Foot length, an accurate predictor of nasotracheal tube length in neonates

Abstract

Background-Existing guidelines for optimal positioning of endotracheal tubes in neonates are based on scanty data and relate to measurements that are either non-linear or poorly reproducible in sick infants. Foot length can be measured simply and rapidly and is related to a number of external body measurements. Objectives-To evaluate the relation of foot length to nasotracheal length in direct measurements at post mortem examinations, and then compare its clinical relevance with traditional weight based estimates in a randomised controlled trial. Methods-The dimensions of the upper airway were measured at autopsy in 39 infants with median (range) postmenstrual age and birth weight of 32 (24-43) weeks and 1630 (640-3530) g. The regression equations with 95% prediction intervals were calculated to estimate the optimal nasotracheal length from foot length. In a randomised trial, 59 neonates were nasally intubated according to foot length and body weight based estimates to assess the achievement of "optimal" and "satisfactory" tube placements. Results-In the direct measurements of the airway at autopsy, foot length was a better predictor of nasotracheal distances (r 2 = 0.79) than body weight, gestational age, and head circumference (r 2 = 0.67, 0.58, and 0.60 respectively). Measurement of foot length was easy and highly reproducible. In the randomised controlled trial, there were no significant diVerences between the foot length and body weight based estimates in the rates of optimal (44% v 56%) and satisfactory (83% v 72%) endotracheal tube placements. Conclusions-Foot length is a reliable and reproducible predictor of nasotracheal tube length and is at least as accurate as the conventional weight based estimation. This method may be particularly valuable in sick unstable infants. (Arch Dis Child Fetal Neonatal Ed 2001;85:F60-F64)

Correlation of foot length and gestational maturity in neonates

“…A study by Embleton et al showed that FL was the best predictor of naris-midtracheal length. 12 They concluded that FL is a reliable and reproducible predictor of nasotracheal tube length and is at least as accurate as the conventional weight based estimation. This method may be particularly valuable in ill and unstable infants.…”

Estimation of length of endotracheal tube insertion by foot length in newborns

“…These finding were consistent with a study by Embleton ND et al, in 2001 which recommended the foot length as a predictor for the optimal nasotracheal intubation depth and this method may be particularly valuable in sick unstable infants. 22 However, the study by Embleton ND et al, had several limitations that is the study by Embleton ND et al, was based on data collected at autopsy in 39 infants with median (range) postmenstrual age and birth weight of 32 (24-43) weeks and 1630 (640-3530)gm. 22 In vivo traction from the diaphragm increases the length of the trachea during inspiration.…”

“…22 However, the study by Embleton ND et al, had several limitations that is the study by Embleton ND et al, was based on data collected at autopsy in 39 infants with median (range) postmenstrual age and birth weight of 32 (24-43) weeks and 1630 (640-3530)gm. 22 In vivo traction from the diaphragm increases the length of the trachea during inspiration. Loss of this traction effect after death results in a shorter trachea.…”

“…Also, in the study by Embleton ND et al, foot length measurements were rounded off to the nearest 0.5cm mark, as the repeatability of this measurement in clinical practice was 4mm and length was determined based on nasotracheal tube lengths. 22 However, in the present study was comprised of 50 newborns with mean gestational age of 34.80±4.25 weeks and mean birth weight was 2.10±0.71Kg. Also, the satisfactory position of the ETT tip was confirmed radiographically.…”

“…Embelton ND et al, in 2001 showed that, foot length is a reliable and reproducible predictor of nasotracheal tube length and is at least as accurate as the conventional weight-based estimation. 22 This method may be particularly valuable in sick unstable infants.…”