TOE Protocol

Reach for TOE when transthoracic imaging can't answer the question and the answer will change management — most often unexplained, treatment-refractory haemodynamic instability.

• Undifferentiated shock unresponsive to treatment — define volume/filling, LV and RV function, tamponade and dynamic obstruction.
• Poor transthoracic windows — ventilated, high PEEP, prone, obese, surgical dressings or chest drains.
• Suspected infective endocarditis — vegetations, abscess and prosthetic-valve involvement (TOE far more sensitive than TTE).
• Aortic dissection — intimal flap, entry site, aortic regurgitation, pericardial effusion and coronary involvement.
• Search for a cardiac source of embolism/stroke — LA appendage thrombus, PFO or ASD, aortic atheroma, valve masses.
• Before cardioversion — exclude LA appendage thrombus when AF has lasted >48 h or the duration is unknown.
• Procedural guidance — ECMO or Impella cannula position, de-airing, and valve interventions.
• Persistent hypoxaemia — right-to-left shunt through a PFO, or massive pulmonary embolism.

In practice — TOE answers a specific question; decide the question before you pass the probe.

TOE places the probe directly behind the heart, so it excels at posterior structures and works when transthoracic windows fail — but it is invasive and has its own blind spots. It complements rather than replaces TTE.

• Superior resolution of posterior structures — left atrium and appendage, mitral valve, interatrial septum, descending aorta.
• The modality of choice for endocarditis (vegetations, abscess), prosthetic valves, and aortic dissection.
• Reliable images in the ventilated, high-PEEP, obese or positioned patient in whom TTE is impossible.
• Excellent for procedural guidance — ECMO/Impella cannula position, de-airing, valve interventions.

Limitations:

• Invasive — needs sedation ± a secured airway; effectively a semi-elective airway procedure in a sick patient.
• Contraindicated in significant oesophageal or gastric pathology.
• Blind spots — the distal ascending aorta / proximal arch (air in the trachea and left main bronchus) and a far-field LV apex.
• Doppler alignment for the LVOT/aortic valve is harder (deep transgastric needed), so gradients tend to be under-read.

In practice — start with TTE, escalate to TOE for the specific question it answers better; decide that question before you scan.

Most contraindications concern bleeding or injury to the upper GI tract; the relative ones are a documented risk–benefit decision, which in a sick ventilated patient often favours scanning.

Absolute:

• Patient refusal (in the awake patient).
• Active upper GI bleeding, or a perforated viscus.
• Oesophagectomy, or recent oesophageal / upper-GI surgery.
• High-risk oesophageal pathology — stricture, tumour, or diverticulum (especially a pharyngeal pouch).

Relative:

• Known oesophageal disease — varices, Barrett's, oesophagitis, symptomatic hiatus hernia.
• Recent upper GI bleed; coagulopathy or thrombocytopenia.
• Cervical spine instability or limited neck movement; prior chest / neck radiotherapy.
• Large thoraco-abdominal aortic aneurysm; prior upper-GI surgery.

In practice — an oesophageal diverticulum is absolute (perforation risk), whereas varices are only relative (bleeding is uncommon; avoid transgastric views if high-risk). An unsecured airway in a patient who can't protect it is a practical contraindication.

Minor complications are common and serious ones rare; injury happens at two points — probe placement and probe manipulation.

• Common / minor — lip or dental trauma (~13%), hoarseness (~12%), sore throat and transient dysphagia (~2%).
• During the procedure — hyper- or hypotension, arrhythmia, hypoxaemia, aspiration, laryngospasm or bronchospasm, ETT displacement.
• Serious / rare — major GI bleeding 0.01–0.8%; oesophageal, gastric or pharyngeal perforation <0.01%; death 0.01–0.03%.
• Probe-related — thermal injury (rare) and pressure necrosis with prolonged monitoring-probe use.
• Red flags afterwards — persistent odynophagia/dysphagia, chest/back/abdominal pain, haematemesis, surgical emphysema or fever suggest perforation.

