Pulmonary Embolism — Non-Massive

Presentation: Hemodynamically stable, no RV strain on echo/biomarkers, normal troponin & BNP

Decision Points: Anticoagulation is cornerstone; PESI score or sPESI for risk assessment

MDM Template:

Patient with confirmed PE without hemodynamic compromise or RV strain. Plan includes parenteral anticoagulation with [heparin/LMWH/fondaparinux], transition to oral anticoagulation. Outpatient follow-up with thromboembolism clinic. No thrombolytics indicated in stable patient. Monitoring for signs of hemodynamic decompensation.

Pulmonary Embolism — Submassive (RV Strain)

Presentation: Hemodynamically stable BUT RV strain present (echo shows RV dilatation OR elevated troponin/BNP)

Key Issue: Risk of decompensation to cardiogenic shock; thrombolysis vs anticoagulation alone is clinical decision

MDM Template:

Patient with submassive PE (RV strain present, hemodynamically stable). Risk stratification by PESI and cardiac biomarkers discussed. Plan: Initiate anticoagulation with [heparin/LMWH/fondaparinux], close hemodynamic monitoring in ICU. Thrombolysis considered if signs of decompensation develop. Echocardiography and serial troponin/BNP monitoring. Consider interventional radiology if rapid deterioration occurs.

Pulmonary Embolism — Massive (Hemodynamic Compromise)

Presentation: Hypotension (SBP <90 mmHg) or cardiogenic shock from acute RV failure

Urgent Intervention: Thrombolytics are indicated; consider catheter embolectomy or ECMO if failed thrombolysis

MDM Template:

Patient presenting with massive PE and hemodynamic compromise (hypotension, shock). Immediate resuscitation initiated: IV access secured, continuous monitoring, supplemental O2 titrated to SpO2 >90%. Alteplase 100mg IV bolus given for thrombolysis [or tissue plasminogen activator per protocol]. Cardiothoracic surgery and interventional radiology consulted for possible embolectomy/mechanical support if thrombolysis fails. Fluid bolus limited due to RV failure; vasopressors initiated (norepinephrine preferred). Close hemodynamic, respiratory, and coagulation monitoring. Expectation of ICU admission.

Pulmonary Hypertension / RV Failure Exacerbation

Presentation: Known or suspected PH with acute RV decompensation, dyspnea, hypoxia, signs of right heart strain

Key Physiology: RV is afterload-sensitive; systemic hypotension worsens RV perfusion and function (RV “spiral of death”)

MDM Template:

Patient with pulmonary hypertension exacerbation presenting with signs of RV failure. Supplemental O2 titrated to SpO2 >90%. Pulmonary vasodilators initiated: inhaled nitric oxide [or epoprostenol IV] started. Hemodynamic support with cautious fluid management and pressors (norepinephrine or low-dose dopamine) to maintain adequate RV coronary perfusion pressure. Diuretics held unless signs of RV-LV interdependence causing LV dysfunction. Mechanical ventilation avoided if possible; if necessary, lung-protective strategy with permissive hypercapnia. Cardiac consultation and possible ICU monitoring with PAC/IABP. Investigation for precipitants (PE, infection, arrhythmia, hypoxia).

PE Risk Stratification & Clinical Decision Tools

PESI Score (Pulmonary Embolism Severity Index):

• Predicts 30-day mortality; incorporates age, hemodynamics, oxygenation, comorbidities, RV strain
• Class I-II (score <100): Low-risk; can be considered for outpatient management
• Class III-V (score ≥100): High-risk; recommend hospitalization

sPESI (Simplified PESI):

• Simplified version: Age >50, SBP <100, O2 sat <90%, signs of DVT/RV strain
• Score 0 = low-risk; ≥1 point = higher risk, consider hospitalization

Role of Imaging & Biomarkers:

• Echo: Assess RV dilatation (RV/LV ratio >0.9), RV dysfunction
• Troponin & BNP: Elevated levels suggest myocardial injury/stress from RV strain; correlate with worse outcomes
• CT pulmonary angiography (CTPA): Gold standard for PE diagnosis; assess clot burden and distribution

Anticoagulation Regimens

Initial (Parenteral) Options:

• Unfractionated Heparin (UFH): IV bolus 80 units/kg, then infusion 18 units/kg/hr. Preferred in massive PE and renal failure (t1/2 ~60-90 min). Rapid reversibility with protamine.
• Low-Molecular-Weight Heparin (LMWH): Enoxaparin 1 mg/kg SC q12h or 1.5 mg/kg daily. Predictable pharmacokinetics; contraindicated in severe renal failure (CrCl <30). Do not use in massive PE requiring potential thrombolysis.
• Fondaparinux: Weight-based SC dosing once daily. Factor Xa inhibitor; use with caution in low body weight or renal impairment.

