Cardiopulmonary effects of three different anaesthesia protocols in cats.

To develop an alternative anaesthetic regimen for cats with cardiomyopathy, the cardiopulmonary effects of three different premedication-induction protocols, followed by one hour maintenance with isoflurane in oxygen: air were evaluated in six cats. Group I: acepromazine (10 microg/kg) + buprenorphine (10 microg/kg) IM, etomidate (1-2 mg/kg) IV induction. Group II: midazolam (1 mg/kg) + ketamine (10 mg/kg) IM induction. Group III: medetomidine (1.5 mg/m2 body surface) IM, propofol (1-2 mg/kg) IV induction. Heart rate, arterial blood pressure, arterial blood gases, respiration rate, and temperature were recorded for the duration of the experiment. In group I the sedative effect after premedication was limited. In the other groups the level of sedation was sufficient. In all groups premedication resulted in a reduced blood pressure which decreased further immediately following induction. The reduction in mean arterial pressure (MAP) reached statistical significance in group I (142+/-22 to 81+/-14 mmHg) and group II (153+/-28 to 98+/-20 mmHg) but not in group III (165+/-24 to 134+/-29 mmHg). Despite the decrease in blood pressure, MAP was judged to have remained within an acceptable range in all groups. During maintenance of anaesthesia, heart rate decreased significantly in group III (from 165+/-24 to 125+/-10 b.p.m. at t=80 min). During anaesthesia the PCO2 and PO2 values increased significantly in all groups. On the basis of the results, the combination acepromazine-buprenorphine is preferred because heart rate, MAP, and respiration are acceptable, it has a limited sedative effect but recovery is smooth.

Clinical efficacy and safety of propofol or ketamine anaesthesia in dogs premedicated with medetomidine.

Combinations of medetomidine with either propofol or ketamine were compared for the sedation and induction of anaesthesia in dogs undergoing a variety of surgical (60 per cent) and non-surgical (40 per cent) procedures. Eighty-four dogs were used at four sites. Medetomidine was administered intramuscularly at a dose of 1000 micrograms/m2 body surface area 10 to 15 minutes before the induction of anaesthesia by the administration of propofol (n = 44) or ketamine (n = 40) dosed to effect. The dogs became sedated by medetomidine after a mean (sd) time of 6.7 (5.4) minutes, and their heart rates and respiration rates decreased. Sixteen of the dogs suffered an adverse effect, 13 of them vomited. Anaesthesia was induced by the intravenous administration of propofol (2.1 [0.7] mg/kg) or ketamine (3.7 [1.9] mg/kg), and further doses of the anaesthetic were given, depending on the length of the operation, once in 17 per cent, twice in 11 per cent and three or more times in 24 per cent of the cases. The heart rate of the dogs anaesthetised with ketamine was significantly higher than that of the dogs anaesthetised with propofol, but there were no other significant physiological differences. There were 11 adverse side-effects in the ketamine group compared with five in the propofol group and they were generally more severe. The quality of the recovery from anaesthesia was considered to be smooth in 89 per cent of the propofol group but in only 63 per cent of the ketamine group.

[Veterinary dentistry (13). Evaluation of the use of medetomidine and ketamine to induce anaesthesia in dogs undergoing dental surgery]. / Veterinaire tandheelkunde [13]. Het gebruik van de combinatie medetomidine/ketamine bij de hond voor anesthesie bij tandheelkundige ingrepen: een evaluatie van een klinische toepassing.

