Determination of hair ketamine cut-off value from Hong Kong ketamine users by LC-MS/MS analysis.

Ketamine is one of the most frequent abused drugs in Hong Kong and South-East Asia, and the cases of ketamine abused have been reported worldwide. Hair has been commonly used as a specimen for the proof of chronic drug abused because of its non-invasiveness and long detection windows. The determinations of ketamine in hair with varieties of state-of-the-art instruments and detection methods have been developed in the past decade; however, the cut-off value for ketamine abuser has not been developed according to the international guidelines. The aim of this study is to propose a cut-off value for ketamine in hair by analyzing ketamine and its metabolite norketamine by LC-MS/MS method in a population of ketamine users in Hong Kong. The limit of detection (LOD) and limit of quantification (LOQ) for ketamine and norketamine were 20pg/mg and 100pg/mg, respectively. From 977 ketamine abusers, the cut-off value for ketamine in hair was proposed to be 400pg/mg of hair. This proposed cut-off value is the concentration of hair ketamine when over 90% of samples are being detected with the presence of norketamine, which is a proof of ketamine abuse. This value could be applied as a screening or occupational cut-off for reference.

Palliative surgery in tetralogy of Fallot.

Because much controversy surrounds the palliative surgical treatment of young children with tetralogy of Fallot the authors review their experience over 13 years with two procedures--the Blalock-Taussig operation and the Waterston shunt. Blalock shunts were performed 195 times in 172 patients; 147 had a single Blalock anastomosis which carried them through the critical period and allowed for later correction of the tetralogy. Thrombosis of the Blalock anastomosis occurred in two patients in the early postoperative period. In 23 patients a second shunt was necessary after the first Blalock shunt became inadequate in spite of being patent. The age of the children ranged from 2 weeks to 9 years, 74% being operated upon under the age of 2 years. There were four early deaths (2%) and five late deaths (2.5%) in this group. Of the last 91 consecutive patients operated upon between Sept. 1, 1972 and June 30, 1980 none have died. Between September 1968 and June 1980, 14 patients with tetralogy of Fallot underwent a Waterston shunt. Their ages ranged from 2 days to 4 years. Six patients were younger than 35 days at the time of operation. There were two operative deaths in this group. The Waterston shunt carries a high risk and is reserved for the occasional patient who needs palliation during the first weeks of life and in whom the anatomy of the subclavian artery does not favour a good Blalock-Taussig shunt. The Blalock-Taussig operation is preferred because it is safe and gives good sustained clinical results. The mortality was much lower than previously reported. The growth of the pulmonary arteries was good in most patients. The Blalock shunt did not increase the pulmonary resistance and it did not influence the operative mortality.