Intraoperative infusion of acetated Ringer solution containing glucose and ionized magnesium reduces ketogenesis and maintains serum magnesium.

The effect of glucose infusion during surgery on glucose metabolism has not been investigated sufficiently. We, therefore, examined the effect after the infusion of 1% glucose acetated Ringer solution containing Mg2+ during surgery on ketogenesis and serum Mg2+ concentrations. Patients, classified as ASA I-II, age 51-80 years, were randomly assigned to receive infusion of acetated Ringer solution. The G/Mg group received infusion with 1% glucose, Na+ 140mEq/L, Mg2+ 2 mEq/L, and the C group received infusion with glucose free solution containing Na+ 130 mEq/L without Mg2+. Both solutions were infused at a rate of 25 mL/kg for the first hour, and main-tained at 4 mL/kg/hr thereafter. Blood samples were collected three times: before infusion and at 1 hour and 4 hours after the start of infusion. Electrolytes and glucose metabolism were evaluated at each sampling. After rapid infusion, blood glucose level significantly increased to 170+/-19mg/dL in the G/Mg group, but it returned to close to baseline after 4 hours and serum ketone bodies did not increase during infusion. In the C group, however, blood glucose never increased beyond 110 mg/dL, but both acetoacetic and hydroxybutyric acids increased significantly at the third measurement.

Amino acid infusion during anesthesia attenuates the surgery induced decline in IGF-1 and diminishes the "diabetes of injury".

BACKGROUND: Surgery, commonly performed after an overnight fast, causes a postoperative decline in the anabolic and glucose lowering insulin-like growth factor-1 (IGF-1). Clinical fasting studies have exhibited a positive correlation between IGF-1 and nitrogen balance during different conditions. A perioperative amino acid infusion changes nitrogen balance and might thereby influence serum IGF-1. We hypothesized that amino acid infusion would enhance IGF-1 and thereby might influence glucose homeostasis after surgery. In this study we examined two different regimes of perioperative amino acids infusion. METHODS: 24 females scheduled for abdominal hysterectomy were randomized into three groups; Ringer's solution infusion throughout anesthesia (Group B), amino acid infusion throughout anesthesia (Group C) and amino acid infusion 1 hour before anesthesia and during 1.5 hrs of surgery (Group D). Six female volunteers, who were not operated, but received the same amino acids infusion after fasting, served as controls (Group A). Fasting levels of IGF-1, Insulin-like growth factor binding protein-1 (IGFBP-1), insulin and P-glucose were studied prior to, and four days following, operation. Homeostasis model assessment (HOMA) was used as an index of insulin resistance. Non-parametric statistical methods were used. RESULTS: During the study the Ringer-group exhibited a decrease in IGF-1 and an increase in insulin and plasma glucose after surgery. Within the other groups there were no significant alterations over time after surgery, with the exception of a postoperative decrease in IGF-1 in group D. Group C had higher IGF-1 levels compared to group B on all days. Also, group D had higher IGF-1 levels than group B on day 2-4. From baseline to the first postoperative day there was a significant increase in HOMA and IGFBP-1 in groups B and C. These changes were not found in group D, in which insulin, glucose, HOMA and IGFBP-1 did not change. Amino acid infusion to the volunteers did not affect any of the variables studied. CONCLUSION: Amino acid infusion during surgery attenuates the decrease in IGF-1 and diminishes the "diabetes of injury".

Amino acid infusion induces thermogenesis and reduces blood loss during hip arthroplasty under spinal anesthesia.

UNLABELLED: The thermic effect of amino acids is augmented under general anesthesia and counteracts hypothermia. Mild hypothermia may increase surgical bleeding. We studied whether amino acids also induce thermogenesis under spinal anesthesia and whether this endogenous heat production reduces bleeding during hip arthroplasty. Rectal temperature, oxygen uptake, and perioperative bleeding were measured in 22 patients receiving an IV amino acid mixture (Vamin 18), 240 kJ/h) for 1 h before and then during spinal anesthesia and in 24 control patients receiving acetated Ringer's solution. Blood loss was calculated after surgery by weighing the swabs and the content of the suction tubes after subtraction of the saline used. After surgery, the closed drains were weighed after 24 h. In the amino acid group, the preanesthesia temperature increased by 0.4 degrees C +/- 0.2 degrees C (P < 0.01) and was unchanged in controls. At end of surgery, core temperature had decreased by 0.9 degrees C +/- 0.4 degrees C in controls and by 0.4 degrees C +/- 0.3 degrees C in the amino acid patients (P < 0.01). Oxygen uptake increased by 26 +/- 7 mL/min, or 16% +/- 5% (P < 0.05), from baseline in the amino acid patients, whereas it was unchanged in the controls. Blood loss during surgery was significantly larger in the control patients (702 +/- 344 mL) than in the amino acid patients (516 +/- 272 mL) (P < 0.05). After surgery, there were no significant differences in shed blood volume. In conclusion, amino acid infusion also induced a thermogenic response under spinal anesthesia. In addition, the prevention of temperature decrease during spinal anesthesia seemed to have a positive effect on intraoperative blood loss. IMPLICATIONS: Infusion of a balanced mixture of amino acids during spinal anesthesia prevented core body temperature decrease. Bleeding was also less pronounced.

Peri-operative amino acid administration and the metabolic response to surgery.

General anaesthesia causes hypothermia due to decreased metabolic rate and impaired thermoregulation. Many warming devices are in use to prevent heat loss, but little attention has been paid to stimulating the body's own heat generation. All nutrients raise energy expenditure, and the highest thermic effect is ascribed to amino acids and proteins, 30-40 % in the awake state. Amino acids infused during general anaesthesia exert a thermic effect that is enhanced compared with that in the awake state. At awakening from anaesthesia, post-operative hypothermia may be prevented without shivering. The tissues involved and the mechanisms by which nutrients stimulate heat production are still not completely understood. However, these findings support the existence of an inhibitory action normally exerted by central thermosensors, in order to maintain oxidative metabolism within certain limits, to prevent hyperthermia. During anaesthesia central thermosensors are silenced and, hence, amino acid thermogenesis is exaggerated. The amino acid-induced heat generation during anaesthesia predominantly occurs in extra-splanchnic tissues, most probably in skeletal muscle. It may reflect an increased protein turnover, as both protein breakdown and synthesis are energy-consuming processes known to generate heat. Possibly, amino acid infusion provides substrates, otherwise mobilized from the body's own tissues, needed for wound healing and immunological function. However, other cellular mechanisms may also contribute to this non-shivering thermogenesis.