Internal jugular vein (IJV) cannulation is a popular approach for central venous access as it has few complications, of which failure to locate the vein and carotid artery puncture are the most common. A variety of manoeuvres and body positioning has been used to maximise IJV size and thereby increase cannulation success rate and decrease complications. Realtime 2D ultrasound can be used to view neck vascular anatomy in vivo and allow IJV size to be measured. Thirty-five volunteers had the lateral diameter of their IJV measured using the SiteRite ultrasound machine to discover the most effective methods of increasing its diameter. No correlation was found between the IJV lateral diameter and subject height, weight, age or neck circumference. Carotid artery palpation and full neck extension reduced its diameter considerably. Increasing Trendelenberg increased diameter. Abdominal binder and the Valsalva manoeuvre were the most efficient methods of increasing its size.

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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)

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