Transition to Oral Anticoagulation:

• Warfarin: Start with parenteral anticoagulation overlap; transition when INR 2-3 achieved (usually 5-7 days)
• Direct Oral Anticoagulants (DOACs): Apixaban, rivaroxaban, dabigatran may be used for long-term management; some studies support earlier transition in stable PE

Duration of Anticoagulation:

• Provoked PE (surgery, immobility): 3 months of anticoagulation
• Unprovoked PE: Consider extended anticoagulation (minimum 3 months, possibly indefinite depending on risk factors)

Thrombolytic Therapy & Massive PE

Indications for Thrombolysis:

• Hemodynamic instability: SBP <90 mmHg or cardiogenic shock from acute RV failure
• Contraindications to thrombolysis and presence of massive PE: Mechanical thrombectomy or extracorporeal support considered

Thrombolytic Regimens:

• Alteplase (tPA): 100 mg IV over 2 hours; accelerated regimen: 10 mg bolus, then 90 mg over 2 hours. Most studied in PE.
• Urokinase or Streptokinase: Alternative agents; less commonly used in modern practice

Timing & Efficacy:

• Maximum benefit if given within 14 days of symptom onset; benefit highest within first 48 hours
• Success rate ~75-80% for resolution of shock; mortality still 5-10% despite thrombolysis

Complications of Thrombolysis:

• Major bleeding: 5-20% (varies by regimen and patient factors)
• Intracranial hemorrhage: 1-3%
• Reperfusion arrhythmias: Can occur as clot dissolves and pulmonary perfusion restored

Mechanical Alternatives:

• Percutaneous Catheter Embolectomy: Consider in massive PE with contraindications to thrombolysis or failed thrombolysis
• Surgical Embolectomy: Rare; reserved for massive PE with failed thrombolysis and available cardiothoracic surgery expertise
• ECMO: Bridge for severe cardiogenic shock while awaiting thrombolysis or mechanical intervention

Subsegmental PE Management

Definition: PE limited to subsegmental branches on CTPA; often detected incidentally on imaging done for other reasons

Controversy: Optimal management remains debated; isolated subsegmental PE often has low mortality without anticoagulation IF no DVT present and no cardiopulmonary compromise

Management Approach:

• Isolated subsegmental PE + no DVT + hemodynamically stable + no RV strain: Close follow-up and clinical observation; anticoagulation may be deferred, though some guidelines recommend 6-week anticoagulation course
• Subsegmental PE + DVT or hemodynamic instability or RV strain: Anticoagulation indicated as for proximal PE
• Consider Wells/PERC/Geneva criteria: Assess pretest probability and use d-dimer (if elevated pretest probability)

RV Failure Physiology & Hemodynamic Goals

Normal RV Physiology:

• RV is thin-walled, afterload-sensitive chamber
• Low-pressure system: Normal RV systolic pressure 15-25 mmHg; minimal myocardial work at rest
• Acute increase in RV afterload (PE, acute PH) → RV dilatation → ventricular interdependence → septum bows into LV → LV dysfunction

RV “Spiral of Death” (Vicious Cycle):

• Acute RV dilatation → RV ischemia (from septal shift and reduced RV coronary perfusion pressure) → RV dysfunction → cardiogenic shock → hypotension → further reduced RV coronary perfusion → worse RV dysfunction
• Intubation and positive-pressure ventilation can precipitate/worsen this cycle by increasing intrathoracic pressure and RV afterload

Hemodynamic Goals in RV Failure:

• MAP (Mean Arterial Pressure): Target MAP ≥65 mmHg to maintain RV coronary perfusion pressure (RV-CPP = MAP – CVP, where CVP is central venous pressure)
• CVP (Central Venous Pressure): Minimize CVP to improve RV coronary perfusion; avoid excessive fluid; target CVP <8 mmHg if possible
• RV Contractility: Support with low-dose inotropes or pulmonary vasodilators; avoid excessive preload (worsens ventricular interdependence)

