Part II — VV ECMO · Chapter 5
Evidence search date: 6 September 2026. Cannulation is the part of ECMO where formal evidence is thinnest and expert technique description is richest. Almost everything here is expert practice or physiological rationale, drawn from primary technique sources and labelled as such. Where a number is quoted, its source is named.
Currency warning — the ELSO ultrasound guidance document has lapsed
ELSO's Ultrasound Guidance for Extracorporeal Membrane Oxygenation — General Guidelines (Nanjayya and Murphy; editors Brechot, Fan, Pellegrino, Brodie) is dated May 2015 and carries its own expiry: "This document is scheduled to expire by May 2018. After this date, users are encouraged to contact the ELSO Guidelines Editorial Board to confirm that this document remains in effect."
It is now more than eight years past that date, and it does not appear on the ELSO guidelines index as at this chapter's search date. Its content remains sound physiology and sound practice — it is used throughout this chapter — but it should be cited as expired guidance, not as current ELSO policy.
Clinical Question
The decision to cannulate has been made. What is the safest sequence from ultrasound probe to running circuit — and which steps are the ones that actually injure patients?
Why This Matters
Cannulation is the highest-risk ten minutes of an ECMO run, and the risk is concentrated in a small number of steps. Chapter 3 established what determines flow and Chapter 4 established who should be cannulated; this chapter is about the part where a needle, a wire and a series of dilators enter a critically ill, often coagulopathic patient.
Two features make it unusual. First, most of the serious harm is mechanical and immediate — a wire in the wrong chamber, a dilator through a vessel wall, a cannula in the hepatic vein — and is therefore preventable by technique rather than by monitoring. Second, the operator is frequently working under time pressure on a patient with no physiological reserve, which is precisely when procedural discipline degrades.
Before the Needle
Step | What it involves | Why it matters |
Focused echocardiogram | Assess biventricular function, exclude pathology that changes the plan | Severe LV dysfunction in a patient presenting as respiratory failure may mean VA rather than VV. Acute cor pulmonale or proximal PA embolus changes the configuration entirely — Chapters 2 and 3 |
Vascular ultrasound survey | Right internal jugular and both femoral veins, supine; Trendelenburg if the jugular is not distended by positive-pressure ventilation | Identifies the vessels, maps anatomical variation, and measures diameter for cannula selection |
Cannula selection | Size from the measured vessel and the required flow | See the sizing rule below — and Chapter 3 for why radius dominates flow |
Kit and team | Micropuncture set, superstiff guidewire, dilators, cannulae, primed circuit, sutures; a named operator, a named assistant for the wire, and someone running the checklist | The commonest avoidable delay is a missing wire or dilator once the field is open |
Anticoagulation timing | Heparin is usually given after the micropuncture sheath is in place | Anticoagulating before access is secured converts a failed puncture into a bleeding complication (ELSO Red Book, 6th ed.) |
Imaging plan | Decide in advance: transthoracic echo, transoesophageal echo, or fluoroscopy — and who is driving it | Image guidance is mandatory for a bicaval dual-lumen cannula. Deciding this mid-procedure wastes the time you do not have |
Physiology — the sizing rule, and why it is a ceiling
The ELSO ultrasound document gives the conversion directly: French gauge of cannula = 3 × vessel diameter in mm. This follows from the French scale itself (3 Fr = 1 mm, Chapter 3), so what the formula actually returns is the cannula size that would exactly fill the vessel.
That is the ceiling, not the target. Chapter 3's principle applies: blood must be able to pass around the cannula. A cannula that occupies the whole lumen produces venous hypertension, stasis, thrombosis and deep venous obstruction — and on the arterial side, the ischaemic limb.
Worked example. A right common femoral vein measured at 9 mm: 3 × 9 = 27 Fr would exactly fill it. The correct choice is the largest cannula comfortably below that which still meets the flow target on the manufacturer's pressure–flow curve. In practice, "a 25 Fr multistage cannula should suffice in most adults" for venous drainage (ELSO Red Book, 6th ed.).
Danger — bigger is not safer, even when flow is the problem
For bicaval dual-lumen cannulae the ELSO Red Book is explicit: "The smallest cannula which will provide adequate support should be chosen because there is a higher incidence of intracranial bleeding with the larger sizes, probably related to venous obstruction."
This is the counterweight to Chapter 3's radius-to-the-fourth-power arithmetic. Upsizing buys flow; it also buys venous obstruction, and in the neck that obstruction has an intracranial consequence. Size for the flow you actually need, not the flow you might one day want.
