Situation: A 45-year-old man with bulky diffuse large B-cell lymphoma is admitted for his first cycle of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone. During his first cycle, fifteen minutes into the first rituximab infusion, he becomes flushed and short of breath, and his blood pressure falls from 128/80 to 94/60 mmHg. What should the nurse do FIRST?

Infusion reactions to rituximab are most common with the first dose. For flushing, dyspnea, or hypotension, the nurse stops the infusion immediately, keeps the line open, stays with the client, notifies the provider, and gives emergency drugs per protocol. Stopping the drug first prevents more of it from entering while help is summoned.

Clinical situation A 45-year-old man receiving his first cycle of R-CHOP for bulky diffuse large B-cell lymphoma develops flushing, dyspnea, and hypotension 15 minutes into the first rituximab infusion. The blood pressure falls from 128/80 to 94/60 mmHg. These are classic signs of an infusion-related reaction (IRR).

Why the first action is to stop the infusion Rituximab is a chimeric monoclonal antibody, and most infusion reactions occur during the first exposure because the immune system has not yet been desensitized to the murine-derived protein component. The reaction is driven by cytokine release, complement activation, and direct mast cell or basophil degranulation. Once flushing, dyspnea, and hypotension appear, the drug is actively entering the circulation and amplifying that cascade. Stopping the infusion immediately halts further drug delivery, which is the only intervention that directly limits the dose of the offending agent. Notifying the provider, giving emergency drugs, and slowing the infusion all depend on first interrupting the source of the reaction. Slowing the infusion is specifically inappropriate because even a reduced rate continues to introduce rituximab into a patient who is already hemodynamically unstable.

Pathophysiology of rituximab infusion-related reaction Rituximab binds CD20 on B cells and triggers rapid cell lysis. In patients with bulky disease, a large tumor burden means more CD20-positive cells are available for binding, which can produce a more intense cytokine release. The resulting release of tumor necrosis factor, interleukin-6, and histamine causes vasodilation, increased vascular permeability, and bronchospasm. The clinical picture is therefore not a true IgE-mediated anaphylaxis in most cases, but a cytokine-mediated reaction that can still be life-threatening. The drop in blood pressure reflects systemic vasodilation and fluid shifts, while dyspnea reflects bronchoconstriction and upper airway edema.

Why the first dose is the highest-risk period Evidence consistently shows that IRRs are most frequent with the initial infusion. A retrospective study of 326 DLBCL patients receiving first-line R-CHOP found that IRR was a clinically significant event during early treatment, although it was not associated with overall survival ^[1]. A quality improvement report noted that rituximab carries a boxed warning for severe or fatal infusion reactions, with most occurring during the initial infusion ^[2]. A separate analysis identified bone marrow involvement as a predictor of IRR, reinforcing that higher disease burden increases the risk ^[3]. Because this patient has bulky disease and is receiving his first dose, the pretest probability of a reaction is high, and the nurse must treat the first signs as an emergency.

Nursing priority and sequence The correct sequence is not simply “stop the infusion” in isolation. After stopping the infusion, the nurse keeps the intravenous line open with normal saline to maintain access, stays with the patient to monitor airway and circulation, notifies the provider, and then administers emergency drugs such as antihistamines, corticosteroids, or epinephrine according to protocol. Stopping the drug first prevents more rituximab from entering the bloodstream while help is being summoned, which is why it takes priority over notification and medication administration. If the nurse notified the provider first, valuable time would pass while the drug continued to infuse. If emergency drugs were given first but the infusion continued, the reaction could worsen despite pharmacologic support.

Comparison of immediate actions

Action	Rationale	Priority
Stop the infusion immediately	Halts delivery of the offending drug; directly limits the dose causing the reaction	First
Notify the provider	Needed for further orders, but does not stop the drug from entering the patient	After stopping
Give prescribed emergency drugs	Treats symptoms, but the reaction continues if the infusion is still running	After stopping and notifying
Slow the infusion to half the rate	Continues to deliver rituximab; inappropriate during hypotension and dyspnea	Never for a severe reaction

Clinical application for licensure exams Key point! For any infusion reaction with airway, breathing, or circulatory compromise, the first nursing action is always to stop the infusion. Watch out! Do not confuse this with a mild reaction where slowing the rate may be acceptable; hypotension and dyspnea indicate a severe reaction that requires complete cessation. The rapid infusion protocols described in the literature apply only to patients who have tolerated the first dose without significant reaction ^[2][4]. This patient is still in the first infusion, so no rapid-infusion pathway is relevant. The nurse must also remember that premedication with acetaminophen, antihistamines, and corticosteroids reduces but does not eliminate the risk of IRR, so monitoring during the first infusion remains essential.