Electrical Impedance Tomography for Positive End-Expiratory Pressure Titration in COVID-19–related Acute Respiratory Distress Syndrome
Philip van der Zee, Peter Somhorst, Henrik Endeman, Diederik Gommers
Abstract
To the Editor:Coronavirus disease (COVID-19) spreads rapidly and has already resulted in severe burden to hospitals and ICUs worldwide.Early reports described progression to acute respiratory distress syndrome (ARDS) in 29% of cases (1).It is unknown how to titrate positive end-expiratory pressure (PEEP) in patients with ARDS.Patient survival improved if higher PEEP successfully recruited atelectatic lung tissue (2).However, excessive PEEP caused alveolar overdistention, resulting in reduced patient survival (3).Therefore, PEEP should be personalized to maximize alveolar recruitment and minimize the amount of alveolar overdistention.Electrical impedance tomography (EIT) provides a reliable bedside approach to detect both alveolar overdistention and alveolar collapse (4).We describe a case series of patients with COVID-19 and moderate to severe ARDS in whom EIT was applied to personalize PEEP based on the lowest relative alveolar overdistention and collapse.Subsequently, we compared this PEEP level with the PEEP that could have been set according to the lower or higher PEEP-FI O 2 table from the ALVEOLI trial (5).These early experiences may help clinicians to titrate PEEP in patients with COVID-19 and ARDS. MethodsStudy design and inclusion criteria.We conducted this case series between March 1, 2020, and March 31, 2020, in our tertiary referral ICU (Erasmus Medical Center, Rotterdam, the Netherlands).All consecutive mechanically ventilated patients admitted to the ICU with COVID-19 and moderate to severe ARDS (according to the Berlin definition of ARDS) were included in this study.COVID-19 was defined as a positive result on a PCR of sputum, nasal swab, or pharyngeal swab specimen.The local medical ethical committee approved this study.Informed consent was obtained from all patients' legal representatives.Study protocol.A PEEP trial was performed daily in all patients according to our local mechanical ventilation protocol.Patients were fully sedated with continuous intravenous infusion of propofol, midazolam, and opiates.Persisting spontaneous breathing efforts were prevented with increased sedation or neuromuscular blockade.Arterial blood pressure was measured continuously.