Hypoxia is closely related to many diseases and often leads to death. Early detection and identification of the hypoxia causes may help to promptly determine the right rescue plan and reduce the mortality. We proposed a new multiparametric monitoring method employing mitochondrial reduced nicotinamide adenine dinucleotide (NADH) fluorescence, regional reflectance, regional cerebral blood flow (CBF), electrocardiography (ECG), and respiration under six kinds of acute hypoxia in four categories to investigate a correlation between the parameter variances and the hypoxia causes. The variation patterns of the parameters were discussed, and the combination of NADH and CBF may contribute to the identification of the causes of hypoxia.

The involvement of mitochondrial dysfunction in many pathophysiological conditions and human diseases is well documented. In order to evaluate mitochondrial function in vitro,many experimental systems have been developed. Nevertheless the number of in vivo monitoring systems for the evaluation of mitochondrial activities in intact animals and patients is relatively limited. The pioneering development of the conceptual and technological aspects ofmitochondrial monitoring, in vitro and in vivo, was done by the late Prof. Britton Chance (July 24, 1913-November 16, 2010) since the early 1950s. It was my privilege to join his laboratory in 1972 and collaborate with him for almost four decades. The main achievements of our collaboration are presented in this paper. Our activities included cycles of technology development, followed by its applications to study various pathophysiological conditions. In the initial stage, the first fiber-optic-based NADH fluorometer was developed. This device enabled us to monitor various organs in anesthetized animals aswell as the brain of nonanesthetized small animals. Later on, the addition of various physiological parameters to NADH monitoring enabled us to correlate mitochondrial function with other cellular functions. The application of the developed technology to clinical situations was a major interest of Prof. Chance and indeed this goal was achieved in the last decade.As of today, the basic tool forNADHmonitoring and the large database of results are available for large-scale experimental and clinical applications.

The use of anesthetics is a well-known treatment for severely injured patients. In the present study we tested the pathophysiology of several levels of injury damage in a rat model and also tested the effect of Equithesin on brain vitality in these models. Traumatic Brain Injury (TBI) was induced using the fluid percussion injury model in four levels: mild, moderate and two levels of severe TBI. Brain real-time evaluation was performed by the multiparametric monitoring assembly (MPA) which enable cerebral blood flow (CBF) monitoring by laser Doppler flowmetry, mitochondrial NADH (Nicotinamide adenine dinucleotide) monitoring by the fluorometric technique, ionic homehostasis using special mini-electrodes, intracranial pressure (ICP) by the ICP camino device and needle electrodes for ECoG (Electrocorticogram) recording. Our results showed high correlation between the level of impact and the extent of changes in the physiological properties of the injury as indicated by the changes in all parameters monitored using the MPA device. Moreover, Equithesin improved CBF, ionic extracellular level and mitochondrial redox state following mild and moderate TBI while in severe TBI, Equithesin did not improve the metabolic state of the cerebral cortex, although it decreased the mortality rate from 66% to 20%, and following extra-severe TBI level, Equithesin did not improve survival rate. In conclusion it seems that Equithesin's protective effect exists under mild to moderate levels of injury and not in case of severe injuries.

Severe body stress induced by hypoxemia and hypotension may lead to total body energy state deterioration. The perfusion of the most vital organs is maintained at the expense of “less vital” organs. In the present study, we used a multi-site multiparametric (MSMP) monitoring system for real-time evaluation of tissue blood flow (TBF) and mitochondrial NADH fluorescence of the brain and the small intestine following hemorrhage. In Group 1, uncontrolled hemorrhage, mean arterial pressure (MAP) was decreased to 40mmHg within 2 minutes and shed blood was re-infused after 30minutes. In Group 2, controlled hemorrhage, during the 30minutes of hemorrhage, MAP was kept at 40mmHg. During hemorrhage, in both groups, the intestinal TBF and NADH deteriorated, while the brain remained relatively well protected. In Group 1, all parameters partly recovered within the hemorrhage phase, while in Group 2, complete recovery occurred only after resuscitation. At the end of the experiment, both models showed a decrease in intestinal viability (TBF decreased, NADH increased), while the brain metabolic state in Group 2 declined slightly. Our unique multi-parametric monitoring device demonstrated that, under hemorrhage, the small intestine responded entirely differently from the brain. This may suggest the potential usefulness of the monitoring of less vital organs, as proxy organs, in critical conditions such as massive hemorrhage. The present study also highlights the importance of mitochondrial function monitoring in similar conditions in the clinical environment.

