Asai T, Barclay K, Power I, Vaughan R S
Department of Anaesthetics and Intensive Care Medicine, University of Wales College of Medicine, Heath Park, Cardiff.
Br J Anaesth. 1995 May;74(5):521-5. doi: 10.1093/bja/74.5.521.
We have studied 22 patients to examine whether or not cricoid pressure affects ventilation of the lungs via the laryngeal mask and its correct positioning. In a randomized, crossover design, the laryngeal mask was inserted with or without cricoid pressure applied with a standardized force of 30 N using a cricoid yoke. A standardized pillow (6 cm in height) was placed under the patient's occiput, but the neck was not supported. Ventilation of the lungs via the laryngeal mask was adequate in all patients when no cricoid pressure was applied, but in only three of 22 patients when cricoid pressure was applied (P << 0.001; 95% confidence interval (CI) 0.72-1.0). The mask was positioned correctly in 18 patients when no pressure was applied, and in none after application of cricoid pressure (P << 0.001; 95% CI 0.66-0.98). We had planned to study, in an additional 20 patients, the effect of cricoid pressure without a pillow under the occiput; placement of the mask, however, was difficult even when cricoid pressure was not applied and there was a high incidence of bleeding from the oropharynx. We thus abandoned that part of the study after eight patients. In those eight patients, the success rate of ventilation via the laryngeal mask was lower when cricoid pressure was applied. We conclude that when sufficient force was applied, cricoid pressure, regardless of the method of application, did impede placement of the laryngeal mask.
我们研究了22例患者，以检查环状软骨压迫是否会通过喉罩影响肺通气及其正确放置。采用随机交叉设计，使用环状软骨轭以30 N的标准化力施加或不施加环状软骨压迫来插入喉罩。在患者枕部下放置一个标准化枕头（高6 cm），但不支撑颈部。不施加环状软骨压迫时，所有患者通过喉罩的肺通气均充足，但施加环状软骨压迫时，22例患者中只有3例通气充足（P << 0.001；95%置信区间（CI）0.72 - 1.0）。不施加压力时，18例患者的喉罩放置正确，施加环状软骨压迫后无一例正确放置（P << 0.001；95% CI 0.66 - 0.98）。我们原计划在另外20例患者中研究枕部下不放置枕头时环状软骨压迫的效果；然而，即使不施加环状软骨压迫，喉罩的放置也很困难，口咽出血的发生率很高。因此，在研究了8例患者后，我们放弃了该部分研究。在这8例患者中，施加环状软骨压迫时通过喉罩通气的成功率较低。我们得出结论，当施加足够的力时，无论施加方法如何，环状软骨压迫确实会妨碍喉罩的放置。
