Management of acute respiratory distress syndrome

ARDS: acute respiratory distress syndrome; COPD: chronic obstructive pulmonary disease; ECMO: extracorporeal membrane oxygenation; ETT: endotracheal tube; FiO₂: fraction of inspired oxygen; LTVV: low tidal volume ventilation; OLV: open lung ventilation; PaCO₂: arterial carbon dioxide tension; PaO₂: arterial oxygen tension; PBW: predicted body weight; PEEP: positive end-expiratory pressure; Vt: tidal volume.

* Most patients respond to lung protective ventilation. For details regarding initial ventilator settings and ARDSNet strategy, refer to UpToDate content.

¶ In some cases, failure to respond to LTVV may be due to under-treatment of underlying etiologies or comorbidities (eg, more aggressive bronchodilation and glucocorticoid therapy in COPD patients, large volume paracentesis in patients with massive ascites, or thoracentesis in patients with compressive effusions).

Δ Abrupt increases in the airway pressure in a patient receiving volume-limited ventilation or decrease in Vt in a patient receiving pressure-limited ventilation should prompt an immediate search for a cause of an acute change in compliance or resistance (eg, pneumothorax or an obstructed endotracheal tube). Refer to UpToDate topic on respiratory distress in the mechanically ventilated patient.

◊ For patients not tolerating volume-limited LTVV, alternative modes of mechanical ventilation are sometimes attempted at bedside. These include pressure-limited modes, airway pressure release ventilation, or volume-targeted pressure-controlled ventilation. Short trials (hours) are typically performed with close observation of ventilator waveforms, airway pressures, Vt, and gas exchange.

§ Absolute contraindications to prone ventilation include spinal instability, patients at risk of spinal instability, unstable fractures (especially facial and pelvic), anterior burns or open wounds, unstable shock, recent tracheal surgery, and raised intracranial pressure. Relative contraindications include hemodynamic instability due to life-threatening arrhythmias, chest tubes with air leaks, cardiac abnormalities (eg, freshly placed pacemaker, life-threatening arrhythmias, ventricular assist devices, balloon pumps), recent thoracic and abdominal surgeries, difficult airway or intubation, and massive or uncontrolled hemoptysis, although successful pronation has been described in some of these situations.

¥ Contraindications may exist for prone positioning, in which case ECMO may need to be considered earlier in the patient's course. Among the interventions for patients with refractory ARDS, data suggest that only prone positioning and ECMO have a mortality benefit.

‡ These treatments are not routine and are not necessarily taken into consideration for ECMO candidacy nor should they delay ECMO evaluation. Most of these treatments should demonstrate effectiveness quickly (eg, minutes [recruitment, high PEEP] to hours [pulmonary vasodilators]) so that if they fail to improve gas exchange promptly, alternate options can be attempted before it is too late.

† There are few absolute contraindications except for a pre-existing condition that is either incompatible with recovery or has no potential for a long-term life-saving therapy. Relative contraindications include uncontrollable bleeding, advanced comorbid conditions that limit recovery, severe immunocompromised status, limited vascular access, or more than 7 days of mechanical ventilation.

** There are no accepted targets, and the parameters listed in the table are suggested parameters only. For example, some experts may allow permissive hypercapnia (eg, pH <7.25, PaCO₂ >60 mmHg) or a PaO₂:FiO₂ ratio <150 mmHg especially if other parameters are improving.

¶¶ High plateau pressures are less worrisome when due to extrapulmonary compression, such as obesity, and may not warrant intervention.