit-dose counts

Most bolus drug totals are exact counts of standard doses, not rounded estimates; propofol is the exception, and zeros are ambiguous.
Date 2026-10-13
Status current
Methods Rounding, heaping and value resolution

Background

  • Nine bolus drug fields: propofol, midazolam, fentanyl, rocuronium, vecuronium, ephedrine, phenylephrine, epinephrine and calcium.
  • The drug fields have no missing values, so 0 means "none given or none recorded".

Data

  • Ephedrine 3,211 non-zero cases; calcium chloride 868; fentanyl 1,168; phenylephrine 844; rocuronium 5,942; propofol 2,335.
  • Midazolam, vecuronium and epinephrine have 80, 12 and 89 non-zero cases.

Method

  • For each drug, found the unit the values sit on and the most common totals.
  • Checked rocuronium against case duration and weight, and propofol against weight.
  • Checked zeros against anaesthesia type.

Results

  • Ephedrine sits on 5 mg (99.4%): a count of 5 mg boluses.
  • Calcium chloride sits on 300 mg (90%) or 150 mg (97%): a count of ampoules, sometimes half.
  • Fentanyl sits mostly on 50 mcg; 100 mcg is the most common total.
  • Phenylephrine sits on 10 mcg (99%): a sum of small boluses.
  • Rocuronium sits on 10 mg (95%): an intubating dose plus top-ups. The total rises with case duration (Spearman 0.61), barely with weight (0.12).
  • Rocuronium is 0 in all 72 sedation cases, in 261 of 273 spinal cases, and in 113 general anaesthetics.
  • Propofol bolus is 0 in 3,719 of 6,043 general anaesthetics, many probably given by infusion (TIVA).

Discussion

  • Agreed: unit-count drugs (ephedrine, calcium chloride, fentanyl, phenylephrine) are exact, with the unit dose as resolution; values off that unit are flagged off_grid.
  • Rocuronium is exact on a 10 mg resolution.
  • Midazolam, vecuronium and epinephrine get native resolution only.
  • A 0 in any drug field returns status zero_or_not_recorded and no distribution.
  • Propofol behaves like a rounded estimate and has its own fitted model (value-model-intraop-ppf).

Limitations

  • Zeros cannot be told apart from drugs given by another route, such as a propofol infusion on the pump tracks.

Worked examples

Example Side Status Summary
Time from a vasopressor bolus to the pressure response both planned How quickly arterial pressure responds to a phenylephrine or ephedrine bolus, with the charted dose times' rounding taken into account. Not feasible in VitalDB, which records bolus totals but no bolus times; kept for a dataset that does.

Tags: from the resolution work