Access: What Ultrasound Prevents
The expired-but-sound ELSO ultrasound document organises the whole procedure into three phases — before, during and after initiation — and is specific about what real-time guidance prevents during access:
- Inadvertent arterial puncture
- Sapheno-femoral junction cannulation
- Transfixation of the inguinal ligament
It makes two further points that deserve emphasis. First, ultrasound is "of immense value in cannulation during a pulseless circulatory state like cardiopulmonary resuscitation, when it is impossible to differentiate between the artery and vein using palpation" — the ECPR case, Chapter 21. Second, femoral vascular anatomy is highly variable, so "relying on blind techniques using surface anatomy is frequently inadequate to prevent complications." The ECPR literature makes the same observation from the surgical side: the femoral vessels frequently lie directly on top of one another.
Clinical Pearl
Use the longitudinal (in-plane) view for the puncture where you can. It shows the needle tip throughout its course and is the view that prevents transfixion of the posterior wall — the mechanism behind most retroperitoneal bleeds. A single clean anterior-wall puncture, on the axis of the vessel, is the single most protective thing an operator does.
For the internal jugular, the ELSO Red Book advises a micropuncture system and, where possible, a needle path anterior to the sternocleidomastoid, which facilitates dilatation of the tract and reduces haematoma formation.
The Wire Is the Procedure
More serious cannulation injuries are caused by the guidewire and the dilators than by the needle. The rules below are technique-source consensus, and they are worth treating as non-negotiable.
Rule | Detail | What it prevents |
Confirm the wire path before dilating | Visualise the J-loop in the IVC (subcostal view) or, with fluoroscopy, confirm it in the intrahepatic veins or running down the contralateral leg | Ventricular wire placement, arrhythmia, and dilatation into the wrong structure |
Use a superstiff wire | Easier to screen into the IVC and a better conduit for dilatation than the standard kit wire | Kinking, loss of tract, failed dilatation |
Wire size matches the cannula | Adult cannulae take an 0.038 inch wire; paediatric cannulae are sized for 0.025 inch and use quarter-inch connectors | Mid-procedure discovery that the wire will not pass |
Skin incision smaller than the cannula | Large enough to admit the tapered dilator tip, no larger — so the skin grips the cannula | Cannula migration and cannulation-site infection |
Dilate to one size below the cannula | Often achievable in a single pass with gently tapered dilators over a superstiff wire; otherwise revert to serial dilation | Vessel tearing from over-dilatation; failure to pass from under-dilatation |
The wire must move freely at all times | Hold the wire in one hand and the dilator or cannula in the other, so you feel it start to drag | Kinking — the point at which the tract is lost and the vessel is at risk |
Danger — the transtricuspid right ventricular wire loop
When a guidewire passes from the jugular through the tricuspid valve and loops in the right ventricle, dilating over it drives a rigid dilator into the RV free wall. The ELSO Red Book describes this outcome as having "potentially disastrous consequences", and it is the specific reason fluoroscopy is considered the ideal modality for bicaval dual-lumen placement: it shows the entire wire in one image, which echocardiography cannot.
The defence is positive confirmation, not absence of resistance: see the wire in the IVC before any dilator touches the skin. For a dual-lumen cannula, the wire should be advanced through the intrahepatic IVC to about the level of the iliac bifurcation — far enough to avoid hepatic vein cannulation and to prevent dislodgement while the cannula is railroaded.
Configuration-Specific Technique
Two-site femoro-jugular
The default, and the most forgiving. Drainage from the femoral vein with the tip at or near the cavo-atrial junction; return via the internal jugular with the tip in the SVC or upper right atrium. Image guidance is not mandatory for single-lumen jugular or femoral insertion, though the Red Book encourages it.
A useful sequencing point: the venous cannula can be connected to the circuit as soon as it is placed. This allows transfusion through the cannula, displaces static blood in the lumen and so reduces clot formation, and gives a route for volume if the second cannulation becomes complicated.
Advance the drainage cannula so the tip sits mid-right atrium or at the RA/SVC junction, then remove dilator and wire, de-air, clamp, and secure to the skin with multiple sutures.
Bicaval dual-lumen, single site
Originally described by Zwischenberger and Wang. Drainage from both the SVC and IVC through one cannula, with the return port aimed at the tricuspid valve — the separation of drainage and return flows is what produces the very low recirculation Chapter 3 quantified.
