Treatment algorithm
Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer
oxygen and ventilation
Although the original low tidal volume trial by the ARDS Network targeted an oxygen saturation between 88% and 95%, two subsequent clinical trials suggest that higher oxygenation targets may be associated with better clinical outcomes.[59][61] Based on the findings of these studies, it seems prudent to target an oxygen saturation of ≥92%.[62]
With the increasing availability of high flow nasal oxygen (HFNO), the number of patients with ARDS who can be managed with either HFNO or non-invasive ventilation has increased. However, the failure rate is high and many patients with ARDS will require endotracheal intubation and mechanical ventilation.[63] The American Thoracic Society (ATS) provides guidance on how to facilitate communication with mechanically ventilated patients as a key component of symptom assessment.[64]
Ventilator-associated lung injury may be limited by the use of a low tidal volume, plateau-pressure-limited protective ventilatory strategy. This therapy has been shown to reduce mortality.[65][66][67][68]
A tidal volume of 4-8 mL/kg predicted body weight should be used to maintain an inspiratory plateau pressure <30 cm H₂O with an initial setting of 6 mL/kg.[69] Predicted body weight for men is calculated as 50 + 0.91 × (height [cm] - 152.4), and for women is 45.5 + 0.91 × (height [cm] - 152.4).[65] If the plateau pressure is >30 cm H₂O, then tidal volume should be lowered to 5 mL/kg or as low as 4 mL/kg, if needed.
Positive end-expiratory pressure (PEEP) and FiO₂ should be titrated using established PEEP titration tables.[65][70] The available data suggest that higher levels of PEEP are safe and may improve oxygenation in some patients.[69][71][72] In a meta-analysis of available trials, there was no overall reduction in mortality with higher PEEP.[73] An earlier meta-analysis suggested that higher PEEP reduces mortality in patients who respond with improved oxygenation.[74]
Respiratory acidosis, a common complication of low tidal volume ventilation, is treated by increasing the respiratory rate. Although it is not known what level of respiratory acidosis is harmful in patients with ARDS, permissive hypercapnia is often tolerated due to low tidal volume ventilation. However, severe hypercapnia is independently associated with higher intensive care unit mortality.[79] Normocapnia often cannot be achieved (and should not be a goal). Clinical guidelines recommend that an arterial pH of 7.30 to 7.45 is maintained, but studies suggest patients who undergo permissive hypercapnia can tolerate a blood pH as low as 7.15. Bicarbonate infusions may be administered when the pH falls below 7.15.
How to insert a tracheal tube in an adult using a laryngoscope.
How to use bag-valve-mask apparatus to deliver ventilatory support to adults. Video demonstrates the two-person technique.
Selected patients with COVID-19 and mild ARDS can be considered for a trial of high-flow nasal oxygen or non-invasive ventilation. Endotracheal intubation should be not delayed if there is no improvement after a short trial (1 hour).[128]
See our topic Coronavirus disease 2019 (COVID-19) for more information on the management of COVID-19.
rescue therapies
Additional treatment recommended for SOME patients in selected patient group
In patients with refractory hypoxaemia despite a fraction of inspired oxygen (FiO₂) of 1.0 and high levels of positive end-expiratory pressure (PEEP), rescue therapies for oxygenation should be considered.[62]
Neuromuscular paralysis improves ventilator-patient synchrony and often improves oxygenation. Intermittent doses of paralytics can be used as effectively as a continuous intravenous infusion. If a patient is on a continuous intravenous infusion of a paralytic, train-of-four monitoring should be used to monitor the muscle fibre twitch response to the drug. Given findings from randomised controlled trials, neuromuscular blockade should be reserved for patients with severe ARDS and refractory hypoxaemia despite low tidal volume ventilation and adequate sedation, particularly if there is still evidence of ventilator-patient dyssynchrony.[62][112][113] The ATS suggests using neuromuscular blockers in patients with early severe ARDS.[69]
Inhaled nitric oxide can improve oxygenation in patients with ARDS, but does not improve mortality and has been associated with acute kidney injury.[114][115][116]
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Thus, it should be used only as a rescue therapy for refractory hypoxaemia.[62] Inhaled prostacyclin is easier to administer than inhaled nitric oxide, and also has the potential to improve oxygenation in ARDS through better ventilation perfusion matching. However, there are currently no published large randomised controlled trials of inhaled prostacyclin; thus, it should be used cautiously and only as a rescue therapy.[117]
Where available, extracorporeal membrane oxygenation (ECMO) should be considered (in conjunction with low tidal volume mechanical ventilation) in select patients with severe ARDS in whom standard therapies are failing (i.e., patients with profound refractory hypoxaemia).[69][118] One multi-centre trial showed that patients with severe ARDS randomised to transfer to a tertiary care center for consideration of ECMO (75% [n=68] of whom actually received ECMO) were more likely to survive to 6 months without disability than patients randomised to continued conventional management (RR 0.69, 95% CI 0.05 to 0.97, P=0.03).[119] One subsequent randomised multi-centre trial (n=249) did not demonstrate significantly lower 60-day mortality in the ECMO treatment group compared with standard care (35% vs. 46%, respectively; P=0.09); however, one meta-analysis pooling data from both trials reported significantly lower 60-day mortality in the venovenous ECMO group compared with the control group (RR 0.73, 95% CI 0.58 to 0.92, P=0.008) despite a moderate risk of major bleeding in the ECMO group.[120][121] An additional meta-analysis that included trials in critically ill patients with indications other than ARDS found that ECMO was associated with a reduction in day‐90 to one‐year all‐cause mortality, along with a threefold increased risk of bleeding.[122]
Routine use of high-frequency oscillatory ventilation (HFOV) in moderate-to-severe ARDS is not beneficial, and may be harmful.[123][124][125][126][127]
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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer
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