Nutrition

Objectives

To guide the administration of oral feeds in the deployed critical care or ward settings.

Scope

Guidance is provided on the initiation of nasogastric feeding, confirmation of NG tube position, consideration of the risks of re-feeding syndrome and it's management,  protection against gastric ulcers. Suggestions are made for the special situations of paediatric patients and improvised feeds.

Audience

Critical care nurses, ACCPs and Doctors.

Ward nurses and physicians.

Initial Assessment & Management

Key Principles

• Consider every patient admitted to deployed ICU at risk of malnutrition
• Nutrition should start unless contraindicated within 48hrs, ideally 24hrs.
• The enteral route is the only viable means of nutrition delivery in the deployed environment.
• Use oral feeding whenever possible
• Do not seek to achieve early full nutrition, start slowly and gradually increase to achieve this within 3 to 7 days

Gastric Ulcer Prophylaxis

• Prescribe omeprazole 40mg OD iv for all adults in deployed ICU.
• Move to enteral route if consistently tolerating feed.
• Consider stopping if following conditions met
  • Fed, and tolerating feed
  • Resolved haemodynamic instability
  • No other indication for gastroprotection e.g. ongoing steroid

Blood glucose control

• Use insulin, ideally by continuous infusion, to achieve glucose target 4-10mmol/L

Feed delivery

• Use oral feeding where patients are able to eat and drink normally
• If not, insert feeding nasogastric tube unless
  • Ryles tube already in place with surgical instruction for free drainage
  • Significant facial trauma
  • Clinical or radiological evidence of base of skull fracture
  • Uncorrected coagulopathy

• By CXR if available
  • Tube must
    • Follow midline to below diaphragm
    • Bisect carina
    • Tip can be seen below left diaphragm
    • 10cm beyond gastroesophageal junction
• If CXR not available, by aspirate with pH of 5.5 or less

IF NOT CONFIRMED DO NOT FEED

Starting feed

• Start nasogastric feeding if tube correctly placed, unless
  • Untreated disruption of GI tract
  • Bowel not in continuity following surgery e.g. stapled ends after DCS
  • Counteracting surgical instruction – seek advice if not made clear in e.g. op note
  • Ongoing severe haemodynamic instability – but consider trophic feed
    • max 10-20ml/hr in order to maintain integrity of gastric mucosa
• Target 25 kcal/kg/day when full nutritional delivery achieved but do not seek to achieve this immediately. Start slowly and aim to achieve “full feed” between 3-7 days after initiation.
• Increase caloric target in major burns. Seek reachback advice if possible.

A possible regime is suggested below.

Feed rate calculator

Calculate total feed volume based on caloric content of whatever formulation available.

Many feeds are 2.4kcal/ml

Feed delivery

• Keep patient 30 degrees head up wherever possible whilst feeding
• Flush NG tube with 30ml water before and after feed.
• Utilise continuous feed pump if available.
• Deliver target feed volume over 20 hours with a 4 hour rest period.

Bolus feeding

• If continuous pump is not available, use an intermittent bolus feeding regime
• Divide feed total volume into 4-6 daily boluses, each delivered over 5-10 minutes
• Initiate feeding with a maximum 80ml bolus size, increasing to a maximum of 300ml as tolerated.
• Flush NG tube with 30ml water before and after feed.

Advanced Assessment & Management

Refeeding

• Consider reducing target by 50% if significant refeeding risk. Consider at risk if any of, and certainly if any 2 of:
  • High intensity operations particularly if on reduced rations
  • Little or nothing to eat for >5 days
  • >10% weight loss in 3-6 months
  • Low BMI
  • Other nutritional problem e.g. alcohol abuse, helminthic infection

• Feed target could be increased to standard rate, if tolerated, after 3-5 days AND patient is appropriately monitored and treated for refeeding electrolyte disturbances.
• Give Pabrinex 1 pair od for 3 days to patients at risk of refeeding syndrome

Electrolyte monitoring and refeeding syndrome

• Monitor electrolytes inc phosphate, magnesium and potassium daily whilst establishing feed (first week) and in patients at risk of, or with, refeeding syndrome
• Monitor electrolytes at least once weekly in patients established on feed
• If phosphate falls below 0.65mmol/L, or falls by more than 0.15mmol/L, replace phosphate and restrict calories (e.g. to 20kcal/hr) for 48 hours before gradual increasing.

Feed intolerance

• Do not routinely measure gastric residual volume in the deployed setting as this increases use of consumables and has minimal supporting evidence of benefit.
• Use clinical assessment to determine feed tolerance. Consider pausing feed and/or reducing rate if
  • Patient reported abdominal pain, bloating, or nausea
  • Vomiting / feed regurgitation
  • Worsening abdominal distension
  • Absent bowel sounds
  • Constipation despite administration of aperients/laxatives
• If clinical evidence of feed intolerance, and no disruption of GI tract, give metoclopramide 10mg iv up to 8 hourly
• Ensure appropriate laxatives used e.g. senna syrup 15mg bd enteral
• Carry out daily ECG and measure QTc

Feed interruptions

• Do not routinely stop feed prior to surgery if already intubated
• Do not stop feed in preparation for intubation or extubation
  • Immediately prior, aspirate NGT to empty stomach
• Stop feed prior to transfer by air or ground as stability of NGT position cannot be guaranteed.

Prolonged Casualty Care

Improvised feeds

It is conceivable that during large scale combat operations the supply of dedicated NG feed will become exhausted and improvised feeds may be considered.

There are no formal guidelines, but the following draws on established practices in the resource-limited setting. 

• Equipment
  • A washable, sealable bag to hang the feed (such as a hydration pack reservoir), alternatively a 50ml syringe 
  • Method to liquidise feed: hand blender ideal, improvise with fork or grater and separate supernatant by squeezing through a fine mesh cloth
  • Method to heat feed (to aid liquidisation and then improve sterility prior to administration).  Standard food hygiene practices are felt to be sufficient.
• Feed
  • Look to utilise whatever is readily available
    • Ration packs
    • Meal replacement powders
    • Milk powders supplemented with peanut butter
    • Locally-available foodstuffs.  Where applicable, those engaged in caring for paediatric patients with malnutrition will likely be a good source of guidance.
  • Emphasis should be on adequate fat and protein content and avoiding excess refined carbohydrate (data supports that this improves glycaemic control, reduces systemic inflammation, facilitating earlier ventilator weans)
• Practicalities
  • Controlling rate is difficult and continuous feeds are likely to obstruct feeding tube.  Utilise burette systems, particularly for paediatric patients, otherwise favour bolus feeding regimes (3 hourly is commonly used)
  • Favour Ryles tube with flushes post- to minimise risk of obstruction.
  • Volume of free-water is likely to be larger than that of dedicated feeds, so account for this in fluid balance calculations.  NG boli of water in combination with feed can be used to conserve intravenous fluid bags.

Paediatric Considerations

• Aim to start nutrition within 24 hours of admission
• Consider age-appropriate use of expressed or donor breast milk
• Use Schofield equation (or similar) to estimate caloric requirements in children

• Calculate fluid maintenance requirement using 4/2/1 rule
  • 4ml/kg/hr up to 10kg of body weight
  • 2 ml/kg/hr for additional weight above 10kg to max 20kg
  • 1ml/kg/hr for any additional weight above 20kg
• Count enteral feed volumes towards this, supplementing with crystalloid as necessary
• If using enteral feeds in very young children ensure daily monitoring of sodium levels