Fingertip photoplethysmographic waveform variability and systemic vascular resistance in intensive care unit patients. - Paul M. Middleton; Gregory S. H. Chan; Elizabeth Steel; Philip Malouf; Christopher Critoph; Gordon Flynn; Emma O'Lone; Branko G. Celler; Nigel H. Lovell (Medical Biol. Eng. Comput., 2011)