feeding

Question 1

definition of parenteral feeding

Answer 1

IV administration of nutrients

may be supplemental to oral or tube eg in short bowel syndrome or Crohn’s - when nutrition cannot be sufficientlt absorbed in the gut

or be the only source - TPN

even if GI disease - enteral is safer, cheaper and at least as efficacious as parenteral nutrition in the perioperative period

Question 2

indication for parenteral nutrition

Answer 2

considered for all patients who are malnourised or at risk of malnutrition

and have a non-functioning or inaccessable GIT preventing enteral feeding, and unlikely to work for 7days

peripheral line (peripherally inserted central catheters - PICCs, or standard cannulae) - short term support

central catheters and tunnelled subclavian vein central lines - >2wks

or dedicated lumen of multilumen catheter

central allows delivery of more concentrated formulations into high flow vessels

tolerance to peripheral is increased with feeds of low osmolarity and neutral pH and use of soft paediatric cannulae

Question 3

parenteral feed preparations

Answer 3

TPN solns have mix of essential and non-essential AA, glucose, fat, electrolytes and micronutrients

Iso-osmotic lipid emulsions are used to provide an energy-rich solution and reduce irritation of veins. - lower conc of glucose to prevent hyperglycaemia or hyperosmolar dehydration

Vitamins including folic acid are infused with the solution, but vitamin B12 must be prescribed separately

Question 4

delivery of parenteral nutrition

Answer 4

introduced at a low rate and gradually increased

TPN is usually deliverd at a continuous flow rate but cyclical regiemes may suit longer use

Question 5

complications of parenteral nutrition

Answer 5

re-feeding syndrome

metabolic imbalance

catheter related complications

infection

liver and gallbladder dysfunction

hyperglycaemia - treatment with hypoglucaemic agents or insulin is often required

the nutrition is thrombogenic and an irritant to veins

Question 6

re-feeding syndrome

Answer 6

in starvation intracellular electrolyte stores, esp phosphate, are depleted (even though serum conc is normal)

feeding stimulates cellular uptake of electrolytes -> electrolyte disturbances - hypophosphtaemia, low Mg, Ca, glucose and thiamine

clinical features appear in 4 days (non-specific)

rhabdomyolysis

red and white cell dysfunction

cardiac failure

hypotension

arrhythmias

resp failure

seizures

coma

sudden death

Question 7

catheter related complications to parenteral feeding

Answer 7

immediate - related to insertion - haemorrhage, pneumothorax, haemothorax, arrhythmias, cardiac tamponade

embolism of IV line tip

long term - thrombosis, PE, pleural or pericardial effusion, subacute bacterial endocarditis, chylothorax and venopulmonary fistula

Question 8

infection with parenteral feeding

Answer 8

staphylococcal (staph aureus, staph epidermidis and eneterococcal species are common

candida spp

Klebsiella pneumoniae

pseudomonas aeruginosa

IE

There must be strict adherence to aseptic and solution bags and giving sets must be discarded after 24 hours of use

look for spiking pyrexia and examine wound at tibe insertion point

stop PN, take line and peripheral cultures

give AB via line

if central venous line sepsis is suspected - remove line

Question 9

thrombosis with parenteral nutrition

Answer 9

central vein thrombosis = PE or SVC obstruction

Question 10

liver and gallbladder dysfunction in parenteral nutrition

Answer 10

majority of patients develop mild cholestasis - high transaminases and ALP

gallstones and gallbladder sludging may occur

Question 11

indications for home parenteral nutrition

Answer 11

pts must have training and information before discharge

individual nutritional care plan is drawn up

pts must be competent in managing feeding systems and aware of the common problems

must be supported by skilled team

GPs must be closely involved to liase and recognose potentially life threatening complications

Question 12

mechanism of refeeding syndrome

Answer 12

refeeding causes shift from fat to carbohydrate metabolism and increases insulin secretion

insulin -> cellular uptake of phosphate and K = hypophosphtaemia and hypokalaemia

clinical manifestations are from low ATP in metabolic pathways and low 2,3 diphosphoglycerate in erythrocytes = tissue hypoxia and impairment of myocardial contractility

