Perfusion Time Calculator for CPB Workflows
Track case intervals with quick start/end time inputs and automatic elapsed-minute calculations.
Time Calculator
Enter 24-hour start/end times to see elapsed minutes and an H:MM readout.
Tap the clock icon to insert the current time.
▶ Methodology
1. Purpose
This time calculator is designed to quickly estimate elapsed time in minutes and H:MM format between two clock times. It is intended for tasks such as documenting CPB time, cross-clamp time, cardioplegia intervals, ECMO procedure time blocks, or other peri-operative events where only start and end times are known.
2. Input format
Times are entered in 24-hour format as HH:MM.
Valid range: 00:00–23:59.
Examples: 07:15, 13:40, 21:05.
The fields accept four digits; after four digits are typed (e.g., 1345), the value is auto-formatted to 13:45.
Each row is independent and can be labelled (e.g., “CPB on–off”, “Cross-clamp”, “Circulatory arrest”).
3. Core calculation
For each row:
Convert start and end times to total minutes from midnight:
totalMinutes = 60 × HH + MM
If the end time is later or equal to the start time (same day):
durationMinutes = endMinutes − startMinutes
If the end time is earlier than the start time, the tool assumes the interval crosses midnight and adds 24 hours:
durationMinutes = (endMinutes + 24 × 60) − startMinutes
The result is reported as:
- Minutes (integer), and
- H:MM format, obtained by: hours = floor(durationMinutes ÷ 60) and minutes = durationMinutes mod 60, displayed as H:MM with a leading zero for minutes (e.g., 3:05).
4. Validation and rounding
Inputs outside 00:00–23:59 are rejected.
Seconds are not supported; any sub-minute timing should be rounded to the nearest minute before entry.
All durations are exact in minutes; no additional rounding is applied.
5. Clinical use & limitations
Useful for: CPB pump time, cross-clamp time, circulatory arrest time; cardioplegia dosing intervals or ECMO procedure segments; operating room or ICU workflow time stamps.
The calculator does not store dates and cannot distinguish different calendar days; any interval longer than 24 hours must be split manually.
Results are for documentation and workflow support only and do not replace clinical records, perfusion charts, or institutional time-keeping systems. For educational use only. Not medical advice or a regulated medical device.
Heparin Management (CPB)
Calculate an initial loading dose with weight strategy safeguards and optional flow targets; toggle resistance cues when ACT response is low.
Patient parameters
Adult CPBAuto switches to ABW when BMI ≥ 30 to reduce overdose risk.
Auto logic: BMI < 30 → TBW; BMI 30–39 → ABW (0.4 correction); BMI ≥ 40 → ABW (0.3) with obesity safety cues.
Devine IBW: Male = 50 + 0.91 × (cm − 152.4), Female = 45.5 + 0.91 × (cm − 152.4).
ABW 0.4 / 0.3 rules: ABW = IBW + factor × (TBW − IBW); factor 0.4 when BMI 30–39, factor 0.3 when BMI ≥ 40.
Safety cap: Obesity flows/doses use IBW/ABW and may cap BSA to avoid extreme UFH and hemodilution.
Initial dose (u/kg)
Risk factors (check all)
Selecting risk factors does not automatically change dosing. (Reference only)
Next steps (reference)
- Rule out basics: confirm heparin delivery, sampling/ACT device issues, temperature/hemodilution.
- Recheck ACT at 3–5 min; if below target, consider additional UFH per local protocol.
- If inadequate response persists, consider checking AT activity and/or anti-Xa (or heparin concentration) and prepare AT supplementation (FFP if AT concentrate not available) per protocol.
- Special situations (e.g., HIT) → follow institutional DTI protocol.
Enter patient parameters to calculate
Height, weight, and dose are required.