Parenteral and Enteral nutrition

Shima Ghavimi, PGY2Howard university Hospital

Learning Points:

INTRODUCTION GOALS Outcomes CONTRAINDICATION INDICATIONS COMPLICATIONS

Introduction

Nutrition support refers to enteral or parenteral provision of calories, protein, electrolytes, vitamins, minerals, trace elements, and fluids.

GOALS

primary goal of nutrition support is to alter the course and outcome of the critical illness.

During recovery from acute illness anabolism >catabolism 1. Nutritional support provides substrate for the anabolic state, during

which the body corrects hypoproteinemia, repairs muscle loss, and replenishes other nutritional stores

2. Provide carbohydrates as a preferred source of energy during this time as fat mobilization will be impaired

3. Provides protein to reduce muscle breakdown to AA as a substrate of GLUCONEOGENESIS

Outcome:

In Adequately nourished patients: Enteral nutrition may decrease the incidence of infection

in critically ill patients but no mortality benefit Mechanism unknown , but preservation of gut immune

function and reduction of inflammation may paly a role

In patient with malnutrition: Most studies excluded malnourished patient It is believed enteral nutrition beneficial to

patient with prolonged period of inadequate intake.

Some observational evidence shows progressive caloric deficit increase mortality.

Parenteral nutrition(PN): Early parenteral nutrition (up to 48 hours) does not alter

mortality but increase risk of nosocomial infection No consistent evidence in critically ill patients suggesting that

early provision of parenteral nutrition improves ventilator-free days or length of stay in the ICU or hospital

Optimal time for starting PN is unknown Typically is not started in one to two weeks

Conclusions:Late initiation of parenteral nutrition was associated with faster

recovery and fewercomplications, as compared with early initiation.

Conclusion: The supplemental use of parenteral nutrition may improve provision of calories and protein but is not associated with any clinical

benefit.

Enteral access:

Gastric(NG or OG tube, PEG tube, percutaneous radiologic gastrostomy tubes, and surgical gastrostomy tubes)

Post-pyloric usually ending in the first or 2nd part of duodenum -mostly useful in patients with prolonged inability to tolerate gastric feeding -gastric outlet obstruction - duodenal obstruction -gastric or duodenal fistula - severe GERD - the inability to have a gastric enteral access tube due to altered anatomy

Formulation for EN:

Standard Concentrated Predigested

Standard:

Isotonic to serum Caloric density of approximately 1 kcal/mL Lactose-free Intact (nonhydrolyzed) protein content of about 40 g/1000 mL (40

g/1000 kcal) Mixture of simple and complex carbohydrates Long-chain fatty acids (although some are now including medium-chain

and omega-3 fatty acids) Essential vitamins, minerals, and micronutrients

Concentrated:

Critically ill patients frequently require volume restriction (eg, patients with respiratory failure, or volume overload).

Is similar to standard EN, but mildly hyperosmolar to serum has a caloric density of 1.2, 1.5, or 2.0 kcal/mL.

Predigested:

Predigested enteral nutrition differs from standard enteral nutrition: -the protein is hydrolyzed to short-chain peptides and the carbohydrates are in a less complex form. -The total amount of fat may be decreased, with an increased proportion of medium-chain triglycerides

and has caloric density of 1 or 1.5 kcal/mL.

When to use predigested?

Thoracic duct leak, chylothorax, or chylous ascites, since the medium-chain triglycerides do not enter the lymphatic capillaries in the small intestine

Digestive defects (eg, malabsorptive syndromes that are unresponsive to supplementation of pancreatic enzymes)

Failure to tolerate standard enteral nutrition

Monitoring:

Patients on tube feeding are at risk for fluid imbalance, gut dysfunction, and electrolyte imbalance

If GRV is measured, volumes of less than 500 mL should not result in the holding of the feeds unless other signs of intolerance, such as distension, nausea, or vomiting, are present.

Gastric residuals should be measured if the patient exhibits a clinical change, such as abdominal pain, abdominal distension, or deterioration in hemodynamics or overall status.

Complications of EN:

Aspiration Diarrhea Metabolic abnormalities Mechanical complication .

Diarrhea

15-18%of critically ill patient who receive enteral nutrition Unknown precise mechanism ,alteration of intestinal transit or intestinal

microflora Usually A/W concomitant use of medications that can cause diarrhea

such as antibiotic, PPIs or medications in suspension due to administration with sorbitol .

fiber is the best accepted therapeutic intervention for enteral nutrition associated diarrhea , but it is contraindicated in patients with impaired peristalsis such as patients on vasopressors.

Metabolic abnormalities:

Hyperglycemia, micronutrient deficiencies, and refeeding syndrome. Refeeding synd: potentially fatal , resulting from rapid changes in fluids

and electrolyte when malnourished patient is given oral , enteral , parenteral feeding.

