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Objective:To systematically review and evaluate the safety and efficacy of high-flow nasal oxygen (HFNO) for pre-oxygenation before anesthesia induction.Methods:Pubmed, Cochrane Library, Embase, China National Knowledge Infrastructure, Wanfang Database, China Science and Technology Journal Database and China Biomedical Literature Database were searched from inception to March 2022.All randomized controlled trials comparing HFNO and facemask ventilation for pre-oxygenation before anesthesia induction were collected.Two researchers independently assessed the quality of trials and extracted data.The primary outcome was the safe apnea time, the secondary outcomes were the lowest SpO 2 during intubation, oxygenation-related complications, patient comfort, PaO 2 and PaCO 2 before and after pre-oxygenation and after intubation.Meta-analysis was performed using RevMan 5.4 software. Results:Seventeen randomized controlled trials involving 843 patients were included in this meta-analysis.The results of meta-analysis showed that the safe apnea time was significantly longer ( MD=67.61, 95% CI 5.94-129.28, P=0.03), the lowest SpO 2 was higher during tracheal intubation ( MD=3.27, 95% CI 2.25-4.29, P<0.01), and PaO 2 was higher after pre-oxygenation ( MD=54.39, 95% CI 9.32-99.46, P=0.02) in the patients using HFNO than those using facemask ventilation.There were no statistically significant differences in the other outcomes ( P>0.05). Conclusions:HFNO for pre-oxygenation before anesthesia induction can significantly prolong the safe apnea time, increase the lowest SpO 2 during tracheal intubation, and improve the levels of PaO 2 after pre-oxygenation, and HFNO does not affect the patient′s comfort or increase the development of preoxygenation-related complications when compared with facemask ventilation.
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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.