Analgetische Wirkung von Romifidin kombiniert mit Butorphanol oder Levomethadon beim Pferd

Gegenstand und Ziel: Zuverlässige Ruhigstellung und Schmerzbekämpfung sind unabdingbar für sichere diagnostische und chirurgische Eingriffe am stehenden Pferd. Die Kombination von α 2-Agonisten mit Opioiden hat sich im Praxisalltag bewährt. In dieser Studie erfolgte eine Prüfung der analgetischen Wirkung von Romifidin in Kombination mit Butorphanol und Levomethadon. Material und Methoden: Bei sechs Pferden in Arbeitskondition wurde der Verlauf der Schmerzschwelle mit zwei Schmerzmodellen untersucht (an die Vorderbeine angelegter kontinuierlich ansteigender Gleichstrom bzw. pneumatischer Druck). Ergebnisse: Mit kontinuierlich von 0 bis maximal 30 mA (Messgrenze) ansteigendem Gleichstrom war die Schmerzschwelle [Basiswert 5,4 (SD 1,5) bis 7,0 (SD 2,3) mA] 4,6-mal (SD 0,4) höher unter Romifidin-Butorphanol, 5,4-mal (SD 0,9) höher unter Romifidin-Levomethadon und 2,7-mal (SD 0,3) höher unter Romifidin allein. Die Wirkung zeigte ihr Maximum 15 Minuten nach Injektion und blieb mit beiden Opioidkombinationen zwischen 15 und 60 Minuten nach Injektion signifikant höher als mit Romifidin allein. Mit kontinuierlich von 0 bis maximal 79,8 kPa (600 mmHg, Messgrenze) ansteigendem pneumatischem Druck lag die Schmerzschwelle [Basiswert 36,4 (SD 12,1) bis 44,3 (SD 15,3) kPa)] ohne signifikanten Unterschied 2,16-mal (SD 0,3) höher unter Romifidin- Butorphanol, 2,3-mal (SD 0,2) höher unter Romifidin- Levomethadon und 2,0-mal (SD 0,3) höher als unter Romifidin allein. Schlussfolgerung und klinische Relevanz: Mit dieser Studie konnte sowohl eine analgetische Wirkung von Romifidin allein als auch die verstärkende analgetische Wirkung von Butorphanol und Levomethadon kombiniert mit Romifidin dokumentiert werden.

Two cases of intraoperative herniation of the endotracheal tube cuff

During anaesthesia for elective procedures, 2 dogs developed acute airway obstruction caused by herniation of the endotracheal cuff. This is an uncommon but potentially fatal complication especially when minimal monitoring of the patient leads to late recognition of the condition. The most typical symptoms are decreased thoracic excursions and tidal volume, absence of gas flow through the endotracheal tube, change in the capnographic waves morphology and increased airway pressures. In both cases desaturation of haemoglobin (measured by pulse oximetry) occurred in-between 6 and 8 minutes after cuff herniation. All signs normalised following partial deflation of the cuff. Careful management of cuff pressures especially when nitrous oxide is used, awareness of the condition and monitoring of the patient can prevent fatal consequences.

Use of pressure waves to confirm the correct placement of epidural needles in dogs

An epidural puncture was performed using the lumbosacral approach in 18 dogs, and the lack of resistance to an injection of saline was used to determine that the needle was positioned correctly. The dogs' arterial blood pressure and epidural pressure were recorded. They were randomly assigned to two groups: in one group an injection of a mixture of local anaesthetic agents was made slowly over 90 seconds and in the other it was made over 30 seconds. After 10 minutes contrast radiography was used to confirm the correct placement of the needle. The mean (sd) initial pressure in the epidural space was 0.1 (0.7) kPa. After the injection the mean maximum epidural pressure in the group injected slowly was 5.5 (2.1) kPa and in the group injected more quickly it was 6.0 (1.9) kPa. At the end of the period of measurement, the epidural pressure in the slow group was 0.8 (0.5) kPa and in the rapid group it was 0.7 (0.5) kPa. Waves synchronous with the arterial pulse wave were observed in 15 of the dogs before the epidural injection, and in all the dogs after the epidural injection.

Stereoselective pharmacokinetics of ketamine and norketamine after racemic ketamine or S-ketamine administration during isoflurane anaesthesia in Shetland ponies

BACKGROUND

The arterial pharmacokinetics of ketamine and norketamine enantiomers after racemic ketamine or S-ketamine i.v. administration were evaluated in seven gelding ponies in a crossover study (2-month interval).

