Topikal administrering av lidokain över mesovarium vid ovariehysterektomi på katt

Sammanfattning: Feline ovariohysterectomy (OHE) is a common surgical procedure in veterinary medicine. This procedure is assumed to cause moderate pain. In addition to general anesthesia there are available techniques for nerve block with local anesthesia, yet these techniques are underutilized and the effects of administering local anesthesia during OHE are not well-studied in cats. The objective of this study was to assess the intraoperative and postoperative analgetic effect of lidocaine administrated topically on the ovarian pedicles in cats undergoing OHE during dissociative anesthesia. This prospective, randomized and blinded study included 25 female cats. Body weight was 3.1 ± 0.8 kg (mean ± SD) and age was 28 ± 27 months. Cats were pre-medicated with medetomidine and methadone, and were also given meloxicam preoperatively. All cats received lidocaine 1 mg/kg as a subcutaneous injection at the incision site. Ketamine 5 mg/kg was injected intramuscular for induction of anesthesia. Cats were randomly assigned to one of two groups; 12 cats received lidocaine 1 mg/kg as topical application on the ovarian pedicles (group L) and 13 cats received an equal volume of sodium chloride at the same sites (group NaCl). In case of increased muscle tone or sudden movement during surgery, cats were given additional ketamine ± medetomidine ± propofol. At end of surgery cats were given atipamezole. Following parameters were measured continuously every second minute during anesthesia: systolic blood pressure, diastolic blood pressure and heart rate. Mean values for those parameters were then compared between the two groups at seven different times: T1 = after ketamine induction; T2 = start of surgery; T3 = administration of local anesthesia; T4 = ligation and extirpation of the first ovary; T5 = ligation and extirpation of the second ovary; T6 = cervix; T7 = suturation of linea alba. Postoperative pain was assessed according to two feline-specific, validated and multidimensional pain scales: UNESP-Botucatu Multidimensional Composite Pain Scale and Glasgow Composite Measure Pain Scale - Feline. Assessments were made at times H0 = preoperatively; H1 = one hour after atipamezole was given; H2 = two hours after atipamezole was given; H3 = three hours after atipamezole was given. The results showed no significant difference between groups concerning systolic blood pressure, diastolic blood pressure or heart rate at any of the times measured. In group (L) systolic blood pressure was significantly higher at the time T4 compared to T2, T3 and T7. In group (NaCl) systolic blood pressure was significantly higher at the time T5 compared to T1, T2, T3 and T7 as also diastolic blood pressure was significantly higher at T5 compared to T1, T2 and T7. Significant difference in heart rate could neither be seen between the two groups, nor within one of the groups at any of the times measured. Three cats in the lidocaine group and eight cats in the placebo group needed supplementary general anesthesia within 45 minutes from ketamine induction. Local anesthesia on the ovarian pedicles was not shown to imply lower pain scores in the postoperative pain assessment in this study.