Step | Detail |
Access | Right internal jugular is the design intent. Left jugular or left subclavian are feasible if the target vessel and innominate vein are large enough |
Image guidance | Mandatory. Fluoroscopy is the consensus ideal; TOE is a reported alternative with good experience. The expired ELSO ultrasound document states that TOE is necessary for bicaval dual-lumen cannulation if an image intensifier is not being used |
Wire | Superstiff, through the intrahepatic IVC to approximately the iliac bifurcation |
Depth and rotation | Accurate insertion depth and radial orientation are both essential for function. Radiopaque markers on the drainage and reinfusion ports aid initial placement and ongoing orientation checks |
Confirmation | TOE demonstration of the reinfusion jet crossing the tricuspid valve is the functional endpoint, not merely a tip position |
Sizing | Smallest cannula that provides adequate support — see the intracranial bleeding warning above |
Clinical Pearl — the left subclavian route
The left subclavian gives "a particularly comfortable fixation and is popular for long-term support such as bridge to lung transplantation" (ELSO Red Book). If Chapter 4's answer to "what is the destination?" was transplant, the access decision should reflect a run measured in weeks, with mobilisation as a goal — not simply the fastest route today.
Clinical Pearl — cannulating alongside an existing line
A dual-lumen cannula can be placed next to an in-situ internal jugular line, or the line can be wire-exchanged for it. Two practical constraints: if the existing line's distal lumen is smaller than 18G, an 0.038 inch wire will not pass and a staged approach with a smaller wire is needed; and if that line is carrying the only vasopressor infusion, establish alternative access and double-pump the infusion first if time allows.
Percutaneous, Cutdown, or Hybrid
Technique | How | Advantages | Disadvantages |
Percutaneous (Seldinger) | Ultrasound-guided puncture, wire, serial dilation, cannula. Preferred in adults and children over ~10 kg | Bedside; no vessel ligation; fewer bleeding complications; fastest in experienced hands | Blind to the vessel wall; hazardous where vessel calibre is unusually small; failure requires rescue |
Surgical cutdown | Vessel exposed, ligatures placed, venotomy or arteriotomy, cannula inserted — or an end-to-side graft with the cannula in the graft | Proper sizing under vision; certainty of intraluminal placement; vessel injury seen as it happens | Surgical-site bleeding; surgical repair needed at decannulation; vessel obstruction if ligated — avoidable with an end-to-side graft |
Hybrid / modified Seldinger | Small incision exposes the vessel; needle puncture made distal to the incision creating a subcutaneous tract; access obtained under direct vision; skin closed around the cannula | Direct visual identification of vein from artery — decisive where vessels overlie one another; higher chance of a single puncture; workable without imaging, including pre-hospital; a fallback in obesity and atherosclerosis | Still a wound; bleeding can relapse once the pump is started |
Evidence — cannulation failure rates, from the ECPR literature
The ECPR setting is where cannulation technique has been measured most explicitly, because time to flow is an outcome. Reported figures, as collated in ECPR and Resuscitative ECMO: hybrid cutdown with a mean implementation time of 21.3 minutes and a 7.6% failure rate; ultrasound-guided percutaneous with a median 19 minutes and 14.5% failure (Chhor et al); and 8% of ultrasound-guided percutaneous cannulations requiring conversion to a surgical approach (Kashiura et al), with failure falling when ultrasound was combined with fluoroscopy.
Certainty: low. Small single-centre series, different populations, no randomised comparison of techniques. The consistent signal is that adding a second imaging modality reduces failure, and that a team competent in more than one technique fails less often.
Pitfall — the second technique you never practise
Every series above reports a failure rate. Failure is not rare, and it arrives in the worst patients: obese, atherosclerotic, hypovolaemic, or under chest compressions. A programme whose operators can only do one technique has no plan for those patients. Decide in advance who converts, to what, and when — not at the point of failure.
Confirming Position
Modality | What it shows well | Limitation |
Fluoroscopy | The entire wire in one image; cannula advancement in real time; kinking | Requires screening equipment and often a move out of the ICU or a mobile intensifier |
Transthoracic echo | Wire in the IVC (subcostal); tip position; pericardial collection | Windows are frequently poor in exactly these patients — ventilated, oedematous, high PEEP |
Transoesophageal echo | Bicaval views; dual-lumen depth and orientation; the reinfusion jet across the tricuspid valve; tamponade | Cannot show the whole wire at once; needs an operator and a probe at the bedside |
Chest and abdominal radiograph | Gross cannula course; gross malposition | The distal end of an ECMO cannula is radiolucent and the tip is frequently not visible — this is exactly why echo is required (ELSO ultrasound guidance, 2015) |
Circuit behaviour | Achievable flow, drainage pressure, chatter — the functional test | Confirms adequacy, not anatomy. A well-flowing cannula can still be in the wrong place |
Repeat echocardiography and a radiograph after initiation to confirm final position and to screen for complications.
