Nares‐to‐carina distance in children: does a ‘modified Morgan formula’ give useful guidance during nasal intubation?

Abstract

The study confirms previous reports: NC distance can be well predicted from height/length. A modified Morgan formula might decrease the risk for accidental endobronchial intubation in infants and children, but ETT position need to be confirmed by auscultation or other verification.

Are preformed endotracheal tubes appropriately designed for pediatric patients?

“…Cuffed nasal preformed tubes in size 3.0 were not marketed in the USA by any, size 3.5 by one, and size 3.5–5.5 by three of the manufacturers (Table ). If the cuffed standard ETTs of the NC reference group had been replaced with cuffed RAE tubes placed with their bend at the nares, the incidence of endobronchial intubations would have varied between 50% and 100%, depending on the size and brand of preformed tube used. All 14 patients intubated with a size 4.0, 4.5 or 5.0 ETT would have been endobronchially intubated, irrespective of the brand used.…”

“…compared FTC measures obtained radiologically in unintubated children to the lengths of the oral preformed tubes that would have been chosen according to age‐based formulas. Because our methodology differed from theirs—rather than relying on ETT size formulas, which are not always clinically reliable, we defined ‘correct ETT size’ as the ETT size selected by the pediatric anesthesiologists in the two reference studies—and almost all patients in our reference groups were intubated with cuffed ETTs, we cannot directly confirm their findings. However, if one accepts that it is appropriate to replace a cuffed ETT by a 0.5 mm larger size uncuffed ETT, our findings do provide indirect support of their conclusion.…”

“…These measures were obtained by recording the intubation depth at the upper front teeth (dental ridge in edentulous patients), or nostril, and then adding the distance from the ETT tip to the carina as recorded from a chest X‐ray. FTC and NC data from reference and were grouped according to the size of the used cuffed standard ETT, and the individual measures were then compared to the bend‐to‐tip length of the same size cuffed preformed ETTs.…”

“…The aim of this study was (i) to measure the bend‐to‐tip distance of currently available oral and nasal preformed tubes and (ii) to use previously obtained front teeth‐to‐carina (FTC) and nares‐to‐carina (NC) measurements and test whether placing the bend of a preformed tube at the upper front teeth or nares would have resulted in endobronchial intubation.…”

“…The aim of this study was (i) to measure the bend-totip distance of currently available oral and nasal preformed tubes and (ii) to use previously obtained front teeth-to-carina (FTC) (2) and nares-to-carina (NC) (3) measurements and test whether placing the bend of a preformed tube at the upper front teeth or nares would have resulted in endobronchial intubation. The distance from the vertex of the bend to the tip of the tube (bend-to-tip distance) was measured with a flexible tape measure placed along the middle of the lateral wall of the tube (Figure 2), similar to the method described by Weiss et al (4).…”