Question 13

Mx of refeeding syndrome

Answer 13

preventative

measured serum K+, phos, Mg, Ca and give IV replacement before refeeding

replace thiamine

daily multivitamin

increase calories gradually

give high dose Pabrinex during re-feeding window

Question 14

metabolic imbalance with parenteral nutrition

Answer 14

refeeding syndrome

deranged plasma gluycose

hyperlipidaemia

deficiency syndromes

acid base disturbance - hypercapnia from excessive CO2 production

Question 15

why are so many pts in hospitals malnourished

Answer 15

increased nutritional requirements - sepsis, burns, surgery

increased nutritional losses - malabsorption, output from stoma

decreased intake - dysphagia, nausea, sedation, coma

effect of treatment - nausea, diarrhoea

enforced starvation - prolongued periods NBM

missed meals - due to Ix

difficulty with feeding - lost dentures, no one available to assist

unappetizing food

Question 16

how do you identify patients at risk of malnutrition

Answer 16

assess nutrition state using Malnutrition universal screening tool, and weight on admission - reassess weekly

Hx

• recent weight loss >20% accounting fro fluid balance
• recent reduced intake
• diet change - ie chnage in consistency
• nausea
• vomiting
• pain
• diarrhoea

O/E

• dehydration
• skin hanging off muscles
• no fat between fold of skin
• hair rough and wiry
• pressure sores
• sores at corner of mouth
• BMI <18.5kg/m2
• anthropomorphic indices - eg mid-arm circumference, skin fold measures and grip strength

Ix

• low albumin - but affected by other things

Question 17

definitions of enteral nutrition

Answer 17

nutrition given into GIT

if possible give nutrition by mouth

Question 18

indictations for enteral nutrition

Answer 18

all fluid diet can meet requirements

if danger of smoking/aspiration - semi-solid diet

early post op enteral nutrition has benefits and may reduce complications

Question 19

what is tube feeding

Answer 19

liquid nutrition via a tube

NG - placed w/o guidance

NJ - require endoscopic placement

they can be inserted surgically ie gastrostomy/jejunosomy

typically initiated at a slow, continuous rate - less nausea and vomiting

may have shorter bolus feeds to free from pump

Question 20

indication for NJ tuve

Answer 20

gastric outlet obstruction

delayed gastric emptying

post-gastrectomy

pancreatitis

Question 21

contents of enteral feeds

Answer 21

polymeric feeds - undigested proteins, starches and long chain fatty acids (eg Nutrison standard, osmolite)

• Normally contain ~1kCal/mL and 4–6g protein per 100mL. Typical requirements met with 2L/24h.

elemental feeds - individual AA, oligo- and monosaccharides needing minimal digestion

Question 22

guidelines for success for enteral feeds

Answer 22

fine bore NG tube

check in right place (NG - pH test, NJ - XR)

build up foods gradually to prevent diarrhoea and distension

weigh weekly

check blood glucose and electrolytes - monitor for refeeding syndrome

treat underlying conditions vigorously - sepsis can impede +ve nitrogen balance

Question 23

complications of enteral feeding

Answer 23

tube complications

infection

gastro-oesophageal reflux and aspiration

gastrointestinal sx

re-feeding syndrome

Question 24

NG tube complications with enteral feeding

Answer 24

• nasopharyngeal discomfort and later nasal erosions, abscesses and sinusitis.
• pharyngeal or oesophageal perforation, intracranial or bronchial insertion
• Longer use may cause oesophagitis, oesophageal ulceration and stricture
• Large stiff NG tubes are particularly unsafe in the presence of varices

Question 25

Percutaneous gastrostomy or jejunostomy tubes complications

Answer 25

related to endoscopy

bowel perf, abdo wall or intraperitoneal bleeding

post-insertion complications include stoma site infections, peritonitis, peristomal leaks, dislodgement and gastrocolic fistula formation

Question 26

gastro-oesophageal reflux and aspiration in enteral feeding

Answer 26

particularly in patients with impaired consciousness, poor gag reflex and when fed in the supine position

Reflux is more likely with accumulation of gastric residues.

Question 27

gastrointestinal sx from enteral feeding

Answer 27

gut motility and absorption are promoted by hormones released during mastication, with co-ordinated stomach emptyinh and the presence of intraluminal nutrients

bypassed during enteral feeding = gastrointestinal symptoms such as abdominal bloating, cramps, nausea, diarrhoea and constipation