Abstract One of the most dreadful complications that can occur during the course of COVID-19 is the cytokine storm—also known as cytokine release syndrome—a form of systemic inflammatory response syndrome triggered by SARS-CoV-2 infection. The cytokine storm is an activation cascade of auto-amplifying cytokines, which leads to excessive activation of immune cells and generation of pro-inflammatory cytokines. It occurs when large numbers of white blood cells are activated and release inflammatory cytokines, in turn activating even more white blood cells, finally resulting in an exaggerated pro-inflammatory–mediated response and ineffective anti-inflammatory control, leading to tissue damage, multiorgan failure, acute respiratory distress syndrome and death. Although cytokine storm pathogenesis is multifactorial, we hypothesize there is a close association between hypoxemia and cytokine storms in COVID-19, although it is difficult to establish the direction of this relationship. Most probably they coexist and, given enough time, one triggers the other in a chain reaction. Careful analysis of the day-to-day clinical evolution of COVID-19 indicates that there are short and slight periods of hypoxemia (confirmed by pulse oximetry and arterial gasometry), even on the day of the onset of persistent cough and/or shortness of breath. We propose the use of continuous positive airway pressure in early stages of COVID-19, at the onset of respiratory symptoms. This non-invasive ventilation method may be useful in individualized treatments to prevent early hypoxemia in COVID-19 patients and thus avoid triggering a cytokine storm. We believe such an approach is relevant everywhere, and in Cuba in particular, since the country has initiated national production of mechanical ventilation systems, including non-invasive ventilators. Moreover, as Cuba’s COVID-19 protocols ensure early patient admission to isolation centers or hospitals, clinicians can prescribe the early use of continuous positive airway pressure as soon as respiratory symptoms begin, averting early hypoxemia and its triggering effect on cytokine storm development, and consequently, avoiding acute respiratory distress syndrome, multi-organ failure, and death.

Introduction: The scientific-technical development of XX century allowed a new medical specialty, the intensive therapy. This medicine advance made that the physician faced a clinical state difficult to imagine some times ago, where the ills lost their functions integrate in encephalon, while other body organs maintained integrity. To arised the following question: These ills with an association a dead encephalon with a live body were lives or deaths? Thus appears the concept of encephalic death (ED), synonym of subject death. Material and Methods: Authors made a review of the death formulations with neurologic bases, as well as of physiopathologic mechanisms for the consciousness generation. Results: It is demonstrated that consciousness is the function providing the human attributes essential of human existence where each subject be unique and to establish the higher level of organism integration. We propose a new death formulation on neurologic basis explaining why the ED is an irreversible state and also an event occurring at the end of disappearance of functions integrated in encephalon. Conclusions: Authors propose a new death formulation allows confirming that ED is synonym of subject death.

Introducción. El desarrollo científico-técnico del siglo XX hizo posible el surgimiento de una nueva especialidad médica, la terapia intensiva. Este adelanto de la medicina llevó al médico a enfrentar un estado clínico, difícil de imaginar pocos años atrás, en el que los enfermos perdían sus funciones integradas en el encéfalo, mientras otros órganos del cuerpo mantenían su integridad. Surgía así una pregunta: ¿Estos enfermos en los que se asociaba un encéfalo muerto con un cuerpo vivo, estaban vivos o muertos? Así surge el concepto de muerte encefálica (ME), sinónimo de muerte del individuo. Material y Método: Se hace una revisión de las formulaciones de la muerte sobre bases neurológicas, así como de los mecanismos fisiopatológicos para la generación de la conciencia. Resultados. Se demuestra que la conciencia es la función que provee los atributos humanos esenciales de la existencia humana, que hacen que cada individuo sea irrepetible, y establece el nivel más alto de integración del organismo. Se propone una nueva formulación sobre la muerte sobre bases neurológicas que explicar por qué la ME es un estado irreversible, y es un evento que ocurre al final de la desaparición de las funciones integradas en el encéfalo. Conclusiones. Se propone una nueva formulación de la muerte que permite afirmar que la ME es sinónimo de muerte del individuo.

