Tpa Calculator - Alteplase Bolus and Infusion

The tPA dose calculator is a clinical reference for acute ischemic stroke that turns the patient's weight in kilograms and hours since symptom onset into the 0.9 mg/kg alteplase total, a 10 percent IV bolus, and a 60 minute infusion under the 90 mg cap. Stroke teams, emergency physicians, and neurology pharmacists use it during door-to-needle time to confirm an Activase dose before reconstitution. The result also surfaces a treatment window reminder based on the 0 to 4.5 hour AHA/ASA recommendation.

• • Stroke activation in the emergency department: A 70 kg adult is brought in 90 minutes after the last known well time. The clinician needs the bolus, infusion, and total dose calculated once and double-checked against the 90 mg cap and the 0 to 4.5 h window before mixing the vial.
• • Dose review for patients over 100 kg: A 130 kg patient would mathematically need 117 mg of alteplase, but the labeled cap stops the displayed total at 90 mg. The calculator pins the bolus to 9 mg and the infusion to 81 mg so the bedside nurse programs the pump against the cap.
• • Onset window screening: When the patient last known well time is more than 4.5 hours, the calculator still computes the dose but flags the onset window for extended-window eligibility, advanced imaging, or thrombectomy transfer review.

The calculator confirms a dose that has already been decided on clinical grounds. It does not decide whether tPA is appropriate or whether a hemorrhagic stroke has been excluded on imaging. The values it produces are reference numbers that help the stroke team avoid arithmetic mistakes.

The same 0.9 mg/kg rule is also used for pulmonary embolism and myocardial infarction with different caps, so this tool is intentionally limited to the IV stroke protocol.

When the stroke team is also documenting cardiac rhythm, the ECG heart rate calculator provides the rate measurement that complements the alteplase dosing workflow above.

The calculator applies a single labeled IV stroke protocol from the Alteplase Summary of Product Characteristics. It scales the patient's weight in kilograms to a 0.9 mg/kg total, splits that total into a 10 percent IV bolus and a 60 minute infusion, and applies absolute caps to every value.

• weight: Patient body weight in kilograms (30 to 250). Values that would push the total above 90 mg trigger the cap.
• onsetHours: Hours since the patient was last known well (0 to 12). Values above 4.5 h are flagged for extended-window eligibility review.
• totalDose: Total IV alteplase in milligrams. Equal to 0.9 mg/kg of body weight, hard-capped at 90 mg.
• bolusDose: 10 percent of the total dose as an IV push over the first minute. Capped at 9 mg.
• infusionDose: Remaining 90 percent of the total dose infused over 60 minutes. Capped at 81 mg.

The formula has two layers. The first is the weight-based 0.9 mg/kg total. The second is the absolute cap of 90 mg that limits the total dose, the 9 mg that limits the bolus, and the 81 mg that limits the 60 minute infusion. The onset hours field does not alter the dose; it surfaces a reminder string when the last known well time is outside the standard window.

According to Alteplase Summary of Product Characteristics, the recommended total alteplase dose is 0.9 mg/kg with a 90 mg maximum, given as 10 percent IV bolus over the first minute and 90 percent as a 60 minute continuous infusion

When the team uses the tPA dose calculator, the NIH stroke scale calculator sits one tab away and provides the 0 to 42 severity score that complements the bolus and infusion review.

The numbers produced by the tPA dose calculator rest on a small set of stroke dosing ideas that are easy to mix up in the middle of a code.

For a parallel example of a labeled mg/kg ceiling with a hard absolute cap, the lidocaine dose calculator shows how 4.5 mg/kg and a 300 mg total limit combine for local anesthetic planning.

Enter the patient's actual body weight in kilograms and the hours since the patient was last known well, then read the bolus, infusion, total, and window status in one screen.

1. 1 Enter the patient weight in kilograms: Use the most recent measured weight. The 0.9 mg/kg total and the 90 mg cap both depend on the actual number.
2. 2 Enter hours since symptom onset: Use the time the patient was last known well, not the time the ambulance arrived. This is the value the AHA/ASA window is measured against.
3. 3 Read the total, bolus, and 60 minute infusion: The calculator shows the total alteplase dose, the IV bolus over 1 minute, and the 60 minute infusion in milligrams rounded to whole milligrams.
4. 4 Check whether the 90 mg cap was applied: When the patient weighs 100 kg or more, the cap status line shows that the 90 mg cap is in effect. Confirm that the bolus is 9 mg and the infusion is 81 mg before reconstitution.
5. 5 Review the treatment window status: Within 4.5 hours is the standard window. Beyond 4.5 hours the calculator still produces a dose but flags the window for extended-window eligibility review.

A 70 kg patient presents 2 hours after the last known well time. The calculator shows a total of 63 mg, a 1 minute IV bolus of 6 mg, and a 60 minute infusion of 57 mg. The cap status reads Not applied and the window reads Within 0-4.5 h window, so the bedside nurse can reconstitute Activase, withdraw 6 mg for the bolus, and program the remaining 57 mg over 60 minutes.

When the same stroke team needs a weight-based volume for FFP, the fresh frozen plasma dose calculator produces the mL per kg and bag count from a single entry, mirroring the workflow above for the alteplase total.

A purpose-built alteplase calculator removes the bedside arithmetic that is most likely to fail during a code, and it shows the dose, the split, and the window together.

• • Prevents arithmetic errors at the bedside: The total, bolus, and 60 minute infusion are computed and rounded together. The stroke team does not have to remember the 0.9 mg/kg rule, the 10 percent split, or the 90 mg cap during door-to-needle time.
• • Pins values to the labeled cap for larger patients: At 100 kg or more, the calculator shows a bolus of 9 mg and an infusion of 81 mg instead of a weight-based number that would overshoot the cap.
• • Surfaces the treatment window reminder: A separate window line reminds the team of the 0 to 4.5 hour AHA/ASA window without changing the dose, so extended-window eligibility, advanced imaging, and thrombectomy transfer are part of the same review.
• • Supports nursing and pharmacy sign-off: The displayed total, bolus, and infusion give the second nurse and the pharmacist a single reference to confirm against the medication administration record.
• • Standardizes dose documentation: The same numbers can be transcribed directly into the stroke order set, the medication administration record, and the after-action review, which keeps documentation consistent across the team.

When a stroke patient also has renal impairment, the GFR calculator provides the estimated creatinine clearance that goes alongside the bolus and infusion review.

Most of the variation in the tPA dose calculator comes from a small set of patient and protocol factors. Knowing which factor changes the dose, and which one only changes the display, prevents misreading the result.

• • The calculator only applies the IV alteplase stroke protocol. Pulmonary embolism, myocardial infarction, catheter-directed lysis, and pediatric stroke use different weight-based rates and caps, and the result should not be reused for those indications.
• • The dose assumes actual body weight and the 0 to 4.5 h treatment window. Adjusted or ideal body weight, body weight above the labeled study range, and any patient with a labeled contraindication should be reviewed by a stroke physician before the bolus is given.

According to Powers et al. 2019 AHA/ASA acute ischemic stroke guideline, IV alteplase is recommended for eligible adults within 0 to 4.5 hours of symptom onset, with additional considerations for the 3 to 4.5 hour window

As published by Activase (alteplase) US prescribing information, Activase is the recombinant tissue plasminogen activator used for acute ischemic stroke with a labeled 0.9 mg/kg total dose and 90 mg maximum

Because the 0 to 4.5 h window is paired with a strict blood pressure ceiling, the blood pressure calculator supports the bedside check that runs before the IV bolus is given.