Parenteral nutrition (PN) is when a liquid feed is given through a vein so the gut is completely bypassed. This is usually done when there is intestinal failure (reduced gut absorption leading potentially to severe dehydration) and this is commonly due to patients having a short gut (from surgical resections), a leaking gut (entero-cutaneous fistulas), obstructed gut, one that has disordered movement (dysmotility) or one that doesn’t function due to mucosal disease (e.g. severe Coeliac disease or Crohn’s disease). Occasionally the parenteral nutrition is given because a feeding tube cannot be inserted into the gut or repeated attempts at enteral nutrition have failed.
a. Insertion site of permanent catheter b. Exit site of catheter with an external segment. The implanted port is situated in the upper chest wall.
The tip of a PN catheter lies close to the heart. The biggest risk with PN is of getting an infection on the line. This will usually arise from the hub connection. To reduce the chances of this happening strict aseptic procedures are used to connect/disconnect the infusion. The infusion fluid usually comes in a bag of a variable amount (usually more than 1.5 litres) which connects via a giving set to the catheter that leads near to the heart. A pump controls the flow of fluid. A patient trained to do the connecting and disconnecting themselves will need to be aware of the alarms that can occur while an infusion is in progress. The feed is usually given overnight but can be given during the day if this is more appropriate for the patient’s lifestyle. A rucksack containing a pump, the feed and administration set can be used and allows the patient to work and socialise. The feeds tend to be fat containing (cloudy bag) or fat free. In general most patients will have at least 2 fat bags a week.
Sometimes the external end of the catheter is under the skin (Portacath®) and for each feed a needle has to be inserted through the skin into the device.
When PN is done at home it is referred to as home parenteral nutrition (HPN).
If the patient or carer is unsure about the procedures or wishes to better understand the procedure they should contact the hospital nutrition nurse specialist or dietitian.
Information and illustrations provided by The Nightingale Trust