Volume Assessment & Management in RV Failure

The Volume Paradox in RV Failure:

• RV is preload-dependent (Frank-Starling curve); some preload is needed for CO
• BUT: Excessive preload worsens ventricular interdependence → septal shift → reduced LV filling → reduced systemic CO
• Goal: Minimal preload needed to maintain adequate CO; typically CVP 8-10 mmHg (lower end desirable)

Assessing Volume Status:

• Clinical exam: JVD, peripheral edema, hepatomegaly (signs of RV failure)
• Ultrasound: IVC diameter and collapsibility; if dilated IVC + absent collapse → volume overload
• Echo: RV/LV ratio; septal position; RV function
• Invasive monitoring: CVP via central line; PAC for PCWP, CO measurement

Volume Management Strategy:

• Avoid aggressive diuresis: Can worsen RV CO and systemic hypotension
• Judicious fluid boluses: Small 250 mL boluses if hypotensive and CVP low; monitor response
• Pressors preferred over fluids: Norepinephrine, low-dose dopamine to maintain MAP and RV perfusion
• Inotropes (dobutamine, milrinone): Caution—may worsen systemic hypotension via vasodilation; reserve for low CO + adequate MAP

Pulmonary Vasodilators & Inhaled Therapeutics

Mechanism of Benefit: Reduce RV afterload, improve RV-LV coupling, restore pulmonary perfusion

Nitric Oxide (NO), Inhaled:

• Mechanism: Selective pulmonary vasodilator; increases cGMP in vascular smooth muscle → vasodilation
• Dosing: 10-20 ppm inhaled; titrate based on response
• Advantage: Pulmonary-selective (doesn’t cause systemic hypotension); rapid onset
• Monitoring: Requires specialized delivery system; metHb monitoring if prolonged use

Intravenous Prostacyclin (Epoprostenol):

• Mechanism: Prostacyclin analog; reduces PVR, improves RV function, anti-platelet effects
• Dosing: Start 2 ng/kg/min IV, titrate by 1-2 ng/kg/min q10-15 min (typical range 4-12 ng/kg/min)
• Advantages: Potent RV afterload reduction; can improve cardiac output in RV failure
• Drawbacks: Continuous IV infusion required (central line preferred); systemic hypotension, flushing, jaw pain common; short half-life (<10 min)

Inhaled Epoprostenol:

• Mechanism: Same as IV, but inhaled delivery → selective pulmonary vasodilation
• Dosing: Typically 25-50 mcg/mL, nebulized; frequency varies (q2-4h)
• Advantage: Pulmonary-selective; less systemic hypotension than IV

Milrinone (Phosphodiesterase-3 Inhibitor):

• Mechanism: Inotropic + vasodilator; increases cAMP, improves contractility and reduces PVR
• Dosing: 0.25-0.75 mcg/kg/min IV infusion
• Use in RV failure: Can improve RV-LV coupling and systemic CO; beware systemic hypotension

Intubation in Pulmonary Hypertension: The Spiral of Death

Why Intubation is Dangerous in RV Failure / PH:

• Increased Intrathoracic Pressure: Positive-pressure ventilation increases RV afterload and reduces RV venous return → decreased RV CO
• Decreased RV Coronary Perfusion: Increased intrathoracic pressure compresses RV coronary vessels; hypotension further reduces RV perfusion pressure
• RV Ischemia → Dysfunction → Shock: Initiates or worsens the spiral of death
• Acute RV Dilation: Can cause acute RV infarction and cardiogenic shock within minutes of intubation

If Intubation Unavoidable:

• Pre-intubation optimization: Maximize hemodynamics FIRST with fluids, vasopressors, inotropes, pulmonary vasodilators
• Sedation choice: Avoid propofol (systemic vasodilation); etomidate or ketamine preferred (maintain BP)
• Paralytic: Rocuronium or vecuronium; avoid histamine-releasing agents (atracurium, mivacurium)
• Ventilator strategy:
  • Lung-protective ventilation: TV 6-8 mL/kg, PEEP 5-10 cm H2O
  • Permissive hypercapnia: Allow PaCO2 to rise (target 45-55) to minimize intrathoracic pressure
  • Avoid high PEEP: Increases RV afterload; use minimum PEEP needed for oxygenation
  • Minimize I:E ratio: Shorter inspiratory time, longer expiratory time → lower mean airway pressure
• Ongoing hemodynamic support: Aggressive use of vasopressors, inotropes, and pulmonary vasodilators to prevent RV collapse

