Ventilators for Nonintensivists. Monitoring Initial Ventilator Settings in Patients with Acute Respiratory Distress Syndrome

Video 1.

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Monitoring initial ventilator settings in acute respiratory distress syndrome.

As coronavirus disease (COVID-19) has rapidly evolved into a pandemic, many physicians without prior critical care training are being called upon to help manage patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection who develop respiratory failure and require mechanical ventilation. This video is intended to provide a brief and simplified approach to mechanical ventilation for nonintensivists, with an overview of monitoring initial ventilator settings for patients with acute respiratory distress syndrome. The parameters that control the arterial oxygen tension and therefore the means for managing hypoxemia are the fraction of inspired oxygen (Fi_O2) and the positive end-expiratory pressure (PEEP). The parameters that control the arterial carbon dioxide tension and therefore the means for managing hypercarbia are the respiratory rate and the tidal volume (Vt). Whether the Vt is set directly (volume control) or indirectly by setting the pressure (pressure control), a lung-protective ventilatory strategy in which the Vt is set at 4–8 ml/kg of predicted body weight is recommended. After setting these initial parameters, the clinician should watch closely for potential negative consequences of mechanical ventilation by assessing the patient’s hemodynamic status, arterial blood gases, plateau pressure (Ppl), and auto-PEEP. The goals of oxygenation are 1) acceptable oxygen saturations (typically 88–95%), 2) Fi_O2 < 60%, and 3) hemodynamic stability. The goals of ventilation are 1) acceptable carbon dioxide tension and pH (typically pH > 7.20), 2) minimal auto-PEEP, and 3) Ppl < 30 cm H₂O. In patients who cooperate with the maneuver, auto-PEEP and Ppl are alveolar pressures that can be measured by end-expiratory and end-inspiratory hold, respectively. An intensivist should be consulted if the goals of oxygenation and ventilation cannot be achieved simultaneously.