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Satiated Before Surgery
Pre-op nutrition is a major component of priming patients for procedures.
Daniel Cook
Publish Date: February 3, 2021   |  Tags:   Pain Management
PRIMED FOR SUCCESS A well-balanced diet and carbohydrate-rich supplement drinks improve post-op healing and contribute to positive outcomes.   |   Lynda Schoppe

Patients who go NPO in the hours leading up to their surgeries aren't physically prepared for the physical trauma they're about to endure. "Surgery is a major stress on the body," says Steven Bisch, MD, FRCSC, BMSc, a surgical fellow in the division of gynecologic oncology at Tom Baker Cancer Centre in Calgary, Alberta. "Individuals who are malnourished have a harder time recovering and are at increased risk of complications."

Malnourishment can be caused by disease factors, dietary habits and by traditional perioperative practices such as excessive periods of fasting and bowel preparation, according to Dr. Bisch. "Studies have shown that the timely identification and correction of preoperative malnourishment improves surgical outcomes and patients' quality of life," he says. "Awareness of this aspect of surgical care is growing among healthcare providers, often as it relates to comprehensive, evidence-based care pathways such as Enhanced Recovery After Surgery (ERAS)."

For patients, prolonged fluid fasting can lead to more anxiety, PONV and poor patient experiences, says Daniel Orlovich, MD, PharmD, a clinical instructor in the department of anesthesiology at Stanford (Calif.) Health Care.

Even just four hours of fasting before surgery can result in the depletion of glycogen and dehydration, according to Dr. Bisch. Glycogen acts as an immediate source of nutrition to fuel repair during and immediately following surgery. "In the absence of glycogen, the body must rely on slower sources of energy, and often utilizes protein as an energy source," explains Dr. Bisch. "These energy sources are less responsive and delay the healing process, and can contribute to the breakdown of muscle tissue." When the body is deprived of nourishment, it goes into a fasting state, during which it attempts to conserve as much energy as possible. "A fasting state leads to insulin resistance as the body tries to avoid using resources — this is not conducive to healing and tissue growth," says Dr. Bisch. "Insulin helps healing by acting as a growth factor for tissue and by allowing glucose to enter cells for use."

Insulin resistance leads to hyperglycemia and impaired immune function, especially in patients with underlying impaired glucose tolerance and diabetes, according to Dr. Bisch. He says hyperglycemia is independently associated with increased post-op morbidity and mortality. He also says the fasting state promotes an aggressive and harmful inflammatory stress response to surgery.

"Traditional NPO guidelines are not best practice for patients," says Dr. Bisch. "They have been debunked and are no longer supported by the majority of world anesthesia societies. The safety of carbohydrate loading and shortened fasting periods has been well proven, and is a key component of ERAS pathways."

Shortened pre-op fasting periods lead to improved glycogen stores, diminished stress response and less insulin resistance, according to Dr. Bisch. "That results in shorter post-op stays, lower complication rates and ultimately lower healthcare costs," he says.

He points out that optimizing the nutritional status of patients by minimizing fasting and with carbohydrate-rich pre-surgical drinks have been shown to improve outcomes as part of ERAS protocols and, importantly, improve quality of life for patients. (Dr. Bisch highlights an important caveat: The safety of shortened fasting periods has not been well studied in patients with impaired stomach emptying, such as those with diabetes, functional gastroparesis, severe acid reflux, significantly elevated estrogen levels or acute abdominal inflammation.)

Dr. Bisch says drinks specially formulated for surgical patients ensure an appropriate carbohydrate load, and provide electrolytes and proteins that modulate the immune system to maximize healing. Their downside is cost, and access for patients. "In many centers with robust ERAS programs, simple clear juices or sports drinks are utilized with benefits shown to patients," says Dr. Bisch. "Unfortunately, larger comparative studies and cost-effectiveness analyses are needed before any definitive statements can be made in this area."

Traditional NPO guidelines are not best practice for patients.
— Steven Bisch, MD, FRCSC, BMSc

Patients at high risk for malnutrition should be referred to a registered dietician familiar with perioperative care, according to Dr. Bisch. He suggests universal nutritional screening of patients with easy-to-implement tools such as Strong for Surgery from the American College of Surgeons (osmag.net/BoK7Pv), and recommends patients commit to a well-balanced diet rich in protein and iron leading up to their procedures. Nutritional supplementation should start at least 10 to 14 days before scheduled surgeries for patients at high risk for malnutrition, he says, and iron-deficiency anemia should be identified and corrected before surgery.

Relatively healthy individuals are less likely to experience negative outcomes related to perioperative malnourishment, but the risk still exists. "Most patients undergoing elective procedures are fairly well nourished by rough standards, yet numerous studies show major complications can occur that are preventable with short-term pre-op nutrition enhancement," says Lary Robinson, MD, a thoracic surgeon at Moffitt Cancer Center in Tampa, Fla.

Dr. Orlovich says even elective procedures can cause significant physiological shifts that may not be readily apparent. "The surgery may be elective, but the physical impact is not," he says. "It's still important to optimize the nutritional status of patients because the interventions are low-cost, easy to implement and may yield positive outcomes."

There's still work to be done to promote the benefits of optimized pre-op nutrition, however. Dr. Robinson believes most providers are unaware of the potential for simple pre-op nutritional measures that can decrease complications, even in patients who are well nourished. "Educating surgeons about the importance of perioperative nutrition is desperately needed, and could save the healthcare system enormous amounts of money," he says.

Dr. Orlovich believes it's now time to reimagine how care is delivered outside of the OR to match the tremendous strides that have been made in how surgery is performed. "Optimizing the nutritional status of patients is an opportunity to provide practical, low-cost and rational recommendations that can impact our healthcare system in a meaningful way," he says.

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