Pitfall — treating a plain film as position confirmation
Because the distal cannula is radiolucent, a chest radiograph that "looks fine" excludes very little. If drainage is poor, or a dual-lumen cannula is underperforming, the question is answered by echocardiography — and Chapter 3's evidence says the first hypothesis should be insertion depth, not device failure.
Securing, and the Handover
Securing is not an afterthought; accidental decannulation is a circuit emergency (Chapter 35) and most of it is preventable here.
- Suture each cannula to the skin at multiple points, not one.
- Secure the circuit tubing to the patient as well, so traction on the tubing is not transmitted to the cannula — the specific mechanism behind decannulation during moves and transfers.
- Apply a compressive dressing to the access site.
- Perform a tug test where a ligature has been used surgically: the vessel should move with the cannula, without slipping.
- For runs expected to last weeks, consider tunnelling, which allows the wound to be closed.
- Mark and document the depth at the skin for every cannula, and re-check it on every round.
Clinical Pearl — the handover sentence
Chapter 3 asked for the configuration to be named at every handover. Cannulation is where that sentence is written: "VV femoro-jugular; 25 Fr multistage drainage, tip at the cavo-atrial junction, 31 cm at the skin; 21 Fr return in the SVC, 17 cm at the skin; ultrasound-guided, single puncture each; position confirmed on TOE." Everything the next clinician needs to interpret a blood gas or diagnose recirculation is in that sentence.
Complications of Cannulation
Complication | Mechanism | Recognition | Immediate action |
Arterial puncture / cannulation | Blind or landmark technique; overlying vessels | Pulsatile flow, bright blood, pressure trace on the needle | Do not dilate. Ultrasound to confirm. If a large cannula has entered the artery, do not remove it before vascular surgical review |
Vessel dissection | Wire or dilator against the wall; loss of a free wire | Resistance, failure to advance, loss of the tract | Stop. Re-image the wire. Do not force a dilator |
Retroperitoneal haemorrhage | Posterior wall transfixion, or puncture above the inguinal ligament | Unexplained hypotension and falling haemoglobin without external bleeding | Imaging, resuscitation, urgent vascular or interventional radiology involvement |
Pseudoaneurysm | Arterial wall injury at the access site | Painful pulsatile swelling; confirmed on ultrasound | Vascular assessment; may require compression, thrombin injection or repair |
Right ventricular or vessel perforation | Dilator over a transtricuspid wire loop; over-deep insertion | Sudden hypotension, tamponade physiology, new pericardial effusion | Echo immediately; surgical rescue; this is a resuscitation, not a troubleshooting exercise |
Malposition | Hepatic vein, contralateral iliac, subclavian, too shallow | Poor drainage, high recirculation, chatter, unexpected pressures | Echo, reposition over a wire; Chapter 34 |
Cannulation-site bleeding | Multiple punctures; oversized skin incision; anticoagulation | Ongoing ooze, expanding haematoma | Compression, review anticoagulation, consider a purse-string suture; Chapter 36 |
Air entrainment | Open access with negative intrathoracic pressure | Air in the circuit at initiation | Prevention: occlude the hub, use Trendelenburg for jugular access; Chapter 35 |
Venous obstruction and DVT | Cannula occupying the lumen | Limb or head-and-neck swelling; late | Correct sizing at insertion is the only reliable prevention |
(Complication mechanisms and management as described in ECMO: A Practical Guide to Management, ELSO Red Book 6th ed., and ECPR and Resuscitative ECMO.)
When Cannulation Is Not Going Well
Clinical Pearls
- See the wire in the IVC before any dilator touches the skin. This single rule prevents the worst mechanical injury in ECMO.
- Scan before you decide the cannula size, not after. The vessel diameter sets the ceiling; the flow requirement selects from below it.
- Heparin after the micropuncture sheath, not before.
- A skin incision smaller than the cannula grips it — fewer migrations, fewer site infections.
- Hold the wire and the cannula in different hands. You will feel a kink before you can see it.
- Confirm function, not just position: for a dual-lumen cannula, the endpoint is the reinfusion jet crossing the tricuspid valve.
- Document depth at the skin for every cannula, and re-check it every round.
