Score - Nutrition and metabolism Flashcards
A previously healthy 19-year-old man presents at a level 1 trauma center following a motor vehicle crash. The unbelted driver in a car traveling at highway speed, he was ejected from the vehicle. He was tachycardic with a heart rate of 115 beats/min and hypotensive with an initial blood pressure of 84/42 mm Hg (emergency medical services). At the scene, he was intubated with a GCS score of 4. He is stabilized with fluid resuscitation, and workup reveals subdural hematoma, rib fractures (right 5 to 9 and left 2 to 4), grade II liver laceration, left pubic rami fracture and right sacral alar fracture, and right subtrochanter femur fracture. He is admitted to the intensive care unit for continued care. Initiating what type of nutrition support would benefit this patient?
Postpyloric enteral feeding
The benefits of enteral feeding increase as the severity of traumatic injury increases. Enteral feeding is the preferred route of nutrition in severely injured trauma patients and has been shown to decrease rates of pneumonia and intra-abdominal infection when compared with parenteral nutrition.
Nutritional support is indicated given the severity of patient injury and expected duration of nil-per-os (NPO; nothing by mouth) status. Early intragastric feeding decreases gastroparesis in burn patients but may exacerbate gastroparesis in major head or torso trauma patients. A general diet should not be administered to this critically ill trauma patient who is intubated with a head injury.
A 54-year-old woman is admitted to the ICU with gallstone pancreatitis. She is intubated, given fluid resuscitation, and started on vasopressors. She develops abdominal compartment syndrome and undergoes decompressive laparotomy. During the operation, her small intestine is lacerated, and a small bowel resection and anastomosis are performed. Her abdomen is left open, and she is transferred back to the ICU. During the operation, a small-bore feeding tube past the ligament of Treitz is placed. Which of the following is a relative contraindication for initiating enteral nutrition in this patient?
High-dose vasopressors
High-dose vasopressors are a relative contraindication to enteral nutrition. A high osmotic load to the small intestine carries a risk of intestinal necrosis in the setting of decreased intestinal perfusion.
Pancreatitis alone is not a contraindication to enteral nutrition; it can be initiated in patients whose abdominal pain is improving and who can tolerate oral intake without symptoms. Bowel sounds are not a sensitive or reliable indicator of bowel function, and enteral nutrition is not indicated in patients without bowel sounds. Enteral nutrition can be initiated in patients who have an open abdomen or a small bowel anastomosis, because there is no evidence that it is harmful in these settings.
A 64-year-old woman undergoes open small bowel resection and primary repair of an umbilical hernia. She is recovering well; however, she has a persistent ileus. Parenteral nutrition is ordered to start on postoperative day 8. She weighs 70 kg and was well nourished preoperatively. If she requires 25-30 kcal/kg/day, how many grams (g) of glucose should be administered in her parenteral nutrition to provide 55% of her total caloric requirements as carbohydrate?
283 to 340 g
Well-nourished or mildly malnourished patients in a low to moderately stressed state require 25 to 30 kcal/kg/day. The estimated requirement for this patient is therefore 1750 to 2100 kcal/day. If 55% of her calories are to come from carbohydrates, she needs 962 to 1155 kcal/day from carbohydrates. Intravenous (IV) glucose as given in parenteral nutrition is hydrated and provides 3.4 kcal/g, whereas glucose given orally or enterally provides 4.0 kcal/g. Because she is receiving parenteral nutrition, 3.4 kcal/g is the appropriate conversion, and she should receive approximately 283 to 340 g of IV glucose. The patient would need 240 to 288 g of glucose if it were administered enterally. The maximum amount of glucose she could process in a day is 504 g. If she were a patient with severe burns, her caloric requirements would be increased and she would need 35-40 kcal/kg/day, with 396 to 452 g of IV glucose or 336 to 396 g of oral glucose.
A 72-year-old man who lives alone presents with altered mental status and cachexia. He is febrile to 38.7°C, with a heart rate of 110 beats/min, a blood pressure of 87/56 mm Hg, and oxygen saturation of 87% on room air. He is intubated for airway protection. Laboratory tests are significant for (1) leukocytosis of 13,000 µ/L and (2) urinalysis that is positive for leukocyte esterase and nitrites and contains 10 white blood cells. Prealbumin is 11 mg/dL. A chest x-ray shows right lower lobe consolidation. The man is given an intravenous fluid bolus, with only mild improvement in his vital signs, and started on broad-spectrum antibiotics and pressors. Given that he appears malnourished and would benefit from nutritional optimization, which one of the following is contraindicated as an immunonutrition supplement?
Arginine
Studies involving septic elderly males have shown that an arginine-supplemented diet increases mortality in these patients. Arginine levels are increased in sepsis because of suppressed arginase activity. Therefore, diet supplementation with arginine is potentially harmful in septic patients, probably related to nitric oxide release. Research has also demonstrated that omega-3 fatty acids, antioxidants, and nucleotides have protected effects in septic patients.
Omega-3 fatty acids reduce the production of proinflammatory molecules.
Antioxidants such as vitamin C and selenium may lead to improved outcomes in terms of organ dysfunction and length of stay in the intensive care unit.
Glutamine reduces permeability in the intestinal mucosa, thereby lowering the risk of bacterial translocation.
A 79-year-old man develops acute-onset abdominal pain, fever, tachycardia, and hypotension. Chest x-ray reveals pneumoperitoneum, and he is taken to the operating room, where a right hemicolectomy and end ileostomy is performed for right colon perforation. He has lost 40 pounds unintentionally over the past 3 months and his BMI is 34. He describes eating less than 75% of his meals during that time due to decreased appetite. He remains intubated in the intensive care unit, with significant and variable vasopressor requirement for hypotension. When would you initiate nutritional support in this patient?
