Oxygen therapy limiting peripheral oxygen saturation to 89-93% is associated with a better survival prognosis for critically ill COVID-19 patients at high altitudes.

Patients admitted to the Intensive Care Unit (ICU) with acute hypoxemic respiratory failure automatically receive oxygen therapy to improve inspiratory oxygen fraction (FiO2). Supplemental oxygen is the most prescribed drug for critically ill patients regardless of altitude of residence. In high altitude dwellers (i.e. in La Paz [≈3,400 m] and El Alto [≈4,150 m] in Bolivia), a peripheral oxygen saturation (SatpO2) of 89-95% and an arterial partial pressure of oxygen (PaO2) of 50-67 mmHg (lower as altitude rises), are considered normal values ​​for arterial blood. Consequently, it has been suggested that limiting oxygen therapy to maintain SatpO2 around normoxia may help avoid episodes of hypoxemia, hyperoxemia, intermittent hypoxemia, and ultimately, mortality. In this study, we evaluated the impact of oxygen therapy on the mortality of critically ill COVID-19 patients who permanently live at high altitudes. A multicenter cross-sectional descriptive observational study was performed on 100 patients admitted to the ICU at the "Clinica Los Andes" (in La Paz city) and "Agramont" and "Del Norte" Hospitals (in El Alto city). Our results show that: 1) as expected, fatal cases were detected only in patients who required intubation and connection to invasive mechanical ventilation as a last resort to overcome their life-threatening desaturation; 2) among intubated patients, prolonged periods in normoxia are associated with survival, prolonged periods in hypoxemia are associated with death, and time spent in hyperoxemia shows no association with survival or mortality; 3) the oxygenation limits required to effectively support the intubated patients' survival in the ICU are between 89% and 93%; 4) among intubated patients with similar periods of normoxemic oxygenation, those with better SOFA scores survive; and 5) a lower frequency of observable reoxygenation events is not associated with survival. In conclusion, our findings indicate that high-altitude patients entering an ICU at altitudes of 3,400 - 4,150 m should undergo oxygen therapy to maintain oxygenation levels between 89 and 93 %.

Low serum erythropoietin levels are associated with fatal COVID-19 cases at 4,150 meters above sea level.

Previous studies suggested that erythropoietin (EPO) may protect against severe COVID-19-induced injuries, ultimately preventing mortality. This hypothesis is based on the fact that, in addition to promoting the increase in red blood cells, EPO is an anti-inflammatory, anti-apoptotic and protective factor in several non-erythropoietic tissues. Furthermore, EPO promotes nitric oxide production in the hypoxic lung and stimulates ventilation by interacting with the respiratory centers of the brainstem. Given that EPO in the blood is increased at high-altitude, we evaluated the serum levels of EPO in critical patients with COVID-19 at "Hospital Agramont" in the city of El Alto (4150 masl) in Bolivia. A total of 16 patients, 15 men, one woman, with a mean age of 55.8 ± 8.49 years, admitted to the Intensive Care Unit were studied. All patients were permanent residents of El Alto, with no travel history below 3000 masl for at least one year. Blood samples were collected upon admission to the ICU. Serum EPO concentration was assessed using an ELISA kit, and a standard technique determined hemoglobin concentration. Only half of the observed patients survived the disease. Remarkably, fatal cases showed 2.5 times lower serum EPO than survivors (2.78 ± 0.8643 mU/mL vs 7.06 ± 2.713 mU/mL; p = 0.0096), and 1.24 times lower hemoglobin levels (13.96 ± 2.56 g/dL vs 17.41 ± 1.61 g/dL; p = 0.0159). While the number of cases evaluated in this work is low, our findings strongly warrant further investigation of EPO levels in COVID-19 patients at high and low altitudes. Our results also support the hypothesis that exogenous EPO administration could help critically ill COVID-19 patients overcome the disease.

Caracterización de la preeclampsia a gran altitud / Characterization of high-altitude preeclampsia

Introducción: La muy alta altitud, es un reto para la adaptación humana debido a la disminución de la presión barométrica y consecuente disminución en la presión parcial arterial de oxígeno. A su vez se encuentra descrito un incremento de endotelina, tromboxano A2 y Factor de necrosis tumoral alfa con reducción asociada de prostaciclina en casos de preeclampsia. El objetivo del presente estudio es describir las características clínicas de pacientes con preeclampsia a 4150 metros sobre el nivel del mar.

Hemorragia intracerebral espontánea durante el embarazo: reporte de caso / Spontaneous intracerebral hemorrhage during pregnancy: case report

Introducción: La hemorragia intracerebral espontánea (HICE) o no traumática es una causa importante de morbilidad y mortalidad en todo el mundo, la cual ha tenido un incremento dramático durante la última década en casos reportados durante el embarazo. El objetivo es presentar en caso de una paciente con hemorragia intracerebral espontanea quien recibió neurocirugía y manejo en cuidados intensivos con evolución favorable de binomio materno fetal.