Risk factors for occurrence of failed interscalene brachial plexus blocks for shoulder arthroscopy using 20 mL 0.5% ropivacaine: a randomised trial - Stasiowski, Michał; Chabierska, Ewa; Marciniak, Radosław; Kolny, Michał; Zuber, Marek; Jałowiecki, Przemysław; Pluta, Aleksandra; Szumera, Izabela (Anestezjologia Intensywna Terapia, 2018)