Authors reviewed on application of multimodality evoked potentials (MEP) for coma neuromonitoring and as confirmatory tests in brain death (BD) diagnosis. Results presented demonstrate the MEPs value in forecast of evolution course of comatose patients, allowing prediction of brain function deterioration and thus, physician may take early therapeutic measures before establishment of irreversible brain lesions. The high time resolution of these tests allows an early detection of bran function changes, making them suitable for neuromonitoring of critical patients. In relation to MEPs and the electroretinogram (ERG) application, as confirmatory tests in the diagnosis of BD, characteristic electrophysiological patterns are found showing a lack of sensorial conduction in three different pathways within the skull. However, when considering a confirmatory test battery but not as isolated techniques, it is possible to optimize the electrophysiological study and to increase diagnostic reliability. By other hand, due to MEPs and ERG resistance to hypothermia, to use of barbiturates, to anesthetics, to intoxications from different drugs, to anoxia, etc, it is possible to apply such test battery in decreasing observation time required to establish the definite diagnosis of BD, and to confirm this diagnosis in clinical circumstances that make difficult this diagnostic procedure.

Se hizo una revisión sobre la aplicación de los potenciales evocados multimodales (PEM) para la neuromonitorización del coma, y como pruebas confirmatorias, en el diagnóstico de la muerte encefálica (ME). Los resultados presentados demuestran el valor de los PEM en la predicción del curso evolutivo del paciente comatoso, al predecir el deterioro de la función encefálica, lo que permite que el médico pueda tomar medidas terapéuticas tempranas, antes de que se establezcan lesiones encefálicas irreversibles. La alta resolución temporal de estas pruebas, capaces de detectar cambios funcionales del encéfalo en milisegundos, las hace idóneas para la neuromonitorización de pacientes críticos. En relación con la aplicación de los PEM y el electrorretinograma (ERG) como pruebas confirmatorias en el diagnóstico de la ME, se encontraron patrones electrofisiológicos característicos que indican la ausencia de la conducción sensorial en 3 vías diferentes, dentro de la cavidad craneana. No obstante, al considerarse una batería de pruebas confirmatorias y no como técnicas aisladas, permite optimizar el estudio electrofisiológico, y aumentar la confiabilidad diagnóstica. Por otro lado, por la resistencia de los PEM y del ERG a la hipotermia, al empleo de barbitúricos, anestésicos, a intoxicaciones por diferentes fármacos, a la anoxia, etc., permite aplicar dicha batería de pruebas para reducir el tiempo de observación requerido para establecer el diagnóstico definitivo de la ME, y confirmar dicho diagnóstico en situaciones que dificulten ese proceder.

During centuries, the irreversible absence of spontaneous cardiorespiratory function was considered as a determinant of the individual's death. However, with the development of intensive therapy, the integrated functions within the brain began to be considered as the main reason to state a definition of human death. There are 3 major trends related to the definition of death in the human being based on neurologic foundations: those which refer to the loss of the essential qualities which identify the human nature; those refering to the loss of body integration as a whole , and those which intend to define the position of the brain that should stop functioning for a person to be dead. These definitions related to human death and oriented to brain functions are discussed, and it is concluded that consciousness (taking into consideration its 2 components: capacity and content), which neural basis are situated in the socalled reticular formation/cortex, is the function which provides the essential human atributes, and at the same time, integrates the functioning of the body as a whole. Thus, human death is defined as the irreversible loss of the capacity and the content of consciousness.

Durante siglos, la ausencia irreversible de la función cardiorrespiratoria espontánea se consideró como determinante de la muerte del individuo. Sin embargo, con el desarrollo de la terapia intensiva, las funciones integradas en el encéfalo comenzaron a ser consideradas como la razón principal para enunciar una definición de la muerte humana. Existen 3 grandes tendencias o escuelas en relación con la definición de la muerte en el hombre sobre bases neurológicas: aquellas que se refieren a la pérdida de tributos esenciales que identifican la naturaleza humana, aquellas que se refieren a la pérdida de la integración del organismo como un todo y las que tratan de definir la porción del encéfalo que debe cesar de funcionar irreversiblemente para que una persona pueda declararse fallecida. Se discuten estas definiciones de la muerte orientadas hacia las funciones encefálicas y se llega a la conclusión de que la conciencia (considerando sus 2 componentes: capacidad y contenido), cuyas bases neurales se ubican en la llamada unidad formación reticular/corteza, es la función que provee los atributos esencialmente humanos y, a la vez, integra el funcionamiento del organismo como un todo. Por tanto, se define la muerte humana como la pérdida irreversible de la capacidad y del contenido de la conciencia.