Pulmonary embolism and air embolism
Stem
Monitors and echo station. A 64-year-old man, 96 kg, six days after a pelvic fracture, is under general anesthesia for external fixator revision. Suddenly the monitor shows:
A rescue TEE is placed. The ME four-chamber loop shows a dilated RV, larger than the LV, with a hypokinetic free wall and a contracting apex, and a small, hyperdynamic LV. The septum bows into the LV.
Question
What does the echo show, and what do you do?
Ideal answer
What the monitor showed: end-tidal CO2 fell from 36 to 19 mmHg with a normal waveform and pressure from 124/72 to 70/40; rhythm and saturation held.
HeadlineAcute RV pressure overload; with this capnogram and pressure in an immobilized trauma patient, massive pulmonary embolism until proven otherwise. I call for help, tell the surgeon to stop.
- RV first, then septum, then LV. RV dilated and hypokinetic, an atypical free-wall pattern with a preserved apex, septum pushed into an underfilled LV: the ASE findings for acute PE;1 RV base above 41 mm is dilated.2
- Look for clot. The ME ascending aortic short-axis and RV inflow-outflow views can show thrombus in the main or right pulmonary artery or in transit.1
- 100% oxygen; norepinephrine and an inotrope; no more fluid. Avoid hypoxemia, hypercarbia and acidosis, which raise pulmonary vascular resistance.
- Discuss reperfusion now. Mid-surgery after recent trauma, thrombolysis carries a high bleeding risk; surgical or catheter-based embolectomy is the alternative, especially with clot in transit.3
Breaking down the answer
PE and air embolism are both on the outline's echo diagnosis list, and the station uses 2D and color flow Doppler only, with no pulsed- or continuous-wave Doppler.4
| Finding | View | Meaning |
|---|---|---|
| RV dilated, basal diameter >41 mm | ME four-chamber or RV-focused apical2 | Pressure or volume overload |
| Free-wall hypokinesis with a preserved apex | ME four-chamber | Atypical RV regional pattern of acute PE1 |
| Septum flattened toward the LV (D-shape) | TG mid-papillary SAX | RV overload; diastolic flattening = volume, systolic = pressure5 |
| Thrombus in the main or right PA | ME ascending aortic SAX and LAX | Direct evidence of central PE1 |
| Bright, swirling echoes in RA and RV | ME four-chamber, bicaval | Venous air1 |
| Bubbles in the LA within 3–6 beats of RA opacification | ME four-chamber or bicaval | Intracardiac right-to-left shunt5 |
- Sensitivity is about the RV, not the clot — direct visualization of thrombus by TEE is insensitive, while signs of RV dysfunction pick up the hemodynamically significant PE.1 I do not need to see clot to act.
- A dilated RV is not specific — RV enlargement lacks both sensitivity and specificity for PE, so I integrate it with the capnogram, the pressure and the clinical setting.6 Chronic pulmonary hypertension also dilates the RV.
- Air: TEE is the most sensitive monitor — it detects even hemodynamically trivial bubbles, which lets me act before air becomes a problem.1
- Why fluid hurts — a fluid bolus into a pressure-overloaded RV pushes the septum further left and lowers LV filling.
Follow-up question
Second scenario: a 47-year-old woman in the sitting position for posterior fossa craniotomy. The monitor shows:
The ME four-chamber loop shows bright echoes swirling in the RA and RV, and a few seconds later the same echoes appear in the LA and LV. What does this mean, and what do you do?
Follow-up answer
What the monitor showed: end-tidal CO2 fell by 10 mmHg, from 34 to 24, with pressure, rhythm and saturation unchanged.
HeadlineVenous air embolism with paradoxical passage into the left heart, likely across a patent foramen ovale; I tell the surgeon immediately.
Field flooded with saline and bone edges waxed, nitrous oxide off, 100% oxygen.7 Fluid and epinephrine as needed; aspirating air through a central line has no clear benefit and must not delay support.7 If she arrests, ACLS, temporary wound closure and repositioning, because CPR in the sitting position is difficult.7 I watch the loops for air clearing and new wall motion abnormalities, since brain and coronaries are at risk. Afterward, a documented neurologic exam, and I consider hyperbaric oxygen for any deficit, ideally within six hours.7
Pitfalls that cost points
- Missing the left-sided bubbles that change air embolism into a stroke risk.
- Describing the LV first and calling a small hyperdynamic LV hypovolemia.
Rapid-fire
Q: Which three views does the ASE ask a basic echocardiographer to use for PE? A: ME four-chamber, ME ascending aortic short-axis and ME RV inflow-outflow.1
Q: How common is air on TEE during sitting craniotomy? A: Up to 76% of cases, though few are hemodynamically significant.1
Q: Bubbles in the LA after more than six beats suggest what? A: Intrapulmonary shunting, such as an arteriovenous malformation, rather than an intracardiac shunt.5
Q: How much air is lethal? A: Estimates range from 50 to 500 mL; rapid entrainment is lethal at smaller volumes.7
Numbers to know
| Item | Value |
|---|---|
| RV basal diameter, dilated | >41 mm2 |
| RV mid-cavity, dilated | >35 mm2 |
| Air on TEE, sitting craniotomy | Up to 76%1 |
| Bubble timing, intracardiac shunt | Within 3–6 beats5 |
| Hyperbaric oxygen window | Ideally within 6 h7 |
Links
- The 11 TEE views, Ventricular function and wall motion, Venous air embolism and the sitting position, Atrial septal defect and aortic dissection, Monitor atlas: other perioperative and peripartum events
- Atlas: The 11 TEE views; The 5 POCUS cardiac views
- ASE/SCA Basic Perioperative TEE consensus statement (2013); 2019 ESC and 2026 AHA/ACC pulmonary embolism guidelines
Sources
- 1.Basic Perioperative Transesophageal Echocardiography Examination: A Consensus Statement · ASE/SCA, 2013 · asecho.orgSections 'Pulmonary Embolism (PE)' and 'Neurosurgery: Air Embolism'.
- 2.Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and EACVI · ASE/EACVI, 2015 · asecho.orgSection 7, RV dimensions.
- 3.Intervention in Acute Pulmonary Embolism: A Comparison of the 2026 AHA/ACC and 2019 ESC Guidelines · JACC Advances (Zuin, Piazza et al.), 2026 · ebi.ac.ukOpen-access full text (PMC13400101) via Europe PMC.
- 4.APPLIED Exam Objective Structured Clinical Examination (OSCE) Content Outline · ABA · theaba.org
- 5.Guidelines for the Echocardiographic Assessment of Atrial Septal Defect and Patent Foramen Ovale · ASE/SCAI, 2015 · asecho.org
- 6.Focused Cardiac Ultrasound: Recommendations from the American Society of Echocardiography · ASE, 2013 · asecho.org
- 7.Venous Air Embolism · OpenAnesthesia (IARS) · openanesthesia.org
Facts on this page were checked against these sources on Oct 15, 2026. Guidelines change; confirm doses against current institutional protocols.