Treating gastrointestinal conditions

Gastrointestinal interventions fall into two main groups: establishing enteral access for feeding and stenting to treat obstruction secondary to malignancy.

Nasogastric/nasojejunal tubes

Most nasogastric tubes are placed on the ward and most nasojejunal tubes are placed by endoscopists. If a request migrates to interventional radiology for these procedures, it is usually because of problems navigating the nasopharynx. Occasionally, it is an issue with an oesophageal stricture and, in that instance, consider whether oesophageal dilation or stenting would allow the patient to maintain oral intake.

This really should be a simple procedure in the vast majority of cases. Initially, try with the tube that the ward wants to use for feeding. Ask the patient which nostril is best, they usually know, as the ward should have tried several times before coming to you. Anaesthetize the throat with lidocaine spray and lubricate the tube. Some operators will try with the patient sitting up without fluoroscopy for their initial attempt. Usually, the best tactic is to place the patient supine and use lateral screening of the hypopharynx to visualize the action. If they can, ask the patient to swallow as the tube approaches the C6 level. We guarantee that nine times out of 10 the standard tube will go through with a little patience. If this fails, then use a vertebral catheter and hydrophilic wire to navigate the hypopharynx. Most people do not have enough hands to manipulate the catheter and wire and keep the catheter in place at the nose (that's three if you're counting.) Enlist the help of the nurse to hold the catheter at the nose, while you manipulate the catheter. Once the wire is well into the stomach, remove the catheter and place the nasogastric tube over the wire.

If placing a nasojejunal tube you will have to manipulate it round the duodenal loop. The tube may be weighted to help and will often be supplied with an internal wire. Try to get round using the tube; turning the patient onto their right-hand side can be useful. If stuck, a 260-cm Terumo wire and 100-cm vertebral or Headhunter catheter can be used to get round.

Tip

Nasogastric tubes vary in their internal diameter and endhole configuration – some are blind-ending with sideholes only. Check the tube you plan to place outside the patient. If it is blind-ended, it is usually possible to place the tube by putting the wire through the last sidehole.

Oesophageal stent

Oesophageal stenting is used to palliate dysphagia, particularly in malignant disease. Self-expanding metallic endoprostheses allow durable palliation of dysphagia in a single treatment session, with minimal morbidity and mortality compared to radiotherapy and plastic endoprostheses. Oesophageal stents come in two main types: covered stents and bare stents. Covered stents have lower rates of occlusion secondary to tumour ingrowth but initial designs had a high rate of migration. Improvements in design have reduced the stent migration rate to <10% and most centres will now use covered stents for all patients. A few stents are available that contain a one-way valve to prevent reflux and even have a suture loop to permit repositioning/retrieval. Advances in radiotherapy and chemotherapy mean retrievable stents are an increasingly used option.

Accurate sizing is not important, but using a device that is approximately appropriate in size is required. In reality, few operators measure the true length of the lesion, as the vast majority of these lesions are covered by a single stent. As a guide, the stent length should be at least 2 cm longer than the lesion at either end. Large-diameter stents, i.e. around 30 mm, are best reserved for the dilated oesophagus as they cause considerable pain in a normal-calibre oesophagus.

Equipment

Oesophageal stent: 18–25-mm diameter
Hydrophilic guidewire, Amplatz super-stiff guidewire: 260 cm
Berenstein/vertebral catheter.

Procedure

Review the pre-existing imaging to identify the approximate level of the stricture. The throat is subsequently anaesthetized with lidocaine spray (Xylocaine) and the patient positioned in the prone oblique position. IV sedation is administered and appropriate monitoring commenced.

