H. R. Guly, O. Bouamra, M. Spiers, P. Dark, T. Coats, and F. E. Lecky, ‘Vital signs and estimated blood loss in patients with major trauma: testing the validity of the ATLS classi-fication of hypovolaemic shock’, Resuscitation, vol. 82, no. 5, pp. 556–559, 2011.