You review a patient on the ward for abdo pain and pyrexia, and they have some sort of tube with feeds going into their stomach. You need to call the surgeons for a consult for their abdo pain. But what you call it? Do you know the difference between your PEGs and gastrostomies? Do you understand about tube calibres and lengths? In this four-part series, Camille Wu covers everything the general paediatrician needs to know about enteral feeding via gastrostomies….
We have already looked at the type of gastrostomy, but now it’s time to look at the types of devices that can be inserted.
Devices can be either tubes or low-profile devices (commonly called “buttons”).
There are many brands of devices (e.g. Mic-Key, Bard, Nutriport, etc), and different sizes depending on the size of the child.
As there is a limit to the size of the buttons, often they don’t come in small enough sizes for neonates. So often the small neonates will end up with a tube.
We can insert either tubes or buttons when we form the gastrostomy (open or laparoscopic), but only the PEG tube can be placed when PEG is performed.
The curved mushroom-cap shaped inner phalange (A) is inside the stomach, to stop tube from falling out.
The flat disc-shaped outer phalange (B) sits on the skin, to stop tube from migrating further into stomach & to oppose the stomach wall up against anterior abdominal wall.
These two things are all that is holding the PEG tube in place.
The position of the outer phalange may be adjusted to accommodate changes in the thickness of the abdominal wall (eg initial post-operative swelling that resolves with time, gradual fattening of the child and abdominal wall as they get more nutrition).
There are two ports (C) for administering feeds and medications (accommodates different types of syringe nozzles).
The patient may choose to swap over from PEG tube to a Button later on, at least 6 weeks after the initial placement, to allow time for the gastrostomy track to mature and fibrose up.
These may be inserted at time of gastrostomy formation (open or laparoscopic), or may be used to replace an existing device (tube or button).
The balloon sits inside the stomach, to keep the tube from falling out.
The disc-like phalange sits on the skin, to stop the tube from migrating further into the stomach. It holds the balloon flush to the gastrostomy site (the hole) to stop gastric contents from leaking out. The position of the phalange may be adjusted to accommodate changes in the thickness of the abdominal wall.
There are three ports on this tube – 2 of them are for administering feeds / medications, 1 of them is the balloon port (labelled “BAL”) through which you can inflate / deflate the balloon.
BEWARE – do not hook feeds up to the balloon port! Seems obvious, but it has happened!
Low profile devices (aka “buttons”) may be inserted primarily (at time of open or laparoscopic gastrostomy formation), or used to replace an existing device.
They are felt to be nicer than having a long tube sticking out of your abdomen.
Buttons are described by 2 numbers:
- Length e.g. 1.5cm (green line)
- Calibre e.g. 18FG (red line)
We choose button size according to shape & size of the patient.
Unlike tubes, the length of the button’s stem is fixed, so cannot be adjusted if thickness of abdominal wall changes (e.g. fattening of the child).
The inner part of the button comes in different types:
- Balloon (which will then have a balloon port to inflate / deflate balloon)
- Soft cap
These last 2 require a stiff metal rod to stretch them out flat in order to remove or insert.
As you can imagine, the difference between a button or a tube is that the length of the “stem” is fixed in a button, but is adjustable in a tube (ie you can move the outer phalange disc to accommodate changes in thickness of abdominal wall).
So in picking the LENGTH of the button, we need to know the thickness of the abdominal wall – which we measure at time of operation, or at the time of the change of the device.
- We don’t want the button to be too short as it can compress the intervening tissues, cause necrosis and the whole device to erode through.
- We don’t want the button too long, as it can flop around and allow leakage of gastric contents.
- (For tubes, we don’t need to know the “length” (ie abdo wall thickness), as we adjust the phalange to where it sits snug.)
In picking the CALIBRE of the device (tube or button), it really depends on the size of the patient, and what stuff you want to put down the tube, or what stuff you want to aspirate out from the tube.
- If it’s just air you want to vent, then a narrow calibre tube is fine.
- If you want to give large volumes of feed, you will need a larger calibre; otherwise the rate of feed will be too slow, and you’ll be there all day.
- If you want to give meds, then we need to check what sort of meds, as some meds can block the tube (e.g. crushed up omeprazole, or Creon – these need a larger calibre tube as well as meticulous tube maintenance).
A gastro-jejunal (GJ) tube is a different type of tube that can be inserted via an existing gastrostomy “hole”. It has two lumina – one shorter channel that goes as far as the stomach, and a longer channel that reaches the jejunum.
This type of tube is useful in children who have gastric emptying problems (eg gastroparesis, gas bloat) so they don’t tolerate feeds via the stomach, BUT who have fairly normal distal small bowel function. Essentially it replaces the function of a nasojejunal tube (i.e. for patients who cannot tolerate feeding into their stomach – e.g. terrible gastroesohageal reflux or very delayed gastric emptying), WITH the added benefit of an extra port/lumen that goes to the stomach (usually to decompress / empty the stomach).
So, the GJ tube can be used to feed them distally (into jejunum) via one channel (the jejunal port), whilst being able to decompress the blown-up stomach via another channel (the gastric port). There is also a balloon port (“BAL”) to inflate the inner balloon that keeps the tube in, and an outer phalange to keep the tube secure & balloon snug up against the inside of the stomach wall.
However, they are tricky creatures, GJ tubes…
- The patient can’t be too small as the tubes are not made small or short enough for small babies.
- GJ tubes are usually inserted into existing gastrostomies, and the jejunal bit needs to be guided into the jejunum – either by Interventional Radiologists (under x-ray guidance), or under direct vision by Endoscopy. (Therefore, we rarely form a gastrostomy and insert the GJ tube at the same time – if you want this, generally it will need to be manually guided in by us via laparotomy.)
- GJ tubes are notorious for their tips flipping up back into the stomach. If this happens, the jejunal feeds end up in the stomach and there will be vomiting and unhappiness. The jejunal part will need to be guided back down into the jejunum by (you guessed it) radiology. And this isn’t always easy or straightforward to do.