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Feeding in POCU
Focussing on postoperative nutrition, this step looks at different ways that we can feed patients in POCU
As we have mentioned, early enteral nutrition is key in the postoperative period. The optimal way to feed a patient postoperatively is via the oral route, however, there will be some instances where the patient needs to have some bridging nutrition in the perioperative period. This can either be via a nasogastric feeding tube, a nasojejunostomy, gastrostomy (PEG/RIG) or parenterally (via a dedicated central venous line).
Can you think of some of the challenges challenges to the oral route of feeding in every day POCU life?
Here are some that we came up with:
- Oesophageal dysfunction, unsafe swallow
- Inadequate oral intake (lack of appetite)
- Significant postoperative ileus
- Reduced level of consciousness (unsafe)
- Dysfunctional intestinal absorption
- Patient refusal
- Surgical contraindication to enteral feed eg Gastric surgery.
What are the Indications for Nutritional Supplementation?
What types of feeding tubes are there?
There are different options for enteral feeding and where they are placed depending on the patients GI tract function.
Feeding routes through the nose include: nasogastric (orogastric), nasoduodenal and nasojejunal.
Nasogastric tube position. (Image credit: Cancer Research UK, via Wikimedia Commons, license)
Gastrostomy options include: percutaneous endoscopic gastrostomy (PEG), balloon gastrostomy and button gastrostomy.
Gastrostomy position. (Image credit: BruceBlaus, via Wikimedia Commons, license)
Jejunostomy options include: Percutaneous endoscopic jejunostomy (PEJ), percutaneous radiological jejunostomy (PRJ), surgically placed and percutaneous endoscopic gastricjejunostomy (PEGJ).
Jejunostomy position. (Image credit: Cancer Research UK, via Wikimedia Commons, license)
Nasogastric Tube
When inserting an NG tube for feeding and/or administration of medication you need to confirm the safe placement of the tube prior to its use. The incorrect placement of an NG tube can result in life-threatening complications. For example, an NG tube can be easily misplaced into down the trachea and into the patient lung.
If this misplaced tube is then used and the patient is fed down it then this can cause an aspiration pneumonia. This is an NHS never event and we have ways of ensuring that that doesn’t happen. It is vital that all NG tubes are checked and confirmed safe to use before any feeding commences.
NGT. (Image credit: Tenbergen, via Wikimedia Commons, license)
Any member of staff asked to insert an NGT must have been trained and found competent and must work only within his/her scope of practice, what follows is NOT a training session, but rather information in support of your learning about nutritional care. NGT training will be offered locally where appropriate to do so.
There are two ways in which we can confidently confirm the correct position of a nasogastric tube:
1.Stomach fluid aspiration
pH indicator strips. (Image credit: Honacan, via Wikimedia Commons, license)
Confirmation of safe NG tube placement can be achieved by testing the pH of NG tube aspirate.
Gastric content has a low pH (1.5-3.5) whereas respiratory tract secretions have a much higher pH. This difference makes it possible to confidently confirm the safe placement of an NG tube using pH testing alone if the pH is within a safe range (typically <5.5).
The acceptable pH range for confirming NG tube placement can differ, so always follow your local trust guidance. In addition, some hospitals may also require a chest X-ray to confirm the safe placement of all NG tubes, regardless of the NG aspirate results, so always consult your local guidelines.
Some limitations of pH testing include:
- Stomach pH can be altered by medications (e.g. proton pump inhibitors eg Omeprazole or Lansoprazole)
- Obtaining aspirate from NG tubes can be difficult, particularly when using a fine bore tube
- Where no aspirate can be obtained from the NGT it may be worth waiting up to an hour and reassessing – of course the tube MUST NOT be used during this time until confirmed it is safely positioned in the stomach.
- Confirming NG tube placement with a chest x-ray:
If pH testing of NG aspirate is not possible, a chest x-ray can be used to confirm the safe placement of an NG tube. To aid the visualisation of an NGT on x-ray, feeding tubes most often come with an inserted wire, which when the tube is inserted can be visualised on x-ray, before it is removed to commence feeding. Occasionally, doctors will insert a small volume of water soluble contrast media into the tube to eventuate its position in the GI tract – although this is a very uncommon procedure.
Limitations of using a chest X-ray to confirm safe NG tube placement include:
- Risk of misinterpretation
- Radiation exposure (minimal)
- Loss of feeding time (whilst awaiting the x-ray)
X-ray confirmation of a correctly placed NGT is a skill, and training is mandatory for those doctors who have this task as part of their core competencies.
Any doubt about the position of an NG tube, you should seek advice from a senior colleague or discuss with the on-call radiologist. Do not use it until it’s correct position has been confirmed – and if you are still unhappy – seek advice, this is important and we must get it right every time.
We show you below two images. The first image shows a correctly placed NG tube which follows the midline, bisects the carina and is clearly visible underneath the diaphragm. The other image shows an NGT placed in the lung and about to cause severe harm. We should also point out that, in the real world, it is rare that the chest x-ray images are as good as those shown below.
Late at night and wanting to start NGT feed in your patient or give enteral medicines, a junior doctor struggles to see the tube – have sympathy and then support them by offering advice “go to speak to a senior, or a radiologist” and both agree not to use the NGT until you have the right assurance: NOBODY will fault you on this: the best care demands high standards.
