ARDS is characterized by
hypoxemic respiratory failure, which can be refractory and life-threatening. Modifications to traditional
mechanical ventilation and nontraditional modes of ventilation are discussed in Part 1 of this two-part series. In this second article, we examine nonventilatory strategies that can influence oxygenation, with particular emphasis on their role in rescue from severe
hypoxemia. A literature search was conducted and a narrative review written to summarize the use of adjunctive, nonventilatory interventions intended to improve oxygenation in ARDS. Several adjunctive interventions have been demonstrated to rapidly ameliorate severe
hypoxemia in many patients with severe ARDS and therefore may be suitable as rescue
therapy for
hypoxemia that is refractory to prior optimization of
mechanical ventilation. These include neuromuscular blockade, inhaled vasoactive agents, prone positioning, and
extracorporeal life support. Although these interventions have been linked to physiologic improvement, including relief from severe
hypoxemia, and some are associated with outcome benefits, such as shorter duration of
mechanical ventilation, demonstration of survival benefit has been rare in clinical trials. Furthermore, some of these nonventilatory interventions carry additional risks and/or high cost; thus, when used as rescue
therapy for
hypoxemia, it is important that they be demonstrated to yield clinically significant improvement in gas exchange, which should be periodically reassessed. Additionally, various management strategies can produce a more gradual improvement in oxygenation in ARDS, such as conservative fluid management, intravenous
corticosteroids, and nutritional modification. Although improvement in oxygenation has been reported with such strategies, demonstration of additional beneficial outcomes, such as reduced duration of
mechanical ventilation or ICU
length of stay, or improved survival in randomized controlled trials, as well as consideration of potential adverse effects should guide decisions on their use. Various nonventilatory interventions can positively impact oxygenation as well as outcomes of ARDS. These interventions may be considered for use, particularly for cases of refractory severe
hypoxemia, with proper appreciation of potential costs and adverse effects.