Dr Armstrong graduated from the University of New South Wales and trained in Anaesthetics at the St George Hospital. Fellowship training at the Childrens Hospital Camperdown and overseas at the University of Washington Medical Centre, Seattle USA and the Nuffield department of Anaesthetics, Oxford UK.

His current interests include cardiothoracic anaesthesia and perfusion, transoesophageal echocardiography and anaesthesia for Obesity surgery. He is a conjoint lecturer at the University of New South Wales and an anatomy demonstrator for the Australian and New Zealand College of Anaesthetists.