What treatment can a paramedic administer in the field for a patient with a suspected saddle embolus, despite adequate cardiopulmonary resuscitation (CPR), 100% oxygen (O2) administration, and supportive care?

From the FDA Drug Label

The dosing recommendations in Table 1 are based on clinical experience be adjusted for the individual patient according to the results of suitable laboratory tests, the following dosage schedules may be used as guidelines:

Table 1: Recommended Adult Full-Dose Heparin Regimens for Therapeutic Anticoagulant Effect *Based on 68 kg patient METHOD OF ADMINISTRATION FREQUENCY RECOMMENDED DOSE Deep Subcutaneous (Intrafat) Injection Use a different site for each injection to prevent the development of hematoma Initial Dose 5,000 units by intravenous injection, followed by 10,000 to 20,000 units of a concentrated solution, subcutaneously Every 8 hours or 8,000 to 10,000 units of a concentrated solution Every 12 hours 15,000 to 20,000 units of a concentrated solution Intermittent Intravenous Injection Initial Dose 10,000 units, either undiluted or in 50 to 100 mL of 0. 9% Sodium Chloride Injection, USP Every 4 to 6 hours 5,000 to 10,000 units, either undiluted or in 50 to 100 mL of 0.9% Sodium Chloride Injection, USP Continuous Intravenous Infusion Initial Dose 5,000 units by intravenous injection Continuous 20,000 to 40,000 units/24 hours in 1,000 mL of 0.9% Sodium Chloride Injection, USP (or in any compatible solution) for infusion

A paramedic could administer heparin in the field for a patient with a suspected saddle embolus, despite adequate cardiopulmonary resuscitation (CPR), 100% oxygen (O2) administration, and supportive care.

• The initial dose could be 5,000 units by intravenous injection, followed by a concentrated solution subcutaneously, or
• 10,000 units, either undiluted or in 50 to 100 mL of 0.9% Sodium Chloride Injection, USP by intermittent intravenous injection. The dosage should be adjusted according to the patient's coagulation test results, as indicated in the label 1.

From the Research

For a patient with a suspected saddle pulmonary embolism not responding to CPR, oxygen, and supportive care, paramedics should administer thrombolytic therapy if protocols permit. This approach is supported by the most recent and highest quality study available, which demonstrates the efficacy and safety of thrombolytic therapy in patients with massive pulmonary embolism 2. The preferred agent in the field is often tenecteplase (TNK), given as a single weight-based IV bolus (30-50 mg), or alteplase (tPA) administered as a 100 mg IV infusion over 2 hours. Before administration, paramedics should rapidly assess for contraindications, including recent surgery, active bleeding, or stroke history. Heparin (80 units/kg IV bolus followed by 18 units/kg/hr infusion) should be given concurrently if possible. These medications work by dissolving the clot obstructing pulmonary blood flow, potentially restoring circulation when standard resuscitation fails. Paramedics should monitor for bleeding complications, maintain two large-bore IVs, and expedite transport to a facility capable of surgical intervention if thrombolysis fails. Some key points to consider when administering thrombolytic therapy include:

• Rapid assessment for contraindications
• Monitoring for bleeding complications
• Maintaining two large-bore IVs
• Expediting transport to a facility capable of surgical intervention if thrombolysis fails
• Considering the use of heparin concurrently with thrombolytic therapy This aggressive approach is justified by the near 100% mortality of untreated massive pulmonary embolism with cardiovascular collapse, as highlighted in the study by 2. It's worth noting that while the study by 3 suggests that most patients with saddle pulmonary embolism are hemodynamically stable and do not require thrombolytic therapy, the patient in question is not responding to CPR, oxygen, and supportive care, making thrombolytic therapy a necessary consideration. Additionally, the study by 4 provides further support for the use of alteplase in the treatment of acute pulmonary embolism, and the study by 5 demonstrates the efficacy of alteplase thrombolysis for ED treatment of pulmonary embolism with shock. However, the most recent and highest quality study, 2, takes precedence in guiding treatment decisions.