Interpretation and use of intraoperative protective ventilation parameters: a scoping review.

Thirty years ago, the traditional approach to mechanical ventilation consisted of the normalization of PaCO2 and pH at the expense of using a tidal volume (VT) of 10-15 mL kg-1. But then, the use of 6-8 mL kg-1 became a dogma for ventilating patients either with acute respiratory distress syndrome (ARDS) or without lung disease in the operating theatre. It is currently recognized that even low tidal volumes may be excessive for some patients and insufficient for others, depending on its distribution in the aerated lung parenchyma. To carry out intraoperative protective mechanical ventilation, medical literature has focused on positive end expiratory pressure (PEEP), plateau pressure (Paw plateau), and airway driving pressure (ΔPaw). However, considering its limitations, other parameters have emerged that represent a better reflection of isolated lung stress, such as transpulmonary pressure (PL) and transpulmonary driving pressure (ΔPL). These parameters are less generalized in clinical practice due to the requirement of an oeso-phageal balloon for their measurement and therefore their cumbersome application in the operating theatre. However, its study helps in the interpretation of the rest of the ventilator pressures to optimize intraoperative mechanical ventilation. This article defines and develops protective ventilation parameters, breaks down their determinants, mentions their limitations, and offers recommendations for their use intraoperatively.

Mecánica respiratoria en anestesia general: Revisión de conceptos / Respiratory mechanics in general anesthesia: Concepts review

In anesthesia practice, mechanical ventilation is a fundamental tool, and its correct configuration is essential in the patients care. Airway pressure is often assumed to reflect the forces applied to the lung and is used to monitor mechanical ventilation. This assumption is erroneous because pressure acts on the respiratory system as a whole and the impact on its components will depend on the ratio of lung and respiratory system elastances. In turn, patients' lungs with the same body size and ventilated with the same tidal volume, may be subjected to different forces depending on their functional size. This is expressed under the concepts of stress and strain. Its surrogate owners, the Paw plateau and the Vt, have shown a poor correlation compared to transpulmonary pressure and the airway driving pressure. This review aims to provide the theoretical-practical tools necessary to optimize mechanical ventilation for each patient.

En la práctica anestésica, la ventilación mecánica es una herramienta fundamental, y su correcta configuración es esencial en el cuidado de los pacientes. La presión de la vía aérea es, muchas veces, asumida como el reflejo de las fuerzas aplicadas en el pulmón y es utilizada para monitorizar la ventilación mecánica. Esta asunción es errónea porque la presión actúa sobre el sistema respiratorio en su totalidad y la repercusión sobre sus componentes va a depender de la relación de elastancias del pulmón y el sistema respiratorio. A su vez, los pulmones de pacientes con el mismo tamaño corporal y ventilados con el mismo volumen corriente, pueden estar sujetos a diferentes fuerzas dependiendo de su tamaño funcional. Esto es expresado bajo los conceptos de stress y strain. Sus respectivos subrogantes, Pawplateau y el Vt, han demostrado tener una pobre correlación en comparación con la presión transpulmonar y la airway driving pressure. Esta revisión pretende brindar las herramientas teórico-prácticas necesarias para optimizar la ventilación mecánica para cada paciente.

Ventilación mecánica compartida: ¿Una herramienta fútil o una estrategia aceptable para superar la crisis? / Shared mechanical ventilation: A futile tool or an acceptable strategy to overcome the crisis?

Different events can trigger health crises, where demand exceeds the response capacity of the health system. In the current context of the COVID-19 pandemic, one edge of this demand may be the need for ventilatory support. Among the strategies to deal with the problem, a new possibility arises: using a single ventilator for more than one patient until adequate resources arrive. This work reviews the available evidence, exposes the physical foundations of its operation and draws attention to the warnings.

Diferentes eventos pueden desencadenar crisis sanitarias, donde la demanda excede la capacidad de respuesta del sistema de salud. En el contexto actual de la pandemia de COVID-19, una arista de esta demanda puede ser la necesidad de soporte ventilatorio. Dentro de las posibles estrategias para afrontar el problema, surge la posibilidad de utilizar un único ventilador para dar soporte a más de un paciente hasta que lleguen los recursos adecuados. Este trabajo pretende revisar la evidencia disponible, exponer los fundamentos físicos de su funcionamiento y llamar la atención sobre las advertencias.