Manifest as severe hypophosphatemia (CV collapse, resp. failure, Rhabdomyolysis, seizure, delirium)

Hypo Mg and hypo K can occur.

Mechanical :

Constipation is a well-known consequence of enteral nutrition support.

Fiber bezoar is less complication of enteral feeding with fiber. More prevalent in patients with impaired peristalsis like being on

vasopressors.

Cause impaction, bowel distention, perforation, and death if not treated early.

Contraindications:

hemodynamically unstable patients who are not fully resuscitated maybe predisposed to bowel ischemia.

Hemodynamic instability is not by it self contraindication for enteral feeding if there is evidence of good perfusion and intravascular resuscitation

Other contraindications: bowel obstruction , severe and protracted ileus, major UGIB, intractable vomiting and diarrhea, high output fistula, severe hemodynamic instability, GI ischemia.

Indication:

If patient does not have contraindication to enteral nutrition, we can start enteral feeding early(within 48hrs) due to outweighs of benefits (lower mortality and fewer infection).

For adequately nourished patients who have contraindications to enteral nutrition, we should NOT initiate early parenteral nutrition and typically do not start feeding parenterally before one to two weeks. This reflects the evidence that early parenteral nutrition may increase the risk of infection and prolong mechanical ventilation, ICU stay, and hospital stay

For inadequately nourished patients who have contraindications to enteral nutrition that are expected to persist for a week or more, we can initiate PN within the first few days.

Although the effects of parenteral nutrition in such patients are unknown; but failure to treat the malnourishment will result in a progressive caloric deficit, which is associated with increased morbidity.

Diagnosing malnutrition:

BMI<18.5 Unintentional loss of>5 lb or 5% of the body weight over one month. unintentional loss of more than 4.5 kg (10 lb) or 10% of body weight

over six months. Temporal muscle wasting, sunken supraclavicular fossae, decreased

adipose stores, and signs of vitamin deficiencies While such findings may be suggestive of malnutrition, they are imperfect because they are just as likely to be a consequence of the catabolic effect of the underlying illness.

A 45-year-old woman is admitted to the intensive care unit after a motor vehicle accident in which she sustained significant burns to 70% of her body. She is intubated and sedated. On physical examination, temperature is 37.9 °C (100.2 °F), blood pressure is 145/85 mm Hg, and her ventilated respiration rate is 15/min. She has extensive burns involving nearly all of the face, neck, and trunk, with notable extravasation of tissue fluid through her dressings.

Which of the following is the most desirable approach to nutritional support in this patient?

1)Enteral nutrition via nasogastric feeding tube 2)Enteral nutrition via percutaneous jejunal feeding tube 3)Parenteral nutrition via central access 4)Parenteral nutrition via peripheral access

Parenteral nutrition:

In order to initiate PN, appropriate access must be obtained and the composition and infusion rate must be determined.

PN given for more than a few days must be via central venous catheter because its high osmotic load is not tolerated by peripheral veins. Parenteral nutrition may be given via a peripheral vein if it is significantly more diluted, so called peripheral parenteral nutrition.

Short-term parenteral nutrition is generally delivered through a peripherally inserted central catheter (PICC), or a subclavian, internal jugular, or femoral central venous catheter.

Long-term parenteral nutrition requires a tunneled central venous catheter (eg, Hickman catheter, Groshong catheter, or implanted infusion port) or a peripherally inserted central catheter (PICC).

Dextrose:

Variety of concentration, most commonly 40,50 and 70 percent The percentage of the calories that is contributed to dextrose titrated

according to individual factors such as severity of the illness, caloric needs of the patients and ability to tolerated fluid volume.

Caloric contribution of dextrose is 3.4kcal/gm

Amino acid and electrolytes:

AA stock solutions come in concentration of 5.5 to 15 % Higher concentration are used to minimize volume and electrolytes

delivered to patient. AA solutions contains most essential and non-essential AAs. Except arginine and glutamine. Caloric contribution of AA is 4kcal/gm

Lipids:

In the United States, lipid emulsion consists of long-chain omega-6 triglycerides derived from soybean and safflower oils and then emulsified using egg phospholipids and glycerin.

The caloric contribution of a typical lipid emulsion is 2 kcal/mL in 20 percent emulsion and 1.1 kcal/mL in 10 percent emulsion.

Use of intravenous fat emulsions should be done with care in patients with prior allergy to eggs as very rare allergic reactions have been reported.

Vitamins and trace elements:

A meta-analysis of 15 randomized trials (1647 patients) found that critically ill patients who received vitamins and trace elements, had a lower mortality rate than patients who did not receive vitamins or trace elements.

