T P A Stroke Dose
70kg patient, 2 hours from symptom onset
Why This Health Metric Matters
Why: This calculation helps assess important health parameters for clinical and personal wellness tracking.
How: Enter your values above and the calculator will apply validated formulas to compute your results.
- ●Evidence-based calculations
- ●Used in clinical settings worldwide
- ●Regular monitoring recommended
Clinical Scenarios
🏥 Typical Stroke Patient
70kg patient, 2 hours from symptom onset
⚡ Early Presentation
Patient arriving within 1 hour of symptom onset
⏰ 3-4.5 Hour Window
Extended window patient with additional criteria
👤 Low Weight Patient
50kg patient - dose capped at 90mg
🏋️ High Weight Patient
120kg patient - dose capped at 90mg
Patient Parameters
⚠️For informational purposes only — not medical advice. Consult a healthcare professional before acting on results.
🏥 Health Facts
— WHO
— CDC
What is tPA (Alteplase) for Stroke?
Tissue plasminogen activator (tPA), marketed as Alteplase or Activase, is a thrombolytic medication that dissolves blood clots blocking cerebral arteries in acute ischemic stroke. It's the only FDA-approved drug treatment for acute ischemic stroke and can significantly improve outcomes when administered within the treatment window. "Time is brain" - every minute of delay results in approximately 1.9 million neurons lost.
Mechanism
Converts plasminogen to plasmin, which breaks down fibrin clots and restores blood flow to ischemic brain tissue.
Key Facts:
- Recombinant human protein
- Half-life: 4-5 minutes
- Fibrin-selective thrombolytic
Time-Critical
"Time is brain" - benefits decrease with time. Must be given within 4.5 hours of symptom onset.
Time Windows:
- 0-3 hours: Standard window
- 3-4.5 hours: Extended (criteria)
- Earlier = Better outcomes
Efficacy
Increases likelihood of good functional outcome by 30-50% when given early.
Benefits:
- NNT 3-8 for benefit
- Improved 3-month outcomes
- Reduced disability
How Does This Calculator Work?
This calculator computes the weight-based tPA dose using the standard 0.9 mg/kg protocol, splits it into bolus and infusion components, and screens for common contraindications based on entered patient parameters.
🔬 Administration Protocol
Dosing Steps
- 1Calculate total dose: 0.9 mg/kg (max 90 mg)
- 2Bolus: 10% IV push over 1 minute
- 3Infusion: 90% over 60 minutes
- 4Monitor BP every 15 minutes during infusion
- 5No anticoagulation for 24 hours
BP Management
- Pre-tPA: SBP ≤185, DBP ≤110
- During/post: SBP ≤180, DBP ≤105
- IV labetalol or nicardipine for control
- Hold tPA if BP cannot be controlled
tPA Stroke Protocol
Bolus (10%)
10% of total dose given IV push over 1 minute
Typically 6-9 mg for most patients
Infusion (90%)
90% of total dose infused over 60 minutes
Via infusion pump at calculated rate
Time Window
0-4.5 hours from symptom onset
Last known well time used
Contraindications and Eligibility
Absolute Contraindications
- • Active internal bleeding
- • Recent intracranial/intraspinal surgery
- • Intracranial hemorrhage on CT
- • Severe uncontrolled hypertension
- • Known AVM or aneurysm
- • Active bleeding diathesis
- • INR >1.7 or PT >15 seconds
- • Platelet count <100,000
- • Heparin within 48h with elevated aPTT
- • Current anticoagulation with elevated markers
Relative Contraindications
- • Minor/resolving symptoms
- • Major surgery within 14 days
- • GI/urinary hemorrhage within 21 days
- • Seizure at onset with residual postictal
- • Arterial puncture at noncompressible site
- • Blood glucose <50 or >400 mg/dL
- • Pregnancy or recent delivery
- • NIHSS >25 (high stroke severity)
- • Extended window (3-4.5h): age >80
Dosing Formula
Total Dose Calculation
Example: 80 kg × 0.9 = 72 mg
Bolus Calculation
Example: 72 mg × 0.10 = 7.2 mg
Infusion Calculation
Example: 72 mg × 0.90 = 64.8 mg over 60 min
Infusion Rate
Example: 64.8 mg = 64.8 mL/hr
Post-tPA Monitoring Protocol
Neurological Checks
- • Every 15 min during infusion
- • Every 30 min × 6 hours
- • Every 60 min × 16 hours
- • NIHSS at 24 hours
Blood Pressure
- • Every 15 min × 2 hours
- • Every 30 min × 6 hours
- • Every 60 min × 16 hours
- • Target: <180/105 mmHg
Complications
- • Worsening neuro = STOP infusion
- • Stat CT head
- • Check fibrinogen, CBC, type/screen
- • ICH: cryoprecipitate, TXA
Contraindications
Careful screening for contraindications is essential before administering tPA to minimize bleeding risk.
Absolute Contraindications
- Intracranial hemorrhage on CT
- Symptoms >4.5 hours (or unknown onset)
- Severe uncontrolled HTN (>185/110)
- Head trauma or stroke within 3 months
- Platelets <100,000/mm³
- INR >1.7 or on anticoagulants
- Active internal bleeding
Relative Contraindications
- Minor or rapidly improving symptoms
- Recent major surgery (14 days)
- GI/GU bleeding (21 days)
- Seizure at onset
- Glucose <50 or >400 mg/dL
- Pregnancy (weigh risk/benefit)
Clinical Pearls
Time is Brain
1.9 million neurons die every minute without blood flow. Door-to-needle target is <60 minutes.
