Poor acute outcome in congestive heart failure is associated with increases in the plasma static oxidation-reduction potentials (sORP) in men but not in women

Unsuitability of the Oxidation-Reduction Potential Measurement for the Quantification of Fecal Redox Status in Inflammatory Bowel Disease

Oxidative stress is a key pathophysiological process associated with the development and progression of inflammatory bowel disease (IBD). Biomarkers for oxidative stress, however, are scarce, as are diagnostic tools that can interrogate an individual's gut redox status. This proof-of-concept study aimed to evaluate the potential utility of an oxidation-reduction potential (ORP) measurement probe, to quantify redox status in the feces of both patients with IBD and healthy controls. Previous studies using this ORP measurement probe demonstrated promising data when comparing ORP from severely malnourished individuals with that of healthy controls. To date, ORP analyses have not been performed in the context of IBD. We hypothesized that measuring the ORP of fecal water in patients with IBD might have diagnostic value. The current study, however, did not show significant differences in ORP measurement values between patients with IBD (median [IQR] 46.5 [33.0-61.2] mV) and healthy controls (25 [8.0-52.0] mV; p = 0.221). Additionally, ORP measurements were highly unstable and rapidly fluctuated throughout time, with ORP values varying from +24 to +303 mV. Due to potential biological processes and limitations of the measuring equipment, this study was unable to reliably measure ORP. As a result, our findings indicate that ORP quantification may not be a suitable method for assessing fecal redox status and, therefore, does not currently support further exploration as a diagnostic or monitoring tool.

Can a biomarker for oxidative stress and antioxidant reserves identify frailty in geriatric trauma patients?

OBJECTIVE

Frailty is a state of systematic physiologic decline and reduced ability to recover from illness. There are no rapid quantitative biological measures to assess frailty. The study objective was to determine whether oxidation-reduction potential (ORP) is correlated with frailty score.

METHODS

This prospective, observational cohort study was performed using plasma samples of geriatric trauma patients (≥65 years) admitted to a level I trauma center. Frailty was measured with the Canadian Study of Health and Aging (CSHA) Clinical Frailty Scale (7-point scale; 1 = robust health and 7 = severely frail). Plasma ORP was determined using the RedoxSYS™ system to measure static ORP (aggregate measure of oxidative stress) and capacity ORP (antioxidant reserves; log transformed). Spearman rank correlation (presented as r_s) and ordinal logistic regression (presented as adjusted odds ratios, AOR) were used to examine the unadjusted and adjusted relationship between frailty score and ORP values.

RESULTS

There were 93 geriatric trauma patients in our study. The majority (86%) had frailty scores 1-5, 11% were moderately frail and 3% were severely frail. There was a u-shaped relationship between ORP and frailty scale that became monotonic for scores 1-5. Each increase in frailty score demonstrated significant decreases in antioxidant reserves (log cORP r_s = -0.26, p = 0.02) and nonsignificant increases in oxidative stress (sORP r_s = 0.17, p = 0.15). After adjustment, variables significantly associated with frailty included log cORP (e.g., fewer antioxidant reserves, AOR: 0.70), age (AOR: 1.82), injury severity score (AOR: 0.50), admission lactate ≥2.5 mMol (AOR: 4.31), and alcohol use (AOR: 0.34).

CONCLUSIONS

The amount of antioxidant reserves (cORP) appears to be a quantitative marker to differentiate the degree of frailty ranging from robust health to mild frailty in geriatric trauma patients. We propose that direct quantification of frailty by way of a biomarker for oxidative reserves could have application in emergent trauma situations.

Rapid screening of critically ill patients for low plasma vitamin C concentrations using a point-of-care oxidation-reduction potential measurement

Background

Hypovitaminosis C and vitamin C deficiency are common in critically ill patients and associated with organ dysfunction. Low vitamin C status often goes unnoticed because determination is challenging. The static oxidation reduction potential (sORP) reflects the amount of oxidative stress in the blood and is a potential suitable surrogate marker for vitamin C. sORP can be measured rapidly using the RedoxSYS system, a point-of-care device. This study aims to validate a model that estimates plasma vitamin C concentration and to determine the diagnostic accuracy of sORP to discriminate between decreased and higher plasma vitamin C concentrations.

Methods

Plasma vitamin C concentrations and sORP were measured in a mixed intensive care (IC) population. Our model estimating vitamin C from sORP was validated by assessing its accuracy in two datasets. Receiver operating characteristic (ROC) curves with areas under the curve (AUC) were constructed to show the diagnostic accuracy of sORP to identify and rule out hypovitaminosis C and vitamin C deficiency. Different cut-off values are provided.

Results

Plasma vitamin C concentration and sORP were measured in 117 samples in dataset 1 and 43 samples in dataset 2. Bias and precision (SD) were 1.3 ± 10.0 µmol/L and 3.9 ± 10.1 µmol/L in dataset 1 and 2, respectively. In patients with low plasma vitamin C concentrations, bias and precision were − 2.6 ± 5.1 µmol/L and − 1.1 ± 5.4 µmol in dataset 1 (n = 40) and 2 (n = 20), respectively. Optimal sORP cut-off values to differentiate hypovitaminosis C and vitamin C deficiency from higher plasma concentrations were found at 114.6 mV (AUC 0.91) and 124.7 mV (AUC 0.93), respectively.

Conclusion

sORP accurately estimates low plasma vitamin C concentrations and can be used to screen for hypovitaminosis C and vitamin C deficiency in critically ill patients. A validated model and multiple sORP cut-off values are presented for subgroup analysis in clinical trials or usage in clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-021-00403-w.

Estimating Vitamin C Status in Critically Ill Patients with a Novel Point-of-Care Oxidation-Reduction Potential Measurement

Vitamin C deficiency is common in critically ill patients. Vitamin C, the most important antioxidant, is likely consumed during oxidative stress and deficiency is associated with organ dysfunction and mortality. Assessment of vitamin C status may be important to identify patients who might benefit from vitamin C administration. Up to now, vitamin C concentrations are not available in daily clinical practice. Recently, a point-of-care device has been developed that measures the static oxidation-reduction potential (sORP), reflecting oxidative stress, and antioxidant capacity (AOC). The aim of this study was to determine whether plasma vitamin C concentrations were associated with plasma sORP and AOC. Plasma vitamin C concentration, sORP and AOC were measured in three groups: healthy volunteers, critically ill patients, and critically ill patients receiving 2- or 10-g vitamin C infusion. Its association was analyzed using regression models and by assessment of concordance. We measured 211 samples obtained from 103 subjects. Vitamin C concentrations were negatively associated with sORP (R² = 0.816) and positively associated with AOC (R² = 0.842). A high concordance of 94–100% was found between vitamin C concentration and sORP/AOC. Thus, plasma vitamin C concentrations are strongly associated with plasma sORP and AOC, as measured with a novel point-of-care device. Therefore, measuring sORP and AOC at the bedside has the potential to identify and monitor patients with oxidative stress and vitamin C deficiency.