College Answer

a)

Sengstaken-Blakemore tube 
(Gastro-oesophageal balloon tamponade device or Minnesota tube acceptable)

b)

• Estimate appropriate length of tube to be inserted for the patient
• Evaluation of compliance curve of gastric balloon pre-insertion by inflation of balloon with incremental 100ml aliquots of air to maximal recommended volume (usually 250 -300ml for SBT, 450-500ml for Minnisota) and notation of corresponding balloon pressure at each step.
• If, post-insertion, balloon pressure on inflation with a given volume is >15 mmHg than the pre-insertion pressure, the balloon may be in the oesophagus and should be deflated and position checked
• iii) Check balloon position with Xray or ultrasound post insertion

OR Any other acceptable technique.

E.g.: inflate gastric balloon with no more than 80 ml of air (or contrast) and confirm position on AXR or via gastroscope then inflate gastric balloon slowly to a volume of 250-300 ml (up to 450 for Minnesota tube) and clamp balloon inlet.

c) 
Aspiration:

• Use only in intubated patient and position patient head-up 30-45o

Oesophageal perforation:

• Ensure both balloons completely deflated prior to insertion
• Avoid inflation of oesophageal balloon
• Ensure gastric balloon is correctly positioned during inflation

Pressure necrosis of gastric mucosa:

• Do not leave SBT in situ for more than 24-36 hr
• Avoid prolonged inflation of gastric balloon – deflate after 12 hr and reinflate if ongoing bleeding

Upper airway obstruction secondary to balloon migration:

• Avoid use in unintubated patient. If SBT in unintubated patient and develops respiratory distress, immediately cut lumens for oesophageal and gastric balloons and remove tube

Discussion

The college had omitted their own image. The picture above was stolen from www.medipicz.com.

The college say "Minnesota tube acceptable". But... is it really? Is there any difference between them?

Well. Yes there is.

The Minnesota tube is actually a modified version of the original Sengstaken-Blakemore device. The modification is an oesophageal suction port, which prevents the pooling of filth in the upper oesophagus. You can tell them apart instantly - the Minnesota tube has four ports at the end, whereas the SB tube has only three. One can also have a Linton-Nachlas tube, which only has two ports, and a single 600ml gastric balloon.

Thus, the device in my picture is properly called a Sengstaken-Blakemore tube, and to call it a Minnesota tube would just be plain wrong.

Now then.

The balloon labelled "A" is the gastric ballon. It inflates to a considerable diameter, and so it is fairly important that you do not inflate it in the oesophagus. Hence the anxiety regarding its position.

One can do this in a number of ways. The college would have accepted "any other acceptable technique".

For instance:

• One can inflate it with a safe 80mls of air, and look for its position on AXR
• One can inflate it with radio-opaque contrast, and look for its position on AXR
• One can position it under direct vision during gastroscopy
• One can compare the balloon pressure pre and post insertion (as suggested by the college), observing a change of 15mmHg as a sign that it is in the oesophagus.

The complications and preventative measures are best presented in the form of a table:

What are the indications for the use of the SB tube? There really is only one. Control of variceal bleeding. However, others have used it to tamponade uterine bleeding, which can possibly extend to rectal bleeding via protocol creep.

What are the contraindications for the use of the SB tube?

Well;

• Unprotected airway
• Oesophageal rupture (eg. Boerhaave syndrome)
• Oesophageal stricture
• Uncertainty regarding the source of bleeding (how do you know it is not duodenal?)