Using fluoroscopic guidance, the oesophagus is catheterized via the oral route; it is tricky to get an oesophageal stent through the nose later in the procedure! It can take a little time to steer past the epiglottis; use a lateral projection and steer posteriorly. Try to avoid putting a guidewire deep into the trachea as this almost certainly will cause a coughing fit. The catheter is advanced to the approximate level of the lesion and a small amount of non-ionic contrast injected to outline the upper extent of the stricture. The catheter is then used to manipulate the hydrophilic guidewire through the stricture, using the techniques outlined in Chapter 31 . If necessary, the catheter can be pulled back while slowly injecting contrast to define the proximal margin. The distal extent of lesions at the gastro-oesophageal junction can usually be outlined by air within the stomach. The position of the stricture can be indicated either by radio-opaque markers placed on the patient or using bony landmarks, but remember these markers are a considerable distance from the oesophagus and even minor patient movement may be significant. The Amplatz guidewire is inserted into the stomach and the stent is then carefully advanced over the Amplatz wire and deployed in position ( Fig. 42.1 ). Deployment mechanisms vary between devices, but most devices are deployed by progressive retraction of a sheath. Most operators do not post-dilate and prefer to wait for the stent to expand itself ( Fig. 42.1 ).

Tip

If the markers move or there is difficulty being sure of the length and position, use a long angiographic sheath over the wire to depict the proximal and distal extent of the stricture without losing wire position.

Fig. 42.1, Deployment of an oesophageal stent.

Aftercare

Clear fluids are permitted 4 h after the procedure. If this proceeds uneventfully, a light diet may be commenced. It is not essential to perform a routine follow-up oesophageal study. All patients should be advised to cut food into small pieces and encouraged to drink fizzy drinks, particularly cola, as they tend to prevent the stent from progressive sludging with food. If the stent extends over the cardia, the patient should be commenced on a proton-pump inhibitor to alleviate symptomatic oesophageal reflux.

Retrievable stents

Most of the available retrievable stents have a suture loop that will collapse down the stent when pulled taut. This is generally easiest under direct visualization at endoscopy, but it can be undertaken by the skilled interventionalist using a short reverse curve catheter to go through the loop and a long wire, which can be directed retrogradely back up the oesophagus and captured in the mouth. Both ends of the wire are then put through a sheath (12–14F will do) and the sheath gently advanced to just above the stent. The guidewire is pulled tight, and the proximal extent of the stent can just about be withdrawn into the sheath, and the entire ensemble can be withdrawn.

Outcomes

Primary technical success is achieved in 95–100% of patients, with significant relief of dysphagia in most series. Complications consist of migration <10% and haemorrhage.

Troubleshooting

The stent migrates through the cardia:

Stent migration is more common with a stent that extends across the cardia and slightly more common with covered stents. If this is partial at the time of insertion, then it may be possible to anchor the stent by inserting an overlapping stent. More often, this occurs some time after the initial insertion and the stent is within the stomach. Most stents are left in situ within the stomach, but if the patient is symptomatic, the stent can be retrieved (but not reused!) at endoscopy, using an overtube.

The stent occludes:

An acute occlusion usually indicates food bolus impaction. Perform a contrast study of the oesophagus; if contrast is still percolating through, then try some cola! If this fails, the stent can usually be readily cleared at endoscopy. More insidious onset of dysphagia indicates the stent has become occluded secondary to tumour overgrowth or tumour ingrowth. If tumour overgrowth has occurred, then often a second stent will resolve this. If the problem is tumour ingrowth, then either a covered stent or laser therapy should be considered.

The lesion is high in the oesophagus:

The majority of lesions are in the lower-third but high lesions in the upper-third of the oesophagus need particularly critical positioning to avoid stenting open the vocal cords! Endoscopy during stent placement to identify the position of the cricopharyngeus muscle can be very useful. The Ultraflex oesophageal stent comes in a proximal release variant, and this permits more accurate proximal placement. It is generally better to use smaller devices in the upper oesophagus and the Ultraflex stent, which has less radial force, may prove more comfortable for the patient.

The patient develops chest pain post-deployment:

This often occurs and is secondary to the expansile force of the stent. The sensation almost always resolves spontaneously.

Oesophageal fistulae and perforations

Covered stents are now usually the first-line intervention in the treatment of oesophageal perforations and fistulae. In particular, malignant fistulae are readily treated by accurate placement of a covered oesophageal stent. Benign perforations are technically fairly straightforward but long-term results may be less favourable due to overgrowth of granulation tissue at the stent margins. In this group of patients, most operators would place a temporary/retrievable covered oesophageal stent.

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