The use of a combination of medetomidine and ketamine as anaesthetic for dental surgery was investigated in 60 dogs. The nature of the interventions varied from inspection of the teeth with cleaning of the teeth or simple tooth extraction to extraction of one or more dental elements or endodontic treatment. The operations lasted between 20 and 70 minutes, with an average of 34 +/- 15 minutes. Medetomidine, 1000 micrograms/m2 body surface administered intramuscularly, was used as premedication. Anaesthesia was induced with intravenously administered ketamine at a dose of 2-3 mg/kg body weight. The effect of premedication was 'good' in 79.5% of patients, 'moderate' in 12%, and 'poor' in 8.5%. Seven patients were given additional 50% medetomidine, which caused the proportion of animals with 'good' premedication to increase to 91.5%. Twelve of the 60 patients showed convulsion-like symptoms of varying severity directly after the administration of ketamine. In 4 patients the tonic cramps were considered severe enough to warrant once-only administration of midazolam. The quality of anaesthesia in the maintenance phase was considered 'good' in 88% of the patients and 'moderate' in 12%. Recovery was 'good' in 74% of the patients, 'moderate' in 11%, and 'poor' in 15%. Heart rate after premedication with medetomidine was 53 +/- 3 beats per minute and increased to 86 +/- 4 beats per minute (P < 0.05) after administration of ketamine. It thereafter decreased, over a period of 20 minutes, to 60 +/- 3 beats per minute. The respiration rate was 15 +/- 1 per minute and remained unchanged throughout the operation. After completion of surgery, medetomidine was antagonized with atipamezole (2500 micrograms/m2) given intramuscularly. In 13% of the animals the recovery period was characterized by tremors and restlessness. It can be concluded that the combination medetomidine and ketamine provides adequate analgesia, hypnosis, and muscle relaxation for various dental surgical interventions to be performed.

Medetomidine as a premedicant for ketamine, propofol or fentanyl anaesthesia in dogs.

This study evaluated the quality of anaesthesia and the cardiorespiratory effects induced by the combination of medetomidine with either ketamine, propofol or fentanyl. Medetomidine premedication (1000 or 1500 micrograms/m2 body surface area) was followed by intravenous induction of anaesthesia with ketamine (3.0 mg/kg), propofol (2.0 mg/kg) or fentanyl (2.0 micrograms/kg) in bitches undergoing elective ovariohysterectomy. Anaesthesia was prolonged by incremental doses of the induction agents as necessary. The mean (sem) overall doses (including induction) were 0.09 (0.01) mg/kg/min for ketamine, 0.06 (0.01) mg/kg/min for propofol and 0.07 (0.005) microgram/kg/min for fentanyl during procedures which lasted 88 (6) minutes, 72 (3) minutes and 79 (7) minutes, respectively. At the end of the procedure, medetomidine was antagonised with atipamezole. The quality of anaesthesia, heart rate and arterial blood pressure were recorded continuously and arterial blood gases were measured at intervals. At the end of the procedure, the animals received 10 micrograms/kg buprenorphine intramuscularly for postoperative analgesia. From the adequacy of anaesthesia, the lack of significant adverse side effects and the reliable and rapid recovery it is concluded that, in healthy dogs anaesthetised with ketamine or propofol, medetomidine is a satisfactory sedative-analgesic premedicant. The differences in haemodynamics and the quality of recovery suggest that the combination of medetomidine with propofol provided the better quality anaesthesia. The combination of medetomidine with fentanyl was unsuitable for obtaining surgical anaesthesia in spontaneously breathing animals owing to the severity of the respiratory depression at dosages needed for general anaesthesia.

[Veterinary dentistry (13). The use of the combination medetomidine/ketamine in dogs for anesthesia in dental procedures: evaluation of its clinical application]. / Veterinaire tandheelkunde (13). Het gebruik van de combinatie medetomidine/ketamine bij de hond voor anesthesie bij tandheelkundige ingrepen: een evaluatie van een klinische toepassing.

The use of a combination of medetomidine and ketamine as anaesthetic for dental surgery was investigated in 60 dogs. The nature of the interventions varied from inspection of the teeth with cleaning of the teeth or simple tooth extraction to extraction of one or more dental elements or endodontic treatment. The operations lasted between 20 and 70 minutes, with an average of 34 +/- 15 minutes. Medetomidine, 1000 m g/m2 body surface administered intramuscularly, was used as premedication. Anaesthesia was induced with intravenously administered ketamine at a dose of 2-3 mg/kg body weight. The effect of premedication was 'good' in 79.5% of patients, 'moderate' in 12%, and 'poor' in 8.5%. Seven patients were given additional 50% medetomidine, which caused the proportion of animals with 'good' premedication to increase to 91.5%. Twelve of the 60 patients showed convulsion-like symptoms of varying severity directly after the administration of ketamine. In 4 patients the tonic cramps were considered severe enough to warrant once-only administration of midazolam. The quality of anaesthesia in the maintenance phase was considered 'good' in 88% of the patients and 'moderate' in 12%. Recovery was 'good' in 74% of the patients, 'moderate' in 11%, and 'poor' in 15%. Heart rate after premedication with medetomidine was 53 +/- 3 beats per minute and increased to 86 +/- 4 beats per minute (P < 0.05) after administration of ketamine. It thereafter decreased, over a period of 20 minutes, to 60 +/- 3 beats per minute. The respiration rate was 15 +/- 1 per minute and remained unchanged throughout the operation. After completion of surgery, medetomidine was antagonized with atipamezole (2500 m g/m2) given intramuscularly. In 13% of the animals the recovery period was characterized by tremors and restlessness. It can be concluded that the combination medetomidine and ketamine provides adequate analgesia, hypnosis, and muscle relaxation for various dental surgical interventions to be performed.

