📚 Guideline basis
ASE 2025 diastolic function update (JASE 2025;38:537–69); ERS/ATS/ESICM/SCCM/SRLF statement on weaning from mechanical ventilation; Teboul, Monnet and colleagues on weaning-induced pulmonary oedema; ESICM 2025 haemodynamic recommendations.
Pathophysiology & Mechanisms
The transition from positive-pressure ventilation to spontaneous breathing is a cardiovascular stress test, and it is the reason a substantial fraction of weaning failure is cardiac rather than respiratory in origin.
Four simultaneous changes occur at the moment ventilatory support is withdrawn:
- Venous return increases. Intrathoracic pressure swings from positive to negative, raising the pressure gradient for systemic venous return and increasing RV preload — and therefore LV preload, two to three beats later.
- LV afterload increases. Negative intrapleural pressure raises LV transmural pressure for any given arterial pressure. The ventricle must generate more wall stress to eject the same stroke volume:
P_transmural = P_LV - P_pleuralWith pleural pressure at −10 cmH₂O instead of +5, the transmural pressure the ventricle must overcome rises substantially.
- Work of breathing rises, increasing total oxygen consumption — in some patients from around 5% to over 25% of total VO₂ — and demanding a rise in cardiac output at the same time that afterload has risen.
- Sympathetic activation with tachycardia, hypertension and increased venous return from the splanchnic reservoir, driven by anxiety, hypercapnia and the work of breathing.
A normal heart absorbs all four. A ventricle with reduced compliance, ischaemic reserve limitation, or significant valvular disease cannot: LV end-diastolic pressure rises, left atrial pressure rises, and pulmonary oedema develops within minutes of a trial that the lungs themselves could have tolerated.
The chain is: increased preload + increased afterload + increased demand → rising LVEDP → rising LAP → hydrostatic pulmonary oedema → increased work of breathing → further sympathetic drive. It is self-reinforcing, and it resolves within minutes of resuming positive-pressure ventilation — which is precisely why it is missed.
Clinical Phenotypes
Weaning-induced pulmonary oedema (WIPO) is a leading cardiac cause of failure in difficult-to-wean patients, identified in a large proportion of weaning failures in cohorts selected for repeated failed trials. It should be actively excluded rather than diagnosed by chance.
Risk factors: known LV systolic or diastolic dysfunction, chronic obstructive pulmonary disease (large inspiratory pleural pressure swings), obesity, significant mitral or aortic valve disease, coronary disease, chronic kidney disease, and a positive cumulative fluid balance.
The clinical presentation — tachypnoea, tachycardia, hypertension, agitation and desaturation late in a spontaneous breathing trial — is indistinguishable at the bedside from respiratory failure of any other cause. The distinction is made by measurement, not by observation.
Diagnostic Synthesis
Protocol
The examination is a paired study, and the pairing is the whole point.
Timing | Acquire |
Baseline, on ventilator support, immediately before the trial | LVEF, LVOT VTI, mitral inflow E and A, mitral annular e′ (septal and lateral), E/e′, TR peak velocity, IVC, lung ultrasound (B-line count in 8 zones), diaphragm thickening fraction |
During the trial, at 10–30 minutes or at the moment of clinical failure | Repeat all of the above at the point of failure — not after resuming support, when the physiology has already reversed |
The single most common protocol failure is scanning after the patient has been put back on the ventilator. WIPO resolves in minutes.
Findings that establish WIPO
Parameter | Change indicating WIPO |
E/e′ | Rise to > 14 (or a marked rise from baseline); the central parameter |
E/A ratio | Rise, often to > 1 or beyond, indicating a shift toward a restrictive filling pattern |
Mitral E velocity | Rise |
TR velocity / PASP | Rise, reflecting the increase in post-capillary pressure |
Lung ultrasound B-lines | Appearance or increase in bilateral B-lines — a direct measure of rising extravascular lung water |
LVOT VTI | May fall (afterload mismatch) or rise (sympathetic drive); not discriminating alone |
LVEF | Often unchanged — a normal EF does not exclude WIPO, since the mechanism is diastolic and afterload-related |
Non-echo corroboration | Rise in haemoglobin/protein concentration (haemoconcentration from fluid transfer into the alveoli); fall in central venous oxygen saturation |
A normal E/e′ that does not change during a failed trial argues strongly against WIPO and redirects attention to the alternative causes below.
Other echocardiographic causes of weaning failure
Cause | Findings | Action |
Dynamic LVOT obstruction | SAM, dagger-shaped late-peaking LVOT envelope appearing during the trial; posteriorly directed MR; driven by sympathetic surge and hypovolaemia | Volume, beta-blockade, stop inotropes (Chapter 28) |
Unmasked or worsening mitral regurgitation | Increased regurgitant volume with the rise in afterload | Afterload reduction |
RV failure | Rising RV:LV, septal shift; the transpulmonary gradient rises with spontaneous effort in a compromised RV | RV-protective strategy; may require ongoing support |
Myocardial ischaemia | New regional wall motion abnormality during the trial | ECG, troponin, anti-ischaemic therapy |
Diaphragm dysfunction | Diaphragm thickening fraction reduced; excursion reduced (Chapter 41) | Not cardiac; different pathway |
Recognising that a patient has more than one mechanism is common and clinically important — WIPO and diaphragm weakness frequently coexist.
