Evaluation of a local anaesthesia regimen following mastectomy.

Breast surgery can be emotionally distressing and physically painful. Acute pain following surgery is often related mainly to the axillary surgery and is aggravated by arm and shoulder movement. We conducted a prospective double-blind, randomised, placebo-controlled trial to determine the influence of local anaesthetic irrigation of axillary wound drains on postoperative pain during the first 24 h following a modified Patey mastectomy (mastectomy with complete axillary node clearance). The treatment group received bupivacaine irrigation through the axillary wound drain 4-hourly for 24 h postoperatively. Controls received irrigation with normal saline. Morphine via a patient controlled analgesia pump was used for postoperative analgesia. Morphine consumption, visual analogue and verbal rating pain scores were recorded. There were no statistical differences in morphine requirements or pain scores between the two groups, nor were there differences in anti-emetic or supplemental analgesic consumption. Bupivacaine irrigation used in this manner does not appear to offer an effective contribution to postoperative analgesia.

Effect of high-lipid high-nitrogen intravenous nutrition on total body nitrogen, visceral protein synthesis and nitrogen balance.

The impact of high-lipid intravenous nutrition (IVN) on selected indices of nitrogen retention following major surgical resection was studied. Twenty-two patients, randomly allocated to two equal well matched groups, received either high-lipid IVN (75 per cent non-protein calories supplied as lipid) or isocaloric isonitrogenous glucose IVN (100 per cent non-protein calories supplied as glucose). Total body nitrogen (assessed by in vivo neutron activation analysis), nitrogen balance and levels of circulating proteins were measured. Mean(s.d.) total body nitrogen and fat-free mass decreased (P = 0.04) in patients receiving high-lipid IVN, -109(36) gN and -1.7(0.4) kg respectively, but not in those given glucose-only IVN, 8(43) gN and 0.1(1.0) kg. This small loss of body protein does not appear to be clinically significant because postoperative hospital stay, complication rates and the acute-phase protein response (immunological and visceral) were similar in the two groups.

Simultaneous human forearm and calf metabolic exchange.

Simultaneous forearm and leg metabolic exchange studies were performed to compare metabolic exchange and change in metabolic activity over time across the forearm and calf skeletal muscle beds in response to nutritional treatment. Seven postoperative upper-gastrointestinal resection patients received intravenous nutrition (IVN) for 10 days. Immediately before IVN was begun, simultaneous ipsilateral forearm and calf blood flow with arterial and venous sampling for plasma glucose and free fatty acids (FFAs), and whole-blood glycerol, lactate, pyruvate, and nitrogen were measured. After 10 days of IVN, these parameters were repeated in carefully standardized steady-state conditions. Although there were no differences between the arm and the leg with mean flux measurements, correlation of arm and leg flux values were only significant for FFA (p < 0.01) and blood nitrogen (p < 0.05). Forearm and leg metabolic exchange results were not in sufficient agreement to permit reliable use of these results interchangeably for individuals. Errors in blood flow measurement appear to be a major determinant of the poor relationship between forearm and leg flux measurements (limits of agreement 3.32-4.72 ml.dl-1 tissue.min-1). In conclusion, both forearm and leg metabolic exchange studies can be used to show the metabolic effects of treatment when groups of subjects are studied, but variability of the methods used result in poor agreement for the measurements of an individual.

Metabolic response to a high-lipid, high-nitrogen peripheral intravenous nutrition solution after major upper-gastrointestinal surgery.

We compared the metabolic response to peripheral intravenous nutrition (peripheral IVN) with the response to central IVN when given after major gastrointestinal surgery. Eighteen consecutive patients who had undergone upper-gastrointestinal surgery were randomly assigned to receive either peripheral IVN (75% nonprotein calories supplied as lipid, n = 9) or central IVN (n = 9). Each group received 0.50 +/- 0.03 g N.kg-1 fat-free mass.day-1 (mean +/- SD with 100:1 kcal:g N (0.42 MJ:1 g N). Metabolic studies were undertaken before IVN (2nd postoperative day) and after 10 days of IVN. Negative nitrogen balance was reversed with both treatments (p < 0.001). The significant net efflux of individual amino acids from peripheral tissue before IVN was reduced toward balance, and there were no significant differences between the groups. The postoperative response of the plasma proteins (fibronectin, prealbumin, and transferrin) was similar in both groups. Peripheral IVN decreased postoperative peripheral net uptake of glucose to a net balance. Central IVN resulted in decreased free fatty acid, glycerol, and beta-hydroxybutyrate concentration with increases in plasma insulin concentration and the net uptake of glucose and pyruvate in peripheral tissue. The effect of intravenous nutrition on the metabolic response to major surgery was similar when nonprotein calories were supplied wholly as glucose requiring a central delivery system or when 75% of nonprotein calories were given as lipid when a peripheral delivery system was used. This study supports the development of peripheral IVN feeding systems.

