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A 65-year-old man in cardiogenic shock with copious pulmonary edema could not be ventilated despite paralysis and was placed on venoarterial-extracorporeal membrane oxygenation. Initial ventilator settings were pressure control ventilation 10 cm H2O, positive end-expiratory pressure 20 cm H2O, and respiratory rate 15 breaths per minute. Both Vt and e were negligible.
An esophageal balloon showed high esophageal pressure (35 cm H2O) and negative values of transpulmonary pressure (estimated as airway pressure − esophageal pressure) (1, 2) during the entire respiratory cycle (from −16 to −6 cm H2O). To obtain a continuous visualization of ventilation during a lung recruitment maneuver, an electrical impedance tomography belt was applied around the patient’s chest (3). Interestingly, air started to enter in the lungs when airway pressure overcame esophageal pressure (airway pressure > 35 cm H2O). As suggested by Yoshida and colleagues (4), esophageal pressure can be used as a surrogate of pleural pressure, and positive end-expiratory pressure should be titrated to reach positive values of transpulmonary pressure to allow ventilation.
Figure 1. Changes of esophageal and airway pressures, electrical impedance tomography images (EIT), and other respiratory mechanic parameters before (absence of ventilation) and immediately after the application of a lung recruitment maneuver and positive end-expiratory pressure (PEEP) titrated to best respiratory system compliance (restored ventilation) (2). Esophageal pressure is represented by the blue trace (35 cm H2O) and airway pressure by the red trace (from 20 to 40 cm H2O). EIT images show in blue areas of ventilated lungs and in gray absence of ventilation (despite PEEP of 20 cm H2O). Airway pressure, flow, and Vt traces are provided; Pplateau, PEEP, and compliance before and during the lung recruitment maneuver are listed. A = anterior; P = posterior; Pplateau = plateau pressure.
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| 1. | Loring SH, Topulos GP, Hubmayr RD. Transpulmonary pressure: the importance of precise definitions and limiting assumptions. Am J Respir Crit Care Med 2016;194:1452–1457. |
| 2. | Pirrone M, Fisher D, Chipman D, Imber DA, Corona J, Mietto C, et al. Recruitment maneuvers and positive end-expiratory pressure titration in morbidly obese ICU patients. Crit Care Med 2016;44:300–307. |
| 3. | Franchineau G, Bréchot N, Lebreton G, Hekimian G, Nieszkowska A, Trouillet JL, et al. Bedside contribution of electrical impedance tomography to setting positive end-expiratory pressure for extracorporeal membrane oxygenation-treated patients with severe acute respiratory distress syndrome. Am J Respir Crit Care Med 2017;196:447–457. |
| 4. | Yoshida T, Amato MBP, Grieco DL, Chen L, Lima CAS, Roldan R, et al. Esophageal manometry and regional transpulmonary pressure in lung injury. Am J Respir Crit Care Med 2018;197:1018–1026. |
Originally Published in Press as DOI: 10.1164/rccm.201805-0938IM on August 10, 2018
Author disclosures are available with the text of this article at www.atsjournals.org.
