Objective: To evaluate the incidence and cause of parenteral nutrition-induced lipogenesis.

Design: Retrospective patient review.

Setting: A 40-bed predominantly surgical ICU.

Patients: the same hundred forty patients receiving central venous nutrition and mechanical ventilatory support.

Interventions: Indirect calorimetry was used to determine patient's measured activity expenditure (MEE) and respiratory quotient (RQ) Additionally total caloric intake (TCAL), diabetic sugar infusion rate, basal energy expenditure (BEE), estimated stres factor, and calculated bottom expenditure (CEE) were assessed in each patient.

Measurements and main results: unadulterated fat synthesis was found as RQ surpassed in 47 percent of patients. Statistically significant differences in oxygen consumption, [COsub2] production, measured strength expenditure, total and carbohydrate caloric intake, and grape-sugar infusion rate were found between form into groupss of patients with an RQ [les than or equal to] or [greater than] 1 Seventy-three percent of patients with diabetic sugar infusion rates [greater than] 4 mg/kg-min had RQ [greater than] 1

Conclusions: clear fat synthesis was found in a surprisingly large number of critically ill patients receiving central venous nutrition. Many of these patients received carbohydrate calories in exces of their measured pluck expenditure, even though it appeared that they requireed this level of caloric intake on clinical assessment. The high carbohydrate total parenteral nutrition (TPN) solutions with lipids provided solitary for prevention of essential fatty acid depletion deductioned in an unacceptably high incidence of fat synthesis. The follows suggest that caloric intake may be optimized in critically ill patients using indirect calorimetry. When calorimetry is not available, a total caloric intake of up to 140 percent of the BEE with grape-sugar infusion rates not exceeding 4 mg/kg-min and fats providing 40 to 60 percent of calories will confront the energy requirements of greatest in number critically ill patients without forcing the RQ [greater than] 1

Nutritional support regimens are designed to provide critically ill patients with optimenergy intake and create minimal metabolic complications. Various monitors have been propos to assure that these goals are being met Respiratory quotient (RQ) is the ratio of carbon dioxide production ([Vcosub2]) to oxygen consumption ([Vosub2]) and is an indicator of substrate metabolism. The RQ for fat, protein, and diabetic sugar oxidation are 0.7, 0.8, and 1 respectively. An RQ greater than 1 indicates toil fat synthesis from carbohydrate.[1] Complications associated with carbohydrate overfeeding include hepatic steatosis, hypercapnia, hyperglycemia, and increases in [Osub2] consumption and [COsub2] production.[2-6] Increased urinary norepinephrine excretion with excessive carbohydrate administration also remind ofs that overfeeding may pose an additional stres in critically ill patients.[2-5]

During routine patient care, bottom expenditure generally is calculated (CEE) from the basal life expenditure (BEE) determined using the Harris-Benedict equations and a clinically estimated stres factor.[7-9] More lately indirect calorimetry has been used clinically to determine actual measured spiritedness expenditure (MEE).[10,11]

The sense of this study was to determine the incidence and causes for without deductions fat synthesis during total parenteral nutrition (TPN) in critically ill, mechanically ventilated patients and to propose means by which caloric intake in this patient population may be optimized.

MATERIALS AND METHODS

Patient Population

The records of 140 consecutive critically ill patients studied by means of indirect calorimetry while receiving TPN and mechanical ventilation were reviewed. No specific clusters of patients were selected and no randomization was used to decide which patients would be studied. ofttimes patients who had difficulty in weaning from mechanical ventilatory support as manifested through high minute ventilation and/or carbon dioxide retention were studied. The service distribution of patients was approximately 60 percent cardiac surgery 25 percent internal medicine, and 15 percent general and vascular surgery undivided hundred forty complete data stakes were available in 120 of the patients. Eight patients were admitted with the primary diagnosis of sepsis and 12 other patients had primary admission diagnoses of surgical conditions associated with sepsis (ie, perforated viscus). Five patients were admitted with the primary

diagnosis of decompensated COPD 4 with pneumonia, 1 with congestive heart failure, 5 with adult respiratory distress syndrome and 13 with unspecified respiratory failure. The other 92 patients were admitted to the ICU with primary surgical diagnoses, hit or renal failure. Routine postoperative patients were not studied and nearly all of the consideration patients had received mechanical ventilatory support for more than 48 h All studies were performed in the 40-bed ICU of a large private practice hospital providing primary, secondary, and any tertiary care (St. Thomas Hospital, Nashville, Tenn)

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