Metabolic evaluation of a 75% lipid/25% glucose high nitrogen solution for intravenous nutrition.

OBJECTIVE: To compare the metabolic response to a 75% lipid/25% glucose regimen of intravenous feeding with that of a regimen of isocaloric isonitrogenous glucose alone. DESIGN: Randomised crossover study. SETTING: University department of surgery. SUBJECTS: 14 Patients (of 18 consecutive) who did not develop infections after major upper gastrointestinal operations. INTERVENTIONS: Patients received five days of each of two regimens, both of which provided 0.38 g nitrogen and 0.155 MJ (37 kcal)/kg/day. MAIN OUTCOME MEASURES: Nitrogen balance, prealbumin and transferrin concentrations, and basal efflux of amino acids from the lower limb before and after a five day course of each regimen. RESULTS: Mean (SD) nitrogen balance increased from -11.4 (2.6) g/day to 1.7 (4.1) and 1.6 (5.5) g/day after lipid/glucose and glucose alone, respectively (p < 0.0001). Basal prealbumin and transferrin concentrations increased after both regimens, but significantly so only after lipid/glucose (p < 0.01 and < 0.02, respectively). Mean (SD) net basal efflux of total amino acids from the lower limb was significantly reduced after both regimens, (p < 0.0001 in each case). Net basal alanine efflux was significantly reduced only by glucose alone, and basal glutamine efflux only by lipid/glucose (p < 0.05 in each case). Plasma free fatty acids were increased only by glucose alone (p < 0.001), and glucose alone augmented tissue uptake of glucose significantly more than lipid/glucose (p < 0.01 and < 0.05, respectively). CONCLUSIONS: The solution high in lipids and nitrogen was well tolerated. There was no difference in improvements in nitrogen balance or amino acid flux across the lower limb, but lipid/glucose was associated with higher increases in visceral protein concentrations.

Peripheral versus central intravenous nutrition: comparison of two delivery systems.

Forty-six surgical patients who required intravenous nutrition (IVN) were randomly allocated to receive complete IVN by a peripheral (n = 23) or central (n = 23) venous delivery system. The peripheral IVN system combined a fine-bore silicone catheter with lipid-based nutrient solutions whereas the central system used a conventional glucose-based nutrient regimen and a single-lumen central venous catheter. The incidence of catheter complications and the complication-free system function over time were compared. Problems of venous access were not observed with peripheral IVN but occurred with one central catheterization. Three patients with central venous catheters developed bacteraemia but only one incident was thought to be catheter related (bacterial translocation). There were no such episodes with peripheral IVN. Peripheral catheterization was not associated with infective phlebitis, although late-onset chemical phlebitis occurred on four occasions after a mean(s.e.m.) time of 22.8(6.1) days, representing a daily risk of phlebitis of 0.009. There was no significant difference in the probability of complication-free system function with time between peripheral and central IVN (P = 0.14). The fine-bore silicone catheter peripheral IVN delivery system resulted in long-term phlebitis-free infusion for periods that were similar to those of single-lumen central catheterization by life-table analysis.

Fine-bore peripheral catheters versus central venous catheters for delivery of intravenous nutrition.

We present a descriptive study of 229 consecutive inpatients requiring intravenous nutrition. These patients received either complete peripheral intravenous nutrition via a fine-bore silicone catheter (n = 80) or short Teflon catheter (n = 15) or received conventional central intravenous nutrition (n = 134). Nutrient delivery was similar for both systems, providing 0.2-0.4 g N.kg-1 x day-1 and 0.13-0.15 mJ.kg-1 x day-1 from preparations containing 4.3 MJ/L total energy (65-75% lipid: 25-35% glucose for peripheral support and 100% glucose for central delivery) with 6 g N/L. We compared the incidence of catheter complication and the probability of catheter function over time for the peripheral and conventional central systems. Venous access complications were seen only with central venous catheterization (10.4%). Chemical phlebitis occurred in 17% of fine-bore catheters and 91.4% of Teflon catheters. The infective phlebitis rate of fine-bore silicone catheters was 1.02% and daily risk of phlebitis 0.016%, with no instance of device-related bacteremia or sepsis. Central-line microbial contamination (21.7%) and catheter-related sepsis (3%) were significantly greater (p < 0.0005, chi 2 goodness-of-fit test) than with fine-bore silicone and Teflon catheters. The probability of complication-free function against time was similar (0.75 < p < 0.90, log-rank test) in fine-bore silicone catheters and central venous catheters. We conclude that fine-bore silicone catheters provide long-term phlebitis-free delivery of complete peripheral intravenous nutrition.