Pitfalls
- Landmark technique at the groin, where anatomy is variable and vessels commonly overlie one another.
- Anticoagulating before access is secured.
- Dilating on the assumption that the wire is in the right place because nothing feels wrong.
- Choosing the biggest cannula the vessel will accept, rather than the smallest that delivers the required flow.
- Accepting a plain radiograph as position confirmation when the distal cannula is radiolucent.
- Securing the cannula but not the tubing.
- Having only one cannulation technique in a programme where 8–15% of attempts fail.
Controversies
Controversy — fluoroscopy or transoesophageal echo for bicaval dual-lumen placement?
Clinical question: Which imaging modality should guide insertion of a bicaval dual-lumen cannula?
Evidence supporting fluoroscopy: The ELSO Red Book states the consensus that fluoroscopy is ideal, because it shows the entire guidewire in a single image and thereby reduces the chance of a transtricuspid right ventricular wire loop — the mechanism with potentially disastrous consequences. In the ECPR literature, adding fluoroscopy to ultrasound reduced cannulation failure.
Evidence supporting TOE: Some centres report good experience with TOE guidance, and the expired ELSO ultrasound document states TOE is necessary where no image intensifier is available. TOE is bedside, avoids transport of an unstable patient, involves no radiation, and uniquely demonstrates the functional endpoint — the reinfusion jet across the tricuspid valve — which fluoroscopy cannot show.
Current consensus: Image guidance of some kind is mandatory; which kind is centre-dependent. The two modalities answer different questions and are complementary rather than interchangeable.
Practical approach: Use fluoroscopy for the wire and TOE for the jet where both are available. Where only one is, know what that modality cannot tell you — fluoroscopy will not confirm the jet, and echo will not show the whole wire.
Knowledge gap: No comparative study of imaging strategies for dual-lumen placement, and no agreed competency standard for either.
Controversy — percutaneous or hybrid cutdown as the default?
Clinical question: Should ultrasound-guided percutaneous cannulation be the default in all settings?
Evidence supporting percutaneous: Bedside, avoids vessel ligation, fewer bleeding complications, and the preferred technique in adults and larger children in every technique source consulted. Reported ECPR implementation times are comparable to hybrid (median 19 versus mean 21.3 minutes).
Evidence supporting hybrid cutdown: Reported failure rate was lower in the hybrid series (7.6% versus 14.5%), it works without imaging — decisive pre-hospital — and it gives direct visual separation of artery from vein where they overlie one another, in obesity, and in atherosclerotic vessels.
Current consensus: Percutaneous is the default; hybrid and cutdown are essential rescue skills rather than alternatives, and the reported complication profile of the hybrid approach is described as broadly similar to both others.
Practical approach: Judge a programme not by its default technique but by whether its operators can convert competently, and how quickly that decision gets made.
Knowledge gap: The comparisons above are between single-centre series with different populations and operators, not between randomised strategies. They cannot be read as an effect of technique.
Evidence Summary
Statement | Certainty | Basis |
Real-time ultrasound guidance for vascular access prevents arterial puncture, sapheno-femoral junction cannulation and inguinal ligament transfixation | Consensus / expert practice | ELSO ultrasound guidance 2015 (expired document); universal in technique sources |
Landmark technique at the femoral vessels is frequently inadequate because anatomy is variable | Consensus | ELSO ultrasound guidance; corroborated independently in the ECPR surgical literature |
Image guidance is mandatory for bicaval dual-lumen cannula insertion | Consensus | ELSO Red Book 6th ed.; ELSO ultrasound guidance |
Fluoroscopy is preferable for the wire because it shows the whole wire at once | Expert practice | ELSO Red Book states this as consensus; no comparative study |
Larger bicaval dual-lumen cannulae carry a higher incidence of intracranial bleeding, probably via venous obstruction | Low to moderate — mechanism plausible, association reported | ELSO Red Book 6th ed.; presented there without a quantified effect estimate |
Cannula French size that exactly fills the vessel = 3 × vessel diameter in mm | High — arithmetic identity | Follows from the French scale (3 Fr = 1 mm); given directly in the ELSO ultrasound document |
The cannula should be smaller than the vessel to allow flow around it | Consensus / physiological rationale | ISCCM manual; ELSO Red Book; Chapter 3 |
Cannulation failure occurs in roughly 8–15% of ultrasound-guided percutaneous attempts in ECPR, falling when fluoroscopy is added | Low | Small single-centre series collated in ECPR and Resuscitative ECMO; no randomised comparison |
Any cannulation technique is superior to another | Not established | No randomised comparison; reported differences are confounded by setting, operator and population |
The distal end of an ECMO cannula is radiolucent, so radiography cannot reliably confirm tip position | High — device property | ELSO ultrasound guidance 2015 |
Key Takeaways
- Most serious cannulation injury is mechanical, immediate, and preventable by technique rather than detected by monitoring.