ICU-Specific Limitations
Confounder | Effect | Response |
Tachycardia with E–A fusion | E/A unmeasurable; E/e′ still obtainable | Use E/e′ and TR velocity; note fusion |
Atrial fibrillation | The ASE 2025 main algorithm excludes AF | Use the AF-specific indicators (Chapter 8): short deceleration time, IVRT ≤ 65 ms, septal E/e′ ≥ 11, TR velocity > 2.8 m/s |
Mitral annular calcification, prosthesis, mitral repair | E/e′ unreliable | Use IVRT-based indices and lung ultrasound B-lines |
RV pressure overload with septal flattening | Septal e′ mechanically depressed, inflating septal E/e′ | Use lateral E/e′ |
Timing | The physiology reverses within minutes of resuming support | Scan at the moment of failure |
Operator availability | The trial and the sonographer must coincide | Schedule the trial around the study, not the reverse |
⚠️ Evidence quality
The 2025 ASE diastolic algorithm was validated in ambulatory and acute hospital-care adults in sinus rhythm and explicitly excludes the intraoperative setting; it was not validated during spontaneous breathing trials. The use of an E/e′ rise to diagnose WIPO rests on a physiologically coherent and reasonably consistent ICU literature, not on a society guideline recommendation.
Therapeutic Logic
Once WIPO is identified, the interventions are specific and effective.
Intervention | Rationale | Endpoint |
Diuresis / negative fluid balance | Reduces preload and the pressure the stiff ventricle must accommodate | Falling baseline E/e′; resolving B-lines; successful subsequent trial |
Afterload reduction — nitrates, ACE inhibition | Directly addresses the transmural pressure mechanism | Improved tolerance of the next trial |
Rate and rhythm control | Preserves diastolic filling time and the atrial contribution | Heart rate 60–90/min in sinus rhythm |
Treat ischaemia | New RWMA during the trial indicates demand ischaemia | Anti-ischaemic therapy; consider revascularisation |
Beta-blockade (selected patients) | For dynamic obstruction or ischaemia; also improves diastolic filling | Resolution of the LVOT gradient |
Prophylactic non-invasive ventilation after extubation | Restores positive intrathoracic pressure, reducing preload and afterload during the vulnerable period | Successful extubation in at-risk patients |
Re-test with objective measurement | Confirms the intervention worked | E/e′ stable and B-lines absent during the repeat trial |
Simply repeating an identical trial after a WIPO failure, without treating the mechanism, produces an identical failure and delays liberation.
🛑 Critical pitfall: Scanning after the patient has been returned to the ventilator. The diagnostic window closes within minutes and the study will be normal.
🛑 Critical pitfall: Excluding a cardiac cause of weaning failure because the ejection fraction is normal. WIPO is predominantly a diastolic and afterload phenomenon and occurs with a normal EF.
🛑 Critical pitfall: Repeating failed trials without an explanation. A patient who has failed three trials needs a paired echocardiographic and lung ultrasound assessment, not a fourth trial.
- 💡 Clinical pearl: Pair the echocardiogram with a lung ultrasound B-line count. Two independent measurements of the same physiology, and the B-line count is the easier one to hand over to the nursing team.
- 💡 Clinical pearl: Establish the baseline before the trial starts. A single measurement at the point of failure, with no comparator, is far weaker evidence.
- 💡 Clinical pearl: If WIPO is confirmed, the next trial should follow a period of negative fluid balance and afterload reduction — the intervention is highly effective and materially shortens ventilator days in this population.
References
- Nagueh SF, Sanborn DY, Oh JK, et al. Recommendations for the evaluation of LV diastolic function by echocardiography and for HFpEF diagnosis: an update from the ASE. J Am Soc Echocardiogr 2025;38:537–69.
- Boles JM, Bion J, Connors A, et al. Weaning from mechanical ventilation. Eur Respir J 2007;29:1033–56.
- Teboul JL. Weaning-induced cardiac dysfunction: where are we today? Intensive Care Med 2014;40:1069–79.
- Liu J, Shen F, Teboul JL, et al. Cardiac dysfunction induced by weaning from mechanical ventilation: incidence, risk factors and effects of fluid removal. Crit Care 2016;20:369.
- Dres M, Teboul JL, Anguel N, et al. Extravascular lung water, B-type natriuretic peptide, and blood volume contraction enable diagnosis of weaning-induced pulmonary edema. Crit Care Med 2014;42:1882–9.