What is the initial management approach for pulmonary embolism in the Intensive Care Unit (ICU)?

ICU Management of Pulmonary Embolism

Immediate Resuscitation and Risk Stratification

For patients with hemodynamically unstable PE (systolic BP <100 mmHg, HR >110 bpm, or requiring vasopressors), immediate anticoagulation with IV heparin should be initiated while simultaneously preparing for systemic thrombolysis as first-line reperfusion therapy. 1, 2

Initial Assessment and Stabilization

• Hemodynamic instability is defined by systolic blood pressure <100 mmHg, heart rate >110 bpm, requirement for inotropes/critical care, or need for thrombolysis/embolectomy 3
• Perform bedside transthoracic echocardiography immediately in hemodynamically unstable patients to assess RV dysfunction and differentiate PE from other life-threatening conditions 1
• Look for clinical patterns: sudden collapse with raised JVP, pulmonary hemorrhage syndrome (pleuritic pain/hemoptysis), or isolated dyspnea without cough 3, 1
• Most patients present with breathlessness and/or tachypnea (respiratory rate >20/min) 3, 1

Anticoagulation Protocol

Immediate Heparin Therapy

Start IV unfractionated heparin immediately upon suspicion of PE, before diagnostic confirmation is complete. 1

Weight-adjusted dosing (preferred):

• Initial bolus: 80 IU/kg IV 4, 5
• Maintenance infusion: 18 IU/kg/hour 4, 5
• Target aPTT: 1.5-2.5 times control (45-75 seconds) 3, 4, 5

Standard dosing (alternative):

• Initial bolus: 5,000-10,000 IU 3, 1
• Maintenance: 1,300 IU/hour 3, 1

aPTT Monitoring Schedule

• First check: 4-6 hours after initial bolus 3, 4
• After any dose change: 6-10 hours later 3, 4
• Once therapeutic: Daily monitoring 3, 4

Warfarin Overlap

• Start warfarin 5-10 mg daily for 2 days as soon as diagnosis is confirmed 3, 6
• Continue heparin for at least 5 days AND until INR is 2.0-3.0 for at least 24-48 hours 6, 4
• Target INR: 2.0-3.0 throughout treatment 3, 6
• Monitor INR every 1-2 days initially until stable 3, 6

Hemodynamic Support

Vasopressor Selection

Norepinephrine is the first-choice vasopressor for hemodynamic support, with vasopressin as an adjunct. 7

• Avoid aggressive fluid resuscitation unless clear hypovolemia exists and RV is not dilated 7
• Administer IV loop diuretics if RV dysfunction or volume overload is present 7
• Avoid beta-blockers or calcium channel blockers in patients with frank cardiac failure 1

Oxygenation Strategy

• Administer supplemental oxygen even without hypoxemia to reduce RV afterload 1, 7
• Consider high-flow nasal cannula for respiratory support 2
• Avoid positive pressure ventilation and endotracheal intubation if possible, as this can precipitate hemodynamic collapse by increasing RV afterload and decreasing preload 7

Reperfusion Therapy for High-Risk PE

Systemic Thrombolysis (First-Line)

For hemodynamically unstable PE, systemic thrombolysis is the first-line reperfusion therapy and should be administered immediately. 2, 7

Stop heparin before thrombolysis; resume at maintenance dose after completion. 3

Thrombolytic regimens:

• rtPA: 100 mg over 2 hours 3
• Streptokinase: 250,000 units over 20 minutes, then 100,000 units/hour for 24 hours (plus hydrocortisone) 3
• Urokinase: 4,400 IU/kg over 10 minutes, then 4,400 IU/kg/hour for 12 hours 3

Alternative Reperfusion Options

• Surgical embolectomy for patients with contraindications to thrombolysis 2
• Catheter-directed interventions as alternative reperfusion strategy 2
• Venoarterial ECMO should be implemented early if ongoing deterioration occurs despite medical interventions 7

Monitoring and Complications

Thrombocytopenia Surveillance

• Obtain platelet counts before and periodically during heparin therapy 5
• If platelet count falls below 100,000/mm³ or recurrent thrombosis develops, immediately discontinue heparin and evaluate for HIT/HITT 3, 5
• HIT can occur 2-20 days (average 5-9 days) after starting heparin, or up to several weeks after discontinuation 5

Hemorrhage Risk

• Monitor hematocrit and occult blood in stool throughout therapy regardless of route 5
• If coagulation tests are unduly prolonged or hemorrhage occurs, discontinue heparin promptly 5
• Gastrointestinal or urinary tract bleeding may indicate underlying occult lesion 5

Special Considerations

Contraindications to Anticoagulation

• If absolute contraindications exist, consider inferior vena cava filter placement 1
• Active bleeding or recent major surgery are key contraindications 3

Heparin Resistance

• Resistance frequently encountered in fever, thrombosis, infections, MI, cancer, post-surgical patients, and antithrombin III deficiency 5
• Consider adjustment based on anti-Factor Xa levels in resistant cases 5

Benzyl Alcohol Warning

• Avoid heparin multiple-dose vials with benzyl alcohol preservative in neonates and infants due to risk of fatal "gasping syndrome" 5