Should patients with intermediate high risk pulmonary embolism (PE) be monitored in a critical care unit?

Monitoring of Intermediate High-Risk Pulmonary Embolism

Patients with intermediate high-risk pulmonary embolism should be closely monitored, though not necessarily in a traditional intensive care unit—a monitored step-down unit or telemetry ward with capability for rapid escalation to ICU-level care is appropriate for most patients. 1

Risk Stratification Framework

Intermediate high-risk PE is defined by hemodynamic stability (systolic BP ≥90 mmHg) combined with evidence of right ventricular dysfunction on imaging (echocardiography or CT) AND elevated cardiac biomarkers (troponin or BNP). 1

The key distinction is that these patients are not candidates for routine systemic thrombolysis, which is reserved for high-risk (hemodynamically unstable) PE. 1

Recommended Monitoring Approach

Level of Care

• Close monitoring is mandatory for intermediate high-risk PE patients to detect early hemodynamic deterioration. 1, 2
• Transfer to intensive care units is highly recommended specifically for patients with severe symptoms, hemodynamic instability (cardiac arrest, syncope, shock), or right ventricular enlargement on echocardiography. 1
• For hemodynamically stable intermediate high-risk patients, a monitored unit with continuous ECG and oxygen saturation monitoring is appropriate, provided rapid escalation to ICU-level care is available. 1

Monitoring Parameters

Continuous monitoring should include:

• Continuous ECG monitoring to detect arrhythmias or signs of worsening RV strain. 1
• Continuous oxygen saturation monitoring to identify respiratory deterioration. 1
• Serial vital signs with particular attention to blood pressure trends, heart rate, and respiratory rate. 3
• Clinical assessment for signs of hemodynamic deterioration including worsening dyspnea, chest pain, syncope, or altered mental status. 1

Treatment During Monitoring Period

Anticoagulation

• Initiate therapeutic anticoagulation immediately with LMWH or fondaparinux (preferred over unfractionated heparin for most patients). 1
• NOACs (apixaban, dabigatran, edoxaban, or rivaroxaban) are preferred over VKA when transitioning to oral anticoagulation. 1

Hemodynamic Support

If signs of RV dysfunction or volume overload are present:

• Norepinephrine is the reasonable first choice for vasopressor support if needed, with vasopressin as an adjunct. 3
• IV loop diuretics may be useful if evidence of RV dysfunction or volume overload is present. 3
• Avoid aggressive fluid resuscitation unless clear evidence of hypovolemia exists and RV dilatation is absent. 3
• Supplemental oxygen should be administered even without documented hypoxemia. 3

Escalation Criteria

Rescue Reperfusion Therapy

Rescue thrombolytic therapy is recommended for patients who develop hemodynamic deterioration while on anticoagulation. 1

Hemodynamic deterioration is defined as:

• Development of sustained hypotension (systolic BP <90 mmHg for ≥15 minutes)
• Need for vasopressor support
• Persistent severe hypoxemia
• Clinical signs of shock 1

Alternative interventions to consider if thrombolysis is contraindicated or fails:

• Surgical embolectomy 1
• Percutaneous catheter-directed treatment 1
• VA-ECMO for refractory cases with ongoing deterioration 3, 4

Evidence on Clinical Outcomes

Real-world data demonstrates that hemodynamic deterioration in intermediate high-risk PE occurs in approximately 2-15% of patients:

• In a prospective study of 98 intermediate high-risk PE patients, only 3 patients (3%) deteriorated hemodynamically, with 2 requiring rescue reperfusion therapy. 2
• Another study found 15% of intermediate-risk patients required escalation therapy, with syncope and severe RV dysfunction on echocardiography being independent predictors. 5
• Intermediate-high risk patients had 50% higher ICU admission rates compared to intermediate-low risk patients, though hospital length of stay was similar. 6

Predictors of Deterioration

Factors associated with higher risk of requiring escalation therapy include:

• Syncope at presentation (HR 2.8) 5
• Severe RV dysfunction on echocardiography (HR 3.5) 5
• Markedly elevated D-dimer levels 5
• Higher RV/LV diameter ratio on CT (>1.5) 5

Common Pitfalls to Avoid

• Do not routinely administer systemic thrombolysis as primary treatment in intermediate-risk PE—this is associated with increased bleeding risk without proven mortality benefit. 1
• Avoid positive pressure ventilation if possible, as it can worsen RV function by increasing afterload. 3
• Do not delay anticoagulation while awaiting definitive imaging if clinical probability is high or intermediate. 1
• Ensure monitoring capability for rapid escalation rather than defaulting all intermediate high-risk patients to ICU admission, which may not be necessary for most. 6, 2

The optimal monitoring strategy balances the need for early detection of deterioration (which occurs in a minority) against resource utilization, with step-down or telemetry units being appropriate for most hemodynamically stable intermediate high-risk PE patients. 6, 2