Unexpected vomiting during anesthesia induction in a patient with undiagnosed congenital esophageal stenosis

was taken for blood gas analysis. This confirmed intraarterial placement. The cannula was left in situ and clearly marked as ‘arterial’. A 22G cannula was then placed in the left external jugular vein. The remainder of the case proceeded uneventfully. The color and perfusion of the left hand was monitored and appeared normal throughout the procedure. The cannula was removed postoperatively in the recovery room. The patient’s hand was observed and there were no sequelae from the incident. Intra-arterial injection in the dorsum of the hand in children has been described in this journal (1) In our patient, the vessel that was probably cannulated was a branch of the SRA. As the radial artery winds laterally around the wrist, it courses through the anatomical snuff box, deep to the tendons defining it. The SRA is an anatomical variation in which the radial artery courses over the tendons defining the snuff box and may end as a single branch passing through the first intermetacarpal space. It is a rare finding, with an incidence of <0.2% of upper limbs (4). The superficial ulnar artery is a more common anomaly than the SRA, observed in 3.75% of specimens in a large cadeveric survey (4). Cannulation of this vessel, in the antero-medial aspect of the forearm, has also been described (2). A recent review discussed the possible complications and management strategies of intra-arterial injection of several anesthetic drugs (5). Fentanyl and atropine have been administered intra-arterially without adverse effect. Intra-arterial atracurium can cause ischemia. Drugs which are not dissolved in water, e.g. propofol, etomidate, diazepam or with an alkaline pH, e.g. thiopentone should be avoided. Features suggestive of intra-arterial cannulation include pulsatile back flow of blood into the i.v. tubing, intense and immediate pain on injection and blanching around the site of the cannula. Unfortunately, many of these signs were not useful in this situation. The patient received an inhalational induction prior to cannulation and the cannula was attached to extension tubing with a locked threeway tap that prevented back flow. Predisposing factors towards intra-arterial cannulation include difficult venous access because of obesity, expected anatomical location of an artery and partial arterial flow occlusion by the use of a tight venous tourniquet. In summary, this case highlights the need to be aware that intra-arterial cannulation can occur when performed in the dorsum of the hand in children and to have an understanding of peripheral upper limb arterial supply and possible variation. It emphasizes the need to be aware of the features suggestive of intra-arterial cannulation and of the side effects of common anesthetic drugs when injected intra-arterially. John Friis Michael Browning Department of Anaesthetics, Maidstone Hospital, Hermitage Lane, Maidstone, Kent ME16 9QQ, UK (email: mikebrowning@nhs.net)