Can the pulmonary artery catheter be replaced by less invasive cardiac out put monitors?

Abstract

Monitoring of cardiac output (CO) is used in the context of anesthesia and intensive care to: (i) detect, before clinical signs become obvious, that cardiovascular performance is altered; (ii) find the causes of alteration; (iii) change therapy; (iv) improve outcome and resource utilization. In the literature, CO monitoring has been approached in different but complimentary knowledge domains. These concern (i) technical issues (what is really measured and how is CO calculated?; are the measurements continuous versus discontinuous ?); (ii) invasiveness, which according to the definition of this term can classify different CO monitors as invasive, minimally invasive or non invasive; it is worth mentioning that it is not because a monitor is considered as non invasive that it can be used under all clinical circumstances; for instance, transoesophageal doppler monitors are considered as non invasive but their use in awake, non intubated patients is nearly impossible; (iii) diagnostic performance as compared to a gold standard or reference technique; most of the literature on comparisons of CO monitors has been dedicated to diagnostic performance; (iv) changes in medical practice based on information provided by each type of CO monitors; (v) changes in outcome and resource utilization. In this presentation, in order to answer the question formulated in the title, I will discuss two issues: (i) comparisons of diagnostic performance with focus on the statistical tools 1-3, used for comparisons and the clinical relevance of these comparisons; with the statistical tools and adequate clinical reasoning we should be able to assert the interchangeability of different CO monitors (ii) the impact of CO monitoring on patient outcome and resource utilization ; I will analyse critically the available literature and attempt to explain why the use of CO monitors has not results in measurable changes in patient outcome.