RESUMEN

The objective of this study was to evaluate the clinical usefulness of the combination of tiletamine-zolazepam used in low doses as a continuous rate infusion in a partial intravenous anesthesia protocol. Fifteen clinically healthy, different breed bitches weighing 25.08 ± 10.39 kg was used in this study. After a food fast for at least 12 hours and water fast for 4 hours, the animals were premedicated with dexmedetomidine. After 15 minutes, the bolus of tiletamine-zolazepam combination was given as an. Induction of general anesthesia, immediately followed by continuous intravenous infusion. The following parameters were measured immediately after the induction of general anesthesia and lasted until the end of the surgery: electrocardiography, heart rate, systolic arterial blood pressure, diastolic arterial blood pressure, mean arterial blood pressure, body temperature respiratory rate end tidal of CO2. During the recovery period, pain level was evaluated as well as sedation assessment. Time for successful intubation after administration of the tiletamine-zolazepam combination was within 3 minutes. Heart rate was within reference values. Systolic, diastolic, and mean arterial blood pressure were also within the reference values. Internal body temperature showed a downward trend for a whole procedure time. During recovery, only 1 patient showed symptoms of pain and signs of dissociation. In summary, the partial intravenous protocol with the use of tiletamine-zolazepam combination and low anesthetic gases concentration is clinically useful because of ensuring the correct level of anesthesia and stability of intraoperative parameters as well as a good recovery period.

Asunto(s)

RESUMEN

Medetomidine partial intravenous anaesthesia (PIVA) has not been compared to xylazine PIVA regarding quality of recovery. This clinical retrospective study compared recoveries following isoflurane anaesthesia balanced with medetomidine or xylazine. The following standard protocol was used: sedation with 7 µg·kg-1 medetomidine or 1.1 mg·kg-1 xylazine, anaesthesia induction with ketamine/diazepam, maintenance with isoflurane and 3.5 µg·kg-1·h-1 medetomidine or 0.7 mg·kg-1·h-1 xylazine, and sedation after anaesthesia with 2 µg·kg-1 medetomidine or 0.3 mg·kg-1 xylazine. Recovery was timed and, using video recordings, numerically scored by two blinded observers. Influence of demographics, procedure, peri-anaesthetic drugs, and intraoperative complications (hypotension, hypoxemia, and tachycardia) on recovery were analysed using regression analysis (p < 0.05). A total of 470 recoveries (medetomidine 279, xylazine 191) were finally included. Following medetomidine, recoveries were significantly longer (median (interquartile range): 57 (43-71) min) than xylazine (43 (32-59) min) (p < 0.001). However, the number of attempts to stand was similar (medetomidine and xylazine: 2 (1-3)). Poorer scores were seen with increased pre-anaesthetic dose of xylazine, intraoperative tetrastarch, or salbutamol. However, use of medetomidine or xylazine did not influence recovery score, concluding that, following medetomidine-isoflurane PIVA, recovery is longer, but of similar quality compared to xylazine.

RESUMEN

OBJECTIVE: To evaluate perioperative stress-related hormones in isoflurane-anesthetized horses administered infusions of dexmedetomidine alone or with butorphanol or remifentanil, compared with ketamine-morphine. STUDY DESIGN: Randomized, prospective, nonblinded clinical study. ANIMALS: A total of 51 horses undergoing elective surgical procedures. METHODS: Horses were premedicated with xylazine, anesthesia induced with ketamine-diazepam and maintained with isoflurane and one of four intravenous infusions. Partial intravenous anesthesia (PIVA) was achieved with dexmedetomidine (1.0 µg kg-1 hour-1; group D; 12 horses); dexmedetomidine (1.0 µg kg-1 hour-1) and butorphanol bolus (0.05 mg kg-1; group DB; 13 horses); dexmedetomidine (1.0 µg kg-1 hour-1) and remifentanil (3.0 µg kg-1 hour-1; group DR; 13 horses); or ketamine (0.6 mg kg-1 hour-1) and morphine (0.15 mg kg-1, 0.1 mg kg-1 hour-1; group KM; 13 horses). Infusions were started postinduction; butorphanol bolus was administered 10 minutes before starting surgery. Blood was collected before drugs were administered (baseline), 10 minutes after ketamine-diazepam, every 30 minutes during surgery and 1 hour after standing. Mean arterial pressure (MAP), pulse rate, end-tidal isoflurane concentration, cortisol, nonesterified fatty acids (NEFA), glucose and insulin concentrations were compared using linear mixed models. Significance was assumed when p < 0.05. RESULTS: Within D, cortisol was lower at 120-180 minutes from starting surgery compared with baseline. Cortisol was higher in KM than in D at 60 minutes from starting surgery. Within all groups, glucose was higher postinduction (except DR) and 60 minutes from starting surgery, and insulin was lower during anesthesia and higher after standing compared with baseline. After standing, NEFA were higher in KM than in DB. In KM, MAP increased at 40-60 minutes from starting surgery compared with 30 minutes postinduction. CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine suppressed cortisol release more than dexmedetomidine-opioid and ketamine-morphine infusions. Ketamine-morphine PIVA might increase catecholamine activity.

Asunto(s)