A 32-year-old gravida 2, para 1 woman at 38 weeks gestation is admitted to the labor and delivery unit with strong, regular contractions. During the active phase of labor, she suddenly develops severe dyspnea, chest pain, and becomes cyanotic. Her blood pressure drops to 80/40 mmHg, heart rate increases to 140 bpm, and oxygen saturation falls to 85%. What is the most critical assessment finding that would confirm the nurse's suspicion of anaphylactoid syndrome of pregnancy (ASP)?

Key Clinical Triad: Sudden onset of respiratory distress, cardiovascular collapse, and coagulopathy (DIC) during labor, delivery, or immediate postpartum period.

• Initiate a rapid response and activate the massive transfusion protocol.
• Administer high-flow oxygen (non-rebreather mask at 15 L/min) and prepare for immediate intubation.
• Position the patient in a left lateral tilt to relieve aortocaval compression and optimize cardiac output.
• Establish two large-bore intravenous lines for fluid resuscitation and blood product administration.

• Monitor for signs of DIC: oozing from IV sites, petechiae, hematuria, or uterine atony with massive hemorrhage.
• Send STAT labs: complete blood count, coagulation panel (PT, aPTT, fibrinogen), and D-dimer. A rapidly falling fibrinogen level is a critical marker.

• Prepare for emergent cesarean delivery if the patient is undelivered and in cardiac arrest (perimortem cesarean).
• Administer blood products (packed red blood cells, fresh frozen plasma, cryoprecipitate, platelets) guided by point-of-care testing.
• Support hemodynamics with vasopressors as ordered; avoid excessive crystalloid to prevent dilutional coagulopathy.