Optical monitoring of tissue physiological and biochemical parameters in real-time is a new approach and a powerful tool for better clinical diagnosis and treatment. Most of the devices available for monitoring patients in critical conditions provide information on body respiratory and hemodynamic functions. Currently, monitoring of patients at the cellular and tissue level is very rare. Realtime monitoring of mitochondrial nicotinamide adenine dinucleotide (NADH) as an indicator of intra-cellular oxygen levels started 50 years ago. Mitochondrial dysfunction was recognized as a key element in the pathogenesis of various illnesses. We developed the “CritiView” — a revolutionary patient monitoring system providing real time data on mitochondrial function as well as microcirculatory blood flow, hemoglobin oxygenation as well as tissue reflectance. We hypothesize that under the development of body O2 insufficiency the well known blood flow redistribution mechanism will protect the most vital organs (brain and heart) by increasing blood flow while the less vital organs (gastrointestinal (GI) tract or urogenital system) will become hypoperfused and O2 delivery will diminish. Therefore, the less vital organs will be the initial responders to O2 imbalances and the last to recover after the end of resuscitation. The urethral wall represents a lessvital organ in the body and may be very sensitive to the development of emergency situations in patients. It is assumed that the beginning of deterioration processes (i.e., internal bleeding) as well as resuscitation end-points in critically ill patients will be detected. In this paper, we review the theoretical, technological, experimental and preliminary clinical results accumulated using the “CritiView”. Preliminary clinical studies suggest that our monitoring approach is practical in collecting data from the urethral wall in critical care medicine. Using CritiView in critical care medicine may shed new light on body O2 balance and the development of body emergency metabolic state.