METHODS

Anaesthesia was induced with isoflurane in oxygen via a face-mask and then maintained at each pony's individual MAC. Racemic ketamine (2.2 mg kg(-1)) or S-ketamine (1.1 mg kg(-1)) was injected in the right jugular vein. Blood samples were collected from the right carotid artery before and at 1, 2, 4, 8, 16, 32, 64, and 128 min after ketamine administration. Ketamine and norketamine enantiomer plasma concentrations were determined by capillary electrophoresis. Individual R-ketamine and S-ketamine concentration vs time curves were analysed by non-linear least square regression two-compartment model analysis using PCNonlin. Plasma disposition curves for R-norketamine and S-norketamine were described by estimating AUC, C(max), and T(max). Pulse rate (PR), respiratory rate (R(f)), tidal volume (V(T)), minute volume ventilation (V(E)), end-tidal partial pressure of carbon dioxide (PE'(CO(2))), and mean arterial blood pressure (MAP) were also evaluated.

RESULTS

The pharmacokinetic parameters of S- and R-ketamine administered in the racemic mixture or S-ketamine administered separately did not differ significantly. Statistically significant higher AUC and C(max) were found for S-norketamine compared with R-norketamine in the racemic group. Overall, R(f), V(E), PE'(CO(2)), and MAP were significantly higher in the racemic group, whereas PR was higher in the S-ketamine group.

CONCLUSIONS

Norketamine enantiomers showed different pharmacokinetic profiles after single i.v. administration of racemic ketamine in ponies anaesthetised with isoflurane in oxygen (1 MAC). Cardiopulmonary variables require further investigation.

Evaluation of the analgesic effect of lidocaine and bupivacaine used to provide a brachial plexus block for forelimb surgery in 10 dogs

Twenty adult dogs weighing between 1.4 and 53.5 kg and aged between six months and nine years were anaesthetised and the brachial plexus was localised with the aid of a nerve stimulator. In 10 of the dogs a brachial plexus block was induced with a mixture of lidocaine and bupivacaine and the other 10 each received 0.25 ml/kg saline as a control. The end-tidal isoflurane concentration was maintained between 1.3 and 1.4 per cent during surgery for carpal arthrodesis or a fracture of the radius or ulna. Acute heart rate or blood pressure increases of 20 per cent or more were treated with 1 microg/kg fentanyl intravenously. Postoperatively, signs of pain were scored by a single blinded observer at hourly intervals until eight hours after the block had been induced, on a scale from 0 to 18. Dogs with pain scores above 5 received 0.1 to 0.2 mg/kg methadone intravenously, repeated as necessary. During surgery the control dogs received significantly more fentanyl (median 0.05 microg/kg/minute, range 0.02 to 0.20 microg/kg/minute) than the group given local anaesthetic (median 0 microg/kg/minute, range 0 to 0.02 microg/kg/minute). Postoperatively, the control group required significantly more methadone (median 0.2 mg/kg, range 0.1 to 1 mg/kg) than the treated group (median 0 mg/kg, range 0 to 0.13 mg/kg).

Inhalation anaesthesia for castration of newborn piglets: experiences with isoflurane and isoflurane/NO

The aim of this study was to evaluate the inhalation anaesthesia with isoflurane and isoflurane/N2O by mask induction for routine castration of piglets under 14 days of age.

MATERIAL AND METHODS

Eighty-five male piglets aged between 4 and 12 days were used in a matched pair test. Two piglets of the same litter with the same weight were selected. One was castrated with, the other without anaesthesia. Induction was performed with either isoflurane (group ISO) or isoflurane/nitrous oxide (group ISO/N2O) in oxygen through a modified bain-breathing system. Induction time was 90 and 60 s for group ISO and group ISO/N2O, respectively. The disappearance of the palpebral reflex was recorded. The reaction of the piglets during castration was judged according to a scoring system separately for both testicles during skin incision and dissection of the spermatic cord. The scores were added and mean values were calculated. Total anaesthesia time, castration time and quality of recovery was recorded. Blood was collected from all piglets immediately after castration for measurement of ACTH and beta-endorphin values. Statistical analysis were performed by the Kruskal-Wallis test for nonparametric data and one-way anova (NCSS 2000, Kaysville, UT, USA).

RESULTS

Induction of anaesthesia proved to be smooth in all cases. The palpebral reflex disappeared after 36.5 s in group ISO/N2O versus 51 s in group ISO. Mean castration scores were 0.6 in group ISO and 0 in group ISO/N2O, whereas 7.7 in piglets with no anaesthesia. These scores were significantly different. Mean anaesthesia time was 128 s (30-390) for group ISO and 123 s (70-220) for group ISO/N2O. No deaths occurred. The differences in the levels of ACTH and beta-endorphins in the blood plasma in the different groups showed no statistical difference.

DISCUSSION

This study demonstrates that isoflurane or isoflurane/N2O anaesthesia by mask induction proves to be a safe, short and reliable method in piglets undergoing castration. Reaction to the castration procedure were significantly reduced. Stress hormone values were not different between the groups because of a large individual difference.