Max Dose = 90mg
For patients >100kg, cap total dose at 90mg. This is different from cardiac dosing.
Tenecteplase Alternative
TNK (0.25 mg/kg, max 25mg) is gaining favor as single bolus alternative to alteplase.
BP Control Critical
Must get BP <185/110 before and <180/105 after tPA. Labetalol, nicardipine are first-line.
sICH Risk ~6%
Symptomatic intracranial hemorrhage is the major risk. Higher with older age, higher NIHSS, hyperglycemia.
Consider Thrombectomy
For large vessel occlusions, mechanical thrombectomy extends window to 24 hours in select patients.
Frequently Asked Questions
Why is the bolus given first?
The 10% bolus provides immediate plasminogen activation, while the infusion maintains therapeutic levels. This achieves rapid clot lysis while minimizing bleeding risk.
Can tPA be given if onset time is unknown?
Generally no, but patients who wake up with stroke ("wake-up strokes") may qualify if MRI shows salvageable tissue. Guidelines allow treatment based on imaging selection.
What if symptoms resolve during tPA infusion?
Continue the full infusion. Improvement is expected and doesn't indicate the clot is fully lysed. Stopping early may lead to re-occlusion.
Can patients on anticoagulants receive tPA?
Patients on warfarin with INR >1.7 should not receive tPA. For DOACs, if last dose was <48h, check drug-specific levels or consider reversal agents before treatment. Recent guidelines are evolving.
What about tenecteplase (TNK) for stroke?
TNK (0.25 mg/kg, max 25mg) is emerging as an alternative to alteplase. It's given as single bolus, which is more convenient. Recent trials suggest similar efficacy and safety, and it's already preferred in some centers.
When should I call a stroke code?
Activate stroke alert for sudden onset of: facial droop, arm weakness, speech difficulty (F.A.S.T.), sudden severe headache, vision loss, difficulty walking, or confusion. Time of symptom onset is critical information.
What is door-to-needle time?
Door-to-needle (DTN) time is from patient arrival to tPA administration. Goal is ≤60 minutes. Shorter DTN is associated with better outcomes. Best practice centers achieve ≤30 minutes.
NIHSS Score Quick Reference
The NIH Stroke Scale quantifies stroke severity from 0-42.
0-4
Minor stroke
5-15
Moderate stroke
16-20
Moderate-severe
21-42
Severe stroke
Stroke Mimics to Consider
Up to 30% of suspected strokes are mimics. Consider these diagnoses before thrombolytic therapy.
Hypoglycemia
Check glucose on ALL stroke alerts. Focal deficits reverse with glucose correction.
Seizure (Todd's paralysis)
Post-ictal weakness can last hours. Witness seizure activity? Consider EEG.
Migraine with Aura
Hemiplegic migraine can mimic stroke. History of migraine? Gradual onset?
Conversion Disorder
Functional neurological symptoms. Look for inconsistencies on exam.
Brain Tumor/Mass
Can present with sudden deficits from hemorrhage or seizure. CT will show.
Drug Toxicity
Lithium, phenytoin, other drugs can cause ataxia and neurological symptoms.
Mechanical Thrombectomy
For large vessel occlusions (LVO), mechanical thrombectomy extends the treatment window significantly beyond tPA.
Indications
- • LVO (ICA, M1, sometimes M2, basilar)
- • Up to 24 hours in select patients (DAWN/DEFUSE-3)
- • Favorable imaging (salvageable tissue)
- • Pre-stroke independence
- • Can be done with or without tPA
Key Points
- • Give tPA if eligible - don't delay for thrombectomy
- • Early transfer to thrombectomy-capable center
- • CTA to identify LVO
- • Better outcomes than tPA alone for LVO
- • NNT ~3-5 for good outcome
Post-tPA Care Checklist
First 24 Hours
- • ICU or stroke unit admission
- • Neuro checks per protocol
- • BP goal <180/105 mmHg
- • No anticoagulants or antiplatelets for 24h
- • No invasive procedures (foley, NG, arterial line) if avoidable
- • Repeat CT at 24h before starting antiplatelet
Secondary Prevention
- • Aspirin 325mg after 24h CT clear
- • Statin therapy initiation
- • DVT prophylaxis (intermittent pneumatic compression first 24h)
- • Swallow evaluation before oral intake
- • Stroke workup (echo, carotid imaging)
- • Rehabilitation assessment
Blood Pressure Targets
| Timing | BP Target | Notes |
|---|---|---|
| Pre-tPA eligibility | <185/110 mmHg | Must achieve to give tPA |
| During infusion | <180/105 mmHg | Check q15min |
| First 24h post-tPA | <180/105 mmHg | Maintain strictly |
| After 24h (stable) | <140/90 mmHg | Long-term goal |
Secondary Prevention Essentials
Antiplatelet Therapy
Aspirin ± clopidogrel short-term for minor stroke/TIA. Long-term aspirin or clopidogrel alone.
Statin Therapy
High-intensity statin for all atherosclerotic strokes. LDL goal <70 mg/dL.
BP Control
Target <130/80 long-term. Start after acute phase stabilized.
Key Numbers to Remember
tPA dose: 0.9 mg/kg (max 90 mg)
Bolus: 10% over 1 minute
Infusion: 90% over 60 minutes
Glucose check: Must rule out hypoglycemia
Time window: ≤4.5 hours
Door-to-needle goal: ≤60 minutes
BP goal pre-tPA: <185/110
Post-tPA monitoring: Neuro checks q15min × 2h
Remember
TIME IS BRAIN - Every minute of delay = ~2 million neurons lost