Similar meta-analyses showed improvement in the duration of mechanical ventilation, but no differences in infectious complications, hospital length of stay, or ICU length of stay.

it seems reasonable to provide vitamins and trace elements to most critically ill patients, regardless of the type of nutrition support that they are receiving.

Monitoring:

Routine monitoring is fluid intake and output

It is reasonable to measure serum electrolytes, glucose, calcium, magnesium, and phosphate daily, or more, until they are stable.

It is similarly reasonable to measure aminotransferases, bilirubin, and triglyceride at least once each week during treatment.

Complication:

Blood stream infection Metabolic affect Complications related to Venus access

Blood stream infection:

Factors A/W blood stream infection : Poor patient hygiene Inserting central Cath in emergent circumstances Severity of illness Duration of central Venous catheterization Proper hand hygiene and maximal barrier precautions during insertion

of the central venous catheter are associated with fewer bloodstream infections

Metabolic affect:

including hyperglycemia, serum electrolyte alterations, macro- or micro-nutrient excess or deficiency, refeeding syndrome , Wernicke's encephalopathy , and hepatic dysfunction.

Venous access:

Including bleeding, vascular injury, pneumothorax, venous thrombosis, arrhythmia, and air embolism.

When prescribing enteral or parenteral nutrition, the appropriate body weight from which to calculate caloric and protein intake (ie, the dosing weight) must first be determined

Dosing weight:

Underweight [BMI] <18.5 kg/m2 Normal (BMI 18.5 to 24.9 kg/m2) use current weight Overweight (BMI 25 to 29.9 kg/m2)

Obese (BMI ≥30 kg/m2) , Adjust dose as absence of metabolic requirements by fat tissues.

dosing weight = IBW + 0.25 (ABW - IBW) 110 percent of the ideal body weight. dosing weight = 1.1 * IBW.

Calories:

Energy expenditure is typically thought to be high in the critically ill. However, with improvement in mechanical ventilation, as well as pain, anxiety, and temperature control, the caloric expenditure of the critically ill may not exceed resting energy expenditure.

starting point is approximately 8 to 10 kcal/kg per day.

Attempting to achieve a goal of 25 to 30 kcal/kg per day after one week .

Conclusion:Conclusion:

Conclusion: low calorie feeding (mean caloric intake 400 kcal/day) for the first six days, compared with full enteral feeding

(mean caloric intake 1300 kcal/day), did not change ventilator-free days, 60-day mortality, or infectious complications, but was

associated with less gastrointestinal intolerance.

Protein:

Mild to moderate illness 0.8 to 1.2 g/kg protein per day.

Critically ill patients 1.2 to 1.5 g/kg per day.

Patients with severe burns may benefit from as much as 2 g/kg per day.

A 51-year-old man was admitted to the intensive care unit 3 days ago for septic shock with multisystem organ failure. Septic shock resulted from peritonitis following colon resection for a ruptured colonic diverticulum. He is on mechanical ventilation and had been treated with vasopressor agents, but these are no longer required. He is able to tolerate enteral nutrition with a standard commercial preparation (1 kcal/mL) at 10 mL/h via a soft nasogastric feeding tube.

On physical examination, temperature is 36.4 °C (97.5 °F), blood pressure is 120/70 mm Hg, pulse rate is 88/min, and respiration rate is 16/min. Weight is 80.0 kg (176.4 lb) and height is 177 cm (69.7 in)

Which of the following is the most appropriate next step in the management of this patient's nutrition?

A)Begin supplemental total parenteral nutrition B)Change to an enhanced preparation of glutamine, arginine,

antioxidants, and omega-3 fatty acids C)Increase the rate of the current nutritional preparation D)Supplement tube feeds with intravenous lipid formulation

Summary:

For critically ill surgical patients without contraindications to enteral nutrition, it is recommended early (eg, within 48 hours) enteral nutrition.

•For critically ill patients who are hemodynamically unstable and have not had their intravascular volume fully resuscitated early enteral nutrition is contraindicated •

For adequately nourished patients who have contraindications to enteral nutrition, it is recommended NOT initiating early parenteral nutrition While the optimal time for starting parenteral nutrition in these patients is unknown, usually it is not recommended to start parenteral feeding before one to two weeks.

For malnourished patients who have contraindications to enteral nutrition that are expected to persist one week or less, it has been suggested NOT initiating parenteral nutrition.

For malnourished patients who have contraindications to enteral nutrition that are expected to persist greater than one week, we suggest parenteral nutrition .

An acceptable initial nutritional goal is 8 to 10 kcal /kg per day and then 18 to 25 kcal/kg/day and 1.5 grams of protein/kg per day after five to seven days.

Uptodate Harrsion principle of internal medicine Pubmed NEJM

Especial thanks to Dr.Laiyemo