The oxygen dissociation curve of blood in COVID-19-An update

Towards an understanding of physical activity-induced post-exertional malaise: Insights into microvascular alterations and immunometabolic interactions in post-COVID condition and myalgic encephalomyelitis/chronic fatigue syndrome

BACKGROUND

A considerable number of patients who contracted SARS-CoV-2 are affected by persistent multi-systemic symptoms, referred to as Post-COVID Condition (PCC). Post-exertional malaise (PEM) has been recognized as one of the most frequent manifestations of PCC and is a diagnostic criterion of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Yet, its underlying pathomechanisms remain poorly elucidated.

PURPOSE AND METHODS

In this review, we describe current evidence indicating that key pathophysiological features of PCC and ME/CFS are involved in physical activity-induced PEM.

RESULTS

Upon physical activity, affected patients exhibit a reduced systemic oxygen extraction and oxidative phosphorylation capacity. Accumulating evidence suggests that these are mediated by dysfunctions in mitochondrial capacities and microcirculation that are maintained by latent immune activation, conjointly impairing peripheral bioenergetics. Aggravating deficits in tissue perfusion and oxygen utilization during activities cause exertional intolerance that are frequently accompanied by tachycardia, dyspnea, early cessation of activity and elicit downstream metabolic effects. The accumulation of molecules such as lactate, reactive oxygen species or prostaglandins might trigger local and systemic immune activation. Subsequent intensification of bioenergetic inflexibilities, muscular ionic disturbances and modulation of central nervous system functions can lead to an exacerbation of existing pathologies and symptoms.

Dynamic Assessment of Hematological Parameters as Predictive Biomarkers for Disease Severity and Prognosis in COVID-19 Patients: A Longitudinal Study

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to substantial morbidity and mortality worldwide. Hematological abnormalities are common in COVID-19 patients and play a significant role in disease pathogenesis and prognosis.

OBJECTIVE

This study aimed to longitudinally monitor hematological parameters in COVID-19 patients and investigate their predictive value for disease severity and prognosis.

METHODS

A prospective longitudinal design was employed to enroll 121 adult patients diagnosed with COVID-19 based on positive SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) test results. Baseline demographic and clinical data were collected, and hematological parameters, including complete blood count (CBC) indices, inflammatory markers, and coagulation profiles, were measured at predefined time points during hospitalization or outpatient visits. Follow-up assessments were conducted longitudinally to monitor the disease progression and clinical outcomes.

RESULTS

This study revealed dynamic changes in hematological parameters over the course of COVID-19. Hemoglobin levels showed a decrease from baseline (mean ± SD: 12.5 ± 1.8 g/dL) to the peak of illness (10.2 ± 2.0 g/dL), indicating the development of anemia during the acute phase of infection. White blood cell counts demonstrated an initial increase (8.9 ± 3.2 × 10^9/L) followed by a decline (5.4 ± 1.9 × 10^9/L) as the disease progressed, suggesting an early inflammatory response followed by immune suppression. The platelet counts fluctuated, with a decrease observed during the acute phase (190 ± 50 × 10^9/L) and subsequent recovery during convalescence (240 ± 60 × 10^9/L). Inflammatory markers, such as C-reactive protein and interleukin-6, were elevated, peaking at 120 and 150 pg/mL, respectively, indicating systemic inflammation. Coagulation profiles showed abnormalities suggestive of COVID-19-associated coagulopathy, including elevated D-dimer levels (mean ± SD: 3.5 ± 1.2 µg/mL) and prolonged prothrombin time (15.8 ± 2.5 seconds). Longitudinal analysis of hematological parameters revealed associations between disease severity and clinical outcomes, with certain abnormalities correlating with an increased risk of complications and a poor prognosis.

CONCLUSION

This study highlights the importance of monitoring hematological parameters in COVID-19 patients for risk stratification, prognostication, and guiding therapeutic interventions.

