Bloqueio ecoguiado do quadrado lombar versus anestesia epidural lombossacral, em gatas submetidas à ovariohisterectomia eletiva

Abstract

Lumbosacral epidural anesthesia (LSA) is the most commonly used neuraxial technique for abdominal anesthesia, and its contraindications are well established. Ultrasound-guided quadratus lumborum block (BLQ) provides anesthesia of the abdominal wall and viscera without affecting patient locomotion. Despite its effectiveness in human medicine, few clinical studies have evaluated BQL in felines, most of which have been performed only in cadaveric trials. This study aimed to compare the physiological effects of BLQ and LSA on the quality of recovery in cats undergoing elective ovariohysterectomy (OH). For this purpose, 20 cats were randomly allocated into two groups (n = 10), designated: GEL, treated with lumbosacral epidural anesthesia with 0.4 ml/kg of levobupivacaine 0.25% and GQL, treated with ultrasound guided quadratus lumborum block with 0.3 ml/kg of levobupivacaine 0.25% per hemiabdomen. The cats were premedicated with 3 mcg/kg of dexmedetomidine, intramuscularly (IM) and 0.1 mg/kg of meloxicam subcutaneously (SC). The animals were induced to anesthesia with propofol at a dose of 1 mg/kg every 10 seconds until satisfactory mandibular relaxation, proceeding to anesthetic maintenance with the same drug, in continuous infusion. The following parameters were recorded: heart rate (HR), respiratory rate (ƒ), partial pressure of carbon dioxide at the end of expiration (EtCO2), oxyhemoglobin saturation (SpO2), systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) and the propofol infusion rate. The recordings were made immediately before the skin incision (T1); at the end of celiotomy (T2); after clamping of the right ovarian pedicle (T3); after clamping of the left ovarian pedicle (T4); after clamping of the uterine cervix (T5); at the beginning of the muscle suture (T6) and at the beginning of the skin suture (T7). At the end of anesthesia, the average propofol infusion rate was calculated. Throughout the procedure, the temperature of the animals was maintained between 37 and 38°C. During recovery from anesthesia, the interval between the end of the anesthetic supply and extubation (TA), the first head movement (TB), and the establishment of the sternal (TC) and quadrupedal (TD) positions were evaluated. Analgesia assessed using the Multidimensional Scale for the Evaluation of Acute Pain in Cats, and the degree of sedation were recorded during 6 hours. No significant physiological parameter differences were found between the groups (p > 0.05). For GEL and GQL, the need for intraoperative analgesic rescue was ruled out. Both techniques promoted satisfactory analgesic comfort and quality of recovery. BQL with 0.25% levobupivacaine is a safe and effective alternative to AEL in cats undergoing ovariohysterectomy.