[1] Univ Cape Town, Dept Anesthesia & Perioperat Med, Cape Town, South Africa
[2] Red Cross War Mem Childrens Hosp, Cape Town, South Africa
[3] Med Campus Univ Oldenburg, Dept Anesthesiol Intens Care Med & Pain Control, Evangel Krankenhaus, Steinweg 13-17, D-26122 Oldenburg, Germany
[4] Univ Cape Town, Chris Barnard Div Cardiothorac Surg, Cape Town, South Africa