Does the endotracheal tube insertion depth predicted by formulas in children have a good concordance with the ideal position observed by X-ray?

ABSTRACT Objective: To evaluate the effectiveness of the different formulas for estimating the insertion depth of an endotracheal tube in children. Methods: This was an observational and cross-sectional study that included children between 29 days and 2 years of age who were hospitalized in a pediatric intensive care unit and mechanically ventilated. The formulas based on height [(height/10) + 5], the inner diameter of the tube (endotracheal tube × 3), and weight (weight + 6) were evaluated to determine which of them showed better concordance with the ideal insertion depth of the endotracheal tube as evaluated by X-ray. Results: The correlation between the height-based calculation and the ideal depth observed on X-ray was strong, with r = 0.88, p < 0.05, and a concordance correlation coefficient of 0.88; the correlation between the weight-based calculation and depth on X-ray was r = 0.75, p < 0.05, and concordance correlation coefficient 0.43; and the correlation between endotracheal tube diameter-based calculation and depth on X-ray was r = 0.80, p < 0.05, and concordance correlation coefficient 0.78. Lin’s concordance correlation analysis indicated that the measurements showed weak concordance (< 0.90). Conclusion: The formulas that estimate the insertion depth of the endotracheal tube in children were not accurate and were discordant with the gold-standard method of X-ray evaluation. There is a need for a new method based on anthropometric variables (weight and height) and age that is effective in guiding health professionals of pediatric intensive care units at the time of intubation.

摘要 目的：评估不同公式估算儿童气管导管（endotracheal tube）插入深度的有效性。方法：本研究为观察性横断面研究，纳入29日龄至2岁、入住儿科重症监护病房（pediatric intensive care unit）并接受机械通气的儿童。本研究对三类估算公式展开评估：基于身高的[(身高/10)+5]、基于气管导管内径的[(气管导管内径×3)]以及基于体重的[(体重+6)]公式，以明确哪类公式与X射线评定的气管导管理想插入深度的一致性更优。结果：基于身高的计算结果与X线观察到的理想深度呈强相关，相关系数r=0.88，p<0.05，一致性相关系数为0.88；基于体重的计算结果与X线深度的相关系数r=0.75，p<0.05，一致性相关系数为0.43；基于气管导管内径的计算结果与X线深度的相关系数r=0.80，p<0.05，一致性相关系数为0.78。Lin一致性相关分析显示，各项测量的一致性较弱（<0.90）。结论：现有估算儿童气管导管插入深度的公式准确性不足，与金标准X线评估方法的一致性较差。亟需开发一种基于人体测量学变量（体重与身高）及年龄的新型方法，以指导儿科重症监护病房医护人员在气管插管时的临床操作。