The catalytic oxidation of potato starch by [MnIV2 (μ-O)3(tmtacn)2][H2O](CH3COO)2 (Mncat, with tmtacn =1,4,7-trimethyl-1,4,7-triazacyclononane) with H2O2, was recently introduced as a promising alternative to ubiquitous sodium hypochlorite (NaOCl). Here, we report an in-depth investigation into interactions of the catalyst with the starch granule. Pitted starches obtained by pre-treatment with high-frequency ultrasound (HFUS) were shown to result in a uniquely homogeneous oxidation. To study this further, fractionation of oxidised potato starch was done which showed a preference for the oxidation of smaller granules with a higher relative surface area. This result was corroborated by chemical surface gelatinisation of fractionated granules. These studies showed that the inside of the granules was oxidised, but that Mncat had a moderate preference for oxidation of the periphery. Together, these results allow for a better understanding of oxidation of starch by Mncat and how it differs from NaOCl oxidation making further optimisation of the process possible.
BACKGROUND: Increasing evidence indicates the potential benefits of restricted fluid management in critically ill patients. Evidence lacks on the optimal fluid management strategy for invasively ventilated COVID-19 patients. We hypothesized that the cumulative fluid balance would affect the successful liberation of invasive ventilation in COVID-19 patients with acute respiratory distress syndrome (ARDS).METHODS: We analyzed data from the multicenter observational 'PRactice of VENTilation in COVID-19 patients' study. Patients with confirmed COVID-19 and ARDS who required invasive ventilation during the first 3 months of the international outbreak (March 1, 2020, to June 2020) across 22 hospitals in the Netherlands were included. The primary outcome was successful liberation of invasive ventilation, modeled as a function of day 3 cumulative fluid balance using Cox proportional hazards models, using the crude and the adjusted association. Sensitivity analyses without missing data and modeling ARDS severity were performed.RESULTS: Among 650 patients, three groups were identified. Patients in the higher, intermediate, and lower groups had a median cumulative fluid balance of 1.98 L (1.27-7.72 L), 0.78 L (0.26-1.27 L), and - 0.35 L (- 6.52-0.26 L), respectively. Higher day 3 cumulative fluid balance was significantly associated with a lower probability of successful ventilation liberation (adjusted hazard ratio 0.86, 95% CI 0.77-0.95, P = 0.0047). Sensitivity analyses showed similar results.CONCLUSIONS: In a cohort of invasively ventilated patients with COVID-19 and ARDS, a higher cumulative fluid balance was associated with a longer ventilation duration, indicating that restricted fluid management in these patients may be beneficial. Trial registration Clinicaltrials.gov ( NCT04346342 ); Date of registration: April 15, 2020.
