Avaliação da eficácia analgésica pós-operatória do bloqueio do plano transverso do abdômen com lidocaína isolada ou associada à dexmedetomidina em cadelas submetidas a ovariohisterectomia.

Abstract

Elective ovariohysterectomy (OH) is a routine procedure that promotes population control, treatment, and prevention of diseases of the reproductive tract. Because it is a procedure potentially associated with intense pain, the adoption of appropriate analgesic protocols is essential. The objective was to evaluate and compare the postoperative analgesic efficacy of the transverse abdominis plane block (TAP Block) technique with lidocaine alone or in combination with dexmedetomidine in dogs undergoing elective ovariohysterectomy. Sixteen female dogs were used, randomly distributed into 2 groups (n=8), designated GL and GDEX. All animals received acepromazine 0.03 mg/kg and meperidine 3 mg/kg IM as pre-anesthetic medication. After 15 minutes, induction was performed with propofol at the dose necessary for intubation. The animals were maintained with isoflurane in sufficient quantity to remain in stage 3, plane II or III according to Guedel. Cephalothin IV 30 mg/kg was administered, followed by a TAP block in all animals, with the lidocaine group (GL) receiving 1% lidocaine at 0.2 ml/kg and the dexmedetomidine group (GDEX) receiving 1% lidocaine combined with 1 mcg/ml dexmedetomidine at 0.2 ml/kg. The block was performed at two points, via the subcostal and umbilical approaches, both bilaterally. After the surgical procedure, all animals were medicated with meloxicam 0.1 mg/kg and dipyrone 25 mg/kg, both subcutaneously. The animals were evaluated in the pre-anesthetic period (MBasal) and post-operatively at 8 time points: 1, 2, 4, 6, 8, 12, 18, and 24 hours after the end of surgery. Heart rate, respiratory rate, systolic blood pressure, rectal temperature, mucous membrane color, capillary refill time, and sedation level were assessed using the Grint scale and the Glasgow Composite Pain Scale (GFPS) and the Numerical Rating Scale (NRS), as well as the level of analgesia. Rescue analgesic with morphine 0.1 mg/kg (IM) would be considered when the SF-GCPS score was above 6. Mixed or Generalized Linear Models were used for continuous and discrete variables followed by Pearson's and Fisher's chi-square tests. Results were considered different when p<0.05. Using the Glasgow Composite Pain Scale, GL was higher than GDEX (p = 0.024). The TAP Block with lidocaine associated with dexmedetomidine showed a better analgesic effect in the postoperative period when compared to lidocaine alone. Although there were no differences in rescue analgesic between the two protocols, animals in the GL group obtained higher scores on the Glasgow Scale than animals in the GDEX group.