Liver transplantation and allergy: transplant-acquired food allergy.

Transplant-acquired food allergy is a well known phenomenon especially linked to liver transplants. Risk factors lie both in transplant recipient and transplant donor - age of recipient and the maturity of immune regulatory mechanisms, family history of atopy in recipient, young age of the donor and atopic history in donor. The exact mechanism has not yet been established and there are many different explanations of this pathophysiologic process. Transplanted liver is a large and well perfused organ, rich in pluripotent hematopoietic stem cells and donor's IgE antibodies that can alter immunological response in the host. Some studies suggest that post-transplant immunosuppression with tacrolimus is linked to an increased occurrence of IgE-mediated sensitization and manifestation of allergic disease. Research in the field of transplant-acquired food allergy is not important only for transplant patients and physicians involved but also for understanding the mechanism of food allergy development in general population and potentially reducing this global health concerning issue.

Effects of age on minimum effective volume of local anesthetic for ultrasound-guided supraclavicular brachial plexus block.

BACKGROUND: Involutional changes of peripheral nervous system occur with aging. The aim of the study was to determine the minimum effective volume of local anesthetic required to offer an effective ultrasound-guided supraclavicular brachial plexus block in 50% of middle-aged (< 50 years) and elderly (> 65 years) patients. We hypothesized reduced minimum effective volume of local anesthetic in elderly patients. METHODS: Middle-aged (n = 22) and elderly (n = 22) patients undergoing upper limb surgery received an ultrasound-guided supraclavicular brachial plexus block. Structural analysis of the brachial plexus in supraclavicular region was obtained by measuring the cross-sectional area. The prospective, observer-blinded study method is a previously validated step-up/step-down sequence model where the local anesthetic volume for the next patient is determined by the outcome of the previous block. The starting volume was 30 ml (50 : 50 mixture, 0.5%wt/vol levobupivacaine, 2%wt/vol lidocaine). The minimum effective volume of local anesthetic was determined using Dixon and Masey method. RESULTS: The minimum effective local anesthetic volume significantly differed between middle-aged and elderly [23.0 ml, 95% confidence interval (CI) 13.7-32.3 vs. 11.9 ml, 95% CI 9.3-14.6; 95% CI of the difference 1.6-20.6, P = 0.027]. The cross-sectional area of brachial plexus was 0.95 ± 0.15 in middle-aged and 0.51 ± 0.06 cm(2) in elderly patients (P < 0.001). CONCLUSIONS: Within the present study, we report a reduced minimum effective anesthetic volume for ultrasound-guided supraclavicular block in elderly patients. Additionally, smaller cross-sectional surface area of brachial plexus in the supraclavicular region was observed.