Lung Recruitment in ARDS

Recently, two papers were published, one a trial and other one a meta analysis about lung recruitment in ARDS.

First study, published in JAMA, was a trial of lung recruitment and Titrated Positive End-Expiratory Pressure (PEEP) vs Low PEEP in ARDS(ART Investigators), published by Cavalcanti AB, Suzumura ÉA et el.

They compared total of 1010 patients of ARDS, to a lung recruitment maneuver and PEEP titration according to the best respiratory-system compliance (n = 501; experimental group) or a control strategy of low PEEP (n = 509). This was a multicenter, randomized trial conducted at 120 intensive care units (ICUs) from 9 countries.

They found that lung recruitment and titrated PEEP compared with low PEEP increased 28-day all-cause mortality. In the experimental group, There were decreased  number of mean ventilator-free days, increased the risk of pneumothorax requiring drainage  and the risk of barotrauma.

However, they used  a PEEP of 25 cm H2O for 1 minute, then a PEEP of 35 cm H2O for 1 minute, and then 45 cm H2O for 2 minutes. During the middle of the trial,  data monitoring committee,
decided to modify the recruitment maneuver and PEEP titration strategy after 3 cases of resuscitated cardiac arrest possibly associated with the experimental group treatment were observed. During the recruitment maneuver, PEEP was increased to 25 cm H2O, 30 cm H2O, and then 35 cm H2O, in steps of 1 minute.

Unfortunately they do not tell us before and after results, making this whole trial unreliable. 

The second paper is meta-analysis of lung recruitment trials published in Annals of American Thoracic Society by Goligher EC, Hodgson CL, Adhikari NKJ et el.

They included 6 trials totaling of 1423 patients Of ARDS who underwent lung rate recruitment maneuvers.These trials were published between 1998 and 2016. Five
of the six trials included a higher PEEP ventilation strategy as a co-intervention with LRMs. 3 Trials used CPAP @ 40 cm H2O for 40 s .  Two trials used Staircase
recruitment to Ppeak 55 cm H2O. Other used PCV 15 cm H2O, PEEP 35-45 cm H2O to achieve Ppeak of 50-60 cm H2O .  All of the trials enrolled moderate to severe ARDS patients (PaO2/FiO2 ≤ 200 mm Hg).

Meta-analysis of all six trials also suggested a significant mortality reduction (six trials; RR, 0.81; 95% CI, 0.69-0.95; evidence grade = moderate). LRMs were also associated with improved oxygenation after 24 hours (six trials; mean increase, 52 mm Hg; 95% CI, 23-81 mm Hg) and less frequent requirement for rescue therapy (three trials; RR, 0.65; 95% CI, 0.45-0.94). LRMs were not associated with an increased rate of barotrauma (four trials; RR, 0.84; 95% CI, 0.46-1.55). The rate of hemodynamic compromise was not significantly increased with LRMs (three trials; RR, 1.30; 95% CI, 0.92-1.78).

This meta-analysis is opposite to the above trial (ART INVESTIGATORS) published this year, therefore, muddying the water further. We need further large well controlled randomized trial to clear the confusion.

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