Pulmonary embolism
Stem
A 74-year-old woman, 70 kg, is having a hip hemiarthroplasty under general anesthesia three days after a fall. Minutes after she is turned into the lateral position, end-tidal CO2 falls from 36 to 19 mmHg, SpO2 drops to 86% on FiO2 0.5, blood pressure is 70/38 and heart rate 126. Airway pressures are unchanged. A quick transthoracic look shows a dilated right ventricle with a flattened septum and an underfilled left ventricle.
Question
What is your diagnosis, and how will you manage her?
Ideal answer
HeadlineHigh-risk pulmonary embolism until proven otherwise. I call for help and the code cart, have the surgeon stop and pack, and give 100% oxygen.
- Norepinephrine first, to support, not load, the right ventricle: it restores RV coronary perfusion; I add an inotrope such as dobutamine or epinephrine if output stays low.1
- Fluid only in small echo-guided aliquots, because volume loading can overdistend the right ventricle and lower output.1
- Modest airway pressures and PEEP, because positive pressure cuts venous return.1
- Unfractionated heparin, because it is the anticoagulant for an unstable patient heading toward reperfusion.2
- Activate the PE response team: systemic thrombolysis is the standard for high-risk PE, but with a fresh surgical wound I discuss surgical embolectomy, catheter-directed therapy or VA-ECMO with cardiology and cardiac surgery.2,1
Watch for: Arterial line; the right ventricle, end-tidal CO2 and lactate.
Breaking down the answer
- Name the risk class — abrupt fall in end-tidal CO2, hypoxemia, systolic below 90 and an acutely dilated RV after three days of immobility.3 Instability (arrest, obstructive shock: systolic below 90 or pressors despite filling, or persistent hypotension) makes her high risk and decides reperfusion.3
- The differential is short but real — fat or cement embolism, air embolism, tension pneumothorax, anaphylaxis and MI; unchanged airway pressures argue against pneumothorax and bronchospasm, and a dilated RV supports a right-sided cause.
- Embolectomy when lysis is barred or fails — surgical embolectomy for patients who cannot have or fail thrombolysis, catheter-directed treatment as an alternative; thrombolysis itself is reserved for high-risk patients.2
- ECMO bridges — VA-ECMO rapidly unloads the right ventricle while a decision is made, although its effect on mortality is uncertain.1
- Echo earns its place — an RV/LV ratio of 1.0 or more and TAPSE below 16 mm carry a poor prognosis.2
Follow-up question
While cardiac surgery is on the way, she loses her pulse; the monitor shows a narrow-complex rhythm at 60 with no arterial waveform. ECMO is at least 45 minutes away.
What now?
Follow-up answer
HeadlinePEA arrest from a presumed massive PE; I say so aloud and start high-quality CPR, running ACLS with epinephrine.
I name a recorder and a timekeeper. Without clot lysis her chance of survival is very low, so the surgical bleeding risk no longer outweighs the benefit. With a strongly suspected PE and no rapid route to ECMO, I give a thrombolytic during CPR, because she has no absolute contraindication.4 Once it is given, I commit to prolonged CPR, warn the surgeon to expect wound bleeding and pack it, and prepare blood products. If she regains circulation, I keep the norepinephrine and inotrope, move her to the cath lab or ICU, and reassess the RV with echo.
Pitfalls that cost points
- Intubating or raising PEEP in an unstable PE patient without having pressors and code drugs ready.4
- Forgetting the bedside echo, which separates PE from the other causes of sudden collapse.
Rapid-fire
Q: What is the alteplase dose for massive PE? A: 100 mg IV over 2 hours.5
Q: When do you start heparin after alteplase? A: Near the end of or right after the infusion, once the aPTT is twice normal or less.5
Q: Name absolute contraindications to alteplase in PE. A: Active internal bleeding, recent stroke, intracranial or intraspinal surgery or serious head trauma within 3 months, bleeding diathesis and severe uncontrolled hypertension.5
Q: Which anticoagulants are preferred for a stable patient? A: LMWH or fondaparinux over UFH, and a DOAC over a vitamin K antagonist when eligible.2
Q: What does a sPESI of 0 mean? A: Low 30-day mortality risk.3
Numbers to know
| Item | Value |
|---|---|
| Obstructive shock | SBP <90 mmHg or pressors to keep ≥903 |
| RV/LV ratio, poor prognosis | ≥1.02 |
| TAPSE, poor prognosis | <16 mm2 |
| Alteplase for PE | 100 mg IV over 2 h5 |
| Anticoagulation after alteplase | When aPTT ≤2× normal5 |
| VA-ECMO survival in severe PE | 38–67%1 |
Links
- Intraoperative hypotension: differential and management, Vasopressors and inotropes: choosing and titrating, Venous air embolism and the sitting position, ACLS adapted to the operating room, Intraoperative cardiac arrest: care after return of circulation
- Atlas: Pulmonary embolism and air embolism; Capnography: waveforms and sudden loss of ETCO2
- 2019 ESC/ERS Guidelines for acute pulmonary embolism
Sources
- 1.Mechanical Circulatory Support Devices in Patients with High-Risk Pulmonary Embolism · Journal of Clinical Medicine, 2024 · pmc.ncbi.nlm.nih.govEllauzi et al. J Clin Med 2024;13(11):3161.
- 2.2019 ESC Guidelines for the Diagnosis and Management of Acute PE (key points) · American College of Cardiology, 2020 · acc.org
- 3.2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism · ESC/ERS (Eur Heart J 2020;41:543–603), 2019 · academic.oup.comDefinitions of haemodynamic instability (Table 4) and risk stratification; the fetched text did not include the treatment sections.
- 4.Management of Moderate to High-Risk Pulmonary Embolism · University of Maryland Emergency Medicine (UMEM Educational Pearls), 2024 · medschool.umaryland.edu
- 5.Activase (alteplase) prescribing information · FDA label (Genentech), via drugs.com · drugs.com
Facts on this page were checked against these sources on Oct 15, 2026. Guidelines change; confirm doses against current institutional protocols.