Use of APRV in TCAV protocol as a rescue ventilatory strategy in severe acute respiratory distress syndrome

Abstract

Introduction: Efforts to minimize VILI and reduce high mortality from severe ARDS are mainly aimed at strategies to protect and rest the lung or to open and keep it open, but since the publication of the 2000 ARMA´s study, the worldwide mortality of patients with severe ARDS has remained unchanged at around 40%. Official data from the Brazilian Ministry of Health indicate that during the Covid-19 pandemic, about 80% of adults who were intubated and mechanically ventilated in Brazil died. In this scenario, where a "tsunami" of patients with severe ARDS has arrived in ICUs worldwide, it is important to better understand how the APRV-TCAV protocol can be clinically useful in the scenario of rescue from hypoxemia caused by severe ARDS, contributing to reduce the microanatomical pulmonary lesion or even avoiding VILI, improving recruitment, alveolar stability and oxygenation, thus seeking to obtain a decisive impact on the reduction of this mortality. Methods: This study analyzed the effects of TCAV method of setting APRV mode in 52 patients with severe ARDS as a strategy to rescue severe refractory hypoxemia in patients classified as "not-recruitable" by the assessment of recruitability (R/I ratio <0.5). Results: In this case series, the use of APRV in a TCAV protocol improved oxygenation, ventilatory mechanics and hemodynamics, increased the PaO2/FiO2 ratio, reduced D(A-a)O2, FiO2, lactate and increased PaCO2, without clinical repercussions. Driving pressure and plateau pressure reduced too. No serious adverse events occurred during the use of APRV in the TCAV protocol. Discussion: The results of this case series corroborate convincing evidence that the use of APRV in a TCAV protocol promotes significant improvements in several experimental models of ARDS and also in patients with severe ARDS. Conclusion: APRV in a TCAV protocol proved to be a clinically viable and effective alternative as a rescue intervention in cases of severe refractory hypoxemia and ECMO´s unavailability or other rescue strategies for advanced life support.