Blood/gas partition coefficients of halothane, isoflurane and sevoflurane in horse blood

BACKGROUND

Blood/gas partition coefficients (lambda(b/g)) for volatile agents in horse blood are reported for halothane but not for isoflurane and sevoflurane. We measured the lambda(b/g) of halothane, isoflurane and sevoflurane in the blood of fasted horses. The correlation with age, weight and some haematological and biochemical variables was studied. The temperature correction factor for isoflurane solubility was calculated.

METHODS

Twenty-four horses were randomly allocated to halothane (n=8), isoflurane (n=8) or sevoflurane (n=8). Blood samples were taken after 10 h' fasting. Calculation of lambda(b/g) was based on the measurement of anaesthetic partial pressures in blood at 37 degrees C, which was achieved with tonometer equilibration and headspace gas chromatography.

RESULTS

Mean lambda(b/g) was 1.66 (SD 0.06) for halothane, 0.92 (0.04) for isoflurane, and 0.47 (0.03) for sevoflurane. The lambda(b/g) values were all significantly lower than in humans (P<0.001). No correlation was found between lambda(b/g) and weight, age, haematocrit, plasma triglycerides, cholesterol or total bilirubin. The change in isoflurane solubility per 1 degrees C temperature increase was -2.63 (0.13)%.

CONCLUSION

The lambda(b/g) values of halothane, isoflurane and sevoflurane in fasted horses are significantly lower than those reported in humans. The lambda(b/g) for halothane in this study agrees with values reported in the literature but a positive correlation with plasma triglycerides could not be confirmed. Knowledge of lambda(b/g) can refine models of anaesthetic uptake.

[Castration of male lambs and calves: explanations and comments of art. 65 TSchV]

Since September 1, 2001, castration of male calves and small ruminants in Switzerland is not allowed without anesthesia. The use of rubber rings for that purpose is forbidden. This change of the legislation has been claimed by the Swiss consumers and is aimed to increase the animal welfare. The current paper provides a review of the different techniques of anesthesia and castration that may be advocated in male ruminants. Sedation with xylazine and injection of lidocaine in the area of the base of the scrotum, followed by closed castration with the Burdizzo represents a safe technique for painfree castration of calves and lambs.

IL-12-dependent, INF-gamma-independent experimental glomerulonephritis

There is evidence that crescentic glomerulonephritis initiated in rodents by heterologous antibodies against the glomerular basement membrane (anti-GBM glomerulonephritis) depends on a Th1-type immune reaction. Interleukin 12 (IL-12) is crucial for the development of Th1 helper cells, and interferon gamma (IFN-gamma) is a major proinflammatory product of these cells. In order to test the role of the two cytokines in anti-GBM glomerulonephritis we used mice lacking either the p40 chain of IL-12 (IL-12-/-) or the IFN-gamma receptor (IFN-gammaR-/-). Glomerulonephritis was induced by injecting a rabbit anti-GBM serum in mice preimmunized against rabbit IgG. Glomerulonephritis was assessed on the basis of proteinuria, immunofluorescence findings and histology. IL-12-/- mice were completely protected against glomerulonephritis. In contrast, IFN-gammaR-/- mice were more severely affected than wild-type mice. Similarly, cutaneous delayed-type hypersensitivity, a typical Th1 response, was abolished in the IL-12-/-, mice but increased in the IFN-gammaR-/- mice. The data obtained in IL-12-/- mice support the view that crescentic glomerulonephritis in this model represents a Th1 response. Since IFN-gamma is not required, other products of Th1 cells are likely to mediate glomerulonephritis.

Duplex-ultrasonographic evaluation of the common carotid artery in the resting, sedated and anesthetized horse

The aim of this study was to determine the blood flow in the carotid artery during halothane anaesthesia by means of duplex-sonography. Seventeen warm blood horses were evaluated in dorsal and lateral recumbency and the results were compared with the values of the same horses resting and under sedation. The cross sectional area of the vessels, the time-averaged maximal blood velocity, time-averaged maximal blood flow and the resistance index were determined and the flow profile was evaluated. During halothane anesthesia the total blood flow shows a significant increase which is not dependent on the positioning of the horse. Mean blood velocity is decreased by sedation and significantly increased during anesthesia. Reduced peripheral resistance is expressed by a decline of the resistance index. After sedation and during recumbency there is an increase in diameter of the carotid artery.

