Sugammadex by ideal body weight versus 20% and 40% corrected weight in bariatric surgery - double-blind randomized clinical trial / Uso de sugamadex pelo peso corporal ideal versus corrigido em 20% e 40% em cirurgia bariátrica - ensaio clínico randômico e duplo-cego

Abstract Background and objectives: The weight parameters for use of sugammadex in morbidly obese patients still need to be defined. Methods: A prospective clinical trial was conducted with sixty participants with body mass index ≥ 40 kg.m-2 during bariatric surgery, randomized into three groups: ideal weight (IW), 20% corrected body weight (CW20) and 40% corrected body weight (CW40). All patients received total intravenous anesthesia. Rocuronium was administered at dose of 0.6 mg.kg-1 of Ideal weight for tracheal intubation, followed by infusion of 0.3-0.6 mg.kg-1.h-1. Train of four (TOF) was used to monitor depth of blockade. After spontaneous recovery TOF-count 2 at the end of surgery, 2 mg.kg-1 of sugammadex was administered. Primary outcome was neuromuscular blockade reversal time to TOF ≥ 0.9. Secondary outcome was the occurrence of postoperative residual curarization in post-anesthesia recovery room, searching the patient's ability to pass from the surgical bed to the transport, adequacy of oxygenation, respiratory pattern, ability to swallow saliva and clarity of vision. Results: Groups were homogenous in gender, age, total body weight, ideal body weight, body mass index, type and time of surgery. The reversal times (s) were (mean ± standard deviation) 225.2 ± 81.2, 173.9 ± 86.8 and 174.1 ± 74.9 respectively, in the IW, CW20 and CW40 groups (p = 0.087). Conclusions: No differences were observed between groups with neuromuscular blockade reversal time and frequency of postoperative residual curarization. We concluded that ideal body weight can be used to calculate sugammadex dose to reverse moderate neuromuscular blockade in morbidly obese patients.

Resumo Justificativa e objetivos: Os parâmetros de peso para o uso de sugamadex em pacientes com obesidade mórbida ainda precisam ser definidos. Métodos: Um ensaio clínico prospectivo foi feito com 60 participantes com índice de massa corporal ≥ 40 kg.m-2, submetidos a cirurgia bariátrica, randomizados em três grupos: peso ideal (PI), peso corrigido em 20% (PC20) e peso corrigido em 40% (PC40). Todos os pacientes receberam anestesia intravenosa total. Rocurônio foi administrado em dose de 0,6 mg.kg-1 para intubação traqueal pelo peso ideal, seguido de infusão (0,3 a 0,6 mg.kg-1.h-1). A sequência de quatro estímulos (TOF) foi usada para monitorar a profundidade do bloqueio. Após recuperação espontânea da segunda resposta do TOF no fim da cirurgia, 2 mg.kg-1 de sugamadex foi administrado. O desfecho primário foi o tempo de reversão do bloqueio neuromuscular até obter TOF ≥ 0,9. O desfecho secundário foi a ocorrência de curarização residual pós-operatória na sala de recuperação pós-anestésica, avaliaram-se a capacidade do paciente de passar do leito cirúrgico para o de transporte, a adequação da oxigenação, o padrão respiratório, a habilidade para deglutir saliva e a clareza de visão. Resultados: Os grupos foram homogêneos quanto a gênero, idade, peso corporal total, peso corporal ideal, índice de massa corporal, tipo e tempo de cirurgia. Os tempos de reversão (segundos) foram (média ± desvio-padrão) 225,2 ± 81,2, 173,9 ± 86,8 e 174,1 ± 74,9, respectivamente, nos grupos PI, PC20 e PC40 (p = 0,087). Conclusões: Não foram observadas diferenças entre os grupos quanto ao tempo de reversão do bloqueio neuromuscular e frequência de curarização residual pós-operatória. Concluímos que o peso corporal ideal pode ser usado para calcular a dose de sugamadex para reverter o bloqueio neuromuscular moderado em pacientes com obesidade mórbida.

