Epidural anesthesia and analgesia in ferrets

Anesthesia and analgesia should be provided to ferrets that are undergoing potentially painful surgical procedures. The epidural route of administration for anesthetic or analgesic drugs can be used. This column outlines the relevant ferret anatomy, indications and contraindications and technique of epidural administration of anesthesia and analgesia in ferrets.     

Epidural blockade improves substrate utilization after surgery

The purpose of this study was to test the hypothesis that epidural blockade with local anesthetic improves the anticatabolic effects of glucose after colorectal surgery. Sixteen patients were randomly assigned to undergo a 6-h stable isotope infusion study (3 h fasted, 3 h glucose infusion at 4 mg. kg(-1). min(-1)) on the second postoperative day with or without perioperative epidural blockade. Protein synthesis, breakdown and oxidation, and glucose production and clearance were assessed by L-[1-(13)C]leucine and [6, 6-(2)H(2)]glucose. Epidural blockade did not affect protein and glucose metabolism in the fasted state. Glucose infusion increased glucose clearance (P < 0.05), accompanied by an increase in the respiratory quotient (P < 0.05) and a decrease in leucine oxidation (P < 0.05) only in the presence of epidural blockade. An inverse correlation (r = -0.74, P < 0.05) between changes in glucose clearance and leucine oxidation was observed. In conclusion, epidural blockade facilitates whole body glucose uptake and inhibits endogenous protein oxidation after abdominal surgery, indicating a shift from a protein to a more glucose-dominated substrate utilization.     

Root-induced nitrogen mineralisation: A nitrogen balance model

The possibility is examined that carbon (C) released into the soil from a root could enhance the availability of nitrogen (N) to plants by stimulating microbial activity. Two models are described, both of which assume that C released from roots is used by bacteria to mineralise and immobilise soil organic N and that immobilised N released when bacteria are grazed by bacterial-feeding nematodes or protozoa is taken up by the plant. The first model simulates the individual transformations of C and N and indicates that root-induced N mineralisation could supply only up to 10% of the plant's requirement, even if unrealistically ideal conditions are assumed. The other model is based on evidence that about 40% of immobilised N is subsequently taken up by the plant. A small net gain of N by the plant is shown (i.e. the plant takes up more N than it loses through exudation), although with exudate of up to C:N 33:1 less than 6% of the plant's requirement is supplied by root-induced N mineralisation. It is argued, however, that rhizosphere bacteria do not use plant-derived C to mineralise soil organic N to any great extent and that in reality root-induced N mineralisation is even less important than these models indicate.     

New appreciation of nitrogen balance obtained from Japanese navy data.

In 1943, one of the authors (Miura) worked on the nutritional study of Japanese navy sailors. Fortunately the raw data of this study were conserved in secret in the private file of Miura. Recently, another author (Hashimoto) was seeking the data concerning nitrogen balance of Japanese people. Miura, recalling the remaining of the old data; he picked up the records of nitrogen metabolism of three sailors (A, B and C). Subject A, 34 years old, showed a net nitrogen balance of 77 g of protein per day; whereas subject B, 20 years old and subject C, 15 years old showed positive nitrogen balance. The authors remarked the relationship between unabsorbed nitrogen and nitrogen balance: The unabsorbed ratio of food nitrogen was the greatest in A (29%), but in B (22%) and C (19%) showed rather low ratio. Recent study using tracers, revealed that some amino acids, especially unabsorbed leucine in the intestine, might act as regulators of nitrogen balance in adults.     

Intra-articular patient-controlled analgesia improves early rehabilitation after knee surgery

The influence of patient-controlled intra-articular analgesia with ropivacaine, morphine and ketorolac (RMK) on postoperative pain relief and early rehabilitation after anterior cruciate ligament reconstruction was studied. Twenty six patients, randomized into two groups, were enrolled in a placebo-controlled, double-blind study. At the end of surgery a catheter was placed intra-articularly and connected to a patient-controlled pump, programmed to deliver 10 mL bolus and 60 min lockout interval. RMK group received 0.25% ropivacaine, morphine 0.2 mg/mL and ketorolac 1 mg/mL; P group saline. Pain was measured with 10 cm visual analog scale. At pain scores > 3 cm, all patients were instructed to self-administer morphine intravenously using a patient-controlled pump. Daily rescue morphine consumption was noted and 48 h rehabilitation programme was evaluated. Daily morphine consumption was significantly lower in the RMK group (p < 0.001). At 24h after surgery, the patients in the RMK group experienced significantly less pain (p < 0.05). The patients in the RMK group achieved higher maximum degree of knee flexion in supine (p < 0.001) and in prone position (p < 0.05) compared to placebo group and better pain free flexion with assistance on day 1 (p < 0.05) and 2 (p > 0.05). The results show that patient-controlled intra-articular analgesia with RMK combination provides effective pain relief following anterior cruciate ligament reconstruction and improves early physical rehabilitation.     

The nitrogen balance of Raphanus sativus X raphanistrum plants. I. Daily nitrogen use under high nitrate supply

Abstract Growth-chamber cultivated Raphanus plants accumulate nitrate during their vegetative growth. After 25 days of growth at a constant supply to the roots of 1 mol m^?3 (NO^?₃) in a balanced nutrient solution, the oldest leaves (eight-leaf stage) accumulated 2.5% NO^?₃-nitrogen (NO₃-N) in their lamina, and almost 5% NO₃-N in their petioles on a dry weight basis. This is equivalent to approximately 190 and 400 mol^?3 m^?3 concentration of NO^?₃ in the lamina and the petiole, respectively, as calculated on a total tissue water content basis. Measurements were made of root NO^?₃ uptake, NO^?₃ fluxes in the xylem, nitrate uptake by the mesophyll cells, and nitrate reduction as measured by an in vivo test. NO^?₃ uptake by roots and mesophyll cells was greater in the light than in the dark. The NO^?₃ concentration in the xylem fluid was constant with leaf age, but showed a distinct daily variation as a result of the independent fluxes of root uptake, transpiration and mesophyll uptake. NO^?₃ was reduced in the leaf at a higher rate in the light than in the dark. The reduction was inhibited at the high concentrations calculated to exist in the mesophyll vacuoles, but reduction continued at a low rate, even when there was no supply from the incubation medium. Sixty-four per cent of the NO^?₃ influx was turned into organic nitrogen, with the remaining NO^?₃ accumulating in both the light and the dark.