Nondepolarizing muscle relaxant improves direct laryngoscopy view with no effect on face mask ventilation

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. 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. 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. 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. 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 levando 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. 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. Antes do relaxamento muscular, 43 pacientes (48%) eram Cormack Grau I, enquanto os 47 pacientes (52