Hyperbaric oxygenation (HBO) treatment protocols utilize low pressures up to 3ATA. Higher pressures may induce side effects such as convulsions due to brain toxicity. The optimal HBO pressure allowing for maximal therapy and minimal toxicity is under controversy. However, it can be evaluated by monitoring oxygen delivery, saturation, and consumption. In this study, the monitoring system fixed on the rats’ brain cortex included a time-sharing fluorometer-reflectometer for monitoring mitochondrial NADH and hemoglobin oxygenation (HbO₂) combined with Laser Doppler Flowmetry (LDF) for blood-flow monitoring. Rats were located in a hyperbaric chamber and exposed to different pressures. The HBO pressure caused an increase in HbO₂ and a decrease in NADH in proportion to the increase in hyperbaric pressure, up to a nearly maximum effect at 2.5ATA. At 6ATA, 15 minutes before convulsions started, blood volume and NADH started to increase, while tissue O₂ supply by hemoglobin remained stable. Oxygen pool includes oxygen dissolved in the plasma and also bounded to hemoglobin. Above 2.5ATA, hemoglobin is fully saturated and the oxygen pool nourishment derives only from the oxygen dissolved in the plasma, exceeding the physiological ability for autoregulation; hence, homeostasis is disturbed and convulsions appear. This information is vital because pressures around 2.5ATA–3ATA are standard clinically applied pressures used to treat most of the pathophysiological problems considering the potential benefit which must be balanced against the potential toxicity. This study enables, for the first time, to evaluate the oxygenation level of hemoglobin in the microcirculation. Furthermore, our study showed that additional oxygen pressure (above 2.5ATA) caused brain oxygen toxicity within a short variable period of time after the pressure elevation.

The involvement of mitochondrial dysfunction in various pathophysiological conditions, developed in experimental and clinical situations, is widely documented. Nevertheless, real time monitoring of mitochondrial function In-vivo is very rare. The pressing question is how the mitochondria of intact tissues behave under In-vivo conditions as compared to isolated mitochondria that had been described by Chance and Williams over 50 years ago. This subject has been recently discussed in detail (Mayevsky and Rogatsky 2007). We reviewed the subject of evaluating mitochondrial function by monitoring NADH fluorescence together with microcirculatory blood flow, Hemoglobin oxygenation and tissue reflectance. These 4 parameters represent the vitality of the tissue and could be monitored in vivo, using optical spectroscopy, in animal models as well as in clinical practice. It is a well known physiological hypothesis that, under emergency conditions, the sympathetic nervous system will give preference to the most vital organs in the body, namely the brain, heart and adrenal glands. The less vital organs, such as the skin, GI-tract, and Urethral wall, will become hypoperfused and their mitochondrial activity will be inhibited. The monitoring of the less vital organs may reveal critical tissue conditions that may manifest an early phase of body deterioration. The aim of the current presentation is to review the experimental and preliminary clinical results accumulated using a new integrated medical device – the “CritiView” which enabled, for the first time, monitoring 4 parameters from the tissue using a single optical probe. The CritiView is a computerized optical device that integrates hardware and software in order to provide real time information on tissue vitality. In preliminary clinical testing, we used a 3-way Foley catheter that includes a bundle of optical fibers enabling the monitoring of the 4 parameters, representing the vitality of the urethral wall (a less vital organ).We found that the exposure of patients to metabolic imbalances in the operation room led to changes in tissue blood flow and inhibition of mitochondrial function in the urethral wall. In conclusion, the new device “CritiView” could provide reliable, real time data on mitochondrial function and tissue vitality in experimental animals as well as in patients.

Focal ischemia due to reduction of cerebral blood flow (CBF), creates 2 zones of damage: the core area, which suffers severe damage, and penumbra area, which surrounds the core and suffers intermediate levels of injury. Objectives: A novel method is introduced, which evaluates mitochondrial function in the core and in the penumbra, during focal cerebral ischemia. Methods: Wistar rats underwent focal cerebral ischemia by middle cerebral artery occlusion (MCAO) for 60 minutes, followed by 60 minutes of reperfusion. Mitochondrial function was assessed by a unique Multi-Site — Multi-Parametric (MSMP) monitoring system, which measures mitochondrial NADH using fluorometric technique, and CBF using Laser Doppler Flowmetry (LDF). Results: At the onset of occlusion, CBF dropped and NADH increased significantly only in the right hemisphere. CBF levels were significantly lower and NADH significantly higher in the core than in the penumbra. After reperfusion, CBF and NADH recovered correspondingly to the intensity of ischemia. Conclusion: Application of the MSMP system can add significant information for the understanding of the cerebral metabolic state under ischemic conditions, with an emphasis on mitochondrial function.