[Spontaneous respiration versus IPPV in pigeons]. / Spontane ademhaling versus IPPV bij de duif.

Veterinary textbook on anaesthesia in birds that volatile anaesthetics can accumulate in the air sac system during spontaneous respiration of birds anaesthetized with inhalational anaesthetics. In order to quantify the extent of accumulation, air samples were collected from the endotracheal tube and from the left abdominal air sac of ten pigeons anaesthetized with O2, NO2, and isoflurane. In this way, O2, CO2, and isoflurane concentrations were measured continuously at two places, during both spontaneous respiration and positive pressure ventilation. During spontaneous respiration, CO2-concentrations were higher in the air sac than in the endotracheal tube in 60% of the animals. The average difference for the whole group was 0.8 volume per cent; individual differences were as high as 2.9 volume per cent. The concentration of isoflurane was on average 1.1 volume per cent lower in the abdominal air sac than in the endotracheal tube. During mechanical ventilation, the percentage of CO2 was lower in the abdominal air sac than in the endotracheal tube in all pigeons. At the same time, the differences between isoflurane concentrations in the endotracheal tube and air sac decreased. Thus the results of our study with isoflurane-anaesthetized pigeons do not support the suggestion that volatile anaesthetics accumulate in the air sacs of spontaneously breathing birds anaesthetized with inhalation anaesthetics. The results also show that, under these conditions, CO2 concentrations in the endotracheal tube can only be measured reliably during positive pressure ventilation.

[Anesthesia in the patient with stomach dilatation-volvulus]. / Anesthesie bij de patiënt met maagdilatatie-volvulus.

Before a decision on the anesthetic protocol and the various patient support measures can be taken, the pathophysiological changes that occur during a gastric dilatation-volvulus need to be evaluated. The most important changes are of a circulatory and/or respiratory nature, inducing hypotension, hypovolaemia, cardiac dysrhythmias, a decreased respiratory minute volume, and subsequently resulting in changes in the acid-base balance and plasma electrolyte concentration. In view of these changes and the increased anaesthetic risk for the patient with gastric dilatation-volvulus, the use of barbiturates or ketamine cannot be recommended for anaesthetising these patients. With the use of neurolept-analgesic combinations, such as methadone-droperidol or sufentanil-midazolam, an increased cardiovascular stability and an ample analgesic effect can be obtained. Especially with the potent sufentanil in combination with midazolam, an excellent anaesthesia for patients with gastric dilatation-volvulus can be achieved.

[Intramuscularly administered non-opiate anesthesia in dogs. A report on the use of ketamine/xylazine, tiletamine/zolazepam, ketamine/midazolam and metomidine]. / Intramusculair toegediende non-opiaat anesthesie bij de hond. Een rapportage over het gebruik van ketamine/xylazine, tiletamine/zolazepam, ketamine/midazolam en medetomidine.

In the present paper, findings on the use of ketamine/xylazine, ketamine/midazolam, tiletamine/zolazepam, and medetomidine following intramuscular injection in dogs are reported. The combined use of ketamine/xylazine induced anaesthesia, the duration of which was thirty minutes. Untoward side-effects were not observed. Administration of tiletamine/zolazepam failed to induce a surgical level of anaesthesia. Recovery was prolonged. In this group, five out of the ten dogs showed signs of post-anaesthetic muscle spasms. Neither the combination ketamine/midazolam nor medetomidine induced a surgical level of anaesthesia. Post-anesthetic muscle spasms were a frequently observed side-effect when the combination ketamine/midazolam was administered. The use of medetomidine resulted in a qualitatively satisfactory and prolonged sedation.