after you agree to take part, you are randomly assigned to receive either a reduced dose or a full dose of alteplase. the assignment is done by a computer and you do not choose the group.

the study drug is given once by iv infusion. if you are in the full‑dose group, you receive 100 mg of alteplase. if you are in the reduced‑dose group, you receive a lower amount as defined by the study protocol. the infusion is delivered over a short period of time under medical supervision.

while the infusion is running, staff continuously check your blood pressure, heart rate, breathing, and oxygen level. they also watch for any signs of bleeding or other adverse reactions.

six hours after the infusion ends, doctors evaluate whether your condition has improved. improvement is defined as a better shock stage or a lower amount of oxygen needed to keep your blood oxygen saturation at 94% or higher.

within the first 24 hours, the team looks for any worsening of your heart or lung function that would require emergency measures such as CPR, intubation, or use of a device called va‑ecmo. if such events occur, they are recorded as clinical deterioration.

you remain in the hospital for up to seven days. during this time staff monitor for several outcomes, including death from any cause, need for CPR or va‑ecmo, a new pulmonary embolism, major bleeding, and any additional rescue treatments such as extra alteplase or surgical procedures.

about thirty days after the start of treatment, you have a follow‑up visit (or a phone call) to check your overall health. the visit includes checking whether you have survived, whether any bleeding events have occurred, and whether any further treatment was needed since leaving the hospital.