[1] Groote Schuur Hosp, Div Crit Care, Cape Town, South Africa
[2] Univ Cape Town, Dept Anaesthesia & Perioperat Med, Div Crit Care, Cape Town, South Africa
[3] Univ Cape Town, Fac Hlth Sci, Dept Surg, Div Gen Surg, Cape Town, South Africa
[4] Univ Cape Town, Fac Hlth Sci, Sch Publ Hlth & Family Med, Cape Town, South Africa
[5] Univ Cape Town, Fac Hlth Sci, Dept Med, Div Pulmonol, Cape Town, South Africa
[6] Univ Cape Town, Fac Hlth Sci, UCT Lung Inst, Cape Town, South Africa
[7] Univ Cape Town, Fac Hlth Sci, Dept Surg, Div Neurosurg, Cape Town, South Africa
[8] Univ Cape Town, Fac Hlth Sci, Dept Anaesthesia & Perioperat Med, Cape Town, South Africa