Influence of two administration rates of propofol at induction of anaesthesia on its relative potency in cats: a pilot study

Effects of different rates of propofol with or without S-ketamine on ventricular function in healthy cats - a randomized study

Propofol is used for anesthetic induction in cats and procedural sedation in countries where alfaxalone is not available. Studies have reported propofol-related effects in echocardiography variables in dogs and humans. However, there is a lack of echocardiography studies investigating propofol-related effects on cats. This study aimed to use echocardiography to investigate echocardiographic changes in three protocols using propofol: propofol-slow (2 mg/kg/min, PS); propofol-fast (8 mg/kg/min, PF); propofol-ketamine (S-ketamine 2 mg/kg bolus followed by propofol 2 mg/kg/min; PK) in healthy premedicated (gabapentin-buprenorphine-acepromazine; 200 mg/cat, 0.4, and 0.1 mg/kg, respectively), non-intubated cats. Echocardiographic measurements were obtained at three time points: baseline (before the administration of propofol), end of propofol titration (end-point, T0), and 15 min after T0 (T15). Propofol at a lower rate continued from T0 to T15. Echocardiographic and physiological variables included fractional shortening (FS%), ejection fraction (EF%), HR, BP, and others. Propofol requirements at T0 for PF, PS, and PK groups were 5.0 ± 0.9, 3.8 ± 0.7, and 2.4 ± 0.5 mg/kg, respectively. EF% neither change over time nor between groups. PF and PK showed a reduction in FS% at T0 (47 ± 6 to 34 ± 6 and 42 ± 6 to 36 ± 5, respectively). BP reduced significantly in PF and PS groups (136 ± 26 to 105 ± 13 and 137 ± 22 to 115 ± 15 mmHg, respectively). It is unclear whether changes in echocardiography variables were of clinical relevance related to treatment groups or a result of within-group individual responses.

Cardiopulmonary and propofol-sparing effects of dexmedetomidine in total intravenous anesthesia in cats undergoing ovariohysterectomy

OBJECTIVES

This study aimed to assess the effect of dexmedetomidine on the propofol-based anesthesia of cats subjected to ovariohysterectomy.

METHODS

Twenty-eight cats were randomly allocated to four groups (seven cats in each) and premedicated with either 5 µg/kg dexmedetomidine (groups Dex 1, Dex 3 and Dex 5) or 0.05 ml saline (Prop group) intramuscularly. After the induction of anesthesia with propofol, total intravenous anesthesia was initiated with 300 µg/kg/min propofol plus 3 ml/kg/h NaCl 0.9% (Prop), or 200 µg/kg/min propofol plus dexmedetomidine at the rates of 1 µg/kg/h (Dex 1), 3 µg/kg/h (Dex 3) or 5 µg/kg/h (Dex 5). Cardiorespiratory variables were assessed 5 mins after induction and every 10 mins thereafter, until the end of anesthesia. The propofol infusion rate was adjusted every 10 mins (± 50 µg/kg/min) to maintain anesthetic depth. The times to extubation, sternal recumbency, ambulation and total recovery were recorded. Pain scoring was performed 1, 2, 4, 8, 12 and 24 h after the end of anesthesia.

RESULTS

Dexmedetomidine produced a propofol-sparing effect of 72.8%, 71.1% and 74.6% in the Dex 1, Dex 3 and Dex 5 groups, respectively. Cats in the Prop group maintained higher heart rate values than the other groups, and the mean arterial pressure remained higher in the Dex 3 and Dex 5 groups. Rescue intraoperative analgesia (fentanyl bolus) was most frequent in the Prop group. There was no significant difference in the time of extubation. Cats in the Dex 1 and Dex 3 groups had a faster anesthetic recovery, with shorter times to achieving sternal recumbency, regaining ambulation and reaching full recovery. Cats in the Dex 1 and Dex 5 groups presented the best recovery quality scores, with 4 (range 4-5) and 4 (range 3-5), respectively, while the Prop group scored 1 (range 1-3), the worst anesthetic recovery score among the groups.

CONCLUSIONS AND RELEVANCE

The use of dexmedetomidine as a total intravenous anesthesia adjuvant, especially at doses of 1 and 3 µg/kg/h, reduces propofol consumption and improves cardiorespiratory stability and intraoperative analgesia, while promoting a better and quicker recovery from anesthesia.

Randomised clinical trial comparing the perioperative analgesic efficacy of oral tramadol and intramuscular tramadol in cats

OBJECTIVES

The aim of this study was to evaluate the analgesic efficacy of oral tramadol in cats undergoing ovariohysterectomy.

