CARDIOPULMONARY AND ANALGESIC EFFECTS OF EPIDURAL LIDOCAINE, ALFENTANIL, AND XYLAZINE IN PIGS ANESTHETIZED WITH ISOFLURANE

To determine cardiopulmonary and analgesic effects of lidocaine, alfen tanil, and xylazine in pigs anesthetized with isoflurane, 18 healthy L andrace-Large White pigs were studied (six for each drug). General ane sthesia was induced with isoflurane in O-2 and maintained with 1% to 1 .2% end-tidal ISO, ensuring presence of a pain response before epidura l drug administration. Heart rate (HR), arterial blood pressures (AP), cardiac output (CO), pulmonary arterial pressure, pulmonary capillary wedge pressure (PCWP), central venous pressure, respiratory rate (RR) , tidal volume (TV), minute volume (MV), arterial blood gas data, core temperature (CT), and analgesic effects (by pricking the lumbar area and the abdominal wall) were determined at various times (2, 5, 15, 30 , 45, 60, and 90 minutes) after epidural administration of lidocaine ( 5 mg/kg), alfentanil (5 mu g/kg), or xylazine (0.2 mg/kg), all diluted in NaCl 0.9% to 0.5 mL/kg. Statistical analysis included two-way anal ysis of variance for repeated measures and the least significant diffe rence test for determining differences among means. A probability leve l of P < .05 was used. The following results were statistically signif icant decreases in systolic AP, HR, TV, RR, MV, CT, pH, PaO2, and TCO2 and increases in PCWP, PaCO2, and HCO3 after LID. After ALF, only CT and HCO3 decreased. Core temperature and TV decreased after XYL. Lidoc aine provided 45 to 60 minutes of analgesia. Alfentanil had no analges ic effects, and xylazine provided 90 minutes of analgesia. The authors conclude that xylazine, when injected epidurally, provides suitable a nalgesia in isoflurane-anesthetized pigs. (C) Copyright 1995 by The Am erican College of Veterinary Surgeons