A Th1 response is essential for induction of crescentic glomerulonephritis in mice

Crescentic glomerulonephritis can be induced in rodents by injection of heterologous antibodies against the glomerular basement membrane. There is evidence that glomerular inflammation in that model represents a delayed-type hypersensitivity response to the heterologous immunoglobulin, whereas the antibody response is not important. The aim of the present study was to test this hypothesis. Delayed-type hypersensitivity is mediated by T cells with the Th1 phenotype. We compared mice immunized with rabbit immunoglobulin G in complete Freund's adjuvant or in incomplete Freund's adjuvant, producing, respectively, Th1- or Th2-biased responses to the antigen. Intravenous injection of rabbit antimouse glomerular basement membrane serum provoked proteinuria, infiltration with T cells and macrophages, as well as profound histological damage in the group treated with complete Freund's adjuvant. There was no evidence of glomerulonephritis in the group which received incomplete Freund's adjuvant. Deposits of mouse IgG along the glomerular basement membrane were similar in both groups. Thus, a Th1 response appears to be essential for the induction of glomerulonephritis in this model.

Is carbon dioxide (CO2) a useful short acting anaesthetic for small laboratory animals?

The anaesthetic effect of carbon dioxide (CO2) was investigated under predetermined exposure times in rats, mice and guinea pigs with admixture of 20% of oxygen (O2), and with 20% of ambient air in rats. In rats first symptoms (median) were detectable between 7 and 9.5 s, the induction time (median) varied between 16 and 20.5 s and the surgical tolerance (median) was 40 s (after 60 s of exposure) and 53.5 s (after 120 s of exposure) to 80% CO2/20% O2. When O2 was replaced by ambient air, a surgical tolerance of 53.5 s (after 60 s of exposure) and 77 s (after 120 s of exposure) was measured. In mice the induction time to 80% CO2/20% O2 was 10 s and the surgical tolerance 19.5 s (after 120 s of exposure). Guinea pigs showed an induction period of 20 s and a surgical tolerance of 50 s (after 30 s of exposure) to 80% CO2/O2. Recovery was short and smooth in all species. This method of general anaesthesia seems to be suitable for short and painful interventions, mainly in rats, but also in guinea pigs.

Inhalation anaesthesia for the castration of piglets: CO2 compared to halothane

General anaesthesia with 80% CO2/20% O2 and 5% halothane in O2 (mask induction) was compared for castration of 3-4 week-old piglets. One group was castrated without anaesthesia. Of the noncastrated control groups one had CO2- and one halothane anaesthesia, one breathed room air through the induction system, and one was held in castration position. The behaviour to induction and castration was assessed, and the cortisol-, ACTH- and beta-endorphin plasma concentrations were determined to quantify the stress elicited by anaesthesia, castration and handling. Violent struggling and vocalization were elicited by CO2 and positioning into the mask induction system while breathing room air; halothane induction was quiet. CO2 induced profound surgical anaesthesia; whereas under halothane anaesthesia some animals exhibited still a slight reaction to castration. Recovery was fast, smooth and quite. Permanent violent struggling and vocalization were elicited by castration without anaesthesia. Plasma cortisol was not a sensitive tool to judge castration stress. The high ACTH and beta-endorphin plasma concentrations elicited by CO2 anaesthesia confirm our clinical experience. General anaesthesia is fast and safely induced with CO2 in piglets and castration can be performed without any reaction, but with CO2 anaesthesia the stress is not reduced.

Effects of alpha 2-agonists on intrauterine pressure and sedation in horses: comparison between detomidine, romifidine and xylazine

The effect of three alpha 2-agonistic sedatives, Detomidine (0.04 mg/kg), Romifidine (0.08 mg/kg) Xylazine (1.1 mg/kg) and placebo (NaCl), on intrauterine pressure was investigated with an intrauterine balloon model in four non-pregnant warmblood mares. Within 6.0 (+/- 2.2) min mean pressure increases of 9.80 (+/- 3.74), 6.88 (+/- 3.95) and 13.95 (+/- 5.19) mmHg were recorded for Detomidine, Romifidine and Xylazine, respectively. Placebo had no significant effect. The mean duration of pressure increase was 30.0 (+/- 5.10), 17.67 (+/- 9.87) and 19.50 (+/- 13.78) min for Detomidine, Romifidine and Xylazine, respectively. There was no significant difference in the degree and duration of sedation between the three treatment groups. It is concluded that alpha 2-agonists exert a marked pressure increase in the uterus with no statistically significant differences in degree and duration between the three substances. With equipotent doses no difference in duration and degree of sedation could be calculated.

[The humanitarian stunning of fowl for slaughter with microwaves (2450 MHz)]

Chickens can be killed in less than one second by exposing their heads to microwave irradiation with a frequency of 2450 MHz. Positioning the head exactly is necessary. The only way to avoid this handling is the exposure of the whole body. But because of a particular high rate of absorption the wings are heated so that the meat is not edible any more. Before slaughtering the chickens are hung up headlong. This causes increased cardiac and respiratory frequencies while the blood pressure is not altered yet. This handling is a considerable stress. Animal-prevention arguments suggest to prefer anaesthesia before hanging the chickens in the conveyor belt.