http://repub.eur.nl/res/aut/23928/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/20089/ 1999-12-22T00:00:00Z Medicine is an art and a science in the service of fellow human beings. On the basis of collected empirical data and information, clinicians select specific diagnoses, rule out other differential diagnoses and eventually make decisions about which and how specific therapeutic interventions are made for the benefit and health of their patients. For a proper interpretation, collected data and information mnst be compared with other, already existing, data and infonnation to assess the exact value of the clinician's findings. Moreover, a clinician compares observed medical data of a patient with knowledge obtained during his or her training as a clinician and with the experience obtained by working with other patients. A prerequisite in this paradigm, however, is that collected empirical data on which the diagnoses of a clinician are based must be as objective as possible. Clinical chemistry takes a pivotal role in this in the sense that the chemical characterisation of a patient's body fluid is one of the ways in medicine that can provide such objective data. Since the beginning of this century, clinical chemisny has evolved into a separate and independent discipline in the field of medicine. Nowadays, most often a single central clinical chemisuy laboratol takes care of the 'analytical needs' of one or more hospitals. Tasks of the clinical chemist rypically include the improvement of existing methods of chemical analysis, the development of new analytical methods and providing the clinician with as much information as possible on the basis of chemical analyses. Especially this last task forms the basis of what has become known as chemometrics, a branch of clinical chemistry that uses mathematical and statistical methods to extract a maximum ofinformation from chemical analyses. This thesis presents a multivariate chemometric approach to the problems that are currently associated with the interpretation and evaluation of those laboratory measurelnents that are used to assess the arterial acid-base status of a patient in an intensive care unit (ICU).