In practice — most morbidity is preventable with gentle technique: never force, and unlock the flexion controls before advancing or withdrawing.

TOE in ICU is a team procedure — treat it as a sedation and airway event with a checklist (a LocSSIP), not just a scan.

• Consent — written if the patient has capacity; documented verbal or best-interests decision if incapacitated.
• Aspiration risk — aspirate and stop NG feed; confirm the airway is protected (usually already intubated in ICU).
• Airway & sedation — secured airway or a clear plan; adequate sedation ± paralysis; resuscitation and difficult-airway equipment to hand.
• Monitoring — continuous ECG, SpO₂, blood pressure and capnography.
• Team & kit — minimum three (operator, assistant, monitoring); echo machine and probe checked for damage; bite guard, lubricant, probe cover.
• Final checks — patient identity, allergies (including latex in the probe cover), contraindications reviewed, patient positioned head-up ~30°.
• Afterwards — reassess sedation and haemodynamics, confirm ETT position and cuff, request a CXR to confirm NG position before resuming feed, document findings and complications, clean the probe per protocol.

In practice — run the LocSSIP sign-in / time-out / sign-out; it catches the avoidable harm.

Four independent movements, plus the electronic multiplane angle, build every view — small adjustments only, never force.

• Advance / withdraw — deeper into the oesophagus or stomach, or back toward the mouth (mid-oesophageal ~30–35 cm; transgastric ~40 cm).
• Turn right (clockwise) / left (anticlockwise) — rotate the shaft to centre a structure.
• Ante-/retroflex — the large wheel flexes the tip anteriorly or posteriorly.
• Flex right / left — the small wheel; rarely needed with multiplane probes.
• Rotate the multiplane angle — electronically sweep the imaging plane 0°→180° without moving the probe.
• Display orientation — transducer (near field) at the top; at 0° the patient's right is on the left of the screen, 90° is a longitudinal plane, and 180° mirrors 0°.

In practice — set the depth first, then rotate the angle; if you're fighting the probe, you're in the wrong place.

Insertion is the highest-risk moment of the study — gentle, midline, minimal force, protecting the airway throughout.

• Prepare — check the probe for damage, unlock the flexion controls, lubricate the tip, insert a bite guard.
• Intubated / anaesthetised patient (the usual ICU case) — head neutral, apply jaw thrust or chin lift, advance in the midline with slight anteflexion; a laryngoscope lifts the tongue and epiglottis if the probe snags.
• Awake patient (rare in ICU) — topical anaesthesia and sedation, left-lateral position, ask the patient to swallow as you advance.
• Never force against resistance — it usually means the tip is in a piriform fossa or is flexed; withdraw, neutralise the tip, and realign in the midline.
• Protect the ETT — insertion and head movement can displace it; have an assistant guard the tube and reconfirm position and cuff pressure afterwards.

In practice — two hands, midline, gentle; the oesophagus tears when the probe is forced or advanced with the tip locked.

Most probe injury is mechanical and preventable; recognise perforation early, because it is lethal if missed.

Prevention:

• Screen contraindications, use gentle technique, and never force the probe.
• Unlock the flexion wheels before advancing or withdrawing, and keep the tip neutral in transit.
• Minimise the number and force of movements; avoid prolonged pressure and excessive flexion against the wall.
• Use a bite guard (protects both probe and teeth) and inspect the probe before and after use.

Recognition:

• During — blood on the probe, new bleeding, arrhythmia or hypoxaemia.
• After — persistent odynophagia or dysphagia beyond 24 h, chest/back/abdominal pain, haematemesis or melaena, fever, surgical emphysema, sepsis.
• Suspected perforation — nil by mouth, broad-spectrum antibiotics, urgent contrast CT/swallow, and an urgent upper-GI surgical and endoscopy opinion.

In practice — any unexplained pain, bleeding or sepsis after TOE is perforation until proven otherwise.