Monitoring of mitochondrial oxygen tension in the operating theatre: An observational study with the novel COMET® monitor.

INTRODUCTION: The newly introduced Cellular Oxygen METabolism (COMET®) monitor enables the measurement of mitochondrial oxygen tension (mitoPO2) using the protoporphyrin IX triplet state lifetime technique (PpIX-TSLT). This study aims to investigate the feasibility and applicability of the COMET® measurements in the operating theatre and study the behavior of the new parameter mitoPO2 during stable operating conditions. METHODS: In this observational study mitochondrial oxygenation was measured in 20 patients during neurosurgical procedures using the COMET® device. Tissue oxygenation and local blood flow were measured by the Oxygen to See (O2C). Primary outcomes included mitoPO2, skin temperature, mean arterial blood pressure, local blood flow and tissue oxygenation. RESULTS: All patients remained hemodynamically stable during surgery. Mean baseline mitoPO2 was 60 ± 19 mmHg (mean ± SD) and mean mitoPO2 remained between 40-60 mmHg during surgery, but tended to decrease over time in line with increasing skin temperature. CONCLUSION: This study presents the feasibility of mitochondrial oxygenation measurements as measured by the COMET® monitor in the operating theatre and shows the parameter mitoPO2 to behave in a stable and predictable way in the absence of notable hemodynamic alterations. The results provide a solid base for further research into the added value of mitochondrial oxygenation measurements in the perioperative trajectory.

Monitoring Mitochondrial Partial Oxygen Pressure During Cardiac Arrest and Extracorporeal Cardiopulmonary Resuscitation. An Experimental Pilot Study in a Pig Model.

Introduction: Ischemia and reperfusion are crucial in determining the outcome after cardiac arrest and can be influenced by extracorporeal cardiopulmonary resuscitation (ECPR). The effect of ECPR on the availability and level of oxygen in mitochondria remains unknown. The aim of this study was to find out if skin mitochondrial partial oxygen pressure (mitoPO2) measurements in cardiac arrest and ECPR are feasible and to investigate its course. Materials and Methods: We performed a feasibility test to determine if skin mitoPO2 measurements in a pig are possible. Next, we aimed to measure skin mitoPO2 in 10 experimental pigs. Measurements were performed using a cellular oxygen metabolism measurement monitor (COMET), at baseline, during cardiac arrest, and during ECPR using the controlled integrated resuscitation device (CIRD). Results: The feasibility test showed continuous mitoPO2 values. Nine experimental pigs could be measured. Measurements in six experimental pigs succeeded. Our results showed a delay until the initial spike of mitoPO2 after ECPR initiation in all six experimental tests. In two experiments (33%) mitoPO2 remained present after the initial spike. A correlation of mitoPO2 with mean arterial pressure (MAP) and arterial partial oxygen pressure measured by CIRD (CIRD-PaO2) seemed not present. One of the experimental pigs survived. Conclusions: This experimental pilot study shows that continuous measurements of skin mitoPO2 in pigs treated with ECPR are feasible. The delay in initial mitoPO2 and discrepancy of mitoPO2 and MAP in our small sample study could point to the possible value of additional measurements besides MAP to monitor the quality of tissue perfusion during cardiac arrest and ECPR.

Non-invasive versus ex vivo measurement of mitochondrial function in an endotoxemia model in rat: Toward monitoring of mitochondrial therapy.

Mitochondrial function has been predominantly measured ex vivo. Due to isolation and preservation procedures ex vivo measurements might misrepresent in vivo mitochondrial conditions. Direct measurement of in vivo mitochondrial oxygen tension (mitoPO2) and oxygen disappearance rate (ODR) with the protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) might increase our understanding of mitochondrial dysfunction in the pathophysiology of acute disease. LPS administration decreased mitochondrial respiration (ODR) in vivo but did not alter mitochondrial function as assessed with ex vivo techniques (high resolution respirometry and specific complex determinations). PpIX-TSLT measures in vivo mitoPO2 and ODR and can be applied non-invasively at the skin.

Prevalence and clinical consequences of herpes simplex virus type 1 DNA in human cornea tissues.

BACKGROUND: We determined the prevalence and clinical consequences of herpes simplex virus (HSV) type 1 (HSV-1), HSV type 2 (HSV-2), and varicella-zoster virus (VZV) in cornea tissues obtained after penetrating keratoplasty (PKP) was performed. METHODS: The excised corneas of 83 patients with a history of herpetic keratitis (HK; hereafter referred to as "patients with HK") and 367 patients without a history of HK (hereafter referred to "patients without HK") were analyzed by real-time polymerase chain reaction (PCR) and virus culture for the presence of HSV-1, HSV-2, and VZV. In addition, 273 post-PKP donor corneoscleral rims were analyzed. The medical records of the transplant patients were reviewed to determine the risk factors influencing intracorneal viral load and graft survival. RESULTS: HSV-1 was the most prevalent herpesvirus. Both the prevalence of HSV-1 and the HSV-1 DNA load were higher in the corneas of patients with HK than in those of patients without HK. The HSV-1 DNA load in the corneas of patients with HK correlated with age, the recurrence-free interval, cornea neovascularization, steroid treatment before PKP, and disease severity. Herpesvirus DNA was detected in 2 of 273 corneoscleral rims. Graft survival was inversely correlated with the corneal HSV-1 DNA load in patients with HK. CONCLUSIONS: The data presented in this study argue for the implementation of real-time HSV-1 PCR to analyze the excised corneas of patients with HK, to improve post-PKP diagnosis and therapy. Screening of donor corneal tissues for herpesviruses is redundant to prevent newly acquired post-PKP HK.