Context-sensitive recovery of neuromuscular function from vecuronium in dogs: Effects of dose and dosing protocol.

Recovery of neuromuscular function is a gradual phenomenon whereby function progresses from absent to normal. The speed of spontaneous recovery can be used to predict the time when neuromuscular function is expected to be restored. However, the speed of recovery might be affected by the dose of the neuromuscular blocker administered, and by the dosing regimen of that dose. The effects of both factors on the speed of spontaneous recovery from vecuronium were evaluated. Seven dogs were anesthetized three times and the train-of-four (TOF) ratio was measured with acceleromyography. Vecuronium was administered at 0.1 mg/kg, 0.2 mg/kg, or 0.1 mg/kg followed by two doses of 0.05 mg/kg was administered each time. In the divided-dose treatment group, aliquots were administered on return of the first twitch (T1) of the TOF from the previous dose. The duration of surgical block, from injection to return of T1, was longest for the divided-dose protocol, intermediate for 0.2 mg/kg single bolus, and shortest for 0.1 mg/kg (P < 0.0001). The recovery period, from return of T1 to a TOF ratio ≥0.9, was longer for 0.2 mg/kg administered as a single bolus than for the other two groups (P = 0.007). Doubling the dose of a single bolus of vecuronium extended the time of surgical block and prolonged the duration of the recovery period. However, dividing that dose into smaller aliquots extended the period of surgical block while shortening the recovery period. Hence, the spontaneous reappearance of T1 should not be used in isolation to predict the time to complete recovery of neuromuscular function.

Use of protocol and evaluation of postoperative residual curarization incidence in the absence of intraoperative acceleromyography - Randomized clinical trial / Aplicação de protocolo e avaliação da incidência de curarização residual pós-operatória na ausência de aceleromiografia intraoperatória - Ensaio clínico randomizado

Abstract Objective Evaluate the incidence of postoperative residual curarization (PORC) in the post-anesthesia care unit (PACU) after the use of protocol and absence of intraoperative acceleromyography (AMG). Methods Randomized clinical trial with 122 patients allocated into two groups (protocol and control). Protocol group received initial and additional doses of rocuronium (0.6 mg·kg-1 and 10 mg, respectively); the use of rocuronium was avoided in the final 45 min; blockade reversal with neostigmine (50 µg·kg-1); time ≥15 min between reversion and extubation. Control: initial and additional doses of rocuronium, blockade reversal, neostigmine dose, and extubation time, all at the discretion of the anesthesiologist. AMG was used in the PACU and PORC considered at T4/T1 ratio <1.0. Results The incidence of PORC was lower in protocol group than in control group (25% vs. 45.2%, p = 0.02). In control group, total dose of rocuronium was higher in patients with PORC than without PORC (0.43 vs. 0.35 mg·kg-1·h-1, p = 0.03) and the time interval between the last administration of rocuronium and neostigmine was lower (75.0 vs. 101.0 min, p < 0.01). In protocol group, there was no difference regarding the analyzed parameters (with PORC vs. without PORC). Considering the entire study population and the presence or absence of PORC, total dose of rocuronium was higher in patients with PORC (0.42 vs. 0.31 mg·kg-1·h-1, p = 0.01), while the time interval between the last administration of rocuronium and neostigmine was lower (72.5 vs. 99.0 min, p ≤ 0.01). Conclusion The proposed systematization reduced PORC incidence in PACU in the absence of intraoperative AMG.

Resumo Objetivo Avaliou-se a incidência de curarização residual pós-operatória (CRPO) na sala de recuperação pós-anestésica (SRPA) após emprego de protocolo e ausência de aceleromiografia (AMG) intraoperatória. Métodos Ensaio clínico, aleatório, com 122 pacientes, distribuídas em dois grupos: protocolo e controle. Protocolo: dose inicial e adicionais de rocurônio foram de 0,6 mg.kg-1 e 10 mg, respectivamente; evitou-se o uso de rocurônio nos 45 minutos finais; reversão do bloqueio com neostigmina (50 µg.kg-1); tempo ≥ 15 minutos entre reversão e extubação. Controle: doses inicial e adicional de rocurônio, reversão do bloqueio, dose de neostigmina e momento da extubação decididos pelo anestesiologista. Foi usada AMG na SRPA e considerado CRPO razão T4/T1 < 1,0. Resultados A incidência de CRPO foi menor no grupo protocolo em relação ao controle (25% vs. 45,2%; p = 0,02). No grupo controle, a dose total de rocurônio foi maior em pacientes com CRPO em relação àqueles sem CRPO (0,43 vs. 0,35 mg.kg-1.h-1; p = 0,03) e o intervalo entre a última administração de rocurônio e a neostigmina foi menor (75,0 vs. 101,0 min; p < 0,01). No grupo protocolo não houve diferença dos parâmetros analisados (com CRPO vs. sem CRPO). Considerando toda a população de estudo e a presença ou não de CRPO, a dose total de rocurônio foi maior em pacientes com CRPO (0,42 vs. 0,31 mg.kg-1.h-1; p = 0,01), enquanto o intervalo entre a última administração de rocurônio e a neostigmina foi menor (72,5 vs. 99,0 min; p ≤ 0,01). Conclusão A sistematização proposta reduziu a incidência de CRPO na SRPA na ausência de AMG intraoperatória.

[Use of protocol and evaluation of postoperative residual curarization incidence in the absence of intraoperative acceleromyography - Randomized clinical trial]. / Aplicação de protocolo e avaliação da incidência de curarização residual pós­operatória na ausência de aceleromiografia intraoperatória ­ Ensaio clínico randomizado.

OBJECTIVE: Evaluate the incidence of postoperative residual curarization (PORC) in the post-anesthesia care unit (PACU) after the use of protocol and absence of intraoperative acceleromyography (AMG). METHODS: Randomized clinical trial with 122 patients allocated into two groups (protocol and control). Protocol group received initial and additional doses of rocuronium (0.6mg.kg-1 and 10mg, respectively); the use of rocuronium was avoided in the final 45minutes; blockade reversal with neostigmine (50µg.kg-1); time ≥ 15minutes between reversion and extubation. CONTROL: initial and additional doses of rocuronium, blockade reversal, neostigmine dose, and extubation time, all at the discretion of the anesthesiologist. AMG was used in the PACU and PORC considered at T4/T1 ratio<1.0. RESULTS: The incidence of PORC was lower in protocol group than in control group (25% vs. 45.2%, p=0.02). In control group, total dose of rocuronium was higher in patients with PORC than without PORC (0.43 vs. 0.35mg.kg-1.h-1, p=0.03) and the time interval between the last administration of rocuronium and neostigmine was lower (75.0 vs. 101.0min, p<0.01). In protocol group, there was no difference regarding the analyzed parameters (with PORC vs. without PORC). Considering the entire study population and the presence or absence of PORC, total dose of rocuronium was higher in patients with PORC (0.42 vs. 0.31mg.kg-1.h-1, p=0.01), while the time interval between the last administration of rocuronium and neostigmine was lower (72.5 vs. 99.0min, p ≤ 0.01). CONCLUSION: The proposed systematization reduced PORC incidence in PACU in the absence of intraoperative AMG.