METHODS

Twenty-four female domestic cats, American Society of Anesthesiologists class I, aged 4-24 months, were included in this positive controlled, randomised, blinded clinical trial. Cats admitted for ovariohysterectomy were allocated to group oral tramadol (GOT, n = 12) or group intramuscular tramadol (GIMT, n = 12). In GOT, tramadol (6 mg/kg) was given orally 60 mins, and saline was given intramuscularly 30 mins, before induction of anaesthesia. In GIMT, granulated sugar in capsules was given orally 60 mins and tramadol (4 mg/kg) intramuscularly 30 mins before induction of anaesthesia. In both groups, dexmedetomidine (0.007 mg/kg) was given intramuscularly 30 mins before induction of anaesthesia with intravenous propofol. Anaesthesia was maintained with isoflurane in oxygen, and atipamezole (0.037 mg/kg) was given intramuscularly 10 mins after extubation. The UNESP-Botucatu multidimensional composite scale was used to conduct pain assessments before premedication and at 20, 60, 120, 240 and 360 mins post-extubation or until rescue analgesia was given. To compare groups, the 60 min postoperative pain scores and the highest postoperative pain scores were analysed via a two-tailed Mann-Whitney test, and the incidences of rescue analgesia were analysed via a Fisher's exact test; P <0.05.

RESULTS

There was no significant difference between groups for the 60 min (P = 0.68) pain scores. The highest postoperative pain score was higher for GIMT compared with GOT (P = 0.04). Only two cats required rescue analgesia, both from GIMT. The incidence of rescue analgesia was not significantly different between groups (P = 0.46).

CONCLUSIONS AND RELEVANCE

In the present study, preoperative administration of oral tramadol at 6 mg/kg to cats provided adequate analgesia for 6 h following ovariohysterectomy surgery.

The impact of a stress-reducing protocol on the quality of pre-anaesthesia in cats

INTRODUCTION

Transport to the clinic is a major source of stress for cats. The process involves being put into a carrier, driven in a car and handled. Cats are therefore removed from the safe-haven of their territory and experience many stressful stimuli and interactions.

METHODS

In the present study, 31 cats were transported to the clinic following a low-stress transport protocol and compared with a control group of 36 cats whose owners did not follow the protocol. This protocol involved preparing a cat carrier basket with F3 pheromone and keeping it covered and stable during the car journey from the home to the clinic. Pre-anaesthesia information was recorded for cardiac rate, respiratory rate, tolerance to handling, time for sedation to be achieved and dose of propofol required for induction and endotracheal intubation.

RESULTS

The group exposed to the low-stress transport protocol took less time to reach sedation and needed a lower dose of propofol for induction than the control group.

CONCLUSION

These results suggest that, in cats, pre-anaesthetic and induction requirements are influenced by lower-stress transport and handling.

Dose requirement and cardiopulmonary effects of diluted and undiluted propofol for induction of anaesthesia in dogs

OBJECTIVE

To compare the dose, cardiopulmonary effects and quality of anaesthetic induction in dogs using propofol (10 mg mL^-1) and diluted propofol (5 mg mL^-1).

STUDY DESIGN

Randomized, blinded, clinical study.

ANIMALS

A total of 28 client-owned dogs (12 males/16 females).

METHODS

Following intramuscular acepromazine (0.02 mg kg^-1) and methadone (0.2 mg kg^-1), propofol (UP, 10 mg mL^-1) or diluted propofol (DP, 5 mg mL^-1) was administered intravenously (0.2 mL kg^-1 minute^-1) by an anaesthetist unaware of the allocated group to achieve tracheal intubation. Sedation, intubation and induction quality were scored from 0 to 3. Pre- and post-induction pulse rate (PR), respiratory rate (f_R) and systolic (SAP), mean (MAP) and diastolic (DAP) arterial blood pressure were compared. Time to first breath and induction dose were recorded. Data were analysed for normality and Mann-Whitney U or Student t tests were performed where appropriate. Significance was set at p < 0.05. Data are presented as mean ± standard deviation or median (range).

RESULTS

The propofol dose administered to achieve induction was lower in the DP group (2.62 ± 0.48 mg kg^-1) than in the UP group (3.48 ± 1.17 mg kg^-1) (p = 0.021). No difference was observed in pre- and post-induction PR, SAP, MAP, DAP and f_R between groups. The differences between post-induction and pre-induction values of these variables were also similar between groups. Time to first breath did not differ between groups. Sedation scores were similar between groups. Quality of tracheal intubation was marginally better with UP 0 (0-1) than with DP 1 (0-2) (p = 0.036), but overall quality of induction was similar between groups [UP 0 (0-1) and DP 0 (0-1), p = 0.549].

CONCLUSION AND CLINICAL RELEVANCE

Diluting propofol reduced the dose to induce anaesthesia without significantly altering the cardiopulmonary variables.