ECMO-/ECLS

Chapter 6
MONITORING IN THE ICU
Aaron R. Jensen, MD, MEd
David W. Bliss, MD
I. INTRODUCTION
Continuous monitoring is one of the most identifiable features of the
intensive care unit environment. Indeed, the original concept of such areas was
to be ‘monitored’ environments where physiologic fluctuations may be tracked
and analyzed in real time. Further, monitoring is essential to understand the
impact of intensive care unit interventions and to characterize the nature and
significance of derangements.
Monitoring strategies are designed to follow individual organ function and,
to a lesser degree, the interaction between systems. Available devices can
analyze physical parameters (pressure, temperature, flow, volume), electrical
function (EEG, ECG, train-of-four), gas dynamics (saturation, partial pressure),
concentrations (hemoglobin), and chemistries (microdialysis).
However, monitors are limited in their ability to interrogate tissue health and
cellular function. Most measurements are surrogates and should be interpreted
carefully while considering population norms, baseline patient capability,
demands of the physiologic circumstance, and tolerance of deviations from
“optimal” or “normal” function. Furthermore, individual monitor values are often
insufficient to draw conclusions about global physiology. For example, a normal