Nondepolarizing muscle relaxant improves direct laryngoscopy view with no effect on face mask ventilation / Relaxantes musculares não despolarizantes melhoram a visibilidade em laringoscopia direta sem efeito sobre a ventilação via máscara facial

Abstract Background: Difficult or impossible face mask ventilation complicated with difficult tracheal intubation during anesthesia induction occurs in 0.4% of adult anesthesia cases, possibly leading to life-threatening complications. Because of such catastrophes, muscle relaxants have been recommended to be administered after confirming adequate face mask ventilation without a solid scientific validation of this principal. Methods: In this observational study, the ease of ventilation and the scores of direct laryngoscopy views before and after administration of cisatracurium were assessed in ninety young healthy adults, without anesthetic risks and without foreseen difficult intubation and who were scheduled for general elective surgeries. Results: Before muscle relaxation, 43 patients (48%) were Cormack Grade I, while the remaining 47 patients (52%) were either Cormack Grade II (28 patients, 31%) or Cormack Grade II (19 patients, 21%). Following muscle relaxation with cisatracurium, the number of patients with Cormack Grade I significantly increased from 43 patients (48%) to 65 patients (72%) (p = 0.0013). Only 1 patient out of 19 patients (5%) improved his Cormack grade from Grade III to Grade I while 16 out 19 patients (84%) improved their Cormack grade from Grade III to Grade II after the use of cisatracurium. The quality of face mask ventilation did not differ with and without muscle relaxants in all patients. Conclusion: The use of cisatracurium in healthy young adults undergoing general elective surgeries with no anticipated difficult endotracheal intubation had no effect on the quality of face mask ventilation despite resulting in a quantifiable improvement in the laryngeal view.

Resumo Justificativa: A ventilação difícil ou impossível via máscara facial complicada pela intubação traqueal difícil durante a indução da anestesia ocorre em 0,4% dos casos de anestesia em adultos, possivelmente leva a complicações fatais. Devido a tais catástrofes, recomendou-se que a administração de relaxantes musculares seja feita após a confirmação de ventilação adequada via máscara facial, sem uma validação científica sólida dessa conduta. Métodos: Neste estudo observacional, a facilidade de ventilação e os escores de visibilidade em laringoscopia direta antes e após a administração de cisatracúrio foram avaliados em 90 adultos jovens e saudáveis, sem riscos anestésicos e sem intubação difícil prevista, agendados para cirurgias eletivas gerais. Resultados: Antes do relaxamento muscular, 43 pacientes (48%) eram Cormack Grau I, enquanto os 47 (52%) restantes eram ou Cormack Grau II (28, 31%) ou Cormack Grade III (19, 21%). Após o relaxamento muscular com cisatracúrio, o número de pacientes com Cormack Grau I aumentou significativamente de 43 (48%) para 65 (72%) (p = 0,0013). Apenas um paciente (5%) dos 19 melhorou sua classificação de Cormack do Grau III para o Grau I, enquanto 16 dos 19 (84%) melhoraram suas classificações de Cormack do Grau III para o grau II após o uso de cisatracúrio. A qualidade da ventilação via máscara facial não diferiu com ou sem relaxantes musculares em todos os pacientes. Conclusão: O uso de cisatracúrio em adultos jovens saudáveis submetidos a cirurgias eletivas gerais sem intubação traqueal difícil prevista não teve efeito sobre a qualidade da ventilação via máscara facial, mesmo resultando em melhora quantificável da visibilidade da laringe.

Anesthesia for Myasthenia Gravis following preoperative plasmapheresis / 대한마취과학회지

Myasthenia gravis is believed to be an autoimmune disease involving morphologic and electrophysiologic disturbances of motor end plates brought about by circulating antibodies against acetylcholine receptors. Its treatment includes the use of steroids, anticholinesterase, immunosuppression and plasmapheresis. Plasmapheresis, in particular, is used either as a stand-alone temporary measure for its often dramatic, though short-lived, effect, or as an adjunctive treatment. Plasmapheresis is considered to be essential not only in preventing and treating myasthenic crisis but in preoperative management of myasthenia gravis, usually before thymectomy. the authors here report a case of myasthenia gravis that underwent preoperative plasmapheresis followed by the use of atracurium for muscle relaxation during anesthesia for thymectomy.

The Train - of - Four Response on the Priming Dose of Various Nondepolarizing Muscle Relaxants / 대한마취과학회지

The priming principle refers to the administration of a small subparalyzing dose (priming dose) of a nondepolarizing muscle relaxant, such dose not cause respiratory depression or any other clinical signs, a few minutes prior to the administration of the larger intubating dose. This study was designed to investigate the influence of a priming dose of vecuronium (0.008 mg/kg), pancuronium (0.008 mg/kg) and d-tubocurarine (0.04 nig/kg) on the relationship between the depres- sion in the first twitch (T2%) of the train-of-four (TOF) and TOF ratio (T4R,%) in 27 ASA class I or II patients. After induction with thiopental sodium 5-6mg/kg, neuromuscular monitoring was carried out by stimulation of ulnar nerve at a frequency of 2 Hz every 20 seconds using a ABM (Datex) to measure the compound evoked electromyographic response of hypothenar muscle. Following calibration of control twitch height, tracheal intubation was performed after succinyl-choline 1 mg/kg IV. Anesthesia was maintained with oxygen, NO (50%) and enflurane (1-2%) in all patients. When the TOF response recovered to 100% of the control, the priming dose was administer-ed. The patients were randomly divided into three groups according to nondepolarizing muscle relax-ant used; vecuronium (n=9), pancuronium (n=8) and tubocurarine (n=10) group respectively. T1 and T4R were measured for 25 minutes after administration of priming dose in each group. The results were as follow: 1) There was no change in T, after priming in all groups. 2) T4R began to decrease significantly at 2 minutes after priming and still decreased significantly at 25 minutes compared to before priming. 3) The time for maximal decrease in T4R (%) proceded by the priming dose was 7 minutes in all groups; 60.7+/-8.6% in vecuronium group, 74.8+/-12.3% in pancuronium group and 78.3+/-11.3% in tubocurarine group.