Low tidal volume ventilation and low driving pressure are key components of managing acute respiratory disease syndrome. But while there are no definitive data on how useful either strategy might be outside of ARDS, there are plenty of opinions. A special pro-con debate on Controversies in Mechanical Ventilation: Low Tidal Volumes and Driving Pressures will help clinicians evaluate the circumstantial and often conflicting evidence to chart a viable strategy for treating their own patients.
The debate will be presented live on Wednesday, October 21, from 2:15 pm to 3:15 pm CT. The session will be available for on-demand viewing 24 hours later on the virtual CHEST 2020 meeting platform through January 18.
“A landmark ARDS Network paper in 2000 established the benefits of putting ARDS patients on low tidal ventilation, conventionally defined as 6 mL/kg of ideal body weight,” said Kusun S. Mathews, MD, MPH, MSCR, assistant professor of pulmonary, critical care, and sleep medicine at the Icahn School of Medicine at Mount Sinai. “The real question today is the benefits and risks for patients who do not have ARDS.”
Dr. Mathews will argue that a lung-protective ventilation strategy is appropriate for every patient. Alice Gallo de Moraes, MD, assistant professor of pulmonary and critical care medicine at Mayo Clinic College of Medicine, will insist that low tidal volume is appropriate for ARDS patients, but not necessarily all patients in respiratory distress.
The PReVENT Trial, published in 2018, found no difference in outcomes between patients randomized to either low tidal volume, 6 mL/kg, and intermediate volume, 10 mL/kg. In the trial, the low tidal volume group did not require higher-dosed sedation, a concern that many clinicians have.
“We are terrible at diagnosing patients with ARDS,” Dr. Mathews said. “If we are giving them a higher tidal volume and don’t recognize ARDS until day 3, 5, or even 7 of their clinical course, this is on us. The risks associated with not using a lung-protective tidal volume in the meantime is something we can easily avoid. We should reset the default tidal volume to something that protects everyone on mechanical ventilation in case they develop ARDS. The harms are minimal, and the benefits are enormous.”
Driving pressure is another key controversy in mechanical ventilation. Observational data and reanalyses of prospective studies suggest that minimizing driving pressure leads to improved patient outcomes.
“It is reasonably clear the lower tidal volumes are good for patients in respiratory distress,” said David Bowton, MD, FCCP, professor of critical care medicine at Wake Forest University. “But large prospective trials that would focus solely on driving pressure would be expensive to undertake and have not been published to date. So, at this time, we have no direct evidence.”
Dr. Bowton will argue the pros and cons of reduced driving pressures with Richard Oeckler, MD, PhD, assistant professor of medicine and physiology, Mayo Clinic College of Medicine. Dr. Oeckler will suggest that one driving pressure does not fit all patients.
“Paying attention to driving pressure makes good sense and trying to minimize driving pressure makes good sense,” Dr. Bowton said. “But we shouldn’t get so full of ourselves that we think we know that reducing driving pressure at all costs is good. Thinking about driving pressure offers insight into ARDS, the physiology of mechanical ventilation, and alerts clinicians to over-inflation and regional over-distension and their potential impact on outcomes.”
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