Journal of clinical monitoring and computing
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J Clin Monit Comput · Aug 2015
CommentEvaluating tissue oxygenation at the bedside: global, regional, or both?
Early recognition of tissue hypoperfusion, and monitoring tissue response to resuscitation interventions, are key points in the management of critically ill patients. In the present issue of J Clin Monit Comput, Dr. Koch and coworkers present the results of a study evaluating regional and global markers of tissue perfusion in a population of septic shock patients. We propose an integrative approach to tissue perfusion assessment, where combining both, global and regional variables, might account for a better understanding of tissue oxygenation status, and might prove useful for septic shock patients' management.
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J Clin Monit Comput · Aug 2015
Cutaneous mitochondrial respirometry: non-invasive monitoring of mitochondrial function.
The recently developed technique for measuring cutaneous mitochondrial oxygen tension (mitoPO2) by means of the Protoporphyrin IX-Triplet State Lifetime Technique (PpIX-TSLT) provides new opportunities for assessing mitochondrial function in vivo. The aims of this work were to study whether cutaneous mitochondrial measurements reflect mitochondrial status in other parts of the body and to demonstrate the feasibility of the technique for potential clinical use. The first part of this paper demonstrates a correlation between alterations in mitochondrial parameters in skin and other tissues during endotoxemia. ⋯ A first prototype of a clinical PpIX-TSLT monitor is described and its usability is demonstrated on human skin. We expect that clinical implementation of this device will greatly contribute to our understanding of mitochondrial oxygenation and oxygen metabolism in perioperative medicine and in critical illness. Our ultimate goal is to develop a clinical monitor for mitochondrial function and the current results are an important step forward.
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J Clin Monit Comput · Aug 2015
Hypoxic guard systems do not prevent rapid hypoxic inspired mixture formation.
Because a case report and theoretical mass balances suggested that hypoxic guard systems may not prevent the formation of hypoxic inspired mixtures (FIO2 ≤ 21 %) over the clinically used fresh gas flow (FGF) range, we measured FIO2 over a wide range of hypoxic guard limits for O2/N2O and O2/air mixtures. After IRB approval, 16 ASA I-II patients received sevoflurane in either O2/N2O (n = 8) or O2/air (n = 8) using a Zeus(®) anesthesia machine in the conventional mode. After using an 8 L/min FGF with FDO2 = 25% for 10 min, the following hypoxic guard limits were tested for 4 min each, expressed as [total FGF in L/min; FDO2 in %]: [0.3;85], [0.4;65], [0.5;50], [0.7;36], [0.85;30], [1.0;25], [1.25;25], [1.5;25], [2;25], [3;25], [5;25], and [8;25]. ⋯ In all 1, 1.25, and 1.5 L/min FGF groups, FIO2 decreased below 21% in all but one patient; this occurred within 1 min in at least one patient. In the 0.7 L/min O2/air group and the 3 L/min late O2/N2O and O2/air groups, FIO2 decreased below 21% in one patient. Current hypoxic guard systems do not reliably prevent a hypoxic FIO2 with O2/N2O and O2/air mixtures, particularly between 0.7 and 3 L/min.