Checking residuals (gastric residuals, that is)

Ah, the fun tradition of “residual 250 cc…hold TF?” This national survey shows that there is very wide variance in how residuals are checked, and how much is “concerning.” 200 cc? 250 cc? 500 cc? Going once, going twice…

Disclaimer: the information below is about adults. Who knows if the answers are the same for a pediatric population? Not me.

This ACG clinical guideline on nutrition in the hospital setting opened my eyes (mostly to how much we don’t know about managing nutrition). The authors write that checking residuals “has been shown to be a poor marker of true gastric volume, gastric emptying, risk of aspiration, pneumonia, and poor outcomes.” The sensitivity of residuals for predicting aspiration is 2-8%. This JAMA study shows that in the ICU, checking residuals didn’t affect development of ventilation-associated pneumonia. In other papers, one of the authors has advocated for the abolishment of checking residuals in nursing practice (see this link for good, practical information).

When is checking residuals useful?

Checking residuals is thought to be most useful in the first 48 hours of initiating tube feeds, as patients are getting increased to goal rate. If the residuals are building up (see below), it might be an indication to pause the tube feeds and make sure there’s nothing wrong with the tube, there are no tube feeds leaking into the peritoneum (this is actually something terrifying that can happen), etc. If your patient is intubated/sedated/obtunded, residuals are the only measure you have–but if the patient is awake and alert, you could talk to them and ask if they’re having worsening nausea, bloating, etc.

How high is too high? When do tube feeds need to be held for residuals?

I don’t know where the adage, “hold TF for residuals >200 cc” comes from. Abbott Nutrition states that when residuals > 500 cc, consider holding tube feeds. (For perspective, the human stomach can accomodate +/- 1 liter.) Check your institutional hospital policy, but…the general message of this post is that you shouldn’t be too worried.

Does checking residuals have harmful effects?

It is known that protein clots when the pH <5.0 (stomach acid pH is usually between 1.5-3.5). Could checking residuals lead to refluxing clotted protein, increasing the likelihood of clogging the tube? This small study (n=30) says, yes. In the group undergoing regular residual checks, there were 10 clogging events, compared to 1 in the no-residual checks group.

Checking residuals can also lead to tube feeds being held unnecessarily–if higher residuals aren’t a good sign of impending aspiration, we’re just holding tube feeds for hours at a time, depriving patients of the nutrition they’re supposed to be getting.

What’s the difference between clear and full liquids, mechanical soft and pureed, diets?

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Clear liquid diet: Strained orange juice or lemonade (no pulp), apple, grape and cranberry juice, tea, black coffee, plain gelatin, popsicles, clear broth.

Full liquid diet: Coffee, tea, cream, milk, milkshakes, fruit and vegetable juices, sodas, Cream of Wheat, Cream of Rice, Coco Wheats, pureed soups, Gelatin (Jell-O), whipped topping, custard-style yogurt, pudding.

Pureed: as one might imagine, pureed everything: soups, vegetables, meats, souffles, pudding, custard.

Mechanical soft: cooked cereals like oatmeal, moistened corn flakes, pudding, soft bananas and pureed fruit, tender meat cut into small pieces, cottage cheese, mashed potatoes, well-cooked vegetables.

Ground diet: A step above mechanical soft, food may be chopped into small pieces but don’t have to be mashed or moistened.


The basic principle is that thicker liquids are easier to swallow. Liquids can be made thicker by adding a “thickener” to it (purchased at most drugstores).

Thin liquids: juice, tea, milk, soda, beer, and broth

Nectar liquids: vegetable juices and thin milkshakes

Honey liquids: liquids are like honey at room temperature

***Patients will hopefully not be on these diets forever (at most 3-5 days). They are intended as a stopgap until the patient recovers more function.

Why give D5W to hospitalized patients?

I was actually asked this on rounds once. I said, I don’t know. I received a 30-minute biochemistry lecture in response.

  • 150 g/day glucose will sustain a person and spare protein from being used for metabolism. Giving D5W should not, on its own, cause hyperglycemia. It should also not dramatically increase blood glucose levels in hypoglycemic patients.
  • Several organs can subsist only on glucose: the brain, the renal medulla, and RBCs.
  • If patients don’t get adequate glucose, they will be “starved” for sugars and shunt to the ketone pathway. Ketones can be used by the brain and muscle, but it’s not good to rely on it for long since it has toxic side-effects.
  • Giving dextrose helps patients retain fluids by promoting hyperaldosteronism (aldosterone increases sodium and water retention).

A few basic points about TPN

TPN (total parenteral nutrition) is a vital part of treating patients with malnutrition or inadequate intake, and it confused the hell out of me as a med student. I only spent one day with the surgical nutrition team at my hospital in medical school, but it was invaluable.

How do you calculate how much TPN a patient needs?

  • Resting energy expenditure (REE) tells you how much the person needs per day at baseline. This can be calculated with the Harris-Benedict equation. It’s usually about 25 kcal/kg/day.
  • REE alone can be supplied by dextrose.
  • The DEE (daily energy expenditure)=1.3*REE.

How much do different types of nutrition supply? (carbs vs lipids vs proteins, etc)

  • TPN is usually given as 1-2 L per day. This equates to about 41 (the number will vary) cc/hr. “Can this result in fluid overload?” you may wonder. I don’t know of any reports of such a thing, but you should be careful to reconcile volume status. You can reduce the amount of volume given by giving a more concentrated formula (1 calorie, 2 calorie, etc).
  • Protein usually 1 g/kg/day
  • Emulsion lipids usually 2x/wk

What should you be aware of when starting a patient on TPN?

  • Especially if transitioning off tube feeds, you want to be cautious about how much you give a patient
  • Initially, it’s okay to “underfeed.” Better underfeed than put someone at risk for refeeding syndrome.
  • It’s also okay to “underfeed” a little if the patient is obese.

How can you tell if a patient is getting adequate nutrition on TPN?

  • The MREE (measured resting energy expenditure). It’s used to assess the response of a patient who has been on TPN for a while—if dropping, you may want to give more TPN, if increasing, you may want to cut back a little bit. Usually a respiratory therapist measures MREE with a mask for about 10 minutes. Usually, it’s less than the DEE.

How do you monitor a patient on TPN?

  • TPN labs: baseline BG, basic chemistry, albumin and prealbumin, retinol-binding protein, Mag/phos/Ca, zinc,etc. Get these for 3 days to make sure TPN is adequately addressing BG, electrolytes, etc.
  • Albumin is pretty worthless as a nutritional lab because it’s an acute phase reaction protein (inflame). Prealbumin is variable.
  • Strict I/Os, daily weights. You can also measure output by how much diarrhea a patient is having.

Myths about TPN:

  • TPN is expensive. At my hospital, it cost $17/day.
  • “if the gut is good, use it.” This is a saying many surgeons are fond of. It means, if a person is able to tolerate PO intake, you should feed them enterally. However, enteral feeding has more complications, like aspiration and intolerance. By contrast, the risks of TPN are usually gastric residues or diarrhea.
  • Pre-existing chemo ports can be used for TPN. Avoid this because the rates of infection go way up if you leave a port line open for a week at a time. Use a PICC line while the patient is in-hospital.
  • Enteral feeding and TPN can’t occur at the same time. PO intake can always be used for comfort feeds, like someone who has a fistula and leaks out what they eat within minutes. But in this type of patient, you’d also want to make sure that they get TPN to provide adequate nutrition. but also gets TPN for actual nutrition.