Start parenteral nutrition immediately postoperatively.
This patient has severe malnutrition despite his body mass index. He should therefore be started on nutritional support immediately because perioperative parenteral nutrition has been shown to decrease complications when used in this patient population. He may have benefited from preoperative nutritional support if his surgery had not been emergent.
Waiting 5 to 10 days to initiate parenteral nutrition support would be appropriate in a well-nourished or mildly malnourished patient but is inappropriate in a severely malnourished patient such as the one described. Similarly, it is unknown when the patient will have return of bowel function. The patient is on significant and variable vasopressors for blood pressure support so enteral nutrition would not be the best choice for nutrition support given the risk of intestinal ischemia. If he was hemodynamically normal on a low dose of stable vasopressor support, enteral nutrition may be appropriate. Lastly, no nutritional support places this patient at increased risk for complications, including starvation-related complications given his preexisting severe malnutrition.
A 75-year-old woman just finished neoadjuvant treatment and presents to the clinic to discuss a gastrectomy for gastric adenocarcinoma. If found in this patient, which characteristic would indicate she is receiving adequate nutrition?
Prognostic Inflammatory Nutritional
Index (PINI) less than 1
A PINI score less than 1 is normal, a score of 1 to 20 indicates mild malnutrition, and a score of more than 20 indicates severe malnutrition. Serum albumin is considered to be the single best marker of nutritional status in stable patients. Weight loss of 5% to 10% over a month or 10% to 20% over 6 months is associated with malnutrition and increased complications. Bodyweight or body mass index may not reflect nutritional status. Malnutrition may exist in the setting of obesity.
A 32-year-old man is involved in a house fire. On examination in the trauma bay, he is noted to have a 60% total body surface area burn and inhalation injury. He is intubated for airway protection and admitted to the burn intensive care unit. Which of the following will most accurately determine his energy needs?
Indirect calorimetry
Indirect calorimetry (via metabolic cart) is the gold standard for determining resting energy requirements in complex patients. It can be performed on all patients (intubated and nonintubated), but accurate measurements require the proper equipment, trained personnel, consideration of a host of patient parameters, and careful coordination with the nursing staff and intensive care unit (ICU) team.
The Fick equation can be performed but requires a pulmonary artery catheter and is not as accurate in most cases. Although direct calorimetry can be performed, it is not practical in the ICU or hospital setting. The Curreri formula and the Harris-Benedict equation (with modifiers) are often used to estimate caloric requirements, but they are not as accurate as indirect calorimetry measurements.
A 35-year-old woman with a body mass index of 45 kg/m² is intubated in the ICU with COVID acute respiratory distress syndrome (ARDS). Before enteral nutrition is initiated, which equation should be used to estimate energy requirements?
Penn State
In critically ill obese patients, if indirect calorimetry is unavailable, the Penn State equation should be used to predict energy expenditure.
In hospitalized obese patients who are not critically ill, the Mifflin-St. Jeor equation should be used. Both the Harris-Benedict and Ireton-Jones equations are less accurate in morbidly obese patients. A purely weight-based formula (25 kcal/kg/day) will most likely overestimate nutritional requirements in an obese patient.
An 84-year-old man is receiving enteral nutrition via a percutaneous endoscopic gastrostomy tube. Which of the following conditions is he at highest risk for?
Aspiration
Enteral nutrition is preferred over parenteral nutrition whenever possible. Enteral nutrition involves risks such as aspiration, diarrhea, and tube dislodgement. However, complications that occur at a higher rate with parenteral nutrition are infection, electrolyte abnormalities, steatosis, and atrophy of gut-associated lymphoid tissue.
A 55-year-old woman is postoperative day 16 from exploratory laparotomy and splenectomy for splenic laceration after a motor vehicle crash. She has had a traumatic brain injury and has impaired swallowing function secondary to this injury and intubation. She has had return of bowel function, and her team has placed a percutaneous gastric feeding tube for enteral nutrition. Which of the following complications is she at risk for as a result?
Aspiration
Patients who receive gastric tube feeds are at risk for aspiration, especially if they have reduced ability to protect their airway for neurologic or other reasons.
Cholestasis is a risk with total parenteral nutrition (TPN), not enteral nutrition. Bacterial overgrowth in the small intestine and mucosal disuse atrophy are risks of TPN due to lack of gastrointestinal stimulation, increased gut permeability, altered gut mucosal architecture, and decreased gut immunity. Line infection is a risk related to central access for TPN.
A 35-year-old woman with a body mass index of 45 kg/m2 is intubated in the ICU with COVID acute respiratory distress syndrome (ARDS). She has been receiving enteral nutrition, but there is concern that overfeeding may be contributing to her high ventilator requirements. Indirect calorimetry is performed, and her respiratory quotient (RQ) is 0.93. Which change should be made to her enteral nutrition regimen based on the RQ?
Make no changes to the current regimen.
The RQ can help identify overfeeding or underfeeding.
Overfeeding causes lipogenesis and increases the RQ to greater than 1; it would be reasonable to decrease the hourly tube feed rate for this RQ.
Underfeeding causes lipolysis and lowers the RQ to less than 0.85; it would be reasonable to increase the hourly tube feed rate for this RQ.
Daily free water amounts are usually increased for higher serum sodium levels, which RQ does not directly affect. Enteral tube feed formulas all contain essential amino acids, sometimes in the form of soy or whey protein or in the form of more hydrolyzed proteins.
