On the complexity of scoring acute respiratory distress syndrome: do not forget hemodynamics!

Abstract

Acute respiratory distress syndrome (ARDS) remains associated with a poor outcome despite recent major therapeutic advances. Forecasting the outcome of patients suffering from such a syndrome is of a crucial interest and many scores have been proposed, all suffering from limits responsible for important discrepancies. Authors try to elaborate simple, routine and reliable scores but most of them do not consider hemodynamics yet acknowledged as a major determinant of outcome. This article aims at reminding the approach of scoring in ARDS and at deeply describing the most recently published one in order to highlight their main pitfall, which is to forget the hemodynamics.

The APPS: an outcome score for the acute respiratory distress syndrome

“…They described their model in 303 patients undergoing colectomy and validated the score in two independent cohorts of 102 and 767 surgical patients. Further reports by independent groups have confirmed the validity and generalization of this surgical Apgar-type score (13 (16) when discussing the value of the APPS in this issue of the journal. Tertile categorization detected useful information about the overall population that was not as evident when evaluating mean values of those variables.…”

Hypothesis: Fever control, a niche for alpha-2 agonists in the setting of septic shock and severe acute respiratory distress syndrome?

“…General anesthesia, paralysis and controlled mandatory ventilation are followed by reduced cardiac output. In turn, lowered cardiac output leads to lowered P/F [103,109]. Then iterative echocardiography, pre-emptive volume loading [166,167], vasopressors, inotropes, etc.…”

“…The 2018 approach combines analytic diagnosis with analytic therapeutics: fever control ((3) and present hypothesis); improved macro [81,103,109] and microcirculation [23,24] to handle circulatory shock, peripheral shut-down, systemic and local acidosis; controlled mandatory ventilation with paralysis and proning (or present hypothesis: spontaneous ventilation-high PEEP-low pressure support [111,155]) to lower the work of breathing and increase ventilatorto-patient synchrony; anti-infectious strategy, etc. Nevertheless, we surmise that this organ-targeted approach (heart, lung, kidney) should extend the analysis to other systems: 1) cognition: minimized cognitive dysfunction following alpha-2 agonists [44,219].…”

Early severe acute respiratory distress syndrome: What’s going on? Part I: pathophysiology

“…Thus, managing an oxygenation defect requires increasing the flow to the alveoli [24,42,43] together with an increase in the O 2 diffusion surface, to the alveolar recruitment [33]: to handle early severe ARDS, circulatory improvement comes first [24, 42−44]. Indeed, the oxygenation index P/F is affected by circulation [26]: a) a "low PvO 2 effect" decreases oxygenation and overestimates lung injury b) by contrast, a low cardiac output lowers the shunt, increases P/F and underestimates the lung injury [45] c) RV overload re-opens a foramen ovale and increases shunt [46].…”