Recognize severe hypoxemic respiratory failure when a patient with respiratory distress is failing standard oxygen therapy. Patients may continue to have increased work of breathing or hypoxemia (SpO2 <90%, PaO2 <60 mmHg [<8.0 kPa]) even when oxygen is delivered via a face mask with reservoir bag. Hypoxemic respiratory failure in ARDS commonly results from intrapulmonary ventilation-perfusion mismatch or shunt and usually requires mechanical ventilation.
In the absence of an indication for endotracheal intubation, a trial of high-flow nasal oxygen (HFNO), continuous positive airway pressure (CPAP) or other non-invasive ventilation (NIV) technique may be considered for adults with COVID-19 and acute hypoxaemic respiratory failure failing standard oxygen therapy.
Patients receiving HFNO, CPAP or other NIV should be in a closely monitored setting and cared for by experienced personnel capable of endotracheal intubation if the patient acutely deteriorates. Intubation should not be delayed in such circumstances.
In addition, NIV and possibly HFNO carry the risk of aerosolization of viral particles. Patients using HFNO or NIV should be nursed in a single patient room using airborne precautions.
The use of the prone position in non-intubated, conscious patients may be beneficial. This can be accomplished with minimal risk, and may offer a potential benefit in oxygenation.
Patients with hypoxaemic respiratory failure may require intubation and mechanical ventilatory support. Detailed recommendations on ventilation strategies are beyond the scope of this guideline. Always consult an intensivist if possible, or alternatively a practitioner experienced with mechanical ventilation. Nonetheless, the general principles to consider include:
Individualise ventilatory strategies based on respiratory mechanics and disease progression.
Use lung-protective ventilation strategies for patients with established ARDS who have low lung compliance.
Aim for an initial tidal volume of 4-6ml/kg. Higher tidal volume up to 8 ml/kg predicted body weight may be needed if minute ventilation requirements are not met in a patient with good lung compliance.
Strive to achieve the lowest plateau pressure possible. Plateau pressures above 30cm H20 are associated with an increased risk of pulmonary injury.
Hypercapnia is permitted if meeting the pH goal of >7.15-7.20.
Application of prone ventilation 12-16 hours a day is strongly recommended for patients with severe ARDS.
In patients with moderate or severe ARDS, identifying optimal PEEP levels will require titration of PEEP.
The use of deep sedation may be required to control respiratory drive, achieve tidal volume targets, and assist with patient-ventilator dyssynchrony.
In patients with moderate-severe ARDS (PaO2/FiO2 <200), neuromuscular blockade by continuous infusion should not be routinely used. Continuous neuromuscular blockade may still be considered in patients with ARDS in certain situations: ventilator dyssynchony despite sedation, such that tidal volume limitation cannot be reliably achieved; or refractory hypoxemia.
Avoid disconnecting the patient from the ventilator, which results in loss of PEEP and atelectasis. Use closed system catheters for airway suctioning and clamp endotracheal tube when disconnection is required (for example, transfer to a transport ventilator).
A high efficiency particulate filter on the expiratory limb of the ventilator circuit should be used.
Answers extracted from: Clinical management of suspected or confirmed COVID-19 disease (Version 4, May 2020)