Role of ECMO: In massive PE with RV failure requiring mechanical ventilation, consider ECMO for oxygenation/support while avoiding or minimizing intubation-related RV compromise

Pressor & Inotrope Selection in RV Failure

Goal of Hemodynamic Support: Maintain adequate systemic perfusion pressure (MAP ≥65 mmHg) while minimizing RV afterload and preserving RV coronary perfusion

Norepinephrine:

• Mechanism: α > β effects at typical doses; increases systemic vascular resistance and contractility
• Use in RV failure: PREFERRED pressor; maintains MAP and RV perfusion pressure; modest increase in PVR at high doses (acceptable trade-off)
• Dosing: Start 0.05 mcg/kg/min IV, titrate to target MAP ≥65 mmHg (typical range 0.1-1 mcg/kg/min)

Dopamine:

• Mechanism: Dose-dependent: At low doses (2-5 mcg/kg/min), dopaminergic (renal/mesenteric vasodilation); at 5-10 mcg/kg/min, β effects (inotropic); at >10 mcg/kg/min, α effects (vasoconstriction)
• Use in RV failure: Low-dose dopamine (2-5 mcg/kg/min) can be used as adjunct but inferior to norepinephrine alone; high-dose dopamine increases PVR (detrimental)

Epinephrine:

• Mechanism: α and β effects; significant inotropic and vasoconstrictive properties
• Use in RV failure: Increases systemic BP and contractility; can worsen PVR at high doses; reserve for refractory cardiogenic shock or cardiac arrest
• Dosing: 0.05-2 mcg/kg/min IV titrated to hemodynamic response

Dobutamine:

• Mechanism: β1-predominant (inotrope) with some α effects and β2 effects (vasodilation)
• Use in RV failure: CAUTION—beta-2 effects can cause systemic hypotension; net effect may be decreased MAP despite improved contractility. Useful only if adequate MAP already present.
• Dosing: 2.5-10 mcg/kg/min IV; higher doses increase risk of hypotension and arrhythmia

Milrinone:

• Mechanism: Phosphodiesterase-3 inhibitor; increases cAMP → inotropic effect + systemic/pulmonary vasodilation
• Use in RV failure: Improves RV contractility and reduces PVR (beneficial); BUT causes systemic hypotension (detrimental). Best combined with norepinephrine for blood pressure support.
• Dosing: 0.25-0.75 mcg/kg/min IV infusion

Inhaled Pulmonary Vasodilators + Pressors: Often use inhaled NO or epoprostenol IN COMBINATION with systemic vasopressor (norepinephrine) to reduce PVR without systemic hypotension

Prostacyclin Pump Management Pearls

Context: Patients on chronic IV epoprostenol therapy for idiopathic/heritable PAH often present to ED for acute decompensation or with pump/line complications

Common Presentations:

• Acute PH exacerbation: Often due to pump malfunction, line infection (tunneled central line sepsis), inadequate dosing, or medication error
• Pump failure / line clot: Results in acute loss of vasodilator → acute RV failure and shock
• Line infection (sepsis): Fever, signs of sepsis; risk of bacteremia, endocarditis

ED Approach:

• Verify pump status: Is the pump running? Check battery, medication reservoir, infusion rate. Contact patient’s PH specialist/anticoagulation clinic if unsure.
• If pump is off or line is occluded: Do NOT rely on ED staff to restart—coordinate with patient’s PH center for restart protocol. Can temporize with IV epoprostenol from ED pharmacy if available and if trained staff can run line.
• Acutely decompensated patient: Support with supplemental O2, IV fluids (cautiously), pressors (norepinephrine), and consider inhaled NO or IV prostacyclin via peripheral line as bridge.
• Line infection suspected: Blood cultures, broad-spectrum antibiotics; urgent cardiothoracic or vascular surgery consultation for line management.
• Contact patient’s PH center: They often have protocols for emergency support and may guide dosing of temporary IV therapy.

Key Points:

• Abrupt cessation of IV epoprostenol is life-threatening (rebound PH crisis)
• ED staff should NOT attempt to change infusion pump settings without specialist input
• Arrange urgent consultation with patient’s PH team and possible ICU/cardiothoracic backup
• Do not delay hemodynamic support (pressors, oxygen, fluids) while awaiting specialist consultation