The effect on protein and amino acid metabolism of an intravenous nutrition regimen providing seventy percent of nonprotein calories as lipid.

BACKGROUND: The purpose of this study was to determine which peripheral intravenous nutrition (IVN) regimen, one containing 70% nonprotein calories as lipid IVN or one containing all nonprotein calories as glucose IVN, was most effective at reversing some effects of surgery on protein metabolism. METHODS: Twenty patients who required IVN after operation were randomized into two well-matched groups that received 36 kcal.kg-1.day-1 glucose IVN or 37 kcal.kg-1.day-1 lipid IVN. RESULTS: Both IVN regimens resulted in similar changes of nitrogen balance, plasma liver enzymes, blood urea, plasma albumin, and plasma prealbumin. Mean plasma transferrin rose significantly after glucose IVN (p less than 0.01), a change greater than that after lipid IVN (p less than 0.05). Lipid IVN resulted in continued net efflux of alanine from peripheral tissues at rates similar to pretreatment values; glucose IVN significantly reduced net alanine efflux (p less than 0.05). Most of the extra alanine produced by peripheral tissues during lipid IVN appeared to derive from an increased uptake of intramuscular glutamate and from an increased uptake of branched chain amino acids. CONCLUSIONS: The results of this study indicate that 38 kcal.kg-1.day-1 lipid IVN was equivalent to glucose IVN, except for the continuing gluconeogenesis of alanine and the delayed recovery of plasma transferrin concentration after surgery. A greater infusion rate of such a regimen may be necessary to provide sufficient glucose to suppress gluconeogenesis.

What rate of infusion of intravenous nutrition solution is required to stimulate uptake of amino acids by peripheral tissues in depleted patients?

We examined the effect of varying the quantities (0, 0.1, 0.2, 0.3, and 0.4 gN.kg-1.[day]-1) of nitrogen input on N balance, 3-methylhistidine (3MH) excretion, plasma amino acid concentration and the net flux of amino acids across the leg in depleted patients requiring parenteral nutrition. The calorie-to-nitrogen ratio was 140 to 1 (kcal:1 gN) and consequently the patients received varying amounts of calories (8, 14, 28, 42, and 56 kcal.kg-1.[day]-10. There was negative nitrogen balance and net loss of amino acids from the limb during fasting. An infusion of 0.2 gN.kg-1.[day]-1 of IVN reversed the net catabolic process and resulted in equilibrium of peripheral total amino acid flux and of tyrosine flux without a decrease in 3MH excretion. Net uptake of total amino acids and tyrosine in peripheral tissues was achieved with 0.4 gN.kg-1.[day]-1 and 56 kcal.kg-1.[day]-1. This was associated with a fivefold increase in 3MH excretion (p less than 0.01), indicating that net anabolism occurred with increased protein turnover. Fifty per cent of the amino acids taken up by peripheral tissues during infusions of 0.4 gN.kg-1.[day]-1 was due to the uptake of glutamate (Glu) and 20% was due to the uptake of branched chain amino acids (BCAA). Plasma Glu concentration, [Glu], did not increase with increasing IVN infusion, but BCAA concentrations did. Although the mean plasma [Glu] did not change with IVN infusion, there was an independent effect of plasma [Glu] (p less than 0.0001) and of N input (p less than 0.0001) on Glu flux, indicating that even at high infusion rates the maximal capacity of peripheral tissues to take up Glu had not been reached.

Combined use of the chemitrode with osmotic minipumps for experimental brain research.

This paper describes a simple-to-build minipump-chemitrode assembly which can be used for long term electrophysiological, chemical and behavioural studies. This system consists of an osmotic minipump, a cannula and an array of nine electrodes which are connected to a miniature Winchester Socket. A detailed plan for construction of both the chemitrode and the minipump-chemitrode is given together with some suggestions for possible usages in brain research(such as kindling). The osmotic minipump consists of a collapsible reservoir of flexible, impermeable material, surrounded by a sealed layer containing an osmotic agent--all of which is contained by a semipermeable membrane. Imbibed water generates hydrostatic pressure on the flexible lining of the reservoir, gradually compressing it, producing a constant flow of its contents through the delivery portal.