Tactile TOF count as a predictive factor for the efficacy of neostigmine reversal of rocuronium-Induced blockade during propofol or sevoflurane anesthesia

This study was done to determine whether train-of-four [TOF] count is a good predictor to the efficacy of neostigmine administration for reversal of rocuronium-induced blockade during propofol or sevoflurane anaesthesia, and to follow subsequent recovery until the TOF reached 0.9. One-hundred-twenty patients, divided into eight equal groups, were randomly allocated to maintenance of anaesthesia with propofol or sevoflurane. The tactile response of the adductor pollicis to TOF stimulation was evaluated on one arm, and the mecha-nomyographic response was recorded on the other Neuromuscular block was induced with rocuronium 0.6 mg.kg[-1] and maintained with rocuronium to 15% of the control first twitch in TOF, neostigmine 0.07mg.Kg[-1] was administered on reappearance of the first [Group I], second [Group II], third [Group III], or fourth [Group IV] tactile TOF-response in each anaesthesia. The times from administration of neostigmine until the ratio recovered to 0.7, 0.8 and 0.9 were recorded. The times [[median [range]] to TOF ratio - 0.9 were 8.2 [4.5-17.3], 7.8 [3.6-11.9], 5.6 [1.8-9.1], and 4.4 [1.1-7.6] min in Groups I-IV during propofol anaesthesia, respectively, and 24.6 [8.1-66.3], 22.8 [7.6-51.1], 15.4 [7.1-39.7], and 9.1 [4.9-22.3] minutes in corresponding groups during sevoflurane anaesthesia, respectively, [p<0.05]. We recommend more than 2 TOF responses with propofol anaesthesia and 4 TOF responses with sevoflurane anaesthesia for adequate reversal within 10 and 15 minutes, respectively. The more tactile TOF responses present at the time of reversal achieved greater adequate recovery

Adverse effects of neuromuscular blockers and their antagonists

Among all the drugs used for general anesthesia, neuromuscular blockers appear to play a prominent role in the incidence of severe adverse reactions. It now seems likely that most serious adverse drug reactions occurring during anesthesia are immunological in type. The frequency of life-threatening anaphylactic or anaphylactoid reactions occuring during anesthesia has been estimated to be between 1 in 1000 and 1 in 25000 anesthetic procedures, with the neuromuscular blockers being involved in 80% of cases. The mortality from such serious reactions is reported to be in the range of 3.4 to 6%. The highly immunogenic drug, suxamethonium chloride [succinylcholine], was found to be the most hazardous agent. Drug- specific immunoglobulin E antibodies to suxamethonium chloride and other neuromuscular blockers have been demonstrated. This sensitivity to neuromuscular blockers seems to be a long-lasting phenomenon. During anesthesia, the clinical features of an allergic reaction are often masked. Tachycardia and circulatory collapse may be the only signs of an allergic reaction, and they are easily misdiagnosed. Bronchospasm is reported to be present in about 40% of cases. Successful management of these patients includes stabilisation during the acute reaction and avoidance of future reactions. The latter is based on the indentification of the causative drug and potentially cross-reacting compounds. The use of suxamethonium chloride is associated with many other adverse effects, such as fasciculations, myalgia, potassium release, changes in the heart rate, increases in intragastric and intraocular pressures, and malignant hyperthermia. Because of the dangers of hyperkalemic cardiac arrest suxamethonium chloride administration in children with unrecognised muscular dystrophy, there have now been moves to limit the use of this drug in children. Although neuromuscular blockers are designed to specifically block nicotinic cholinergic receptors at the neuromuscular junction, many bind to muscarinic cholinergic receptors on ganglia and smooth muscle, and alter parasympathetically mediated heart rate and airway calibre. Most benzylisoquinolinium muscle relaxants can induce histamine release, especially when they are administered rapidly, which can lead to disturbances of cardiovascular function. In addition, nondepolarising neuromuscular blockers have been implicated in causing generalised weakness following their long term administration to patients on an intensive care unit. The problem with these adverse drug reactions is their unpredictable nature. Therefore, prompt recognition with appropriate therapy can help to improve the outcome

Antagonismo do bloqueio neuromuscular / Neuromuscular blockade antagonism

O autor faz uma revisäo da farmacocinética e farmacodinâmica dos anticolinesterásicos, que constituem os principais antagonistas dos relaxantes neuromusculares. Os fatores que alteram o antagonismo säo discutidos além das possíveis interaçöes com outras drogas. A monitorizaçäo da atividade da junçäo mioneural, bem como a avaliaçäo do antagonismo, säo abordadas do ponto de vista clínico