title: Erratum to: Does using two Doppler cardiac output monitors in tandem provide a reliable trend line of changes for validation studies?
authors.affiliation: Department of Anaesthesia and Surgical Intensive Care, Peking University First Hospital, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, SAR.
authors.forename: Lester A H
authors.initials: LA
authors.lastname: Critchley
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, SAR. joannyzh@gmail.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang