Table of Contents
ISRN Pediatrics
Volume 2011, Article ID 296418, 6 pages
http://dx.doi.org/10.5402/2011/296418
Research Article

An Exploratory Investigation of Some Statistical Summaries of Oximeter Oxygen Saturation Data from Preterm Babies

1Department of Mathematics and Statistics, University of Canterbury, Christchurch 8140, New Zealand
2Imperial College Healthcare NHS Trust, London W2 1NY, UK
3Department of Paediatrics, Christchurch School of Medicine and Health Sciences, University of Otago, Christchurch 8140, New Zealand

Received 28 January 2011; Accepted 30 March 2011

Academic Editors: Y. Ersahin and J. Gonzalez de Dios

Copyright © 2011 Dominic S. Lee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Aim. To explore the potential usefulness of the mean, standard deviation (SD), and coefficient of variation (CV = SD/mean) of oximeter oxygen saturations in the clinical care of preterm babies. Methods. This was an exploratory investigation involving 31 preterm babies at 36 weeks postmenstrual age. All babies were healthy, but two were considered to be clinically unstable and required greater attention. Each baby's oxygen saturations were recorded using an oximeter and summarized by the mean, SD, and CV. The potential usefulness of each measure was assessed by its ability to distinguish the two unstable babies from the others. This was achieved using box plots and hierarchical clustering together with the Calinski-Harabasz (CH) index to quantify clustering performance (higher CH index indicates stronger clustering outcome). Results. The box plots flagged both unstable babies as outliers and none of the other babies. Successful clustering of the stable and unstable babies was achieved using the CV (CH = 72.8) and SD (CH = 63.3) but not with the mean. Conclusion. Taking the box plots and clustering results together, it seems plausible that variability might be more effective than mean level for detecting instability in oxygen saturation in preterm babies and that the combination of variability and level through the CV might be even better.