Journal of Veterinary Anaesthesia最新文献

A new inhalant anaesthetic, sevoflurane, was used to maintain anaesthesia in 40 animals (2 mules and 38 horses of 9 breeds) presented for various surgical procedures. Eighteen mares, 11 stallions and 11 geldings underwent 6 orthopaedic and 34 soft tissue operations. Induction of anaesthesia was achieved with combinations of xylazine (0.5–1.1 mg/kg), diazepam (0.03–0.1 mg/kg), butorphanol (0.02 mg/kg), guaifenesin (50–84 mg/kg) and ketamine (1.1 mg/kg). Following tracheal intubation, a surgical plane of anaesthesia was maintained with sevoflurane in oxygen delivered from a precision vaporiser. Temperature, ECG, arterial blood pressure and expired gas composition were monitored. Mechanical ventilation was used in most animals (n=37) because of hypoventilation (P_aCO₂ > 7.31 kPa [55 mmHg]). Following surgery, horses were moved to a recovery room and allowed to recover alone (n=36) or with assistance (n=4). Time to sternal recumbency, standing, the time when satisfactory coordination was present (after standing) and the number of attempts to stand were recorded. The quality of recovery was scored on a 1 (best) to 6 (worst) scale. Mean blood pressures at 30, 60, 90, 120 and 150 min of anaesthesia were 72, 73, 74, 75 and 72 mmHg, respectively. Systolic and diastolic pressures at 30, 60, 90, 120 and 150 min of anaesthesia were 97, 97, 94, 96, 93 and 59, 63, 64, 68, 67 mmHg, respectively. Dobutamine was used in 23 horses to maintain mean arterial blood pressure > 60 mmHg. Mean heart and respiratory rates at 30, 60, 90, 120 and 150 min of anaesthesia were 36, 38, 39, 38 and 38 beats/min, and 9, 8, 8, 8 and 8 breaths/min. Mean duration of anaesthesia was 121 rnin (sd: 56 min), mean time to sternal recumbency was 27 min (sd: 13 min), average time to standing (all horses) was 33 min (sd: 12 min) and time to satisfactory coordination was 44 min (sd: 13 min). Most horses (n=37) received xylazine during recovery (mean dose 0.18 mg/kg iv). The median number of attempts to sternal recumbency and standing were 1.0 (range; 1–7) and 2.0 (range; 1–20), respectively, while the median recovery score was 1.5 (range; 14). The ‘depth’ of anaesthesia was easy to control and recoveries were generally very satisfactory.

The purpose of this study was to investigate the effect of a single dose (50 mg/kg) of guaiphenesin on recumbency time, surgical conditions and the ‘quality’ of anaesthesia in ponies anaesthetised for castration. Sixteen ponies were sedated with romifidine 100 μg/kg and anaesthetised with ketamine (2.2 mg/kg). Ponies allocated to Group A received no treatment and those in Group B were given 50 mg/kg of a 15% guaiphenesin solution. Guaiphenesin was given as a rapid iv injection immediately after induction of anaesthesia. All ponies were subsequently castrated. The mean (± se) time of recumbency in Group A was 20.9 ± 1.37 min and in Group B 27.2 ± 2.1 min to (P<0.05). Subjective assessment scores for the quality of surgical conditions and anaesthesia itself were significantly greater (indicating better conditions) in ponies receiving guaiphenesin, although there was no difference between groups in the quality of recovery.

The study aimed to investigate the stimulus to adrenocortical activity that is induced by halothane anaesthesia. Groups of 7 sheep were anaesthetised with thiopentone and halothane (TH) or acepromazine, thiopentone and halothane (ATH). During 120 min of anaesthesia hypotension was prevented (mean arterial blood pressure kept at pre-anaesthetic level) by infusion of a modified gelatine plasma replacer given to effect (0.34–1.1 litres with TH and 1.1–3.1 litres with ATH). Pulse rate, arterial blood pressure and gases were measured and sequential samples withdrawn for analysis of plasma cortisol, adrenocorticotrophic hormone (ACTH), arginine vasopressin (AVP), glucose and lactate. Heart rate increased in the ATH but not the TH group. All sheep were well oxygenated but developed hypercapnia and respiratory acidosis. In both groups, cortisol increased more than 2-fold 20 min after the end of anaesthesia but there were no significant changes in ACTH. AVP was measured in the TH group only and increased 3-fold at the end of anaesthesia. Glucose and lactate remained stable except for lactate in the TH group which decreased during anaesthesia. These data indicate that hypotension is a major component of the stimulus inducing adrenocortical activity during halothane anaesthesia. However, maintenance of normotension did not entirely depress the response; halothane itself or decreased perfusion may also contribute.