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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Venous air embolism during surgery is a rare but important complication and can be rapidly fatal. We present two cases of fatal air embolism in the prone position occurring in small children undergoing surgery for progressive scoliosis. Venous air embolism is a rare complication in the prone position. This is thought to be because in this position there is virtually no gravitational gradient between the site of surgery and the right atrium. The possible sites of entry of air and ways that this may be minimized are discussed.

We measured ventilation in 12 subjects anaesthetized with enflurane (end-tidal concentration 1.25-1.45%) and nitrous oxide to assess the effect of surgical stimulation on ventilation in humans. Tidal volume and respiratory timing were measured by pneumotachograph before and just after a standardized surgical skin incision. Surgical stimulation increased ventilation by increasing tidal volume, which increased progressively over the first five breaths after incision. The first breath after the stimulus was prolonged, but the timing of the subsequent breaths returned rapidly to the duration observed before incision. Ventilation increased from median 3.6 (quartiles 2.9, 4.3) to 5.4 (3.8, 7.0) litre min-1 (P < 0.01). The increased tidal volume was not associated consistently with shortening of inspiratory duration.

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