title: Estimation of cardiac output and systemic vascular resistance using a multivariate regression model with features selected from the finger photoplethysmogram and routine cardiovascular measurements.
abstract: BACKGROUND
  Cardiac output (CO) and systemic vascular resistance (SVR) are two important parameters of the cardiovascular system. The ability to measure these parameters continuously and noninvasively may assist in diagnosing and monitoring patients with suspected cardiovascular diseases, or other critical illnesses. In this study, a method is proposed to estimate both the CO and SVR of a heterogeneous cohort of intensive care unit patients (N=48).
  
  
  METHODS
  Spectral and morphological features were extracted from the finger photoplethysmogram, and added to heart rate and mean arterial pressure as input features to a multivariate regression model to estimate CO and SVR. A stepwise feature search algorithm was employed to select statistically significant features. Leave-one-out cross validation was used to assess the generalized model performance. The degree of agreement between the estimation method and the gold standard was assessed using Bland-Altman analysis.
  
  
  RESULTS
  The Bland-Altman bias ±precision (1.96 times standard deviation) for CO was -0.01 ±2.70 L min-1 when only photoplethysmogram (PPG) features were used, and for SVR was -0.87 ±412 dyn.s.cm-5 when only one PPG variability feature was used.
  
  
  CONCLUSIONS
  These promising results indicate the feasibility of using the method described as a non-invasive preliminary diagnostic tool in supervised or unsupervised clinical settings.
authors: School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, Australia. qimyi.lee@unsw.edu.au
authors: Qim Y
authors: QY
authors: Lee
authors: Stephen J
authors: SJ
authors: Redmond
authors: Gregory Sh
authors: GSh
authors: Chan
authors: Paul M
authors: PM
authors: Middleton
authors: Elizabeth
authors: E
authors: Steel
authors: Philip
authors: P
authors: Malouf
authors: Cristopher
authors: C
authors: Critoph
authors: Gordon
authors: G
authors: Flynn
authors: Emma
authors: E
authors: O'Lone
authors: Nigel H
authors: NH
authors: Lovell
mesh_terms: D000368:Aged; D062186:Arterial Pressure; D001794:Blood Pressure; D002302:Cardiac Output / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000503:physiopathology; D002319:Cardiovascular System / Q000503:physiopathology; D005260:Female; D005385:Fingers / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D015999:Multivariate Analysis; D017156:Photoplethysmography / Q000379:methods*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014655:Vascular Resistance / Q000502:physiology*