From the Authors:
We thank Dr. Shekar and Dr. Schmidt for their letter regarding our recent publication (1). They raise important questions about the clinical impact and potential drawbacks of the near-apneic protocol tested in our study.
Regarding intrapulmonary shunt, we measured it at the end of the experiment (data not shown) and found no differences between the near-apneic group and the group ventilated with conventional protective ventilation, which suggests that near-apneic ventilation did not promote further atelectasis. Moreover, in the near-apneic ventilation, the contribution of the native lungs to oxygenation was significant by the end of the experiment, as indicated by oxygen tensions of 78 ± 4 mm Hg in the mixed venous blood and 300 ± 31 mm Hg in the arterial blood.
As pointed out in the Discussion of our study, we agree with Dr. Shekar and Dr. Schmidt in that applying very low respiratory rates and Vt during near-apneic ventilation may require deep sedation and neuromuscular blockade, which ideally should be avoided. However, observational studies have shown that during the first 3 days after connection to extracorporeal membrane oxygenation, most patients with acute respiratory distress syndrome are deeply sedated and paralyzed, even if they are not receiving near-apneic ventilation (2, 3).
To overcome these controversies, we now need clinical studies to identify the optimal ventilatory strategies for patients with acute respiratory distress syndrome connected to extracorporeal membrane oxygenation.
Footnotes
Originally Published in Press as DOI: 10.1164/rccm.201903-0690LE on April 2, 2019
Author disclosures are available with the text of this letter at www.atsjournals.org.
References
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