Role of Preoperative Parenteral Nutrition

Introduction:

In patients undergoing surgeries, poor nourishment is common. This condition is commonly seen in patients with severe illness, malignancy, organ failure, etc. Malnutrition can also occur due to the impact of surgeries themselves. Preoperative nutrition helps patients with a speedy recovery, shortens the hospital stay, and reduces complications and even mortality. Certain valid tools are used to assess nutritional status and to find malnutrition in patients preoperatively. After evaluating the nutritional status, preoperative nutrition is given. If enteral nutrients (nutrients through the oral route) are inadequate or the patient cannot take nutrients orally, the parenteral route is opted.

How Is Nutritional Screening Done?

Nutritional status should be assessed in every patient preoperatively. Thus the patient can be treated effectively against malnourishment occurring after surgery. Valid tools of nutrition screening should be used.

Various tools are,

• Checking body mass index (BMI).

• Check the weight if the weight loss is greater than ten percent.

• Checking the serum albumin level.

• Various measuring indexes are used to assess the patient's nutritional status: the nutrition index (NI) and the nutrition risk index (NRI).

• In certain studies, various other factors are taken to assess circumference around the middle arm area, skinfold thickness, blood count like total lymphocyte count, etc.

• The European Society for Clinical Nutrition and Metabolism (ESPEN) gave guidelines for clinical nutrition in surgery. They consider the risk of malnutrition if one of the following criteria is present;

- Body mass index (BMI) is less than 18 kg/m2.

- Weight loss greater than 10 - 15 % within a six month period.

- Subjective global assessment, Grade C.

- Serum albumin less than 30 g/L (without evidence of liver or kidney dysfunction).

- Serum albumin would not change in response to changes in the diet or nutrients, thus;

it is not considered a valid marker in nutritional assessment.

• Additionally, nutritional care should be given to all ongoing surgery patients to provide a better outcome.

• CNST - It is the Canadian Nutrition Screening Tool used for assessing nutritional status, and this tool is used to identify the risk of malnutrition.

What Are the Benefits of Preoperative Parenteral Nutrition?

• Various studies compared enteral nutrition with parenteral nutrition. In the case of mortality, enteral nutrition does not find any advantage over parenteral nutrition. Patients with enteral nutrition show more chances of vomiting and hypoglycemia in some instances.

• In cases where a patient is experiencing more weight loss, like more than ten percent, parenteral usage of nutrition decreases the impact of the development of an intra-abdominal abscess.

• In some instances, patients have side effects like vomiting, gastrointestinal problems, and abdominal pain in response to enteral nutrition, and enteral nutrition takes longer than parenteral nutrition. So we can say the patients mainly utilize parenteral nutrition, or the benefits of the parenteral nutrition are most in patients with gastrointestinal diseases like inflammatory bowel disease, stomach cancer, etc., and patients unable to tolerate enteral nutrition.

What Is the Dosage of Preoperative Parenteral Nutrition?

• In preoperative parenteral nutrition, energy and protein are given not for weight gain but repletion of energy and protein storage, and micronutrient deficiencies, to withstand the nutrient loss at the time of surgery.

• Preoperative parenteral nutrition should start at least 7 - 10 days before the surgery, but this range may vary in patients with cancer.

• According to ESPEN guidelines, estimated energy and protein are 25 - 30 kcal/kg/day and 1.5 g/kg/day, respectively.

• An adequate supply of micronutrients should be done because it has an impact on postoperative outcomes. According to RDA - recommended dietary allowance, micronutrients are given. The dosage depends on the nutrients provided, either enteral, parenteral intravenous, etc.

• Parenteral nutrition is not much needed in patients with good nutrition. Intravenous administration in well-nourished patients has even fatal side effects so thorough assessment and guidelines should be followed for preoperative parenteral nutrition.

What Are the New Directions in Preoperative Parenteral Nutrition?

• This is done in intra-abdominal surgeries.

• This outpatient parenteral nutrition is also done to evaluate outcomes like postoperative outcomes, including the length of hospital stay, recovery, etc.

• Clearly, undernourished and major surgeries impact the quality of life and affect patients' daily activities. Preoperative parenteral nutrition has increased the positive results post-surgically, especially in terminally ill patients like patients with cancer. So more advanced studies are happening to improve various steps in preoperative parenteral nutrition and also to find more postoperative results.

• An important step in preoperative parenteral nutrition is an assessment of each patient for malnutrition for the treatment plan. Several factors like serum albumin level, nutrition status, patient body weight, and measurements are used. But these factors are not relevant because these factors are influenced by various other things and would not show a sudden change in response to nutrition. Thus specific nutrition assessment factors should be identified.

What Are the Complications and Prevention of Preoperative Parenteral Nutrition?

There are different types of complications associated with preoperative parenteral nutrition. It can be catheter-related complications or parenteral nutrition-related complications. Catheter-related complications are due to its path of administration like the intravenous path of administration.

• Intravenous administration of nutrients helps maintain nitrogen balance and quickly speed up the recovery. But in the intravenous path, nutrients are administered into the vein, so complications are there, some early complications like embolism (air embolism - it occurs when a bubble enters into the blood vessel and blocks the blood supply), bleeding, conditions like pneumothorax (when air enter into the space between lung and wall of the chest), artery puncture and cardiac arrhythmia (improper beating of the heart).

• Late intravenous complications are permeability, and venous thrombosis (blood clots formed will dislodge from the site and enter the lungs - a quite a serious condition).

• Catheter-related infections are not easy to find and so proper catheter care should be taken to avoid this type of complication.

Parenteral nutrition-related complications are also early and late,

• It includes alteration in glucose level (hypoglycemia or hyperglycemia), abnormalities in electrolyte balance, abnormal liver function, and refeeding syndrome.

• There may be psychological problems associated with the administration of parenteral nutrients. These are all the complications associated but not so common.

Prevention Methods - Signs of vascular access device complications and volume overload should be monitored during PN. Blood tests for electrolyte, liver function, triglyceride, and renal function should be checked daily. Blood sugar levels should also be checked and monitored regularly and kept under 180 mg/dL.

Conclusion

Preoperative parenteral nutrition is associated with positive post-surgical outcomes. It is very effective in patients with malnourishment. In some patients who are not compatible with enteral nutrition (such as gastric cancer, intolerance, etc.) in such cases parenteral nutrition is found to be useful. Assessment of the patient for nutritional status is mandatory in the process of parenteral nourishment to find out the needful patients. There are few complications for parenteral nutrition, but they are rare; thus, under close monitoring of patients' vitals and keeping everything in control, preoperative parenteral nutrition can be given to obtain a positive post-surgical outcome.