Blood oxygenation state in COVID-19 patients: Unexplored role of 2,3-bisphosphoglycerate

BACKGROUND

COVID-19 reduces lung functionality causing a decrease of blood oxygen levels (hypoxemia) often related to a decreased cellular oxygenation (hypoxia). Besides lung injury, other factors are implicated in the regulation of oxygen availability such as pH, partial arterial carbon dioxide tension (PaCO2), temperature, and erythrocytic 2,3-bisphosphoglycerate (2,3-BPG) levels, all factors affecting hemoglobin saturation curve. However, few data are currently available regarding the 2,3-BPG modulation in SARS-CoV-2 affected patients at the hospital admission.

MATERIAL AND METHODS

Sixty-eight COVID-19 patients were enrolled at hospital admission. The lung involvement was quantified using chest-Computer Tomography (CT) analysed with automatic software (CALIPER). Haemoglobin concentrations, glycemia, and routine analysis were evaluated in the whole blood, while partial arterial oxygen tension (PaO2), PaCO2, pH, and HCO3- were assessed by arterial blood gas analysis. 2,3-BPG levels were assessed by specific immunoenzymatic assays in RBCs.

RESULTS

A higher percentage of interstitial lung disease (ILD) and vascular pulmonary-related structure (VRS) volume on chest-CT quantified with CALIPER had been found in COVID-19 patients with a worse disease outcome (R = 0.4342; and R = 0.3641, respectively). Furthermore, patients with lower PaO2 showed an imbalanced acid-base equilibrium (pH, p = 0.0208; PaCO2, p = 0.0496) and a higher 2,3-BPG levels (p = 0.0221). The 2,3-BPG levels were also lower in patients with metabolic alkalosis (p = 0.0012 vs. no alkalosis; and p = 0.0383 vs. respiratory alkalosis).

CONCLUSIONS

Overall, the data reveal a different pattern of activation of blood oxygenation compensatory mechanisms reflecting a different course of the COVID-19 disease specifically focusing on 2,3-BPG modulation.

Development of novel polymer haemoglobin based particles as an antioxidant, antibacterial and an oxygen carrier agents

This innovative work aims to develop highly biocompatible and degradable nanoparticles by encapsulating haemoglobin (Hb) within poly-ε-caprolactone for novel biomedical applications. We used a modified double emulsion solvent evaporation method to fabricate the particles. A Scanning electron microscope (SEM) characterized them for surface morphology. Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet-visible spectroscopies (UV-visible) elucidated preserved chemical and biological structure of encapsulated haemoglobin. The airproof equilibrium apparatus obtained the oxygen-carrying capacity and P50 values. The DPPH assay assessed free radical scavenging potential. The antibacterial properties were observed using four different bacterial strains by disk diffusion method. The MTT assay investigates the cytotoxic effects on mouse fibroblast cultured cell lines (L-929). The MTT assay showed that nanoparticles have no toxicity over large concentrations. The well-preserved structure of Hb within particles, no toxicity, high oxygen affinity, P50 value, and IC50 values open the area of new research, which may be used as artificial oxygen carriers, antioxidant, and antibacterial agents, potential therapeutic agents as well as drug carrier particles to treat the cancerous cells. The novelty of this work is the antioxidant and antibacterial properties of developed nanoparticles are not been reported yet. Results showed that the prepared particles have strong antioxidant and antibacterial potential.

Changes in Hematological and Hemorheological Parameters Following Mild COVID-19: A 4-Month Follow-Up Study

BACKGROUND

Coronavirus Disease 2019 (COVID-19) was described to affect red blood cells (RBC) in both severe and mild disease courses. The aim of this study was to investigate whether hematological and hemorheological changes that were previously described for COVID-19 patients after the acute infection state are still prominent after another 4 months to assess potential long-term effects.

METHODS

Hematological and RBC rheological parameters, including deformability and aggregation, were measured 41 days after infection in COVID-19 patients and non-COVID control (T0) and 4 months later in COVID-19 patients (T1).

RESULTS

The data confirm alterations in hematological parameters, mainly related to cell volume and hemoglobin concentration, but also reduced deformability and increased aggregation at T0 compared to control. While RBC deformability seems to have recovered, hemoglobin-related parameters and RBC aggregation were still impaired at T1. The changes were thus more pronounced in male COVID-19 patients.

CONCLUSION

COVID-19-related changes of the RBC partly consist of several months and might be related to persistent symptoms reported by many COVID-19 patients.