Lower-PEEP Strategy Promising in Critically Ill Patients Without Respiratory Distress

By Megan Brooks

December 17, 2020

NEW YORK (Reuters Health) - For critically ill patients without acute respiratory distress syndrome (ARDS), a ventilation strategy with lower positive end-expiratory pressure (PEEP) was as good as a strategy using higher PEEP with respect ventilator-free days in the RELAx study.

Dr. Marcus Schultz with Amsterdam University Medical Centers, in the Netherlands, presented the study results December 9 at the European Society of Intensive Care Medicine (ESICM) virtual meeting, with simultaneous publication in JAMA.

Several randomized clinical trials over the last two decades have showed no benefit of a higher- versus lower-PEEP strategy in patients with ARDS, he explained. One meta-analysis suggested benefit, but only in patients with moderate to severe ARDS, while harm was suggested in patients with mild ARDS, as in these patients, it seemed to delay extubation.

Much less attention has been paid to the use of PEEP in patients without ARDS, although "observational data suggest a higher PEEP level is increasingly being used but the benefits and potential harms are not well understood," Dr. Schultz said.

In patients without ARDS, benefit could exist with higher PEEP "if there is improved aeration, leading to a better oxygenation, and some studies suggest that there may be less ARDS. There also may be less ventilator-associated pneumonia with the use of higher PEEP. Animal studies, however, suggest that there is a risk of over-distention, and maybe an increase in the worsening or inducing of new lung injuries," Dr. Schultz explained. Impaired hemodynamics and delay in extubation are also possible.

The RELAx trial was a noninferiority study conducted in eight intensive-care units (ICUs) in the Netherlands. It enrolled 980 patients (mean age, 66 years) without ARDS expected not to be extubated within 24 hours of intubation. Patients were randomly allocated to a lower-PEEP strategy (lowest level between 0 to 5 cm H2O) or a higher PEEP strategy (8 cm H2O).

Results showed no significant difference in the primary outcome of the number of ventilator-free days by study day 28 (18 days with the lower-PEEP strategy and 17 days with the higher-PEEP strategy). The lower-PEEP strategy was within the noninferiority margin of -10%.

The findings show that there is "no inferiority of the lower-PEEP strategy versus a higher-PEEP strategy in these patients. Meaning that a lower-PEEP strategy is as good as a higher PEEP strategy," Dr. Schultz reported.

There were no between-group differences in duration until extubation, hospital and ICU length of stay and 28-day mortality.

In the lower-PEEP group, rates of severe hypoxemia (20.6% vs. 17.6%) and the need for rescue therapy (19.7% vs. 14.6%) were numerically higher but not statistically significantly different in adjusted analysis, "suggesting the possibility that lower PEEP may have been inferior for some patients," caution the co-authors of a JAMA editorial.

"For an average patient without ARDS, however, the results suggest that clinicians should feel as comfortable choosing a lower PEEP as they do choosing a higher PEEP," write Dr. Arthur Slutsky of St. Michael's Hospital, in Toronto, and colleagues.

"Ultimately, clinicians will need to decide what the results of this study mean for the care of patients receiving mechanical ventilation. A PEEP of 0 to 5 cm H2O is noninferior to a PEEP of 8 cm H2O with respect to ventilator-free days. However, given the concern about possible increased rates of hypoxemia and need for rescue strategies in the lower PEEP group, an intermediate option of 5 to 8 cm H2O that is consistent with the current PEEP management for many non-ARDS patients is likely reasonable and may be safer than a very low," the editorialists conclude.

SOURCE: http://bit.ly/2We3ti6 and http://bit.ly/2WkR9fK JAMA, online December 9, 2020.

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