Peripheral microcirculatory alterations are associated with the severity of acute respiratory distress syndrome in COVID-19 patients admitted to intermediate respiratory and intensive care units.

BACKGROUND: COVID-19 is primarily a respiratory disease; however, there is also evidence that it causes endothelial damage in the microvasculature of several organs. The aim of the present study is to characterize in vivo the microvascular reactivity in peripheral skeletal muscle of severe COVID-19 patients. METHODS: This is a prospective observational study carried out in Spain, Mexico and Brazil. Healthy subjects and severe COVID-19 patients admitted to the intermediate respiratory (IRCU) and intensive care units (ICU) due to hypoxemia were studied. Local tissue/blood oxygen saturation (StO2) and local hemoglobin concentration (THC) were non-invasively measured on the forearm by near-infrared spectroscopy (NIRS). A vascular occlusion test (VOT), a three-minute induced ischemia, was performed in order to obtain dynamic StO2 parameters: deoxygenation rate (DeO2), reoxygenation rate (ReO2), and hyperemic response (HAUC). In COVID-19 patients, the severity of ARDS was evaluated by the ratio between peripheral arterial oxygen saturation (SpO2) and the fraction of inspired oxygen (FiO2) (SF ratio). RESULTS: Healthy controls (32) and COVID-19 patients (73) were studied. Baseline StO2 and THC did not differ between the two groups. Dynamic VOT-derived parameters were significantly impaired in COVID-19 patients showing lower metabolic rate (DeO2) and diminished endothelial reactivity. At enrollment, most COVID-19 patients were receiving invasive mechanical ventilation (MV) (53%) or high-flow nasal cannula support (32%). Patients on MV were also receiving sedative agents (100%) and vasopressors (29%). Baseline StO2 and DeO2 negatively correlated with SF ratio, while ReO2 showed a positive correlation with SF ratio. There were significant differences in baseline StO2 and ReO2 among the different ARDS groups according to SF ratio, but not among different respiratory support therapies. CONCLUSION: Patients with severe COVID-19 show systemic microcirculatory alterations suggestive of endothelial dysfunction, and these alterations are associated with the severity of ARDS. Further evaluation is needed to determine whether these observations have prognostic implications. These results represent interim findings of the ongoing HEMOCOVID-19 trial. Trial registration ClinicalTrials.gov NCT04689477 . Retrospectively registered 30 December 2020.

Pentoxifylline, total urinary protein excretion rate and arterial blood pressure in long-term insulin-dependent diabetic patients with overt nephropathy.

A specific hemorheologic treatment might reduce urinary protein excretion and the decline in kidney function in diabetic patients with overt clinical nephropathy. Twenty-one insulin dependent (type I) diabetic patients were randomized and assigned to a treatment with conventional antihypertensive therapy (protocol I) or with pentoxifylline (Trental 400) (protocol II). A marked improvement of blood rheology pattern, together with a reduction of urinary albumin excretion rate and total urinary protein excretion rate, was demonstrated throughout a 1-year follow-up study with pentoxifylline. Furthermore a decrease of systolic and diastolic blood pressure levels was found during the treatment. The modification of these parameters was followed by a significant increase of creatinine clearance in each of the patients studied. The results obtained during pentoxifylline therapy were comparable to those obtained in patients treated with conventional antihypertensive drugs. Pentoxifylline may therefore be used in the treatment of advanced nephropathy in diabetic patients.

Determination of albuminuria in type 1 and type 2 diabetic patients with microproteinuria and overt nephropathy. Comparative evaluation between a radial immunodiffusion procedure and a highly sensitive radioimmunoassay.

We have studied the correlation between urinary albumin excretion rate evaluated by a radial immunodiffusion technique and a highly sensitive radioimmunoassay in type 1 and type 2 diabetic patients with microproteinuria and overt clinical nephropathy. Several statistically significant correlations were found between urinary albumin excretion rate measured by radial immunodiffusion and by radioimmunoassay, both in patients with microproteinuria and overt nephropathy. Moreover, statistically significant correlations between urinary albumin excretion rate, albumin clearance and total urinary protein excretion rate were observed in each of the groups studied. The radial immunodiffusion procedure can therefore be considered a useful and sensitive method for the evaluation of urinary albumin excretion rate both in diabetic patients with microproteinuria and in patients with overt clinical nephropathy.