Correctly placed NGT vs Incorrectly placed
Nasogastric tube in the stomach. (Image source)
NGT tube in left main bronchus before being pushed through lung parenchyma and the visceral pleura into the pleural space. (Image source)
The second image shows the NG tube is positioned in the left lung. You will see how it deflects off to the left at the carina and doesn’t pass below the diaphragm. This is not safe to use and should be removed and repositioned immediately.
Nasogastric tube length
The optimal length an NGT should be placed into the gut (measured at the patients nostril) is an unreliable source of assessing whether the tube is adequately situated in the stomach and should NOT be used. The length documented at the patients nostril is only useful as a part-assurance that the tube has not migrated out of the stomach during your shift. PACU teams, like ward teams, check and document the position of the tube every shift and use it, in combination, with other safety checks before they assume responsibility for its safe use.
NG tubes as drains
We often use NG-tubes as drainage tubes, to keep the stomach empty and reduce the risk of patients vomiting and/or aspirating stomach contents. Such tubes are large bore, to aid free drainage of gastric contents and are harder and less well tolerated than the smaller soft-rubber feeding tubes. For short periods, they can be used to feed patients if correctly placed, but it is generally accepted that they tubes are less well tolerated by patients and as such should be replaced with feeding NG tubes at an appropriate time.
Enteral feeding equipment. (Image credit: Ashashyou, via Wikimedia Commons, license)
Nutrition care bundles
The standard NG feeds used to supplement nutrition in our POCU patients are most often an off the shelf preparation (see the note below on TPN contents). There is some variation an content, some containing more calories (concentrated feed), some less potassium and are even gluten free! We tend to NGT feed over 24 hours as it allows us better blood glucose control and holding feed should only occur when there are concerns around absorption, a plan for surgery or other intervention, or to allow certain drugs to be absorbed.
On your POCU in your hospital – what are the regulations around patients families bringing in home-cooked food for their relatives? This is particularly important in an ethnical diverse community where hospital catering may not be what patients are used to. Nutrition might be seen as “food” and food is good for the soul – do not underestimate the value of family members bringing in a little something special for their loved ones. Just be sure it’s appropriate and the timing is right!
Parenteral Nutrition
Most of the time in POCU patients will either be eating and drinking orally or in some cases via an NG tube. However, there are some cases where patients will have an extended period of malnutrition or time where their GI tract is unable to tolerate some or any enteral feeding.
In these cases, patients may require parenteral nutrition which bypasses the stomach and bowel altogether to deliver calories and nutritional supplements straight into the patient’s circulation. This must be through a dedicated port on the central line into a large vein.
Total parenteral nutrition. (Image credit: Tristanb, via English Wikipedia, license)
Total Parenteral Nutrition (TPN) is formulated specifically for individual patients, but ‘off the shelf’ bags can be used when a comprehensive nutritional assessment is yet to be performed by your POCU Dietician.
The POCU Dietician will assess and calculate daily patient requirements for all major substrates including carbohydrates, proteins and fats, but will also include vitamins and other trace elements to formulate a balanced nutritional prescription which is signed off by the POCU doctor and made up in sterile conditions within a pharmacy department.
TPN MUST be handled with attention to asepsis. The content of the bag is a rich medium in which life-threatening bacteria grow and as such the risk of introduce infection directly into the blood stream is significant.
The visiting surgeon or POCU doctor disconnecting TPN infusions to give occasional drugs is not acceptable in POCU, the bedside nurse must defend safe, aseptic principles and report incidents of failure to comply with these measures – another patient safety issue!
Complications of nasogastric feeding and/or parenteral nutrition
Patients with feeding tubes are at risk of many complications, such as aspiration, tube malposition or dislodgment, re-feeding syndrome, medication-related complications, fluid imbalance, insertion-site infection, and agitation.
There are things we can do in the POCU to help reduce these complications. For example:
- Nurse the patient at 30 degrees head up to reduce the risk of reflux and aspiration.
- Monitor gastric residual volume every four hours in patients receiving continuous tube feeding (see your own department policy on this).
- Check feeding tube position at the beginning of each shift and record the length at which it is secured.
- Monitor patients for gastric distention, nausea, bloating, and vomiting. Stop the infusion and notify the doctor if the patient experiences acute abdominal pain, abdominal rigidity, or vomiting.
Re-feeding Syndrome
Patients with sustained malnutrition are at risk for re-feeding syndrome. Refeeding syndrome is defined as the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial re-feeding. This syndrome may trigger life-threatening arrhythmias and multisystem dysfunction.
You should have a high index of suspicion when looking after patients with long-term malnutrition.
Whilst on the PACU, it is important to monitor for intolerance at the onset of enteral feedings by checking heart rate/rhythm and electrolyte levels. The incidence of re-feeding syndrome is low but failure to recognise the drop in potassium and magnesium can be catastrophic.
In order to reduce the risk of re-feeding in these high-risk patients, they should be identified pre-operatively and reviewed by the dietician with a formal plan put in place. These patients may require vitamin supplementation and close monitoring whilst (with an ECG and electrolyte monitoring) in the perioperative period.
This is a good example of why the multidisciplinary team is so crucial on POCU.
This article is from the online course:
Road to Recovery: Mastering Postoperative Care of the High-Risk Patient
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This article is from the free online
Road to Recovery: Mastering Postoperative Care of the High-Risk Patient
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