School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill Health Campus, Aberdeen, AB25 2ZD, UK. s.shaji.16@abdn.ac.uk. School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill Health Campus, Aberdeen, AB25 2ZD, UK. c.smith.16@abdn.ac.uk. School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Foresterhill Health Campus, Aberdeen, AB25 2ZD, UK. Department of Anaesthesia, NHS Grampian, Aberdeen, UK.