Monitoring mitochondrial PO2: the next step

Abstract

Purpose of reviewTo fully exploit the concept of hemodynamic coherence in resuscitating critically ill one should preferably take into account information about the state of parenchymal cells. Monitoring of mitochondrial oxygen tension (mitoPO 2 ) has emerged as a clinical means to assess information of oxygen delivery and oxygen utilization at the mitochondrial level. This review will outline the basics of the technique, summarize its development and describe the rationale of measuring oxygen at the mitochondrial level. Recent findingsMitochondrial oxygen tension can be measured by means of the protoporphyrin IX-Triplet State Lifetime Technique (PpIX-TSLT). After validation and use in preclinical animal models, the technique has recently become commercially available in the form of a clinical measuring system. This system has now been used in a number of healthy volunteer studies and is currently being evaluated in studies in perioperative and intensive care patients in several European university hospitals. SummaryPpIX-TSLT is a noninvasive and well tolerated method to assess aspects of mitochondrial function at the bedside. It allows doctors to look beyond the macrocirculation and microcirculation and to take the oxygen balance at the cellular level into account in treatment strategies.

Mitochondrial Oxygen Monitoring During Surgical Repair of Congenital Diaphragmatic Hernia or Esophageal Atresia: A Feasibility Study

“…Clinical data until now are scarce and normal values for mitoPO 2 remain to be determined, as well as the influence of patient factors (such as age) and clinical circumstances. Although we do think mitochondrial oxygen tension is in general higher than anticipated ( 12 ), the reader should realize that mitoPO 2 in other organs and tissues is likely to differ. Differences in tissue oxygen levels exist between organs, tissues, and tissue compartments ( 43 ) and metabolic activity (for example muscle contraction) is also of influence.…”

“…The recent introduction of the non-invasive Cellular Oxygen METabolism (COMET) monitor (Photonics Healthcare B.V., Utrecht, The Netherlands) makes it possible to measure in vivo mitochondrial oxygen tension (mitoPO 2 ). Although mitochondrial oxygen sensing has been recognized as a promising technique for pediatric ICU and anesthesia ( 11 , 12 ), until now reported use has been limited to adults ( 13 – 16 ). The present study tests feasibility and safety of intraoperative use of COMET monitoring in infants for the first time.…”

Pathophysiology and clinical implications of the veno-arterial PCO2 gap

“…Mitochondrial defects have been demonstrated in several tissues obtained from animals in various models of sepsis, and limited data also exist on altered mitochondrial metabolism in human biopsy samples or circulating blood cells [20]. The detection of cytopathic hypoxia, however, is still not feasible at the bedside, although new techniques such as the measurement of mitochondrial O 2 tension using protoporphyrin IX-Triplet State Lifetime Technique (PpIX-TSLT) are currently being developed [21]. Furthermore, impaired O 2 extraction in sepsis does not necessary imply cytopathic hypoxia, as it may be related to impaired microcirculation.…”

Hypoxia Inducible Factors as Central Players in the Pathogenesis and Pathophysiology of Cardiovascular Diseases

“…Recently, emerging evidence suggested measuring mitochondrial oxygen tension as an alternative to gasometry. The rationale for this is mitochondria are the ultimate destination of oxygen utilization (8). Therefore, a precise understanding of the location of the hypoxic insult is relevant to develop a more accurate measurement of regional hypoxia.…”