The optimal time between clinical brain death diagnosis and confirmation using CT angiography: a retrospective study.

BACKGROUND: In several countries, a computed tomography angiography (CTA) is used to confirm brain death (BD). A six­hour interval is recommended between clinical diagnosis and CTA acquisition despite the lack of strong evidence to support this interval. The aim of this study was to determine the optimal timing for CTA in the confirmation of BD. METHODS: This retrospective observational study enrolled all adult patients admitted between January 2009 and December 2013 to the intensive care units of a French university hospital with clinically diagnosed BD and at least one CTA performed as a confirmatory test. The CTAs were identified as conclusive (e.g. yielding confirmation of BD) or inconclusive (e.g. showing persistent brain circulation). RESULTS: One hundred and four patients (sex ratio M/F 1.8; age 55 years [41­64]) underwent 117 CTAs. CTAs confirmed cerebral circulatory arrest in 94 cases yielding a sensitivity of 80%. Inconclusive CTAs were performed earlier than conclusive ones (2 hours [1­3] vs. 4 hours [2­9], P=0.03) and were associated with decompressive craniectomy (5 cases [23%] vs. 6 cases [7%], P=0.05) and the failure to complete full neurological examination (5 cases [23%] vs. 4 cases [5%], P=0.02). Six hours after BD clinical diagnosis, the proportion of conclusive CTA was only 51%, with progressive increase overtime with more than 80% of conclusive CTA after 12 hours. CONCLUSIONS: A 12­hour interval might be appropriate in order to limit the risk of inconclusive CTAs.

A modified lateral approach to the sciatic nerve: magnetic resonance imaging simulation and clinical study.

BACKGROUND: The authors describe a new lateral approach to the sciatic nerve (SN) block in the popliteal fossa by using magnetic resonance imaging (MRI) and assessed its clinical feasibility. METHODS: The authors reviewed the MRI of the SN of 40 patients to compare a new landmark with the classical one. For the modified technique, the landmarks were the upper edge of the patella and the tendon of the biceps femoris. A line was drawn vertically from the upper edge of the patella. The puncture site was located at the intersection of this line with the lower part of the tendon. For the MRI study from the puncture point, the authors determined simulated needle direction to access the neurovascular bundle and measured its depth. RESULTS: The mean +/- standard deviation distance from the skin puncture to the tibial nerve was 48 +/- 6 mm in the classic group versus 26 +/- 5 mm (P < .0001) and to the common peroneal nerve 42 +/- 6 mm in the classic group versus 19 +/- 5 mm (P < .0001). The success rate was 94% (95% confidence interval 89-99) in 100 patients. Ten patients required general anesthesia; 4 because of the saphenous nerve failure (not analyzed as a failure) and 6 because of SN block failure. CONCLUSIONS: Based on the MRI images, a needle inserted below the biceps femoris tendon provides an easy access point to the common peroneal and/or the tibial nerve. This modified lateral approach to the SN was easy to perform, had a high success rate, and was without complication in this small cohort.