Respiratory Changes Induced by the Large Glucose Loads of Total Parenteral Nutrition

Abstract

Total parenteral nutrition (TPN) using glucose as nonprotein calories was associated with increases in O2 consumption (VO2) and CO2 production (VCO2). The magnitude of the changes was a function of the patient's clinical state and glucose load. Depleted patients showed a minimal increase in VO2, while VCO2 increased 23%. Minute ventilation (VE) increased 32%. Hypermetabolic patients (major trauma, sepsis) had a 30% increase in VO2 and a 57% increase in VCO2, while VE increased 71%. Patients with mild to moderate injuries (energy expenditure +/- 15% of normal) showed a 21% increase in VO2 and a 53% increase in VCO2, while VE increased 121%. Large carbohydrate intakes were associated with increases in CO2 production in all patients, while increases in O2 consumption were seen primarily in hypermetabolic patients. These changes suggest that the high glucose loads of TPN may be a physiologic stress.

Total parenteral nutrition–associated hyperglycemia correlates with prolonged mechanical ventilation and hospital stay in septic infants

“…In addition to promoting immunocompromise, caloric overfeeding can have a significant negative effect on respiration because of increased carbon dioxide production [15,25]. Premature neonates have a substantially decreased pulmonary reserve and inadequate ability to eliminate increased amounts of carbon dioxide, which can prolong ventilator dependency.…”

Efecto de la nutrición en los resultados de pacientes con compromiso pulmonar en la Unidad de Cuidado Intensivo

“…Desde hace más de 30 años se tiene el conocimiento de los efectos deletéreos de la alta ingesta de hidratos de carbono, en términos del aumento en la producción de CO 2 en los pacientes con enfermedad pulmonar, usando la glucosa como calorías no proteicas en nutrición parenteral total 48 . El incremento en la producción de CO 2 se puede predecir en el paciente depletado (como es el caso de aquel con enfermedad pulmonar obstructiva crónica) por un aumento en el CR, mientras que en el paciente hipermetabólico (por ejemplo, con sepsis) el aumento en el cociente respiratorio puede no reflejar cambios en la producción de CO 2 ; esto es debido a que en sujetos normales, la respuesta a una carga de energía por encima de los requerimientos es convertir el exceso de glucosa en glucógeno y grasa, con lo que la conversión a grasa (CR 8,0) produce un incremento importante en la producción de CO 2 .…”

Specialized Enteral Formulas in Acute and Chronic Pulmonary Disease

“…5,6,16 In a well-known study by Talpers et al, 17 20 mechanically ventilated patients received either varying amounts of CHO (40%, 60%, or 75%) or total calories (1, 1.5, or 2 times the basal energy expenditure). Carbon dioxide production (Vco 2 ) was measured in both groups of patients 48 hours following a change in nutrient regimen.…”

“…This article reviews the rationale for use of modified enteral formulas in both chronic and acute pulmonary disease, the 1980s when case reports outlined hypercapnia and respiratory failure in patients receiving high-CHO parenteral formulations. [4][5][6][7] Standard practice at that time was to provide 100% of nonprotein calories as dextrose and provide lipid intermittently as a source of essential fatty acids. Based on the detrimental effects observed with excessive dextrose intake, practice recommendations were made to alter PN formulas and provide increased lipid with reduced dextrose.…”