- Ultrasound before the needle: identify the vessels, map the variation, measure the diameter.
- The sizing formula (Fr = 3 × mm) returns the cannula that would exactly fill the vessel. That is the ceiling; choose from below it.
- For dual-lumen cannulae, choose the smallest that supports the patient — larger sizes carry more intracranial bleeding, probably through venous obstruction.
- Confirm the wire in the IVC before dilating. The transtricuspid RV loop is the injury this prevents.
- Image guidance is mandatory for bicaval dual-lumen placement. Fluoroscopy shows the wire; TOE shows the jet; they are complementary.
- Depth and rotational orientation both determine dual-lumen function.
- A plain radiograph cannot confirm tip position, because the distal cannula is radiolucent.
- Secure the cannula and the tubing, document the depth at the skin, and re-check it every round.
- Cannulation fails often enough that every programme needs a second technique and a rehearsed decision to convert.
Key References
- Nanjayya VB, Murphy D (authors); Brechot N, Fan E, Pellegrino V, Brodie D (editors). Ultrasound Guidance for Extracorporeal Membrane Oxygenation — General Guidelines. Extracorporeal Life Support Organization, May 2015. Expired by its own terms in May 2018 and not listed on the ELSO guidelines index as at 6 September 2026 — cite as expired guidance
- Brodie D, Peek G, MacLaren G, et al. (eds). Extracorporeal Life Support: The ELSO Red Book, 6th edition — Chapter 4, Cannulation (percutaneous VV technique in older children and adults; bicaval dual-lumen insertion; wire and dilator technique; sizing and the intracranial bleeding warning; potential pitfalls)
- Taha AR, Caridi-Scheible M, Leiendecker E, et al. ECMO: A Practical Guide to Management — Chapter 7, ECMO Cannulation and Configuration (ultrasound survey; dual-lumen wire technique and TOE confirmation; percutaneous, cutdown and modified Seldinger approaches; complications of cannulation)
- Shinar Z, Badulak J (eds). ECPR and Resuscitative ECMO — hybrid cutdown technique; implementation times and cannulation failure rates; securing cannulae
- Indian Society of Critical Care Medicine. ISCCM Manual of RRT and ECMO in ICU — Seldinger technique; cannula sizing relative to vessel diameter
- Cross-references: Chapter 3 (configuration anatomy; cannula flow physics; recirculation and insertion depth), Chapter 4 (selection and the destination question that shapes the access decision), Chapter 6 (VV physiology), Chapter 7 (initial management after cannulation), Chapter 9 (hypoxaemia and recirculation), Chapter 17 (limb ischaemia), Chapters 34–36 (cannula problems, circuit emergencies, bleeding), Chapter 21 (ECPR cannulation)
Citation verification status. The ELSO ultrasound guidance document was read in full from the project library during this cycle; its authorship, date, expiry statement, the three-phase framework, the sizing formula, the list of access complications ultrasound prevents, the TTE-versus-TOE position and the radiolucent-cannula statement are quoted directly from that text. Its absence from the current ELSO guidelines index was checked against the index retrieved on 6 September 2026 for Chapter 1.
All technique detail, quoted phrases and the cannulation-failure figures are attributed to the named project texts — the ELSO Red Book 6th edition, ECMO: A Practical Guide to Management, ECPR and Resuscitative ECMO, and the ISCCM manual. These are expert-synthesis sources, not primary evidence, and the chapter labels them as such throughout.
Not verified this cycle: the primary studies behind the ECPR cannulation-failure figures (Chhor et al, Kashiura et al, Voicu et al) — these are cited as collated in ECPR and Resuscitative ECMO rather than from the original papers, and the individual citations should be retrieved before the numbers are quoted elsewhere. A narrative review of ECMO vascular complications was identified but could not be retrieved (PMC reCAPTCHA), so no complication incidence rates are quoted in this chapter; the complications table describes mechanisms and management only.
Educational use only. This chapter does not replace institutional ECMO protocols, local policy, specialist consultation, current guidelines or patient-specific clinical judgement. Cannulation should be performed only by operators trained and credentialled to do so.