Correct pressure for gastric decompression

dudette10, MSN, RN · Jun 4, 2014

Sometimes, the stuff just doesn't get sucked out at LIS, and the pt suffers n/v. MIS isn't a wrong order, but I wonder if a "high" LIS would have sufficed. Is it possible that the suction had inadvertently decreased over time, and it was no longer adequately suctioning within the LIS range?

In general, the lowest suction needed to adequately suck it out would be an appropriate order. Our machine dials are very touchy and the machine tends to lose suction over time, and I usually have to stand there and mess with it to get it on the appropriate suction. I also recheck it every time I'm in the room.

A lot of our time as RNs is troubleshooting.

nurseprnRN, BSN, RN · Jun 4, 2014

1) It's not pressure, it's the inverse of pressure, suction.

2) The number one problem with sucking out stomach contents has nothing to do with the suction and everything to do with the Salem sump tube, because more nurses than I can count do not have a good working understanding of how it works and what you have to do to keep it working. And yes, it can take a lot of screwing around to make it stay functioning.

A Salem sump has two lumens, the main one that pulls fluid out, and a smaller one (the blue pigtail, usually) that allows air in. Why is that?

Think about why there are two lumens in this tube. Imagine there were just the main one, connected to suction. When the fluid is all drained, or there is very little accumulating, the suction keeps...sucking, and will pull on the lining of the stomach, resulting in damage to the mucosa. This is, in fact, why that air vent was invented: to break the suction and prevent mucosal damage.

So, knowing that, you can see why you NEVER clamp off the air vent when the main lumen is to suction. You'd be defeating its protective purpose.

There should always be air going down the air vent lumen (listen or feel it with your fingertip briefly), and fluid or at least air coming up the main lumen. If either of those is not happening, it's your job to investigate and fix it.

If fluid is coming up the air vent (a common cause of inappropriate clamping) it's because, well, air isn't going down it, probably because the main lumen is obstructed and there's no suction pulling air down the vent. To figure this out, IF there is no contraindication to moving the tube a bit, irrigate the main lumen with a bit of saline and /or withdraw it a few inches, move it up and down. Chances are it will suddenly start to drain and the air will start to go down the air vent. You can push a little air down the vent to clear it. When you have it draining properly, re-secure it.

Be prepared to do this often. These things will occur regularly. Ignoring them, defeating the safety feature of the tube, or just saying the heck with it is risky for your patient and defeats the purpose of the drain being there in the first place. There's a reason it's there: make sure it does what it should do.

If you don't clear the main lumen AND you have clamped the air vent (because it's making a mess on the pillowcase) you now have NO suction to the stomach, and when enough fluid builds up the patient can aspirate. This IS dangerous.

dudette10, MSN, RN · Jun 4, 2014

I completely forgot about the air vent! Surgery has resorted to nursing communications that state, "If air vent leaks or NG stops draining, infuse a small amount of air into the air vent."

I shoulda just shut up and let you answer first, GrnTea.

ChipNurse · Jun 4, 2014

I check for placement with air bolus and then always flush with water to keep the line patent. I try to do this every few hours or so. Some of the gastric secretions are thick and get clogged. I have seen orders for continuous suction.

nurseprnRN, BSN, RN · Jun 4, 2014

You don't want to flush with water, because some will be absorbed through the gastric mucosa and can result in dilutional hyponatremia. (And your docs scratching their heads wondering how the heck their patient got hyponatremic.) Use NS instead.

Been there,done that, ASN, RN · Jun 5, 2014

Low intermittent suction is the standard order. Low suction is all that is needed to keep gastric secretions from accumulating.

In order to clear ACCUMULATED secretions.. we gotta suck a little harder.

That RN that cannot understand that basic rationale.. is not capable of critical thinking.

LionessRN · Jun 5, 2014

Thanks everyone! I learned from your replies

K+MgSO4, BSN · Jun 6, 2014

Wow, I work with Ryles tubes to free drainage via gravity and 4 hourly aspirations with a 50ml syringe. I have pulled over a liter on aspiration despite very little to gravity. Warm gastric contents gross but strangely satisfying

~PedsRN~, BSN, RN · Jun 7, 2014

"Gross but strangely satisfying" - :laugh:

Us Nurses, we are a strange breed.

GrnTea - great response!!!!!!

Christy1019, ASN, RN · Jun 8, 2014

1) It's not pressure, it's the inverse of pressure, suction.

2) The number one problem with sucking out stomach contents has nothing to do with the suction and everything to do with the Salem sump tube, because more nurses than I can count do not have a good working understanding of how it works and what you have to do to keep it working. And yes, it can take a lot of screwing around to make it stay functioning.

A Salem sump has two lumens, the main one that pulls fluid out, and a smaller one (the blue pigtail, usually) that allows air in. Why is that?

Think about why there are two lumens in this tube. Imagine there were just the main one, connected to suction. When the fluid is all drained, or there is very little accumulating, the suction keeps...sucking, and will pull on the lining of the stomach, resulting in damage to the mucosa. This is, in fact, why that air vent was invented: to break the suction and prevent mucosal damage.

So, knowing that, you can see why you NEVER clamp off the air vent when the main lumen is to suction. You'd be defeating its protective purpose.

There should always be air going down the air vent lumen (listen or feel it with your fingertip briefly), and fluid or at least air coming up the main lumen. If either of those is not happening, it's your job to investigate and fix it.

If fluid is coming up the air vent (a common cause of inappropriate clamping) it's because, well, air isn't going down it, probably because the main lumen is obstructed and there's no suction pulling air down the vent. To figure this out, IF there is no contraindication to moving the tube a bit, irrigate the main lumen with a bit of saline and /or withdraw it a few inches, move it up and down. Chances are it will suddenly start to drain and the air will start to go down the air vent. You can push a little air down the vent to clear it. When you have it draining properly, re-secure it.

Be prepared to do this often. These things will occur regularly. Ignoring them, defeating the safety feature of the tube, or just saying the heck with it is risky for your patient and defeats the purpose of the drain being there in the first place. There's a reason it's there: make sure it does what it should do.

If you don't clear the main lumen AND you have clamped the air vent (because it's making a mess on the pillowcase) you now have NO suction to the stomach, and when enough fluid builds up the patient can aspirate. This IS dangerous.

Omg I have been a nurse for 6 years and didn't know about the blue lumen/air vent. I don't remember learning it in school or seeing anyone leaving it unplugged (that blue and white plug that comes in the NGT package). I feel even more dumb for never thinking "I wonder what the purpose of this blue tube is".

I can't use smileys on the phone app but you can be sure that I'm slapping myself right now...