Onset and duration of action of escalating doses of atracurium in anesthetized healthy goats.

OBJECTIVE: The aim of this study was to describe the onset and duration of action of escalating doses of atracurium in healthy, anesthetized goats. STUDY DESIGN: Randomized, blinded, triple crossover study. Animals A total of eight (five males and three females) healthy goats weighing 42.7-123.5 kg and aged from 11 months to 8 years. METHODS: Goats were anesthetized three times with propofol and anesthesia was maintained with isoflurane. One of three doses of atracurium was administered intravenously 30 minutes after induction: 0.25 mg kg-1 (AT25), 0.5 mg kg-1 (AT50) or 0.75 mg kg-1 (AT75). Acceleromyographic train-of-four ratio (TOFR) followed by train-of-four counts (TOFC) were recorded at 30 second intervals after atracurium administration to determine blockade onset (TOFC = 0). The TOFR followed by TOFC were recorded at 5 minute intervals until return to pre-atracurium baseline (TOFR = 1.0). Normally distributed data were analyzed with repeated measures anova and a Tukey multiple comparison test. Data not normally distributed were analyzed with a Friedman test and a Dunn's multiple comparison test. RESULTS: For AT50 and AT75, 100% of goats achieved TOFC = 0 after atracurium administration. For AT25, however, 87.5% of goats achieved TOFC = 0 after atracurium administration. The onset time was shorter for AT75 [1.5 (0.5-1.5) minutes; median (range)] than for AT25 [2 (1-4) minutes] (p = 0.048). The duration of action [from onset time to complete reversal (TOFR = 1.0)] was significantly shorter for AT25 (52 ± 12 minutes, mean ± SD) than for AT50 (77 ± 18 minutes) (p < 0.001) and AT75 (85 ± 16 minutes) (p < 0.001). There was no significant difference in duration between AT50 and AT75 (p = 0.238). CONCLUSIONS AND CLINICAL RELEVANCE: Doses of 0.5 and 0.75 mg kg-1 atracurium may produce complete neuromuscular blockade in healthy, anesthetized goats.

Bloqueio motor e sensitivo da lidocaína ou da ropivacaína peridural em cães / [Motor and sensitive blockade provided by epidural lidocaine or ropivacaine in dogs]

Objetivou-se avaliar o bloqueio sensitivo e motor da administração peridural de 0,2mL/kg de duas concentrações de ropivacaína em comparação à lidocaína em cães. Utilizaram-se 24 cães, distribuídos em quatro grupos: NaCl a 0,9% (GS), lidocaína a 2% (GL), ropivacaína a 0,5% (GR5) e ropivacaína a 0,75% (GR7,5). Avaliaram-se a presença de movimentação espontânea, deambulação, sensibilidade superficial e profunda nos momentos cinco, 10, 15, 20, 25, 30, 45, 60, 90, 120, 180, 240 e 300 minutos após peridural. O retorno à movimentação espontânea foi semelhante entre GL (42,50 ± 6,12) e GR7,5 (69,2 ± 58,9). O tempo para deambulação foi mais prolongado em GR7,5 (107,5 ± 79,3) que em GS (9,2 ± 3,8) e em GR5 (32,5 ± 20,9). O retorno da sensibilidade profunda foi maior em GR 7,5 (152,5 ± 89,2) que em GS (5,8 ± 2,0), GR5 (46,7 ± 46,3) e GL (52,5 ± 20,7). O tempo de retorno da sensibilidade superficial foi maior em GR7,5 (205,0 ± 129,3) que em GS (7,5 ± 2,7), GL (72,5 ± 19,9) e GR5 (97,5 ± 55,1). Apesar do retorno precoce da movimentação, ropivacaína 0,75% está relacionada a tempo prolongado de recuperação da função muscular e bloqueio sensitivo mais prolongado que lidocaína e ropivacaína 0,5%.(AU)

The aim of the present study was to evaluate the sensory and motor blockade of epidural 0.5% and 0.75% Ropivacaine or Lidocaine in dogs. Twenty-four dogs were distributed in four groups: 0.9% NaCl (GS), 2% lidocaine (GL), 0.5% ropivacaine (GR5) and 0.75% ropivacaine (GR7.5). Spontaneous movement, ability to walk, superficial, and deep pain response were assessed 5, 10, 15, 20, 25, 30, 45, 60, 90, 120, 180, 240 and 300 minutes after epidural. Time to return to spontaneous movement was similar between GL (42.50 ± 6.12) and GR7.5 (69.2 ± 58.9). Time to return to ambulation was longer in GR7.5 (107.5 ± 79.3) than in GS (9.2 ± 3.8) and GR5 (32.5 ± 20.9). Time to recover deep sensitivity was longer in GR 7.5 (152.5 ± 89.2) than in GS (5.8 ± 2.0), GR5 (46.7 ± 46.3) and GL (52.5 ± 20.7). Time to return superficial sensitivity was longer in GR7.5 (205.0 ± 129.3) when compared to GS (7.5 ± 2.7), GL (72.5 ± 19.9) and GR5 (97.5 ± 55.1). Despite the early return of spontaneous movement, 0.75% ropivacaine is related to longer periods for muscle function recovery and longer sensory block than lidocaine and 0.5% ropivacaine.(AU)