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Item Extracorporeal membrane oxygenation support for SARS-CoV-2: a multi-centered, prospective, observational study in critically ill 92 patients in Saudi Arabia(BMC, 2021-12-09) Alhumaid, Saad; Al Mutair, Abbas; Alghazal, Header A.; Alhaddad, Ali J.; Al‑Helal, Hassan; Al Salman, Sadiq A.; Alali, Jalal; Almahmoud, Sana; Alhejy, Zulfa M.; Albagshi, Ahmad A.; Muhammad, Javed; Khan, Amjad; Sulaiman, Tarek; Al‑Mozaini, Maha; Dhama, Kuldeep; Al‑Tawfiq, Jaffar A.; Rabaan, Ali A.; Medicine, School of MedicineBackground: Extracorporeal membrane oxygenation (ECMO) has been used as a rescue strategy in patients with severe with acute respiratory distress syndrome (ARDS) due to SARS-CoV-2 infection, but there has been little evidence of its efficacy. Objectives: To describe the effect of ECMO rescue therapy on patient-important outcomes in patients with severe SARS-CoV-2. Methods: A case series study was conducted for the laboratory-confirmed SARS-CoV-2 patients who were admitted to the ICUs of 22 Saudi hospitals, between March 1, 2020, and October 30, 2020, by reviewing patient's medical records prospectively. Results: ECMO use was associated with higher in-hospital mortality (40.2% vs. 48.9%; p = 0.000); lower COVID-19 virological cure (41.3% vs 14.1%, p = 0.000); and longer hospitalization (20.2 days vs 29.1 days; p = 0.000), ICU stay (12.6 vs 26 days; p = 0.000) and mechanical ventilation use (14.2 days vs 22.4 days; p = 0.000) compared to non-ECMO group. Also, there was a high number of patients with septic shock (19.6%) and multiple organ failure (10.9%); and more complications occurred at any time during hospitalization [pneumothorax (5% vs 29.3%, p = 0.000), bleeding requiring blood transfusion (7.1% vs 38%, p = 0.000), pulmonary embolism (6.4% vs 15.2%, p = 0.016), and gastrointestinal bleeding (3.3% vs 8.7%, p = 0.017)] in the ECMO group. However, PaO2 was significantly higher in the 72-h post-ECMO initiation group and PCO2 was significantly lower in the 72-h post-ECMO start group than those in the 12-h pre-ECMO group (62.9 vs. 70 mmHg, p = 0.002 and 61.8 vs. 51 mmHg, p = 0.042, respectively). Conclusion: Following the use of ECMO, the mortality rate of patients and length of ICU and hospital stay were not improved. However, these findings need to be carefully interpreted, as most of our cohort patients were relatively old and had multiple severe comorbidities. Future randomized trials, although challenging to conduct, are highly needed to confirm or dispute reported observations.Item Metabolic blood flow regulation in a hybrid model of the human retinal microcirculation(Elsevier, 2023) Albright, Amanda; Fry, Brendan C.; Verticchio, Alice; Siesky, Brent; Harris, Alon; Arciero, Julia; Mathematical Sciences, School of ScienceThe retinal vascular network supplies perfusion to vital visual structures, including retinal ganglion cells responsible for vision. Impairments in retinal blood flow and oxygenation are involved in the progression of many ocular diseases, including glaucoma. In this study, an established theoretical hybrid model of a retinal microvascular network is extended to include the effects of local blood flow regulation on oxygenation. A heterogeneous representation of the arterioles based on confocal microscopy images is combined with a compartmental description of the downstream capillaries and venules. A Green’s function method is used to simulate oxygen transport in the arterioles, and a Krogh cylinder model is applied to the capillary and venular compartments. Acute blood flow regulation is simulated in response to changes in pressure, shear stress, and metabolism. Model results predict that both increased intraocular pressure and impairment of blood flow regulation can cause decreased tissue oxygenation, indicating that both mechanisms represent factors that could lead to impaired oxygenation characteristic of ocular disease. Results also indicate that the metabolic response mechanism reduces the fraction of poorly oxygenated tissue but that the pressure- and shear stress-dependent response mechanisms may hinder the vascular response to changes in oxygenation. Importantly, the heterogeneity of the vascular network demonstrates that traditionally reported average values of tissue oxygen levels hide significant localized defects in tissue oxygenation that may be involved in disease processes, including glaucoma. Ultimately, the model framework presented in this study will facilitate future comparisons to sectorial-specific clinical data to better assess the role of impaired blood flow regulation in ocular disease.